Update godep to support boltdb backend

Signed-off-by: Chun Chen <ramichen@tencent.com>
This commit is contained in:
Chun Chen 2015-09-16 19:37:47 +08:00
parent a561351a12
commit 56e3c1e9d5
40 changed files with 11175 additions and 0 deletions

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@ -167,6 +167,11 @@
{
"ImportPath": "github.com/vishvananda/netns",
"Rev": "493029407eeb434d0c2d44e02ea072ff2488d322"
},
{
"ImportPath": "github.com/boltdb/bolt",
"Comment": "v1.0-117-g0f053fa",
"Rev": "0f053fabc06119583d61937a0a06ef0ba0f1b301"
}
]
}

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*.prof
*.test
*.swp
/bin/

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The MIT License (MIT)
Copyright (c) 2013 Ben Johnson
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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TEST=.
BENCH=.
COVERPROFILE=/tmp/c.out
BRANCH=`git rev-parse --abbrev-ref HEAD`
COMMIT=`git rev-parse --short HEAD`
GOLDFLAGS="-X main.branch $(BRANCH) -X main.commit $(COMMIT)"
default: build
bench:
go test -v -test.run=NOTHINCONTAINSTHIS -test.bench=$(BENCH)
# http://cloc.sourceforge.net/
cloc:
@cloc --not-match-f='Makefile|_test.go' .
cover: fmt
go test -coverprofile=$(COVERPROFILE) -test.run=$(TEST) $(COVERFLAG) .
go tool cover -html=$(COVERPROFILE)
rm $(COVERPROFILE)
cpuprofile: fmt
@go test -c
@./bolt.test -test.v -test.run=$(TEST) -test.cpuprofile cpu.prof
# go get github.com/kisielk/errcheck
errcheck:
@echo "=== errcheck ==="
@errcheck github.com/boltdb/bolt
fmt:
@go fmt ./...
get:
@go get -d ./...
build: get
@mkdir -p bin
@go build -ldflags=$(GOLDFLAGS) -a -o bin/bolt ./cmd/bolt
test: fmt
@go get github.com/stretchr/testify/assert
@echo "=== TESTS ==="
@go test -v -cover -test.run=$(TEST)
@echo ""
@echo ""
@echo "=== CLI ==="
@go test -v -test.run=$(TEST) ./cmd/bolt
@echo ""
@echo ""
@echo "=== RACE DETECTOR ==="
@go test -v -race -test.run="TestSimulate_(100op|1000op)"
.PHONY: bench cloc cover cpuprofile fmt memprofile test

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Bolt [![Build Status](https://drone.io/github.com/boltdb/bolt/status.png)](https://drone.io/github.com/boltdb/bolt/latest) [![Coverage Status](https://coveralls.io/repos/boltdb/bolt/badge.png?branch=master)](https://coveralls.io/r/boltdb/bolt?branch=master) [![GoDoc](https://godoc.org/github.com/boltdb/bolt?status.png)](https://godoc.org/github.com/boltdb/bolt) ![Version](http://img.shields.io/badge/version-1.0-green.png)
====
Bolt is a pure Go key/value store inspired by [Howard Chu's][hyc_symas] and
the [LMDB project][lmdb]. The goal of the project is to provide a simple,
fast, and reliable database for projects that don't require a full database
server such as Postgres or MySQL.
Since Bolt is meant to be used as such a low-level piece of functionality,
simplicity is key. The API will be small and only focus on getting values
and setting values. That's it.
[hyc_symas]: https://twitter.com/hyc_symas
[lmdb]: http://symas.com/mdb/
## Project Status
Bolt is stable and the API is fixed. Full unit test coverage and randomized
black box testing are used to ensure database consistency and thread safety.
Bolt is currently in high-load production environments serving databases as
large as 1TB. Many companies such as Shopify and Heroku use Bolt-backed
services every day.
## Getting Started
### Installing
To start using Bolt, install Go and run `go get`:
```sh
$ go get github.com/boltdb/bolt/...
```
This will retrieve the library and install the `bolt` command line utility into
your `$GOBIN` path.
### Opening a database
The top-level object in Bolt is a `DB`. It is represented as a single file on
your disk and represents a consistent snapshot of your data.
To open your database, simply use the `bolt.Open()` function:
```go
package main
import (
"log"
"github.com/boltdb/bolt"
)
func main() {
// Open the my.db data file in your current directory.
// It will be created if it doesn't exist.
db, err := bolt.Open("my.db", 0600, nil)
if err != nil {
log.Fatal(err)
}
defer db.Close()
...
}
```
Please note that Bolt obtains a file lock on the data file so multiple processes
cannot open the same database at the same time. Opening an already open Bolt
database will cause it to hang until the other process closes it. To prevent
an indefinite wait you can pass a timeout option to the `Open()` function:
```go
db, err := bolt.Open("my.db", 0600, &bolt.Options{Timeout: 1 * time.Second})
```
### Transactions
Bolt allows only one read-write transaction at a time but allows as many
read-only transactions as you want at a time. Each transaction has a consistent
view of the data as it existed when the transaction started.
Individual transactions and all objects created from them (e.g. buckets, keys)
are not thread safe. To work with data in multiple goroutines you must start
a transaction for each one or use locking to ensure only one goroutine accesses
a transaction at a time. Creating transaction from the `DB` is thread safe.
Read-only transactions and read-write transactions should not depend on one
another and generally shouldn't be opened simultaneously in the same goroutine.
This can cause a deadlock as the read-write transaction needs to periodically
re-map the data file but it cannot do so while a read-only transaction is open.
#### Read-write transactions
To start a read-write transaction, you can use the `DB.Update()` function:
```go
err := db.Update(func(tx *bolt.Tx) error {
...
return nil
})
```
Inside the closure, you have a consistent view of the database. You commit the
transaction by returning `nil` at the end. You can also rollback the transaction
at any point by returning an error. All database operations are allowed inside
a read-write transaction.
Always check the return error as it will report any disk failures that can cause
your transaction to not complete. If you return an error within your closure
it will be passed through.
#### Read-only transactions
To start a read-only transaction, you can use the `DB.View()` function:
```go
err := db.View(func(tx *bolt.Tx) error {
...
return nil
})
```
You also get a consistent view of the database within this closure, however,
no mutating operations are allowed within a read-only transaction. You can only
retrieve buckets, retrieve values, and copy the database within a read-only
transaction.
#### Batch read-write transactions
Each `DB.Update()` waits for disk to commit the writes. This overhead
can be minimized by combining multiple updates with the `DB.Batch()`
function:
```go
err := db.Batch(func(tx *bolt.Tx) error {
...
return nil
})
```
Concurrent Batch calls are opportunistically combined into larger
transactions. Batch is only useful when there are multiple goroutines
calling it.
The trade-off is that `Batch` can call the given
function multiple times, if parts of the transaction fail. The
function must be idempotent and side effects must take effect only
after a successful return from `DB.Batch()`.
For example: don't display messages from inside the function, instead
set variables in the enclosing scope:
```go
var id uint64
err := db.Batch(func(tx *bolt.Tx) error {
// Find last key in bucket, decode as bigendian uint64, increment
// by one, encode back to []byte, and add new key.
...
id = newValue
return nil
})
if err != nil {
return ...
}
fmt.Println("Allocated ID %d", id)
```
#### Managing transactions manually
The `DB.View()` and `DB.Update()` functions are wrappers around the `DB.Begin()`
function. These helper functions will start the transaction, execute a function,
and then safely close your transaction if an error is returned. This is the
recommended way to use Bolt transactions.
However, sometimes you may want to manually start and end your transactions.
You can use the `Tx.Begin()` function directly but _please_ be sure to close the
transaction.
```go
// Start a writable transaction.
tx, err := db.Begin(true)
if err != nil {
return err
}
defer tx.Rollback()
// Use the transaction...
_, err := tx.CreateBucket([]byte("MyBucket"))
if err != nil {
return err
}
// Commit the transaction and check for error.
if err := tx.Commit(); err != nil {
return err
}
```
The first argument to `DB.Begin()` is a boolean stating if the transaction
should be writable.
### Using buckets
Buckets are collections of key/value pairs within the database. All keys in a
bucket must be unique. You can create a bucket using the `DB.CreateBucket()`
function:
```go
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("MyBucket"))
if err != nil {
return fmt.Errorf("create bucket: %s", err)
}
return nil
})
```
You can also create a bucket only if it doesn't exist by using the
`Tx.CreateBucketIfNotExists()` function. It's a common pattern to call this
function for all your top-level buckets after you open your database so you can
guarantee that they exist for future transactions.
To delete a bucket, simply call the `Tx.DeleteBucket()` function.
### Using key/value pairs
To save a key/value pair to a bucket, use the `Bucket.Put()` function:
```go
db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("MyBucket"))
err := b.Put([]byte("answer"), []byte("42"))
return err
})
```
This will set the value of the `"answer"` key to `"42"` in the `MyBucket`
bucket. To retrieve this value, we can use the `Bucket.Get()` function:
```go
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("MyBucket"))
v := b.Get([]byte("answer"))
fmt.Printf("The answer is: %s\n", v)
return nil
})
```
The `Get()` function does not return an error because its operation is
guarenteed to work (unless there is some kind of system failure). If the key
exists then it will return its byte slice value. If it doesn't exist then it
will return `nil`. It's important to note that you can have a zero-length value
set to a key which is different than the key not existing.
Use the `Bucket.Delete()` function to delete a key from the bucket.
Please note that values returned from `Get()` are only valid while the
transaction is open. If you need to use a value outside of the transaction
then you must use `copy()` to copy it to another byte slice.
### Iterating over keys
Bolt stores its keys in byte-sorted order within a bucket. This makes sequential
iteration over these keys extremely fast. To iterate over keys we'll use a
`Cursor`:
```go
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("MyBucket"))
c := b.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("key=%s, value=%s\n", k, v)
}
return nil
})
```
The cursor allows you to move to a specific point in the list of keys and move
forward or backward through the keys one at a time.
The following functions are available on the cursor:
```
First() Move to the first key.
Last() Move to the last key.
Seek() Move to a specific key.
Next() Move to the next key.
Prev() Move to the previous key.
```
When you have iterated to the end of the cursor then `Next()` will return `nil`.
You must seek to a position using `First()`, `Last()`, or `Seek()` before
calling `Next()` or `Prev()`. If you do not seek to a position then these
functions will return `nil`.
#### Prefix scans
To iterate over a key prefix, you can combine `Seek()` and `bytes.HasPrefix()`:
```go
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("MyBucket")).Cursor()
prefix := []byte("1234")
for k, v := c.Seek(prefix); bytes.HasPrefix(k, prefix); k, v = c.Next() {
fmt.Printf("key=%s, value=%s\n", k, v)
}
return nil
})
```
#### Range scans
Another common use case is scanning over a range such as a time range. If you
use a sortable time encoding such as RFC3339 then you can query a specific
date range like this:
```go
db.View(func(tx *bolt.Tx) error {
// Assume our events bucket has RFC3339 encoded time keys.
c := tx.Bucket([]byte("Events")).Cursor()
// Our time range spans the 90's decade.
min := []byte("1990-01-01T00:00:00Z")
max := []byte("2000-01-01T00:00:00Z")
// Iterate over the 90's.
for k, v := c.Seek(min); k != nil && bytes.Compare(k, max) <= 0; k, v = c.Next() {
fmt.Printf("%s: %s\n", k, v)
}
return nil
})
```
#### ForEach()
You can also use the function `ForEach()` if you know you'll be iterating over
all the keys in a bucket:
```go
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("MyBucket"))
b.ForEach(func(k, v []byte) error {
fmt.Printf("key=%s, value=%s\n", k, v)
return nil
})
return nil
})
```
### Nested buckets
You can also store a bucket in a key to create nested buckets. The API is the
same as the bucket management API on the `DB` object:
```go
func (*Bucket) CreateBucket(key []byte) (*Bucket, error)
func (*Bucket) CreateBucketIfNotExists(key []byte) (*Bucket, error)
func (*Bucket) DeleteBucket(key []byte) error
```
### Database backups
Bolt is a single file so it's easy to backup. You can use the `Tx.WriteTo()`
function to write a consistent view of the database to a writer. If you call
this from a read-only transaction, it will perform a hot backup and not block
your other database reads and writes. It will also use `O_DIRECT` when available
to prevent page cache trashing.
One common use case is to backup over HTTP so you can use tools like `cURL` to
do database backups:
```go
func BackupHandleFunc(w http.ResponseWriter, req *http.Request) {
err := db.View(func(tx *bolt.Tx) error {
w.Header().Set("Content-Type", "application/octet-stream")
w.Header().Set("Content-Disposition", `attachment; filename="my.db"`)
w.Header().Set("Content-Length", strconv.Itoa(int(tx.Size())))
_, err := tx.WriteTo(w)
return err
})
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
```
Then you can backup using this command:
```sh
$ curl http://localhost/backup > my.db
```
Or you can open your browser to `http://localhost/backup` and it will download
automatically.
If you want to backup to another file you can use the `Tx.CopyFile()` helper
function.
### Statistics
The database keeps a running count of many of the internal operations it
performs so you can better understand what's going on. By grabbing a snapshot
of these stats at two points in time we can see what operations were performed
in that time range.
For example, we could start a goroutine to log stats every 10 seconds:
```go
go func() {
// Grab the initial stats.
prev := db.Stats()
for {
// Wait for 10s.
time.Sleep(10 * time.Second)
// Grab the current stats and diff them.
stats := db.Stats()
diff := stats.Sub(&prev)
// Encode stats to JSON and print to STDERR.
json.NewEncoder(os.Stderr).Encode(diff)
// Save stats for the next loop.
prev = stats
}
}()
```
It's also useful to pipe these stats to a service such as statsd for monitoring
or to provide an HTTP endpoint that will perform a fixed-length sample.
### Read-Only Mode
Sometimes it is useful to create a shared, read-only Bolt database. To this,
set the `Options.ReadOnly` flag when opening your database. Read-only mode
uses a shared lock to allow multiple processes to read from the database but
it will block any processes from opening the database in read-write mode.
```go
db, err := bolt.Open("my.db", 0666, &bolt.Options{ReadOnly: true})
if err != nil {
log.Fatal(err)
}
```
## Resources
For more information on getting started with Bolt, check out the following articles:
* [Intro to BoltDB: Painless Performant Persistence](http://npf.io/2014/07/intro-to-boltdb-painless-performant-persistence/) by [Nate Finch](https://github.com/natefinch).
* [Bolt -- an embedded key/value database for Go](https://www.progville.com/go/bolt-embedded-db-golang/) by Progville
## Comparison with other databases
### Postgres, MySQL, & other relational databases
Relational databases structure data into rows and are only accessible through
the use of SQL. This approach provides flexibility in how you store and query
your data but also incurs overhead in parsing and planning SQL statements. Bolt
accesses all data by a byte slice key. This makes Bolt fast to read and write
data by key but provides no built-in support for joining values together.
Most relational databases (with the exception of SQLite) are standalone servers
that run separately from your application. This gives your systems
flexibility to connect multiple application servers to a single database
server but also adds overhead in serializing and transporting data over the
network. Bolt runs as a library included in your application so all data access
has to go through your application's process. This brings data closer to your
application but limits multi-process access to the data.
### LevelDB, RocksDB
LevelDB and its derivatives (RocksDB, HyperLevelDB) are similar to Bolt in that
they are libraries bundled into the application, however, their underlying
structure is a log-structured merge-tree (LSM tree). An LSM tree optimizes
random writes by using a write ahead log and multi-tiered, sorted files called
SSTables. Bolt uses a B+tree internally and only a single file. Both approaches
have trade offs.
If you require a high random write throughput (>10,000 w/sec) or you need to use
spinning disks then LevelDB could be a good choice. If your application is
read-heavy or does a lot of range scans then Bolt could be a good choice.
One other important consideration is that LevelDB does not have transactions.
It supports batch writing of key/values pairs and it supports read snapshots
but it will not give you the ability to do a compare-and-swap operation safely.
Bolt supports fully serializable ACID transactions.
### LMDB
Bolt was originally a port of LMDB so it is architecturally similar. Both use
a B+tree, have ACID semantics with fully serializable transactions, and support
lock-free MVCC using a single writer and multiple readers.
The two projects have somewhat diverged. LMDB heavily focuses on raw performance
while Bolt has focused on simplicity and ease of use. For example, LMDB allows
several unsafe actions such as direct writes for the sake of performance. Bolt
opts to disallow actions which can leave the database in a corrupted state. The
only exception to this in Bolt is `DB.NoSync`.
There are also a few differences in API. LMDB requires a maximum mmap size when
opening an `mdb_env` whereas Bolt will handle incremental mmap resizing
automatically. LMDB overloads the getter and setter functions with multiple
flags whereas Bolt splits these specialized cases into their own functions.
## Caveats & Limitations
It's important to pick the right tool for the job and Bolt is no exception.
Here are a few things to note when evaluating and using Bolt:
* Bolt is good for read intensive workloads. Sequential write performance is
also fast but random writes can be slow. You can add a write-ahead log or
[transaction coalescer](https://github.com/boltdb/coalescer) in front of Bolt
to mitigate this issue.
* Bolt uses a B+tree internally so there can be a lot of random page access.
SSDs provide a significant performance boost over spinning disks.
* Try to avoid long running read transactions. Bolt uses copy-on-write so
old pages cannot be reclaimed while an old transaction is using them.
* Byte slices returned from Bolt are only valid during a transaction. Once the
transaction has been committed or rolled back then the memory they point to
can be reused by a new page or can be unmapped from virtual memory and you'll
see an `unexpected fault address` panic when accessing it.
* Be careful when using `Bucket.FillPercent`. Setting a high fill percent for
buckets that have random inserts will cause your database to have very poor
page utilization.
* Use larger buckets in general. Smaller buckets causes poor page utilization
once they become larger than the page size (typically 4KB).
* Bulk loading a lot of random writes into a new bucket can be slow as the
page will not split until the transaction is committed. Randomly inserting
more than 100,000 key/value pairs into a single new bucket in a single
transaction is not advised.
* Bolt uses a memory-mapped file so the underlying operating system handles the
caching of the data. Typically, the OS will cache as much of the file as it
can in memory and will release memory as needed to other processes. This means
that Bolt can show very high memory usage when working with large databases.
However, this is expected and the OS will release memory as needed. Bolt can
handle databases much larger than the available physical RAM.
* The data structures in the Bolt database are memory mapped so the data file
will be endian specific. This means that you cannot copy a Bolt file from a
little endian machine to a big endian machine and have it work. For most
users this is not a concern since most modern CPUs are little endian.
* Because of the way pages are laid out on disk, Bolt cannot truncate data files
and return free pages back to the disk. Instead, Bolt maintains a free list
of unused pages within its data file. These free pages can be reused by later
transactions. This works well for many use cases as databases generally tend
to grow. However, it's important to note that deleting large chunks of data
will not allow you to reclaim that space on disk.
For more information on page allocation, [see this comment][page-allocation].
[page-allocation]: https://github.com/boltdb/bolt/issues/308#issuecomment-74811638
## Other Projects Using Bolt
Below is a list of public, open source projects that use Bolt:
* [Operation Go: A Routine Mission](http://gocode.io) - An online programming game for Golang using Bolt for user accounts and a leaderboard.
* [Bazil](https://bazil.org/) - A file system that lets your data reside where it is most convenient for it to reside.
* [DVID](https://github.com/janelia-flyem/dvid) - Added Bolt as optional storage engine and testing it against Basho-tuned leveldb.
* [Skybox Analytics](https://github.com/skybox/skybox) - A standalone funnel analysis tool for web analytics.
* [Scuttlebutt](https://github.com/benbjohnson/scuttlebutt) - Uses Bolt to store and process all Twitter mentions of GitHub projects.
* [Wiki](https://github.com/peterhellberg/wiki) - A tiny wiki using Goji, BoltDB and Blackfriday.
* [ChainStore](https://github.com/nulayer/chainstore) - Simple key-value interface to a variety of storage engines organized as a chain of operations.
* [MetricBase](https://github.com/msiebuhr/MetricBase) - Single-binary version of Graphite.
* [Gitchain](https://github.com/gitchain/gitchain) - Decentralized, peer-to-peer Git repositories aka "Git meets Bitcoin".
* [event-shuttle](https://github.com/sclasen/event-shuttle) - A Unix system service to collect and reliably deliver messages to Kafka.
* [ipxed](https://github.com/kelseyhightower/ipxed) - Web interface and api for ipxed.
* [BoltStore](https://github.com/yosssi/boltstore) - Session store using Bolt.
* [photosite/session](http://godoc.org/bitbucket.org/kardianos/photosite/session) - Sessions for a photo viewing site.
* [LedisDB](https://github.com/siddontang/ledisdb) - A high performance NoSQL, using Bolt as optional storage.
* [ipLocator](https://github.com/AndreasBriese/ipLocator) - A fast ip-geo-location-server using bolt with bloom filters.
* [cayley](https://github.com/google/cayley) - Cayley is an open-source graph database using Bolt as optional backend.
* [bleve](http://www.blevesearch.com/) - A pure Go search engine similar to ElasticSearch that uses Bolt as the default storage backend.
* [tentacool](https://github.com/optiflows/tentacool) - REST api server to manage system stuff (IP, DNS, Gateway...) on a linux server.
* [SkyDB](https://github.com/skydb/sky) - Behavioral analytics database.
* [Seaweed File System](https://github.com/chrislusf/weed-fs) - Highly scalable distributed key~file system with O(1) disk read.
* [InfluxDB](http://influxdb.com) - Scalable datastore for metrics, events, and real-time analytics.
* [Freehold](http://tshannon.bitbucket.org/freehold/) - An open, secure, and lightweight platform for your files and data.
* [Prometheus Annotation Server](https://github.com/oliver006/prom_annotation_server) - Annotation server for PromDash & Prometheus service monitoring system.
* [Consul](https://github.com/hashicorp/consul) - Consul is service discovery and configuration made easy. Distributed, highly available, and datacenter-aware.
* [Kala](https://github.com/ajvb/kala) - Kala is a modern job scheduler optimized to run on a single node. It is persistant, JSON over HTTP API, ISO 8601 duration notation, and dependent jobs.
* [drive](https://github.com/odeke-em/drive) - drive is an unofficial Google Drive command line client for \*NIX operating systems.
If you are using Bolt in a project please send a pull request to add it to the list.

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package bolt
import (
"errors"
"fmt"
"sync"
"time"
)
// Batch calls fn as part of a batch. It behaves similar to Update,
// except:
//
// 1. concurrent Batch calls can be combined into a single Bolt
// transaction.
//
// 2. the function passed to Batch may be called multiple times,
// regardless of whether it returns error or not.
//
// This means that Batch function side effects must be idempotent and
// take permanent effect only after a successful return is seen in
// caller.
//
// The maximum batch size and delay can be adjusted with DB.MaxBatchSize
// and DB.MaxBatchDelay, respectively.
//
// Batch is only useful when there are multiple goroutines calling it.
func (db *DB) Batch(fn func(*Tx) error) error {
errCh := make(chan error, 1)
db.batchMu.Lock()
if (db.batch == nil) || (db.batch != nil && len(db.batch.calls) >= db.MaxBatchSize) {
// There is no existing batch, or the existing batch is full; start a new one.
db.batch = &batch{
db: db,
}
db.batch.timer = time.AfterFunc(db.MaxBatchDelay, db.batch.trigger)
}
db.batch.calls = append(db.batch.calls, call{fn: fn, err: errCh})
if len(db.batch.calls) >= db.MaxBatchSize {
// wake up batch, it's ready to run
go db.batch.trigger()
}
db.batchMu.Unlock()
err := <-errCh
if err == trySolo {
err = db.Update(fn)
}
return err
}
type call struct {
fn func(*Tx) error
err chan<- error
}
type batch struct {
db *DB
timer *time.Timer
start sync.Once
calls []call
}
// trigger runs the batch if it hasn't already been run.
func (b *batch) trigger() {
b.start.Do(b.run)
}
// run performs the transactions in the batch and communicates results
// back to DB.Batch.
func (b *batch) run() {
b.db.batchMu.Lock()
b.timer.Stop()
// Make sure no new work is added to this batch, but don't break
// other batches.
if b.db.batch == b {
b.db.batch = nil
}
b.db.batchMu.Unlock()
retry:
for len(b.calls) > 0 {
var failIdx = -1
err := b.db.Update(func(tx *Tx) error {
for i, c := range b.calls {
if err := safelyCall(c.fn, tx); err != nil {
failIdx = i
return err
}
}
return nil
})
if failIdx >= 0 {
// take the failing transaction out of the batch. it's
// safe to shorten b.calls here because db.batch no longer
// points to us, and we hold the mutex anyway.
c := b.calls[failIdx]
b.calls[failIdx], b.calls = b.calls[len(b.calls)-1], b.calls[:len(b.calls)-1]
// tell the submitter re-run it solo, continue with the rest of the batch
c.err <- trySolo
continue retry
}
// pass success, or bolt internal errors, to all callers
for _, c := range b.calls {
if c.err != nil {
c.err <- err
}
}
break retry
}
}
// trySolo is a special sentinel error value used for signaling that a
// transaction function should be re-run. It should never be seen by
// callers.
var trySolo = errors.New("batch function returned an error and should be re-run solo")
type panicked struct {
reason interface{}
}
func (p panicked) Error() string {
if err, ok := p.reason.(error); ok {
return err.Error()
}
return fmt.Sprintf("panic: %v", p.reason)
}
func safelyCall(fn func(*Tx) error, tx *Tx) (err error) {
defer func() {
if p := recover(); p != nil {
err = panicked{p}
}
}()
return fn(tx)
}

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package bolt_test
import (
"bytes"
"encoding/binary"
"errors"
"hash/fnv"
"sync"
"testing"
"github.com/boltdb/bolt"
)
func validateBatchBench(b *testing.B, db *TestDB) {
var rollback = errors.New("sentinel error to cause rollback")
validate := func(tx *bolt.Tx) error {
bucket := tx.Bucket([]byte("bench"))
h := fnv.New32a()
buf := make([]byte, 4)
for id := uint32(0); id < 1000; id++ {
binary.LittleEndian.PutUint32(buf, id)
h.Reset()
h.Write(buf[:])
k := h.Sum(nil)
v := bucket.Get(k)
if v == nil {
b.Errorf("not found id=%d key=%x", id, k)
continue
}
if g, e := v, []byte("filler"); !bytes.Equal(g, e) {
b.Errorf("bad value for id=%d key=%x: %s != %q", id, k, g, e)
}
if err := bucket.Delete(k); err != nil {
return err
}
}
// should be empty now
c := bucket.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
b.Errorf("unexpected key: %x = %q", k, v)
}
return rollback
}
if err := db.Update(validate); err != nil && err != rollback {
b.Error(err)
}
}
func BenchmarkDBBatchAutomatic(b *testing.B) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("bench"))
b.ResetTimer()
for i := 0; i < b.N; i++ {
start := make(chan struct{})
var wg sync.WaitGroup
for round := 0; round < 1000; round++ {
wg.Add(1)
go func(id uint32) {
defer wg.Done()
<-start
h := fnv.New32a()
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, id)
h.Write(buf[:])
k := h.Sum(nil)
insert := func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("bench"))
return b.Put(k, []byte("filler"))
}
if err := db.Batch(insert); err != nil {
b.Error(err)
return
}
}(uint32(round))
}
close(start)
wg.Wait()
}
b.StopTimer()
validateBatchBench(b, db)
}
func BenchmarkDBBatchSingle(b *testing.B) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("bench"))
b.ResetTimer()
for i := 0; i < b.N; i++ {
start := make(chan struct{})
var wg sync.WaitGroup
for round := 0; round < 1000; round++ {
wg.Add(1)
go func(id uint32) {
defer wg.Done()
<-start
h := fnv.New32a()
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, id)
h.Write(buf[:])
k := h.Sum(nil)
insert := func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("bench"))
return b.Put(k, []byte("filler"))
}
if err := db.Update(insert); err != nil {
b.Error(err)
return
}
}(uint32(round))
}
close(start)
wg.Wait()
}
b.StopTimer()
validateBatchBench(b, db)
}
func BenchmarkDBBatchManual10x100(b *testing.B) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("bench"))
b.ResetTimer()
for i := 0; i < b.N; i++ {
start := make(chan struct{})
var wg sync.WaitGroup
for major := 0; major < 10; major++ {
wg.Add(1)
go func(id uint32) {
defer wg.Done()
<-start
insert100 := func(tx *bolt.Tx) error {
h := fnv.New32a()
buf := make([]byte, 4)
for minor := uint32(0); minor < 100; minor++ {
binary.LittleEndian.PutUint32(buf, uint32(id*100+minor))
h.Reset()
h.Write(buf[:])
k := h.Sum(nil)
b := tx.Bucket([]byte("bench"))
if err := b.Put(k, []byte("filler")); err != nil {
return err
}
}
return nil
}
if err := db.Update(insert100); err != nil {
b.Fatal(err)
}
}(uint32(major))
}
close(start)
wg.Wait()
}
b.StopTimer()
validateBatchBench(b, db)
}

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package bolt_test
import (
"encoding/binary"
"fmt"
"io/ioutil"
"log"
"math/rand"
"net/http"
"net/http/httptest"
"os"
"github.com/boltdb/bolt"
)
// Set this to see how the counts are actually updated.
const verbose = false
// Counter updates a counter in Bolt for every URL path requested.
type counter struct {
db *bolt.DB
}
func (c counter) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
// Communicates the new count from a successful database
// transaction.
var result uint64
increment := func(tx *bolt.Tx) error {
b, err := tx.CreateBucketIfNotExists([]byte("hits"))
if err != nil {
return err
}
key := []byte(req.URL.String())
// Decode handles key not found for us.
count := decode(b.Get(key)) + 1
b.Put(key, encode(count))
// All good, communicate new count.
result = count
return nil
}
if err := c.db.Batch(increment); err != nil {
http.Error(rw, err.Error(), 500)
return
}
if verbose {
log.Printf("server: %s: %d", req.URL.String(), result)
}
rw.Header().Set("Content-Type", "application/octet-stream")
fmt.Fprintf(rw, "%d\n", result)
}
func client(id int, base string, paths []string) error {
// Process paths in random order.
rng := rand.New(rand.NewSource(int64(id)))
permutation := rng.Perm(len(paths))
for i := range paths {
path := paths[permutation[i]]
resp, err := http.Get(base + path)
if err != nil {
return err
}
defer resp.Body.Close()
buf, err := ioutil.ReadAll(resp.Body)
if err != nil {
return err
}
if verbose {
log.Printf("client: %s: %s", path, buf)
}
}
return nil
}
func ExampleDB_Batch() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Start our web server
count := counter{db}
srv := httptest.NewServer(count)
defer srv.Close()
// Decrease the batch size to make things more interesting.
db.MaxBatchSize = 3
// Get every path multiple times concurrently.
const clients = 10
paths := []string{
"/foo",
"/bar",
"/baz",
"/quux",
"/thud",
"/xyzzy",
}
errors := make(chan error, clients)
for i := 0; i < clients; i++ {
go func(id int) {
errors <- client(id, srv.URL, paths)
}(i)
}
// Check all responses to make sure there's no error.
for i := 0; i < clients; i++ {
if err := <-errors; err != nil {
fmt.Printf("client error: %v", err)
return
}
}
// Check the final result
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("hits"))
c := b.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("hits to %s: %d\n", k, decode(v))
}
return nil
})
// Output:
// hits to /bar: 10
// hits to /baz: 10
// hits to /foo: 10
// hits to /quux: 10
// hits to /thud: 10
// hits to /xyzzy: 10
}
// encode marshals a counter.
func encode(n uint64) []byte {
buf := make([]byte, 8)
binary.BigEndian.PutUint64(buf, n)
return buf
}
// decode unmarshals a counter. Nil buffers are decoded as 0.
func decode(buf []byte) uint64 {
if buf == nil {
return 0
}
return binary.BigEndian.Uint64(buf)
}

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package bolt_test
import (
"testing"
"time"
"github.com/boltdb/bolt"
)
// Ensure two functions can perform updates in a single batch.
func TestDB_Batch(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("widgets"))
// Iterate over multiple updates in separate goroutines.
n := 2
ch := make(chan error)
for i := 0; i < n; i++ {
go func(i int) {
ch <- db.Batch(func(tx *bolt.Tx) error {
return tx.Bucket([]byte("widgets")).Put(u64tob(uint64(i)), []byte{})
})
}(i)
}
// Check all responses to make sure there's no error.
for i := 0; i < n; i++ {
if err := <-ch; err != nil {
t.Fatal(err)
}
}
// Ensure data is correct.
db.MustView(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
for i := 0; i < n; i++ {
if v := b.Get(u64tob(uint64(i))); v == nil {
t.Errorf("key not found: %d", i)
}
}
return nil
})
}
func TestDB_Batch_Panic(t *testing.T) {
db := NewTestDB()
defer db.Close()
var sentinel int
var bork = &sentinel
var problem interface{}
var err error
// Execute a function inside a batch that panics.
func() {
defer func() {
if p := recover(); p != nil {
problem = p
}
}()
err = db.Batch(func(tx *bolt.Tx) error {
panic(bork)
})
}()
// Verify there is no error.
if g, e := err, error(nil); g != e {
t.Fatalf("wrong error: %v != %v", g, e)
}
// Verify the panic was captured.
if g, e := problem, bork; g != e {
t.Fatalf("wrong error: %v != %v", g, e)
}
}
func TestDB_BatchFull(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("widgets"))
const size = 3
// buffered so we never leak goroutines
ch := make(chan error, size)
put := func(i int) {
ch <- db.Batch(func(tx *bolt.Tx) error {
return tx.Bucket([]byte("widgets")).Put(u64tob(uint64(i)), []byte{})
})
}
db.MaxBatchSize = size
// high enough to never trigger here
db.MaxBatchDelay = 1 * time.Hour
go put(1)
go put(2)
// Give the batch a chance to exhibit bugs.
time.Sleep(10 * time.Millisecond)
// not triggered yet
select {
case <-ch:
t.Fatalf("batch triggered too early")
default:
}
go put(3)
// Check all responses to make sure there's no error.
for i := 0; i < size; i++ {
if err := <-ch; err != nil {
t.Fatal(err)
}
}
// Ensure data is correct.
db.MustView(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
for i := 1; i <= size; i++ {
if v := b.Get(u64tob(uint64(i))); v == nil {
t.Errorf("key not found: %d", i)
}
}
return nil
})
}
func TestDB_BatchTime(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.MustCreateBucket([]byte("widgets"))
const size = 1
// buffered so we never leak goroutines
ch := make(chan error, size)
put := func(i int) {
ch <- db.Batch(func(tx *bolt.Tx) error {
return tx.Bucket([]byte("widgets")).Put(u64tob(uint64(i)), []byte{})
})
}
db.MaxBatchSize = 1000
db.MaxBatchDelay = 0
go put(1)
// Batch must trigger by time alone.
// Check all responses to make sure there's no error.
for i := 0; i < size; i++ {
if err := <-ch; err != nil {
t.Fatal(err)
}
}
// Ensure data is correct.
db.MustView(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
for i := 1; i <= size; i++ {
if v := b.Get(u64tob(uint64(i))); v == nil {
t.Errorf("key not found: %d", i)
}
}
return nil
})
}

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package bolt
// maxMapSize represents the largest mmap size supported by Bolt.
const maxMapSize = 0x7FFFFFFF // 2GB
// maxAllocSize is the size used when creating array pointers.
const maxAllocSize = 0xFFFFFFF

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@ -0,0 +1,7 @@
package bolt
// maxMapSize represents the largest mmap size supported by Bolt.
const maxMapSize = 0xFFFFFFFFFFFF // 256TB
// maxAllocSize is the size used when creating array pointers.
const maxAllocSize = 0x7FFFFFFF

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@ -0,0 +1,7 @@
package bolt
// maxMapSize represents the largest mmap size supported by Bolt.
const maxMapSize = 0x7FFFFFFF // 2GB
// maxAllocSize is the size used when creating array pointers.
const maxAllocSize = 0xFFFFFFF

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package bolt
import (
"syscall"
)
var odirect = syscall.O_DIRECT
// fdatasync flushes written data to a file descriptor.
func fdatasync(db *DB) error {
return syscall.Fdatasync(int(db.file.Fd()))
}

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@ -0,0 +1,29 @@
package bolt
import (
"syscall"
"unsafe"
)
const (
msAsync = 1 << iota // perform asynchronous writes
msSync // perform synchronous writes
msInvalidate // invalidate cached data
)
var odirect int
func msync(db *DB) error {
_, _, errno := syscall.Syscall(syscall.SYS_MSYNC, uintptr(unsafe.Pointer(db.data)), uintptr(db.datasz), msInvalidate)
if errno != 0 {
return errno
}
return nil
}
func fdatasync(db *DB) error {
if db.data != nil {
return msync(db)
}
return db.file.Sync()
}

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@ -0,0 +1,36 @@
package bolt_test
import (
"fmt"
"path/filepath"
"reflect"
"runtime"
"testing"
)
// assert fails the test if the condition is false.
func assert(tb testing.TB, condition bool, msg string, v ...interface{}) {
if !condition {
_, file, line, _ := runtime.Caller(1)
fmt.Printf("\033[31m%s:%d: "+msg+"\033[39m\n\n", append([]interface{}{filepath.Base(file), line}, v...)...)
tb.FailNow()
}
}
// ok fails the test if an err is not nil.
func ok(tb testing.TB, err error) {
if err != nil {
_, file, line, _ := runtime.Caller(1)
fmt.Printf("\033[31m%s:%d: unexpected error: %s\033[39m\n\n", filepath.Base(file), line, err.Error())
tb.FailNow()
}
}
// equals fails the test if exp is not equal to act.
func equals(tb testing.TB, exp, act interface{}) {
if !reflect.DeepEqual(exp, act) {
_, file, line, _ := runtime.Caller(1)
fmt.Printf("\033[31m%s:%d:\n\n\texp: %#v\n\n\tgot: %#v\033[39m\n\n", filepath.Base(file), line, exp, act)
tb.FailNow()
}
}

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// +build !windows,!plan9
package bolt
import (
"fmt"
"os"
"syscall"
"time"
"unsafe"
)
// flock acquires an advisory lock on a file descriptor.
func flock(f *os.File, exclusive bool, timeout time.Duration) error {
var t time.Time
for {
// If we're beyond our timeout then return an error.
// This can only occur after we've attempted a flock once.
if t.IsZero() {
t = time.Now()
} else if timeout > 0 && time.Since(t) > timeout {
return ErrTimeout
}
flag := syscall.LOCK_SH
if exclusive {
flag = syscall.LOCK_EX
}
// Otherwise attempt to obtain an exclusive lock.
err := syscall.Flock(int(f.Fd()), flag|syscall.LOCK_NB)
if err == nil {
return nil
} else if err != syscall.EWOULDBLOCK {
return err
}
// Wait for a bit and try again.
time.Sleep(50 * time.Millisecond)
}
}
// funlock releases an advisory lock on a file descriptor.
func funlock(f *os.File) error {
return syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
}
// mmap memory maps a DB's data file.
func mmap(db *DB, sz int) error {
// Truncate and fsync to ensure file size metadata is flushed.
// https://github.com/boltdb/bolt/issues/284
if !db.NoGrowSync && !db.readOnly {
if err := db.file.Truncate(int64(sz)); err != nil {
return fmt.Errorf("file resize error: %s", err)
}
if err := db.file.Sync(); err != nil {
return fmt.Errorf("file sync error: %s", err)
}
}
// Map the data file to memory.
b, err := syscall.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED)
if err != nil {
return err
}
// Advise the kernel that the mmap is accessed randomly.
if err := madvise(b, syscall.MADV_RANDOM); err != nil {
return fmt.Errorf("madvise: %s", err)
}
// Save the original byte slice and convert to a byte array pointer.
db.dataref = b
db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
db.datasz = sz
return nil
}
// munmap unmaps a DB's data file from memory.
func munmap(db *DB) error {
// Ignore the unmap if we have no mapped data.
if db.dataref == nil {
return nil
}
// Unmap using the original byte slice.
err := syscall.Munmap(db.dataref)
db.dataref = nil
db.data = nil
db.datasz = 0
return err
}
// NOTE: This function is copied from stdlib because it is not available on darwin.
func madvise(b []byte, advice int) (err error) {
_, _, e1 := syscall.Syscall(syscall.SYS_MADVISE, uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)), uintptr(advice))
if e1 != 0 {
err = e1
}
return
}

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package bolt
import (
"fmt"
"os"
"syscall"
"time"
"unsafe"
)
var odirect int
// fdatasync flushes written data to a file descriptor.
func fdatasync(db *DB) error {
return db.file.Sync()
}
// flock acquires an advisory lock on a file descriptor.
func flock(f *os.File, _ bool, _ time.Duration) error {
return nil
}
// funlock releases an advisory lock on a file descriptor.
func funlock(f *os.File) error {
return nil
}
// mmap memory maps a DB's data file.
// Based on: https://github.com/edsrzf/mmap-go
func mmap(db *DB, sz int) error {
if !db.readOnly {
// Truncate the database to the size of the mmap.
if err := db.file.Truncate(int64(sz)); err != nil {
return fmt.Errorf("truncate: %s", err)
}
}
// Open a file mapping handle.
sizelo := uint32(sz >> 32)
sizehi := uint32(sz) & 0xffffffff
h, errno := syscall.CreateFileMapping(syscall.Handle(db.file.Fd()), nil, syscall.PAGE_READONLY, sizelo, sizehi, nil)
if h == 0 {
return os.NewSyscallError("CreateFileMapping", errno)
}
// Create the memory map.
addr, errno := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, 0, 0, uintptr(sz))
if addr == 0 {
return os.NewSyscallError("MapViewOfFile", errno)
}
// Close mapping handle.
if err := syscall.CloseHandle(syscall.Handle(h)); err != nil {
return os.NewSyscallError("CloseHandle", err)
}
// Convert to a byte array.
db.data = ((*[maxMapSize]byte)(unsafe.Pointer(addr)))
db.datasz = sz
return nil
}
// munmap unmaps a pointer from a file.
// Based on: https://github.com/edsrzf/mmap-go
func munmap(db *DB) error {
if db.data == nil {
return nil
}
addr := (uintptr)(unsafe.Pointer(&db.data[0]))
if err := syscall.UnmapViewOfFile(addr); err != nil {
return os.NewSyscallError("UnmapViewOfFile", err)
}
return nil
}

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// +build !windows,!plan9,!linux,!openbsd
package bolt
var odirect int
// fdatasync flushes written data to a file descriptor.
func fdatasync(db *DB) error {
return db.file.Sync()
}

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package bolt
import (
"bytes"
"fmt"
"unsafe"
)
const (
// MaxKeySize is the maximum length of a key, in bytes.
MaxKeySize = 32768
// MaxValueSize is the maximum length of a value, in bytes.
MaxValueSize = 4294967295
)
const (
maxUint = ^uint(0)
minUint = 0
maxInt = int(^uint(0) >> 1)
minInt = -maxInt - 1
)
const bucketHeaderSize = int(unsafe.Sizeof(bucket{}))
const (
minFillPercent = 0.1
maxFillPercent = 1.0
)
// DefaultFillPercent is the percentage that split pages are filled.
// This value can be changed by setting Bucket.FillPercent.
const DefaultFillPercent = 0.5
// Bucket represents a collection of key/value pairs inside the database.
type Bucket struct {
*bucket
tx *Tx // the associated transaction
buckets map[string]*Bucket // subbucket cache
page *page // inline page reference
rootNode *node // materialized node for the root page.
nodes map[pgid]*node // node cache
// Sets the threshold for filling nodes when they split. By default,
// the bucket will fill to 50% but it can be useful to increase this
// amount if you know that your write workloads are mostly append-only.
//
// This is non-persisted across transactions so it must be set in every Tx.
FillPercent float64
}
// bucket represents the on-file representation of a bucket.
// This is stored as the "value" of a bucket key. If the bucket is small enough,
// then its root page can be stored inline in the "value", after the bucket
// header. In the case of inline buckets, the "root" will be 0.
type bucket struct {
root pgid // page id of the bucket's root-level page
sequence uint64 // monotonically incrementing, used by NextSequence()
}
// newBucket returns a new bucket associated with a transaction.
func newBucket(tx *Tx) Bucket {
var b = Bucket{tx: tx, FillPercent: DefaultFillPercent}
if tx.writable {
b.buckets = make(map[string]*Bucket)
b.nodes = make(map[pgid]*node)
}
return b
}
// Tx returns the tx of the bucket.
func (b *Bucket) Tx() *Tx {
return b.tx
}
// Root returns the root of the bucket.
func (b *Bucket) Root() pgid {
return b.root
}
// Writable returns whether the bucket is writable.
func (b *Bucket) Writable() bool {
return b.tx.writable
}
// Cursor creates a cursor associated with the bucket.
// The cursor is only valid as long as the transaction is open.
// Do not use a cursor after the transaction is closed.
func (b *Bucket) Cursor() *Cursor {
// Update transaction statistics.
b.tx.stats.CursorCount++
// Allocate and return a cursor.
return &Cursor{
bucket: b,
stack: make([]elemRef, 0),
}
}
// Bucket retrieves a nested bucket by name.
// Returns nil if the bucket does not exist.
func (b *Bucket) Bucket(name []byte) *Bucket {
if b.buckets != nil {
if child := b.buckets[string(name)]; child != nil {
return child
}
}
// Move cursor to key.
c := b.Cursor()
k, v, flags := c.seek(name)
// Return nil if the key doesn't exist or it is not a bucket.
if !bytes.Equal(name, k) || (flags&bucketLeafFlag) == 0 {
return nil
}
// Otherwise create a bucket and cache it.
var child = b.openBucket(v)
if b.buckets != nil {
b.buckets[string(name)] = child
}
return child
}
// Helper method that re-interprets a sub-bucket value
// from a parent into a Bucket
func (b *Bucket) openBucket(value []byte) *Bucket {
var child = newBucket(b.tx)
// If this is a writable transaction then we need to copy the bucket entry.
// Read-only transactions can point directly at the mmap entry.
if b.tx.writable {
child.bucket = &bucket{}
*child.bucket = *(*bucket)(unsafe.Pointer(&value[0]))
} else {
child.bucket = (*bucket)(unsafe.Pointer(&value[0]))
}
// Save a reference to the inline page if the bucket is inline.
if child.root == 0 {
child.page = (*page)(unsafe.Pointer(&value[bucketHeaderSize]))
}
return &child
}
// CreateBucket creates a new bucket at the given key and returns the new bucket.
// Returns an error if the key already exists, if the bucket name is blank, or if the bucket name is too long.
func (b *Bucket) CreateBucket(key []byte) (*Bucket, error) {
if b.tx.db == nil {
return nil, ErrTxClosed
} else if !b.tx.writable {
return nil, ErrTxNotWritable
} else if len(key) == 0 {
return nil, ErrBucketNameRequired
}
// Move cursor to correct position.
c := b.Cursor()
k, _, flags := c.seek(key)
// Return an error if there is an existing key.
if bytes.Equal(key, k) {
if (flags & bucketLeafFlag) != 0 {
return nil, ErrBucketExists
} else {
return nil, ErrIncompatibleValue
}
}
// Create empty, inline bucket.
var bucket = Bucket{
bucket: &bucket{},
rootNode: &node{isLeaf: true},
FillPercent: DefaultFillPercent,
}
var value = bucket.write()
// Insert into node.
key = cloneBytes(key)
c.node().put(key, key, value, 0, bucketLeafFlag)
// Since subbuckets are not allowed on inline buckets, we need to
// dereference the inline page, if it exists. This will cause the bucket
// to be treated as a regular, non-inline bucket for the rest of the tx.
b.page = nil
return b.Bucket(key), nil
}
// CreateBucketIfNotExists creates a new bucket if it doesn't already exist and returns a reference to it.
// Returns an error if the bucket name is blank, or if the bucket name is too long.
func (b *Bucket) CreateBucketIfNotExists(key []byte) (*Bucket, error) {
child, err := b.CreateBucket(key)
if err == ErrBucketExists {
return b.Bucket(key), nil
} else if err != nil {
return nil, err
}
return child, nil
}
// DeleteBucket deletes a bucket at the given key.
// Returns an error if the bucket does not exists, or if the key represents a non-bucket value.
func (b *Bucket) DeleteBucket(key []byte) error {
if b.tx.db == nil {
return ErrTxClosed
} else if !b.Writable() {
return ErrTxNotWritable
}
// Move cursor to correct position.
c := b.Cursor()
k, _, flags := c.seek(key)
// Return an error if bucket doesn't exist or is not a bucket.
if !bytes.Equal(key, k) {
return ErrBucketNotFound
} else if (flags & bucketLeafFlag) == 0 {
return ErrIncompatibleValue
}
// Recursively delete all child buckets.
child := b.Bucket(key)
err := child.ForEach(func(k, v []byte) error {
if v == nil {
if err := child.DeleteBucket(k); err != nil {
return fmt.Errorf("delete bucket: %s", err)
}
}
return nil
})
if err != nil {
return err
}
// Remove cached copy.
delete(b.buckets, string(key))
// Release all bucket pages to freelist.
child.nodes = nil
child.rootNode = nil
child.free()
// Delete the node if we have a matching key.
c.node().del(key)
return nil
}
// Get retrieves the value for a key in the bucket.
// Returns a nil value if the key does not exist or if the key is a nested bucket.
// The returned value is only valid for the life of the transaction.
func (b *Bucket) Get(key []byte) []byte {
k, v, flags := b.Cursor().seek(key)
// Return nil if this is a bucket.
if (flags & bucketLeafFlag) != 0 {
return nil
}
// If our target node isn't the same key as what's passed in then return nil.
if !bytes.Equal(key, k) {
return nil
}
return v
}
// Put sets the value for a key in the bucket.
// If the key exist then its previous value will be overwritten.
// Returns an error if the bucket was created from a read-only transaction, if the key is blank, if the key is too large, or if the value is too large.
func (b *Bucket) Put(key []byte, value []byte) error {
if b.tx.db == nil {
return ErrTxClosed
} else if !b.Writable() {
return ErrTxNotWritable
} else if len(key) == 0 {
return ErrKeyRequired
} else if len(key) > MaxKeySize {
return ErrKeyTooLarge
} else if int64(len(value)) > MaxValueSize {
return ErrValueTooLarge
}
// Move cursor to correct position.
c := b.Cursor()
k, _, flags := c.seek(key)
// Return an error if there is an existing key with a bucket value.
if bytes.Equal(key, k) && (flags&bucketLeafFlag) != 0 {
return ErrIncompatibleValue
}
// Insert into node.
key = cloneBytes(key)
c.node().put(key, key, value, 0, 0)
return nil
}
// Delete removes a key from the bucket.
// If the key does not exist then nothing is done and a nil error is returned.
// Returns an error if the bucket was created from a read-only transaction.
func (b *Bucket) Delete(key []byte) error {
if b.tx.db == nil {
return ErrTxClosed
} else if !b.Writable() {
return ErrTxNotWritable
}
// Move cursor to correct position.
c := b.Cursor()
_, _, flags := c.seek(key)
// Return an error if there is already existing bucket value.
if (flags & bucketLeafFlag) != 0 {
return ErrIncompatibleValue
}
// Delete the node if we have a matching key.
c.node().del(key)
return nil
}
// NextSequence returns an autoincrementing integer for the bucket.
func (b *Bucket) NextSequence() (uint64, error) {
if b.tx.db == nil {
return 0, ErrTxClosed
} else if !b.Writable() {
return 0, ErrTxNotWritable
}
// Materialize the root node if it hasn't been already so that the
// bucket will be saved during commit.
if b.rootNode == nil {
_ = b.node(b.root, nil)
}
// Increment and return the sequence.
b.bucket.sequence++
return b.bucket.sequence, nil
}
// ForEach executes a function for each key/value pair in a bucket.
// If the provided function returns an error then the iteration is stopped and
// the error is returned to the caller.
func (b *Bucket) ForEach(fn func(k, v []byte) error) error {
if b.tx.db == nil {
return ErrTxClosed
}
c := b.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
if err := fn(k, v); err != nil {
return err
}
}
return nil
}
// Stat returns stats on a bucket.
func (b *Bucket) Stats() BucketStats {
var s, subStats BucketStats
pageSize := b.tx.db.pageSize
s.BucketN += 1
if b.root == 0 {
s.InlineBucketN += 1
}
b.forEachPage(func(p *page, depth int) {
if (p.flags & leafPageFlag) != 0 {
s.KeyN += int(p.count)
// used totals the used bytes for the page
used := pageHeaderSize
if p.count != 0 {
// If page has any elements, add all element headers.
used += leafPageElementSize * int(p.count-1)
// Add all element key, value sizes.
// The computation takes advantage of the fact that the position
// of the last element's key/value equals to the total of the sizes
// of all previous elements' keys and values.
// It also includes the last element's header.
lastElement := p.leafPageElement(p.count - 1)
used += int(lastElement.pos + lastElement.ksize + lastElement.vsize)
}
if b.root == 0 {
// For inlined bucket just update the inline stats
s.InlineBucketInuse += used
} else {
// For non-inlined bucket update all the leaf stats
s.LeafPageN++
s.LeafInuse += used
s.LeafOverflowN += int(p.overflow)
// Collect stats from sub-buckets.
// Do that by iterating over all element headers
// looking for the ones with the bucketLeafFlag.
for i := uint16(0); i < p.count; i++ {
e := p.leafPageElement(i)
if (e.flags & bucketLeafFlag) != 0 {
// For any bucket element, open the element value
// and recursively call Stats on the contained bucket.
subStats.Add(b.openBucket(e.value()).Stats())
}
}
}
} else if (p.flags & branchPageFlag) != 0 {
s.BranchPageN++
lastElement := p.branchPageElement(p.count - 1)
// used totals the used bytes for the page
// Add header and all element headers.
used := pageHeaderSize + (branchPageElementSize * int(p.count-1))
// Add size of all keys and values.
// Again, use the fact that last element's position equals to
// the total of key, value sizes of all previous elements.
used += int(lastElement.pos + lastElement.ksize)
s.BranchInuse += used
s.BranchOverflowN += int(p.overflow)
}
// Keep track of maximum page depth.
if depth+1 > s.Depth {
s.Depth = (depth + 1)
}
})
// Alloc stats can be computed from page counts and pageSize.
s.BranchAlloc = (s.BranchPageN + s.BranchOverflowN) * pageSize
s.LeafAlloc = (s.LeafPageN + s.LeafOverflowN) * pageSize
// Add the max depth of sub-buckets to get total nested depth.
s.Depth += subStats.Depth
// Add the stats for all sub-buckets
s.Add(subStats)
return s
}
// forEachPage iterates over every page in a bucket, including inline pages.
func (b *Bucket) forEachPage(fn func(*page, int)) {
// If we have an inline page then just use that.
if b.page != nil {
fn(b.page, 0)
return
}
// Otherwise traverse the page hierarchy.
b.tx.forEachPage(b.root, 0, fn)
}
// forEachPageNode iterates over every page (or node) in a bucket.
// This also includes inline pages.
func (b *Bucket) forEachPageNode(fn func(*page, *node, int)) {
// If we have an inline page or root node then just use that.
if b.page != nil {
fn(b.page, nil, 0)
return
}
b._forEachPageNode(b.root, 0, fn)
}
func (b *Bucket) _forEachPageNode(pgid pgid, depth int, fn func(*page, *node, int)) {
var p, n = b.pageNode(pgid)
// Execute function.
fn(p, n, depth)
// Recursively loop over children.
if p != nil {
if (p.flags & branchPageFlag) != 0 {
for i := 0; i < int(p.count); i++ {
elem := p.branchPageElement(uint16(i))
b._forEachPageNode(elem.pgid, depth+1, fn)
}
}
} else {
if !n.isLeaf {
for _, inode := range n.inodes {
b._forEachPageNode(inode.pgid, depth+1, fn)
}
}
}
}
// spill writes all the nodes for this bucket to dirty pages.
func (b *Bucket) spill() error {
// Spill all child buckets first.
for name, child := range b.buckets {
// If the child bucket is small enough and it has no child buckets then
// write it inline into the parent bucket's page. Otherwise spill it
// like a normal bucket and make the parent value a pointer to the page.
var value []byte
if child.inlineable() {
child.free()
value = child.write()
} else {
if err := child.spill(); err != nil {
return err
}
// Update the child bucket header in this bucket.
value = make([]byte, unsafe.Sizeof(bucket{}))
var bucket = (*bucket)(unsafe.Pointer(&value[0]))
*bucket = *child.bucket
}
// Skip writing the bucket if there are no materialized nodes.
if child.rootNode == nil {
continue
}
// Update parent node.
var c = b.Cursor()
k, _, flags := c.seek([]byte(name))
if !bytes.Equal([]byte(name), k) {
panic(fmt.Sprintf("misplaced bucket header: %x -> %x", []byte(name), k))
}
if flags&bucketLeafFlag == 0 {
panic(fmt.Sprintf("unexpected bucket header flag: %x", flags))
}
c.node().put([]byte(name), []byte(name), value, 0, bucketLeafFlag)
}
// Ignore if there's not a materialized root node.
if b.rootNode == nil {
return nil
}
// Spill nodes.
if err := b.rootNode.spill(); err != nil {
return err
}
b.rootNode = b.rootNode.root()
// Update the root node for this bucket.
if b.rootNode.pgid >= b.tx.meta.pgid {
panic(fmt.Sprintf("pgid (%d) above high water mark (%d)", b.rootNode.pgid, b.tx.meta.pgid))
}
b.root = b.rootNode.pgid
return nil
}
// inlineable returns true if a bucket is small enough to be written inline
// and if it contains no subbuckets. Otherwise returns false.
func (b *Bucket) inlineable() bool {
var n = b.rootNode
// Bucket must only contain a single leaf node.
if n == nil || !n.isLeaf {
return false
}
// Bucket is not inlineable if it contains subbuckets or if it goes beyond
// our threshold for inline bucket size.
var size = pageHeaderSize
for _, inode := range n.inodes {
size += leafPageElementSize + len(inode.key) + len(inode.value)
if inode.flags&bucketLeafFlag != 0 {
return false
} else if size > b.maxInlineBucketSize() {
return false
}
}
return true
}
// Returns the maximum total size of a bucket to make it a candidate for inlining.
func (b *Bucket) maxInlineBucketSize() int {
return b.tx.db.pageSize / 4
}
// write allocates and writes a bucket to a byte slice.
func (b *Bucket) write() []byte {
// Allocate the appropriate size.
var n = b.rootNode
var value = make([]byte, bucketHeaderSize+n.size())
// Write a bucket header.
var bucket = (*bucket)(unsafe.Pointer(&value[0]))
*bucket = *b.bucket
// Convert byte slice to a fake page and write the root node.
var p = (*page)(unsafe.Pointer(&value[bucketHeaderSize]))
n.write(p)
return value
}
// rebalance attempts to balance all nodes.
func (b *Bucket) rebalance() {
for _, n := range b.nodes {
n.rebalance()
}
for _, child := range b.buckets {
child.rebalance()
}
}
// node creates a node from a page and associates it with a given parent.
func (b *Bucket) node(pgid pgid, parent *node) *node {
_assert(b.nodes != nil, "nodes map expected")
// Retrieve node if it's already been created.
if n := b.nodes[pgid]; n != nil {
return n
}
// Otherwise create a node and cache it.
n := &node{bucket: b, parent: parent}
if parent == nil {
b.rootNode = n
} else {
parent.children = append(parent.children, n)
}
// Use the inline page if this is an inline bucket.
var p = b.page
if p == nil {
p = b.tx.page(pgid)
}
// Read the page into the node and cache it.
n.read(p)
b.nodes[pgid] = n
// Update statistics.
b.tx.stats.NodeCount++
return n
}
// free recursively frees all pages in the bucket.
func (b *Bucket) free() {
if b.root == 0 {
return
}
var tx = b.tx
b.forEachPageNode(func(p *page, n *node, _ int) {
if p != nil {
tx.db.freelist.free(tx.meta.txid, p)
} else {
n.free()
}
})
b.root = 0
}
// dereference removes all references to the old mmap.
func (b *Bucket) dereference() {
if b.rootNode != nil {
b.rootNode.root().dereference()
}
for _, child := range b.buckets {
child.dereference()
}
}
// pageNode returns the in-memory node, if it exists.
// Otherwise returns the underlying page.
func (b *Bucket) pageNode(id pgid) (*page, *node) {
// Inline buckets have a fake page embedded in their value so treat them
// differently. We'll return the rootNode (if available) or the fake page.
if b.root == 0 {
if id != 0 {
panic(fmt.Sprintf("inline bucket non-zero page access(2): %d != 0", id))
}
if b.rootNode != nil {
return nil, b.rootNode
}
return b.page, nil
}
// Check the node cache for non-inline buckets.
if b.nodes != nil {
if n := b.nodes[id]; n != nil {
return nil, n
}
}
// Finally lookup the page from the transaction if no node is materialized.
return b.tx.page(id), nil
}
// BucketStats records statistics about resources used by a bucket.
type BucketStats struct {
// Page count statistics.
BranchPageN int // number of logical branch pages
BranchOverflowN int // number of physical branch overflow pages
LeafPageN int // number of logical leaf pages
LeafOverflowN int // number of physical leaf overflow pages
// Tree statistics.
KeyN int // number of keys/value pairs
Depth int // number of levels in B+tree
// Page size utilization.
BranchAlloc int // bytes allocated for physical branch pages
BranchInuse int // bytes actually used for branch data
LeafAlloc int // bytes allocated for physical leaf pages
LeafInuse int // bytes actually used for leaf data
// Bucket statistics
BucketN int // total number of buckets including the top bucket
InlineBucketN int // total number on inlined buckets
InlineBucketInuse int // bytes used for inlined buckets (also accounted for in LeafInuse)
}
func (s *BucketStats) Add(other BucketStats) {
s.BranchPageN += other.BranchPageN
s.BranchOverflowN += other.BranchOverflowN
s.LeafPageN += other.LeafPageN
s.LeafOverflowN += other.LeafOverflowN
s.KeyN += other.KeyN
if s.Depth < other.Depth {
s.Depth = other.Depth
}
s.BranchAlloc += other.BranchAlloc
s.BranchInuse += other.BranchInuse
s.LeafAlloc += other.LeafAlloc
s.LeafInuse += other.LeafInuse
s.BucketN += other.BucketN
s.InlineBucketN += other.InlineBucketN
s.InlineBucketInuse += other.InlineBucketInuse
}
// cloneBytes returns a copy of a given slice.
func cloneBytes(v []byte) []byte {
var clone = make([]byte, len(v))
copy(clone, v)
return clone
}

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package main_test
import (
"bytes"
"io/ioutil"
"os"
"strconv"
"testing"
"github.com/boltdb/bolt"
"github.com/boltdb/bolt/cmd/bolt"
)
// Ensure the "info" command can print information about a database.
func TestInfoCommand_Run(t *testing.T) {
db := MustOpen(0666, nil)
db.DB.Close()
defer db.Close()
// Run the info command.
m := NewMain()
if err := m.Run("info", db.Path); err != nil {
t.Fatal(err)
}
}
// Ensure the "stats" command can execute correctly.
func TestStatsCommand_Run(t *testing.T) {
// Ignore
if os.Getpagesize() != 4096 {
t.Skip("system does not use 4KB page size")
}
db := MustOpen(0666, nil)
defer db.Close()
if err := db.Update(func(tx *bolt.Tx) error {
// Create "foo" bucket.
b, err := tx.CreateBucket([]byte("foo"))
if err != nil {
return err
}
for i := 0; i < 10; i++ {
if err := b.Put([]byte(strconv.Itoa(i)), []byte(strconv.Itoa(i))); err != nil {
return err
}
}
// Create "bar" bucket.
b, err = tx.CreateBucket([]byte("bar"))
if err != nil {
return err
}
for i := 0; i < 100; i++ {
if err := b.Put([]byte(strconv.Itoa(i)), []byte(strconv.Itoa(i))); err != nil {
return err
}
}
// Create "baz" bucket.
b, err = tx.CreateBucket([]byte("baz"))
if err != nil {
return err
}
if err := b.Put([]byte("key"), []byte("value")); err != nil {
return err
}
return nil
}); err != nil {
t.Fatal(err)
}
db.DB.Close()
// Generate expected result.
exp := "Aggregate statistics for 3 buckets\n\n" +
"Page count statistics\n" +
"\tNumber of logical branch pages: 0\n" +
"\tNumber of physical branch overflow pages: 0\n" +
"\tNumber of logical leaf pages: 1\n" +
"\tNumber of physical leaf overflow pages: 0\n" +
"Tree statistics\n" +
"\tNumber of keys/value pairs: 111\n" +
"\tNumber of levels in B+tree: 1\n" +
"Page size utilization\n" +
"\tBytes allocated for physical branch pages: 0\n" +
"\tBytes actually used for branch data: 0 (0%)\n" +
"\tBytes allocated for physical leaf pages: 4096\n" +
"\tBytes actually used for leaf data: 1996 (48%)\n" +
"Bucket statistics\n" +
"\tTotal number of buckets: 3\n" +
"\tTotal number on inlined buckets: 2 (66%)\n" +
"\tBytes used for inlined buckets: 236 (11%)\n"
// Run the command.
m := NewMain()
if err := m.Run("stats", db.Path); err != nil {
t.Fatal(err)
} else if m.Stdout.String() != exp {
t.Fatalf("unexpected stdout:\n\n%s", m.Stdout.String())
}
}
// Main represents a test wrapper for main.Main that records output.
type Main struct {
*main.Main
Stdin bytes.Buffer
Stdout bytes.Buffer
Stderr bytes.Buffer
}
// NewMain returns a new instance of Main.
func NewMain() *Main {
m := &Main{Main: main.NewMain()}
m.Main.Stdin = &m.Stdin
m.Main.Stdout = &m.Stdout
m.Main.Stderr = &m.Stderr
return m
}
// MustOpen creates a Bolt database in a temporary location.
func MustOpen(mode os.FileMode, options *bolt.Options) *DB {
// Create temporary path.
f, _ := ioutil.TempFile("", "bolt-")
f.Close()
os.Remove(f.Name())
db, err := bolt.Open(f.Name(), mode, options)
if err != nil {
panic(err.Error())
}
return &DB{DB: db, Path: f.Name()}
}
// DB is a test wrapper for bolt.DB.
type DB struct {
*bolt.DB
Path string
}
// Close closes and removes the database.
func (db *DB) Close() error {
defer os.Remove(db.Path)
return db.DB.Close()
}

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package bolt
import (
"bytes"
"fmt"
"sort"
)
// Cursor represents an iterator that can traverse over all key/value pairs in a bucket in sorted order.
// Cursors see nested buckets with value == nil.
// Cursors can be obtained from a transaction and are valid as long as the transaction is open.
//
// Keys and values returned from the cursor are only valid for the life of the transaction.
//
// Changing data while traversing with a cursor may cause it to be invalidated
// and return unexpected keys and/or values. You must reposition your cursor
// after mutating data.
type Cursor struct {
bucket *Bucket
stack []elemRef
}
// Bucket returns the bucket that this cursor was created from.
func (c *Cursor) Bucket() *Bucket {
return c.bucket
}
// First moves the cursor to the first item in the bucket and returns its key and value.
// If the bucket is empty then a nil key and value are returned.
// The returned key and value are only valid for the life of the transaction.
func (c *Cursor) First() (key []byte, value []byte) {
_assert(c.bucket.tx.db != nil, "tx closed")
c.stack = c.stack[:0]
p, n := c.bucket.pageNode(c.bucket.root)
c.stack = append(c.stack, elemRef{page: p, node: n, index: 0})
c.first()
k, v, flags := c.keyValue()
if (flags & uint32(bucketLeafFlag)) != 0 {
return k, nil
}
return k, v
}
// Last moves the cursor to the last item in the bucket and returns its key and value.
// If the bucket is empty then a nil key and value are returned.
// The returned key and value are only valid for the life of the transaction.
func (c *Cursor) Last() (key []byte, value []byte) {
_assert(c.bucket.tx.db != nil, "tx closed")
c.stack = c.stack[:0]
p, n := c.bucket.pageNode(c.bucket.root)
ref := elemRef{page: p, node: n}
ref.index = ref.count() - 1
c.stack = append(c.stack, ref)
c.last()
k, v, flags := c.keyValue()
if (flags & uint32(bucketLeafFlag)) != 0 {
return k, nil
}
return k, v
}
// Next moves the cursor to the next item in the bucket and returns its key and value.
// If the cursor is at the end of the bucket then a nil key and value are returned.
// The returned key and value are only valid for the life of the transaction.
func (c *Cursor) Next() (key []byte, value []byte) {
_assert(c.bucket.tx.db != nil, "tx closed")
k, v, flags := c.next()
if (flags & uint32(bucketLeafFlag)) != 0 {
return k, nil
}
return k, v
}
// Prev moves the cursor to the previous item in the bucket and returns its key and value.
// If the cursor is at the beginning of the bucket then a nil key and value are returned.
// The returned key and value are only valid for the life of the transaction.
func (c *Cursor) Prev() (key []byte, value []byte) {
_assert(c.bucket.tx.db != nil, "tx closed")
// Attempt to move back one element until we're successful.
// Move up the stack as we hit the beginning of each page in our stack.
for i := len(c.stack) - 1; i >= 0; i-- {
elem := &c.stack[i]
if elem.index > 0 {
elem.index--
break
}
c.stack = c.stack[:i]
}
// If we've hit the end then return nil.
if len(c.stack) == 0 {
return nil, nil
}
// Move down the stack to find the last element of the last leaf under this branch.
c.last()
k, v, flags := c.keyValue()
if (flags & uint32(bucketLeafFlag)) != 0 {
return k, nil
}
return k, v
}
// Seek moves the cursor to a given key and returns it.
// If the key does not exist then the next key is used. If no keys
// follow, a nil key is returned.
// The returned key and value are only valid for the life of the transaction.
func (c *Cursor) Seek(seek []byte) (key []byte, value []byte) {
k, v, flags := c.seek(seek)
// If we ended up after the last element of a page then move to the next one.
if ref := &c.stack[len(c.stack)-1]; ref.index >= ref.count() {
k, v, flags = c.next()
}
if k == nil {
return nil, nil
} else if (flags & uint32(bucketLeafFlag)) != 0 {
return k, nil
}
return k, v
}
// Delete removes the current key/value under the cursor from the bucket.
// Delete fails if current key/value is a bucket or if the transaction is not writable.
func (c *Cursor) Delete() error {
if c.bucket.tx.db == nil {
return ErrTxClosed
} else if !c.bucket.Writable() {
return ErrTxNotWritable
}
key, _, flags := c.keyValue()
// Return an error if current value is a bucket.
if (flags & bucketLeafFlag) != 0 {
return ErrIncompatibleValue
}
c.node().del(key)
return nil
}
// seek moves the cursor to a given key and returns it.
// If the key does not exist then the next key is used.
func (c *Cursor) seek(seek []byte) (key []byte, value []byte, flags uint32) {
_assert(c.bucket.tx.db != nil, "tx closed")
// Start from root page/node and traverse to correct page.
c.stack = c.stack[:0]
c.search(seek, c.bucket.root)
ref := &c.stack[len(c.stack)-1]
// If the cursor is pointing to the end of page/node then return nil.
if ref.index >= ref.count() {
return nil, nil, 0
}
// If this is a bucket then return a nil value.
return c.keyValue()
}
// first moves the cursor to the first leaf element under the last page in the stack.
func (c *Cursor) first() {
for {
// Exit when we hit a leaf page.
var ref = &c.stack[len(c.stack)-1]
if ref.isLeaf() {
break
}
// Keep adding pages pointing to the first element to the stack.
var pgid pgid
if ref.node != nil {
pgid = ref.node.inodes[ref.index].pgid
} else {
pgid = ref.page.branchPageElement(uint16(ref.index)).pgid
}
p, n := c.bucket.pageNode(pgid)
c.stack = append(c.stack, elemRef{page: p, node: n, index: 0})
}
}
// last moves the cursor to the last leaf element under the last page in the stack.
func (c *Cursor) last() {
for {
// Exit when we hit a leaf page.
ref := &c.stack[len(c.stack)-1]
if ref.isLeaf() {
break
}
// Keep adding pages pointing to the last element in the stack.
var pgid pgid
if ref.node != nil {
pgid = ref.node.inodes[ref.index].pgid
} else {
pgid = ref.page.branchPageElement(uint16(ref.index)).pgid
}
p, n := c.bucket.pageNode(pgid)
var nextRef = elemRef{page: p, node: n}
nextRef.index = nextRef.count() - 1
c.stack = append(c.stack, nextRef)
}
}
// next moves to the next leaf element and returns the key and value.
// If the cursor is at the last leaf element then it stays there and returns nil.
func (c *Cursor) next() (key []byte, value []byte, flags uint32) {
// Attempt to move over one element until we're successful.
// Move up the stack as we hit the end of each page in our stack.
var i int
for i = len(c.stack) - 1; i >= 0; i-- {
elem := &c.stack[i]
if elem.index < elem.count()-1 {
elem.index++
break
}
}
// If we've hit the root page then stop and return. This will leave the
// cursor on the last element of the last page.
if i == -1 {
return nil, nil, 0
}
// Otherwise start from where we left off in the stack and find the
// first element of the first leaf page.
c.stack = c.stack[:i+1]
c.first()
return c.keyValue()
}
// search recursively performs a binary search against a given page/node until it finds a given key.
func (c *Cursor) search(key []byte, pgid pgid) {
p, n := c.bucket.pageNode(pgid)
if p != nil && (p.flags&(branchPageFlag|leafPageFlag)) == 0 {
panic(fmt.Sprintf("invalid page type: %d: %x", p.id, p.flags))
}
e := elemRef{page: p, node: n}
c.stack = append(c.stack, e)
// If we're on a leaf page/node then find the specific node.
if e.isLeaf() {
c.nsearch(key)
return
}
if n != nil {
c.searchNode(key, n)
return
}
c.searchPage(key, p)
}
func (c *Cursor) searchNode(key []byte, n *node) {
var exact bool
index := sort.Search(len(n.inodes), func(i int) bool {
// TODO(benbjohnson): Optimize this range search. It's a bit hacky right now.
// sort.Search() finds the lowest index where f() != -1 but we need the highest index.
ret := bytes.Compare(n.inodes[i].key, key)
if ret == 0 {
exact = true
}
return ret != -1
})
if !exact && index > 0 {
index--
}
c.stack[len(c.stack)-1].index = index
// Recursively search to the next page.
c.search(key, n.inodes[index].pgid)
}
func (c *Cursor) searchPage(key []byte, p *page) {
// Binary search for the correct range.
inodes := p.branchPageElements()
var exact bool
index := sort.Search(int(p.count), func(i int) bool {
// TODO(benbjohnson): Optimize this range search. It's a bit hacky right now.
// sort.Search() finds the lowest index where f() != -1 but we need the highest index.
ret := bytes.Compare(inodes[i].key(), key)
if ret == 0 {
exact = true
}
return ret != -1
})
if !exact && index > 0 {
index--
}
c.stack[len(c.stack)-1].index = index
// Recursively search to the next page.
c.search(key, inodes[index].pgid)
}
// nsearch searches the leaf node on the top of the stack for a key.
func (c *Cursor) nsearch(key []byte) {
e := &c.stack[len(c.stack)-1]
p, n := e.page, e.node
// If we have a node then search its inodes.
if n != nil {
index := sort.Search(len(n.inodes), func(i int) bool {
return bytes.Compare(n.inodes[i].key, key) != -1
})
e.index = index
return
}
// If we have a page then search its leaf elements.
inodes := p.leafPageElements()
index := sort.Search(int(p.count), func(i int) bool {
return bytes.Compare(inodes[i].key(), key) != -1
})
e.index = index
}
// keyValue returns the key and value of the current leaf element.
func (c *Cursor) keyValue() ([]byte, []byte, uint32) {
ref := &c.stack[len(c.stack)-1]
if ref.count() == 0 || ref.index >= ref.count() {
return nil, nil, 0
}
// Retrieve value from node.
if ref.node != nil {
inode := &ref.node.inodes[ref.index]
return inode.key, inode.value, inode.flags
}
// Or retrieve value from page.
elem := ref.page.leafPageElement(uint16(ref.index))
return elem.key(), elem.value(), elem.flags
}
// node returns the node that the cursor is currently positioned on.
func (c *Cursor) node() *node {
_assert(len(c.stack) > 0, "accessing a node with a zero-length cursor stack")
// If the top of the stack is a leaf node then just return it.
if ref := &c.stack[len(c.stack)-1]; ref.node != nil && ref.isLeaf() {
return ref.node
}
// Start from root and traverse down the hierarchy.
var n = c.stack[0].node
if n == nil {
n = c.bucket.node(c.stack[0].page.id, nil)
}
for _, ref := range c.stack[:len(c.stack)-1] {
_assert(!n.isLeaf, "expected branch node")
n = n.childAt(int(ref.index))
}
_assert(n.isLeaf, "expected leaf node")
return n
}
// elemRef represents a reference to an element on a given page/node.
type elemRef struct {
page *page
node *node
index int
}
// isLeaf returns whether the ref is pointing at a leaf page/node.
func (r *elemRef) isLeaf() bool {
if r.node != nil {
return r.node.isLeaf
}
return (r.page.flags & leafPageFlag) != 0
}
// count returns the number of inodes or page elements.
func (r *elemRef) count() int {
if r.node != nil {
return len(r.node.inodes)
}
return int(r.page.count)
}

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package bolt_test
import (
"bytes"
"encoding/binary"
"fmt"
"os"
"sort"
"testing"
"testing/quick"
"github.com/boltdb/bolt"
)
// Ensure that a cursor can return a reference to the bucket that created it.
func TestCursor_Bucket(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, _ := tx.CreateBucket([]byte("widgets"))
c := b.Cursor()
equals(t, b, c.Bucket())
return nil
})
}
// Ensure that a Tx cursor can seek to the appropriate keys.
func TestCursor_Seek(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
ok(t, err)
ok(t, b.Put([]byte("foo"), []byte("0001")))
ok(t, b.Put([]byte("bar"), []byte("0002")))
ok(t, b.Put([]byte("baz"), []byte("0003")))
_, err = b.CreateBucket([]byte("bkt"))
ok(t, err)
return nil
})
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("widgets")).Cursor()
// Exact match should go to the key.
k, v := c.Seek([]byte("bar"))
equals(t, []byte("bar"), k)
equals(t, []byte("0002"), v)
// Inexact match should go to the next key.
k, v = c.Seek([]byte("bas"))
equals(t, []byte("baz"), k)
equals(t, []byte("0003"), v)
// Low key should go to the first key.
k, v = c.Seek([]byte(""))
equals(t, []byte("bar"), k)
equals(t, []byte("0002"), v)
// High key should return no key.
k, v = c.Seek([]byte("zzz"))
assert(t, k == nil, "")
assert(t, v == nil, "")
// Buckets should return their key but no value.
k, v = c.Seek([]byte("bkt"))
equals(t, []byte("bkt"), k)
assert(t, v == nil, "")
return nil
})
}
func TestCursor_Delete(t *testing.T) {
db := NewTestDB()
defer db.Close()
var count = 1000
// Insert every other key between 0 and $count.
db.Update(func(tx *bolt.Tx) error {
b, _ := tx.CreateBucket([]byte("widgets"))
for i := 0; i < count; i += 1 {
k := make([]byte, 8)
binary.BigEndian.PutUint64(k, uint64(i))
b.Put(k, make([]byte, 100))
}
b.CreateBucket([]byte("sub"))
return nil
})
db.Update(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("widgets")).Cursor()
bound := make([]byte, 8)
binary.BigEndian.PutUint64(bound, uint64(count/2))
for key, _ := c.First(); bytes.Compare(key, bound) < 0; key, _ = c.Next() {
if err := c.Delete(); err != nil {
return err
}
}
c.Seek([]byte("sub"))
err := c.Delete()
equals(t, err, bolt.ErrIncompatibleValue)
return nil
})
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
equals(t, b.Stats().KeyN, count/2+1)
return nil
})
}
// Ensure that a Tx cursor can seek to the appropriate keys when there are a
// large number of keys. This test also checks that seek will always move
// forward to the next key.
//
// Related: https://github.com/boltdb/bolt/pull/187
func TestCursor_Seek_Large(t *testing.T) {
db := NewTestDB()
defer db.Close()
var count = 10000
// Insert every other key between 0 and $count.
db.Update(func(tx *bolt.Tx) error {
b, _ := tx.CreateBucket([]byte("widgets"))
for i := 0; i < count; i += 100 {
for j := i; j < i+100; j += 2 {
k := make([]byte, 8)
binary.BigEndian.PutUint64(k, uint64(j))
b.Put(k, make([]byte, 100))
}
}
return nil
})
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("widgets")).Cursor()
for i := 0; i < count; i++ {
seek := make([]byte, 8)
binary.BigEndian.PutUint64(seek, uint64(i))
k, _ := c.Seek(seek)
// The last seek is beyond the end of the the range so
// it should return nil.
if i == count-1 {
assert(t, k == nil, "")
continue
}
// Otherwise we should seek to the exact key or the next key.
num := binary.BigEndian.Uint64(k)
if i%2 == 0 {
equals(t, uint64(i), num)
} else {
equals(t, uint64(i+1), num)
}
}
return nil
})
}
// Ensure that a cursor can iterate over an empty bucket without error.
func TestCursor_EmptyBucket(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("widgets")).Cursor()
k, v := c.First()
assert(t, k == nil, "")
assert(t, v == nil, "")
return nil
})
}
// Ensure that a Tx cursor can reverse iterate over an empty bucket without error.
func TestCursor_EmptyBucketReverse(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("widgets")).Cursor()
k, v := c.Last()
assert(t, k == nil, "")
assert(t, v == nil, "")
return nil
})
}
// Ensure that a Tx cursor can iterate over a single root with a couple elements.
func TestCursor_Iterate_Leaf(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte{})
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte{0})
tx.Bucket([]byte("widgets")).Put([]byte("bar"), []byte{1})
return nil
})
tx, _ := db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
k, v := c.First()
equals(t, string(k), "bar")
equals(t, v, []byte{1})
k, v = c.Next()
equals(t, string(k), "baz")
equals(t, v, []byte{})
k, v = c.Next()
equals(t, string(k), "foo")
equals(t, v, []byte{0})
k, v = c.Next()
assert(t, k == nil, "")
assert(t, v == nil, "")
k, v = c.Next()
assert(t, k == nil, "")
assert(t, v == nil, "")
tx.Rollback()
}
// Ensure that a Tx cursor can iterate in reverse over a single root with a couple elements.
func TestCursor_LeafRootReverse(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte{})
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte{0})
tx.Bucket([]byte("widgets")).Put([]byte("bar"), []byte{1})
return nil
})
tx, _ := db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
k, v := c.Last()
equals(t, string(k), "foo")
equals(t, v, []byte{0})
k, v = c.Prev()
equals(t, string(k), "baz")
equals(t, v, []byte{})
k, v = c.Prev()
equals(t, string(k), "bar")
equals(t, v, []byte{1})
k, v = c.Prev()
assert(t, k == nil, "")
assert(t, v == nil, "")
k, v = c.Prev()
assert(t, k == nil, "")
assert(t, v == nil, "")
tx.Rollback()
}
// Ensure that a Tx cursor can restart from the beginning.
func TestCursor_Restart(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("bar"), []byte{})
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte{})
return nil
})
tx, _ := db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
k, _ := c.First()
equals(t, string(k), "bar")
k, _ = c.Next()
equals(t, string(k), "foo")
k, _ = c.First()
equals(t, string(k), "bar")
k, _ = c.Next()
equals(t, string(k), "foo")
tx.Rollback()
}
// Ensure that a Tx can iterate over all elements in a bucket.
func TestCursor_QuickCheck(t *testing.T) {
f := func(items testdata) bool {
db := NewTestDB()
defer db.Close()
// Bulk insert all values.
tx, _ := db.Begin(true)
tx.CreateBucket([]byte("widgets"))
b := tx.Bucket([]byte("widgets"))
for _, item := range items {
ok(t, b.Put(item.Key, item.Value))
}
ok(t, tx.Commit())
// Sort test data.
sort.Sort(items)
// Iterate over all items and check consistency.
var index = 0
tx, _ = db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
for k, v := c.First(); k != nil && index < len(items); k, v = c.Next() {
equals(t, k, items[index].Key)
equals(t, v, items[index].Value)
index++
}
equals(t, len(items), index)
tx.Rollback()
return true
}
if err := quick.Check(f, qconfig()); err != nil {
t.Error(err)
}
}
// Ensure that a transaction can iterate over all elements in a bucket in reverse.
func TestCursor_QuickCheck_Reverse(t *testing.T) {
f := func(items testdata) bool {
db := NewTestDB()
defer db.Close()
// Bulk insert all values.
tx, _ := db.Begin(true)
tx.CreateBucket([]byte("widgets"))
b := tx.Bucket([]byte("widgets"))
for _, item := range items {
ok(t, b.Put(item.Key, item.Value))
}
ok(t, tx.Commit())
// Sort test data.
sort.Sort(revtestdata(items))
// Iterate over all items and check consistency.
var index = 0
tx, _ = db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
for k, v := c.Last(); k != nil && index < len(items); k, v = c.Prev() {
equals(t, k, items[index].Key)
equals(t, v, items[index].Value)
index++
}
equals(t, len(items), index)
tx.Rollback()
return true
}
if err := quick.Check(f, qconfig()); err != nil {
t.Error(err)
}
}
// Ensure that a Tx cursor can iterate over subbuckets.
func TestCursor_QuickCheck_BucketsOnly(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
ok(t, err)
_, err = b.CreateBucket([]byte("foo"))
ok(t, err)
_, err = b.CreateBucket([]byte("bar"))
ok(t, err)
_, err = b.CreateBucket([]byte("baz"))
ok(t, err)
return nil
})
db.View(func(tx *bolt.Tx) error {
var names []string
c := tx.Bucket([]byte("widgets")).Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
names = append(names, string(k))
assert(t, v == nil, "")
}
equals(t, names, []string{"bar", "baz", "foo"})
return nil
})
}
// Ensure that a Tx cursor can reverse iterate over subbuckets.
func TestCursor_QuickCheck_BucketsOnly_Reverse(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
ok(t, err)
_, err = b.CreateBucket([]byte("foo"))
ok(t, err)
_, err = b.CreateBucket([]byte("bar"))
ok(t, err)
_, err = b.CreateBucket([]byte("baz"))
ok(t, err)
return nil
})
db.View(func(tx *bolt.Tx) error {
var names []string
c := tx.Bucket([]byte("widgets")).Cursor()
for k, v := c.Last(); k != nil; k, v = c.Prev() {
names = append(names, string(k))
assert(t, v == nil, "")
}
equals(t, names, []string{"foo", "baz", "bar"})
return nil
})
}
func ExampleCursor() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Start a read-write transaction.
db.Update(func(tx *bolt.Tx) error {
// Create a new bucket.
tx.CreateBucket([]byte("animals"))
// Insert data into a bucket.
b := tx.Bucket([]byte("animals"))
b.Put([]byte("dog"), []byte("fun"))
b.Put([]byte("cat"), []byte("lame"))
b.Put([]byte("liger"), []byte("awesome"))
// Create a cursor for iteration.
c := b.Cursor()
// Iterate over items in sorted key order. This starts from the
// first key/value pair and updates the k/v variables to the
// next key/value on each iteration.
//
// The loop finishes at the end of the cursor when a nil key is returned.
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("A %s is %s.\n", k, v)
}
return nil
})
// Output:
// A cat is lame.
// A dog is fun.
// A liger is awesome.
}
func ExampleCursor_reverse() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Start a read-write transaction.
db.Update(func(tx *bolt.Tx) error {
// Create a new bucket.
tx.CreateBucket([]byte("animals"))
// Insert data into a bucket.
b := tx.Bucket([]byte("animals"))
b.Put([]byte("dog"), []byte("fun"))
b.Put([]byte("cat"), []byte("lame"))
b.Put([]byte("liger"), []byte("awesome"))
// Create a cursor for iteration.
c := b.Cursor()
// Iterate over items in reverse sorted key order. This starts
// from the last key/value pair and updates the k/v variables to
// the previous key/value on each iteration.
//
// The loop finishes at the beginning of the cursor when a nil key
// is returned.
for k, v := c.Last(); k != nil; k, v = c.Prev() {
fmt.Printf("A %s is %s.\n", k, v)
}
return nil
})
// Output:
// A liger is awesome.
// A dog is fun.
// A cat is lame.
}

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package bolt
import (
"fmt"
"hash/fnv"
"os"
"runtime"
"runtime/debug"
"strings"
"sync"
"time"
"unsafe"
)
// The largest step that can be taken when remapping the mmap.
const maxMmapStep = 1 << 30 // 1GB
// The data file format version.
const version = 2
// Represents a marker value to indicate that a file is a Bolt DB.
const magic uint32 = 0xED0CDAED
// IgnoreNoSync specifies whether the NoSync field of a DB is ignored when
// syncing changes to a file. This is required as some operating systems,
// such as OpenBSD, do not have a unified buffer cache (UBC) and writes
// must be synchronzied using the msync(2) syscall.
const IgnoreNoSync = runtime.GOOS == "openbsd"
// Default values if not set in a DB instance.
const (
DefaultMaxBatchSize int = 1000
DefaultMaxBatchDelay = 10 * time.Millisecond
)
// DB represents a collection of buckets persisted to a file on disk.
// All data access is performed through transactions which can be obtained through the DB.
// All the functions on DB will return a ErrDatabaseNotOpen if accessed before Open() is called.
type DB struct {
// When enabled, the database will perform a Check() after every commit.
// A panic is issued if the database is in an inconsistent state. This
// flag has a large performance impact so it should only be used for
// debugging purposes.
StrictMode bool
// Setting the NoSync flag will cause the database to skip fsync()
// calls after each commit. This can be useful when bulk loading data
// into a database and you can restart the bulk load in the event of
// a system failure or database corruption. Do not set this flag for
// normal use.
//
// If the package global IgnoreNoSync constant is true, this value is
// ignored. See the comment on that constant for more details.
//
// THIS IS UNSAFE. PLEASE USE WITH CAUTION.
NoSync bool
// When true, skips the truncate call when growing the database.
// Setting this to true is only safe on non-ext3/ext4 systems.
// Skipping truncation avoids preallocation of hard drive space and
// bypasses a truncate() and fsync() syscall on remapping.
//
// https://github.com/boltdb/bolt/issues/284
NoGrowSync bool
// MaxBatchSize is the maximum size of a batch. Default value is
// copied from DefaultMaxBatchSize in Open.
//
// If <=0, disables batching.
//
// Do not change concurrently with calls to Batch.
MaxBatchSize int
// MaxBatchDelay is the maximum delay before a batch starts.
// Default value is copied from DefaultMaxBatchDelay in Open.
//
// If <=0, effectively disables batching.
//
// Do not change concurrently with calls to Batch.
MaxBatchDelay time.Duration
path string
file *os.File
dataref []byte // mmap'ed readonly, write throws SEGV
data *[maxMapSize]byte
datasz int
meta0 *meta
meta1 *meta
pageSize int
opened bool
rwtx *Tx
txs []*Tx
freelist *freelist
stats Stats
batchMu sync.Mutex
batch *batch
rwlock sync.Mutex // Allows only one writer at a time.
metalock sync.Mutex // Protects meta page access.
mmaplock sync.RWMutex // Protects mmap access during remapping.
statlock sync.RWMutex // Protects stats access.
ops struct {
writeAt func(b []byte, off int64) (n int, err error)
}
// Read only mode.
// When true, Update() and Begin(true) return ErrDatabaseReadOnly immediately.
readOnly bool
}
// Path returns the path to currently open database file.
func (db *DB) Path() string {
return db.path
}
// GoString returns the Go string representation of the database.
func (db *DB) GoString() string {
return fmt.Sprintf("bolt.DB{path:%q}", db.path)
}
// String returns the string representation of the database.
func (db *DB) String() string {
return fmt.Sprintf("DB<%q>", db.path)
}
// Open creates and opens a database at the given path.
// If the file does not exist then it will be created automatically.
// Passing in nil options will cause Bolt to open the database with the default options.
func Open(path string, mode os.FileMode, options *Options) (*DB, error) {
var db = &DB{opened: true}
// Set default options if no options are provided.
if options == nil {
options = DefaultOptions
}
db.NoGrowSync = options.NoGrowSync
// Set default values for later DB operations.
db.MaxBatchSize = DefaultMaxBatchSize
db.MaxBatchDelay = DefaultMaxBatchDelay
flag := os.O_RDWR
if options.ReadOnly {
flag = os.O_RDONLY
db.readOnly = true
}
// Open data file and separate sync handler for metadata writes.
db.path = path
var err error
if db.file, err = os.OpenFile(db.path, flag|os.O_CREATE, mode); err != nil {
_ = db.close()
return nil, err
}
// Lock file so that other processes using Bolt in read-write mode cannot
// use the database at the same time. This would cause corruption since
// the two processes would write meta pages and free pages separately.
// The database file is locked exclusively (only one process can grab the lock)
// if !options.ReadOnly.
// The database file is locked using the shared lock (more than one process may
// hold a lock at the same time) otherwise (options.ReadOnly is set).
if err := flock(db.file, !db.readOnly, options.Timeout); err != nil {
_ = db.close()
return nil, err
}
// Default values for test hooks
db.ops.writeAt = db.file.WriteAt
// Initialize the database if it doesn't exist.
if info, err := db.file.Stat(); err != nil {
return nil, fmt.Errorf("stat error: %s", err)
} else if info.Size() == 0 {
// Initialize new files with meta pages.
if err := db.init(); err != nil {
return nil, err
}
} else {
// Read the first meta page to determine the page size.
var buf [0x1000]byte
if _, err := db.file.ReadAt(buf[:], 0); err == nil {
m := db.pageInBuffer(buf[:], 0).meta()
if err := m.validate(); err != nil {
return nil, fmt.Errorf("meta0 error: %s", err)
}
db.pageSize = int(m.pageSize)
}
}
// Memory map the data file.
if err := db.mmap(0); err != nil {
_ = db.close()
return nil, err
}
// Read in the freelist.
db.freelist = newFreelist()
db.freelist.read(db.page(db.meta().freelist))
// Mark the database as opened and return.
return db, nil
}
// mmap opens the underlying memory-mapped file and initializes the meta references.
// minsz is the minimum size that the new mmap can be.
func (db *DB) mmap(minsz int) error {
db.mmaplock.Lock()
defer db.mmaplock.Unlock()
info, err := db.file.Stat()
if err != nil {
return fmt.Errorf("mmap stat error: %s", err)
} else if int(info.Size()) < db.pageSize*2 {
return fmt.Errorf("file size too small")
}
// Ensure the size is at least the minimum size.
var size = int(info.Size())
if size < minsz {
size = minsz
}
size, err = db.mmapSize(size)
if err != nil {
return err
}
// Dereference all mmap references before unmapping.
if db.rwtx != nil {
db.rwtx.root.dereference()
}
// Unmap existing data before continuing.
if err := db.munmap(); err != nil {
return err
}
// Memory-map the data file as a byte slice.
if err := mmap(db, size); err != nil {
return err
}
// Save references to the meta pages.
db.meta0 = db.page(0).meta()
db.meta1 = db.page(1).meta()
// Validate the meta pages.
if err := db.meta0.validate(); err != nil {
return fmt.Errorf("meta0 error: %s", err)
}
if err := db.meta1.validate(); err != nil {
return fmt.Errorf("meta1 error: %s", err)
}
return nil
}
// munmap unmaps the data file from memory.
func (db *DB) munmap() error {
if err := munmap(db); err != nil {
return fmt.Errorf("unmap error: " + err.Error())
}
return nil
}
// mmapSize determines the appropriate size for the mmap given the current size
// of the database. The minimum size is 1MB and doubles until it reaches 1GB.
// Returns an error if the new mmap size is greater than the max allowed.
func (db *DB) mmapSize(size int) (int, error) {
// Double the size from 32KB until 1GB.
for i := uint(15); i <= 30; i++ {
if size <= 1<<i {
return 1 << i, nil
}
}
// Verify the requested size is not above the maximum allowed.
if size > maxMapSize {
return 0, fmt.Errorf("mmap too large")
}
// If larger than 1GB then grow by 1GB at a time.
sz := int64(size)
if remainder := sz % int64(maxMmapStep); remainder > 0 {
sz += int64(maxMmapStep) - remainder
}
// Ensure that the mmap size is a multiple of the page size.
// This should always be true since we're incrementing in MBs.
pageSize := int64(db.pageSize)
if (sz % pageSize) != 0 {
sz = ((sz / pageSize) + 1) * pageSize
}
// If we've exceeded the max size then only grow up to the max size.
if sz > maxMapSize {
sz = maxMapSize
}
return int(sz), nil
}
// init creates a new database file and initializes its meta pages.
func (db *DB) init() error {
// Set the page size to the OS page size.
db.pageSize = os.Getpagesize()
// Create two meta pages on a buffer.
buf := make([]byte, db.pageSize*4)
for i := 0; i < 2; i++ {
p := db.pageInBuffer(buf[:], pgid(i))
p.id = pgid(i)
p.flags = metaPageFlag
// Initialize the meta page.
m := p.meta()
m.magic = magic
m.version = version
m.pageSize = uint32(db.pageSize)
m.freelist = 2
m.root = bucket{root: 3}
m.pgid = 4
m.txid = txid(i)
}
// Write an empty freelist at page 3.
p := db.pageInBuffer(buf[:], pgid(2))
p.id = pgid(2)
p.flags = freelistPageFlag
p.count = 0
// Write an empty leaf page at page 4.
p = db.pageInBuffer(buf[:], pgid(3))
p.id = pgid(3)
p.flags = leafPageFlag
p.count = 0
// Write the buffer to our data file.
if _, err := db.ops.writeAt(buf, 0); err != nil {
return err
}
if err := fdatasync(db); err != nil {
return err
}
return nil
}
// Close releases all database resources.
// All transactions must be closed before closing the database.
func (db *DB) Close() error {
db.rwlock.Lock()
defer db.rwlock.Unlock()
db.metalock.Lock()
defer db.metalock.Unlock()
db.mmaplock.RLock()
defer db.mmaplock.RUnlock()
return db.close()
}
func (db *DB) close() error {
db.opened = false
db.freelist = nil
db.path = ""
// Clear ops.
db.ops.writeAt = nil
// Close the mmap.
if err := db.munmap(); err != nil {
return err
}
// Close file handles.
if db.file != nil {
// No need to unlock read-only file.
if !db.readOnly {
// Unlock the file.
_ = funlock(db.file)
}
// Close the file descriptor.
if err := db.file.Close(); err != nil {
return fmt.Errorf("db file close: %s", err)
}
db.file = nil
}
return nil
}
// Begin starts a new transaction.
// Multiple read-only transactions can be used concurrently but only one
// write transaction can be used at a time. Starting multiple write transactions
// will cause the calls to block and be serialized until the current write
// transaction finishes.
//
// Transactions should not be depedent on one another. Opening a read
// transaction and a write transaction in the same goroutine can cause the
// writer to deadlock because the database periodically needs to re-mmap itself
// as it grows and it cannot do that while a read transaction is open.
//
// IMPORTANT: You must close read-only transactions after you are finished or
// else the database will not reclaim old pages.
func (db *DB) Begin(writable bool) (*Tx, error) {
if writable {
return db.beginRWTx()
}
return db.beginTx()
}
func (db *DB) beginTx() (*Tx, error) {
// Lock the meta pages while we initialize the transaction. We obtain
// the meta lock before the mmap lock because that's the order that the
// write transaction will obtain them.
db.metalock.Lock()
// Obtain a read-only lock on the mmap. When the mmap is remapped it will
// obtain a write lock so all transactions must finish before it can be
// remapped.
db.mmaplock.RLock()
// Exit if the database is not open yet.
if !db.opened {
db.mmaplock.RUnlock()
db.metalock.Unlock()
return nil, ErrDatabaseNotOpen
}
// Create a transaction associated with the database.
t := &Tx{}
t.init(db)
// Keep track of transaction until it closes.
db.txs = append(db.txs, t)
n := len(db.txs)
// Unlock the meta pages.
db.metalock.Unlock()
// Update the transaction stats.
db.statlock.Lock()
db.stats.TxN++
db.stats.OpenTxN = n
db.statlock.Unlock()
return t, nil
}
func (db *DB) beginRWTx() (*Tx, error) {
// If the database was opened with Options.ReadOnly, return an error.
if db.readOnly {
return nil, ErrDatabaseReadOnly
}
// Obtain writer lock. This is released by the transaction when it closes.
// This enforces only one writer transaction at a time.
db.rwlock.Lock()
// Once we have the writer lock then we can lock the meta pages so that
// we can set up the transaction.
db.metalock.Lock()
defer db.metalock.Unlock()
// Exit if the database is not open yet.
if !db.opened {
db.rwlock.Unlock()
return nil, ErrDatabaseNotOpen
}
// Create a transaction associated with the database.
t := &Tx{writable: true}
t.init(db)
db.rwtx = t
// Free any pages associated with closed read-only transactions.
var minid txid = 0xFFFFFFFFFFFFFFFF
for _, t := range db.txs {
if t.meta.txid < minid {
minid = t.meta.txid
}
}
if minid > 0 {
db.freelist.release(minid - 1)
}
return t, nil
}
// removeTx removes a transaction from the database.
func (db *DB) removeTx(tx *Tx) {
// Release the read lock on the mmap.
db.mmaplock.RUnlock()
// Use the meta lock to restrict access to the DB object.
db.metalock.Lock()
// Remove the transaction.
for i, t := range db.txs {
if t == tx {
db.txs = append(db.txs[:i], db.txs[i+1:]...)
break
}
}
n := len(db.txs)
// Unlock the meta pages.
db.metalock.Unlock()
// Merge statistics.
db.statlock.Lock()
db.stats.OpenTxN = n
db.stats.TxStats.add(&tx.stats)
db.statlock.Unlock()
}
// Update executes a function within the context of a read-write managed transaction.
// If no error is returned from the function then the transaction is committed.
// If an error is returned then the entire transaction is rolled back.
// Any error that is returned from the function or returned from the commit is
// returned from the Update() method.
//
// Attempting to manually commit or rollback within the function will cause a panic.
func (db *DB) Update(fn func(*Tx) error) error {
t, err := db.Begin(true)
if err != nil {
return err
}
// Make sure the transaction rolls back in the event of a panic.
defer func() {
if t.db != nil {
t.rollback()
}
}()
// Mark as a managed tx so that the inner function cannot manually commit.
t.managed = true
// If an error is returned from the function then rollback and return error.
err = fn(t)
t.managed = false
if err != nil {
_ = t.Rollback()
return err
}
return t.Commit()
}
// View executes a function within the context of a managed read-only transaction.
// Any error that is returned from the function is returned from the View() method.
//
// Attempting to manually rollback within the function will cause a panic.
func (db *DB) View(fn func(*Tx) error) error {
t, err := db.Begin(false)
if err != nil {
return err
}
// Make sure the transaction rolls back in the event of a panic.
defer func() {
if t.db != nil {
t.rollback()
}
}()
// Mark as a managed tx so that the inner function cannot manually rollback.
t.managed = true
// If an error is returned from the function then pass it through.
err = fn(t)
t.managed = false
if err != nil {
_ = t.Rollback()
return err
}
if err := t.Rollback(); err != nil {
return err
}
return nil
}
// Sync executes fdatasync() against the database file handle.
//
// This is not necessary under normal operation, however, if you use NoSync
// then it allows you to force the database file to sync against the disk.
func (db *DB) Sync() error { return fdatasync(db) }
// Stats retrieves ongoing performance stats for the database.
// This is only updated when a transaction closes.
func (db *DB) Stats() Stats {
db.statlock.RLock()
defer db.statlock.RUnlock()
return db.stats
}
// This is for internal access to the raw data bytes from the C cursor, use
// carefully, or not at all.
func (db *DB) Info() *Info {
return &Info{uintptr(unsafe.Pointer(&db.data[0])), db.pageSize}
}
// page retrieves a page reference from the mmap based on the current page size.
func (db *DB) page(id pgid) *page {
pos := id * pgid(db.pageSize)
return (*page)(unsafe.Pointer(&db.data[pos]))
}
// pageInBuffer retrieves a page reference from a given byte array based on the current page size.
func (db *DB) pageInBuffer(b []byte, id pgid) *page {
return (*page)(unsafe.Pointer(&b[id*pgid(db.pageSize)]))
}
// meta retrieves the current meta page reference.
func (db *DB) meta() *meta {
if db.meta0.txid > db.meta1.txid {
return db.meta0
}
return db.meta1
}
// allocate returns a contiguous block of memory starting at a given page.
func (db *DB) allocate(count int) (*page, error) {
// Allocate a temporary buffer for the page.
buf := make([]byte, count*db.pageSize)
p := (*page)(unsafe.Pointer(&buf[0]))
p.overflow = uint32(count - 1)
// Use pages from the freelist if they are available.
if p.id = db.freelist.allocate(count); p.id != 0 {
return p, nil
}
// Resize mmap() if we're at the end.
p.id = db.rwtx.meta.pgid
var minsz = int((p.id+pgid(count))+1) * db.pageSize
if minsz >= db.datasz {
if err := db.mmap(minsz); err != nil {
return nil, fmt.Errorf("mmap allocate error: %s", err)
}
}
// Move the page id high water mark.
db.rwtx.meta.pgid += pgid(count)
return p, nil
}
func (db *DB) IsReadOnly() bool {
return db.readOnly
}
// Options represents the options that can be set when opening a database.
type Options struct {
// Timeout is the amount of time to wait to obtain a file lock.
// When set to zero it will wait indefinitely. This option is only
// available on Darwin and Linux.
Timeout time.Duration
// Sets the DB.NoGrowSync flag before memory mapping the file.
NoGrowSync bool
// Open database in read-only mode. Uses flock(..., LOCK_SH |LOCK_NB) to
// grab a shared lock (UNIX).
ReadOnly bool
}
// DefaultOptions represent the options used if nil options are passed into Open().
// No timeout is used which will cause Bolt to wait indefinitely for a lock.
var DefaultOptions = &Options{
Timeout: 0,
NoGrowSync: false,
}
// Stats represents statistics about the database.
type Stats struct {
// Freelist stats
FreePageN int // total number of free pages on the freelist
PendingPageN int // total number of pending pages on the freelist
FreeAlloc int // total bytes allocated in free pages
FreelistInuse int // total bytes used by the freelist
// Transaction stats
TxN int // total number of started read transactions
OpenTxN int // number of currently open read transactions
TxStats TxStats // global, ongoing stats.
}
// Sub calculates and returns the difference between two sets of database stats.
// This is useful when obtaining stats at two different points and time and
// you need the performance counters that occurred within that time span.
func (s *Stats) Sub(other *Stats) Stats {
if other == nil {
return *s
}
var diff Stats
diff.FreePageN = s.FreePageN
diff.PendingPageN = s.PendingPageN
diff.FreeAlloc = s.FreeAlloc
diff.FreelistInuse = s.FreelistInuse
diff.TxN = other.TxN - s.TxN
diff.TxStats = s.TxStats.Sub(&other.TxStats)
return diff
}
func (s *Stats) add(other *Stats) {
s.TxStats.add(&other.TxStats)
}
type Info struct {
Data uintptr
PageSize int
}
type meta struct {
magic uint32
version uint32
pageSize uint32
flags uint32
root bucket
freelist pgid
pgid pgid
txid txid
checksum uint64
}
// validate checks the marker bytes and version of the meta page to ensure it matches this binary.
func (m *meta) validate() error {
if m.checksum != 0 && m.checksum != m.sum64() {
return ErrChecksum
} else if m.magic != magic {
return ErrInvalid
} else if m.version != version {
return ErrVersionMismatch
}
return nil
}
// copy copies one meta object to another.
func (m *meta) copy(dest *meta) {
*dest = *m
}
// write writes the meta onto a page.
func (m *meta) write(p *page) {
if m.root.root >= m.pgid {
panic(fmt.Sprintf("root bucket pgid (%d) above high water mark (%d)", m.root.root, m.pgid))
} else if m.freelist >= m.pgid {
panic(fmt.Sprintf("freelist pgid (%d) above high water mark (%d)", m.freelist, m.pgid))
}
// Page id is either going to be 0 or 1 which we can determine by the transaction ID.
p.id = pgid(m.txid % 2)
p.flags |= metaPageFlag
// Calculate the checksum.
m.checksum = m.sum64()
m.copy(p.meta())
}
// generates the checksum for the meta.
func (m *meta) sum64() uint64 {
var h = fnv.New64a()
_, _ = h.Write((*[unsafe.Offsetof(meta{}.checksum)]byte)(unsafe.Pointer(m))[:])
return h.Sum64()
}
// _assert will panic with a given formatted message if the given condition is false.
func _assert(condition bool, msg string, v ...interface{}) {
if !condition {
panic(fmt.Sprintf("assertion failed: "+msg, v...))
}
}
func warn(v ...interface{}) { fmt.Fprintln(os.Stderr, v...) }
func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr, msg+"\n", v...) }
func printstack() {
stack := strings.Join(strings.Split(string(debug.Stack()), "\n")[2:], "\n")
fmt.Fprintln(os.Stderr, stack)
}

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@ -0,0 +1,903 @@
package bolt_test
import (
"encoding/binary"
"errors"
"flag"
"fmt"
"io/ioutil"
"os"
"regexp"
"runtime"
"sort"
"strings"
"testing"
"time"
"github.com/boltdb/bolt"
)
var statsFlag = flag.Bool("stats", false, "show performance stats")
// Ensure that opening a database with a bad path returns an error.
func TestOpen_BadPath(t *testing.T) {
db, err := bolt.Open("", 0666, nil)
assert(t, err != nil, "err: %s", err)
assert(t, db == nil, "")
}
// Ensure that a database can be opened without error.
func TestOpen(t *testing.T) {
path := tempfile()
defer os.Remove(path)
db, err := bolt.Open(path, 0666, nil)
assert(t, db != nil, "")
ok(t, err)
equals(t, db.Path(), path)
ok(t, db.Close())
}
// Ensure that opening an already open database file will timeout.
func TestOpen_Timeout(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("timeout not supported on windows")
}
path := tempfile()
defer os.Remove(path)
// Open a data file.
db0, err := bolt.Open(path, 0666, nil)
assert(t, db0 != nil, "")
ok(t, err)
// Attempt to open the database again.
start := time.Now()
db1, err := bolt.Open(path, 0666, &bolt.Options{Timeout: 100 * time.Millisecond})
assert(t, db1 == nil, "")
equals(t, bolt.ErrTimeout, err)
assert(t, time.Since(start) > 100*time.Millisecond, "")
db0.Close()
}
// Ensure that opening an already open database file will wait until its closed.
func TestOpen_Wait(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("timeout not supported on windows")
}
path := tempfile()
defer os.Remove(path)
// Open a data file.
db0, err := bolt.Open(path, 0666, nil)
assert(t, db0 != nil, "")
ok(t, err)
// Close it in just a bit.
time.AfterFunc(100*time.Millisecond, func() { db0.Close() })
// Attempt to open the database again.
start := time.Now()
db1, err := bolt.Open(path, 0666, &bolt.Options{Timeout: 200 * time.Millisecond})
assert(t, db1 != nil, "")
ok(t, err)
assert(t, time.Since(start) > 100*time.Millisecond, "")
}
// Ensure that opening a database does not increase its size.
// https://github.com/boltdb/bolt/issues/291
func TestOpen_Size(t *testing.T) {
// Open a data file.
db := NewTestDB()
path := db.Path()
defer db.Close()
// Insert until we get above the minimum 4MB size.
ok(t, db.Update(func(tx *bolt.Tx) error {
b, _ := tx.CreateBucketIfNotExists([]byte("data"))
for i := 0; i < 10000; i++ {
ok(t, b.Put([]byte(fmt.Sprintf("%04d", i)), make([]byte, 1000)))
}
return nil
}))
// Close database and grab the size.
db.DB.Close()
sz := fileSize(path)
if sz == 0 {
t.Fatalf("unexpected new file size: %d", sz)
}
// Reopen database, update, and check size again.
db0, err := bolt.Open(path, 0666, nil)
ok(t, err)
ok(t, db0.Update(func(tx *bolt.Tx) error { return tx.Bucket([]byte("data")).Put([]byte{0}, []byte{0}) }))
ok(t, db0.Close())
newSz := fileSize(path)
if newSz == 0 {
t.Fatalf("unexpected new file size: %d", newSz)
}
// Compare the original size with the new size.
if sz != newSz {
t.Fatalf("unexpected file growth: %d => %d", sz, newSz)
}
}
// Ensure that opening a database beyond the max step size does not increase its size.
// https://github.com/boltdb/bolt/issues/303
func TestOpen_Size_Large(t *testing.T) {
if testing.Short() {
t.Skip("short mode")
}
// Open a data file.
db := NewTestDB()
path := db.Path()
defer db.Close()
// Insert until we get above the minimum 4MB size.
var index uint64
for i := 0; i < 10000; i++ {
ok(t, db.Update(func(tx *bolt.Tx) error {
b, _ := tx.CreateBucketIfNotExists([]byte("data"))
for j := 0; j < 1000; j++ {
ok(t, b.Put(u64tob(index), make([]byte, 50)))
index++
}
return nil
}))
}
// Close database and grab the size.
db.DB.Close()
sz := fileSize(path)
if sz == 0 {
t.Fatalf("unexpected new file size: %d", sz)
} else if sz < (1 << 30) {
t.Fatalf("expected larger initial size: %d", sz)
}
// Reopen database, update, and check size again.
db0, err := bolt.Open(path, 0666, nil)
ok(t, err)
ok(t, db0.Update(func(tx *bolt.Tx) error { return tx.Bucket([]byte("data")).Put([]byte{0}, []byte{0}) }))
ok(t, db0.Close())
newSz := fileSize(path)
if newSz == 0 {
t.Fatalf("unexpected new file size: %d", newSz)
}
// Compare the original size with the new size.
if sz != newSz {
t.Fatalf("unexpected file growth: %d => %d", sz, newSz)
}
}
// Ensure that a re-opened database is consistent.
func TestOpen_Check(t *testing.T) {
path := tempfile()
defer os.Remove(path)
db, err := bolt.Open(path, 0666, nil)
ok(t, err)
ok(t, db.View(func(tx *bolt.Tx) error { return <-tx.Check() }))
db.Close()
db, err = bolt.Open(path, 0666, nil)
ok(t, err)
ok(t, db.View(func(tx *bolt.Tx) error { return <-tx.Check() }))
db.Close()
}
// Ensure that the database returns an error if the file handle cannot be open.
func TestDB_Open_FileError(t *testing.T) {
path := tempfile()
defer os.Remove(path)
_, err := bolt.Open(path+"/youre-not-my-real-parent", 0666, nil)
assert(t, err.(*os.PathError) != nil, "")
equals(t, path+"/youre-not-my-real-parent", err.(*os.PathError).Path)
equals(t, "open", err.(*os.PathError).Op)
}
// Ensure that write errors to the meta file handler during initialization are returned.
func TestDB_Open_MetaInitWriteError(t *testing.T) {
t.Skip("pending")
}
// Ensure that a database that is too small returns an error.
func TestDB_Open_FileTooSmall(t *testing.T) {
path := tempfile()
defer os.Remove(path)
db, err := bolt.Open(path, 0666, nil)
ok(t, err)
db.Close()
// corrupt the database
ok(t, os.Truncate(path, int64(os.Getpagesize())))
db, err = bolt.Open(path, 0666, nil)
equals(t, errors.New("file size too small"), err)
}
// Ensure that a database can be opened in read-only mode by multiple processes
// and that a database can not be opened in read-write mode and in read-only
// mode at the same time.
func TestOpen_ReadOnly(t *testing.T) {
bucket, key, value := []byte(`bucket`), []byte(`key`), []byte(`value`)
path := tempfile()
defer os.Remove(path)
// Open in read-write mode.
db, err := bolt.Open(path, 0666, nil)
ok(t, db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket(bucket)
if err != nil {
return err
}
return b.Put(key, value)
}))
assert(t, db != nil, "")
assert(t, !db.IsReadOnly(), "")
ok(t, err)
ok(t, db.Close())
// Open in read-only mode.
db0, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
ok(t, err)
defer db0.Close()
// Opening in read-write mode should return an error.
_, err = bolt.Open(path, 0666, &bolt.Options{Timeout: time.Millisecond * 100})
assert(t, err != nil, "")
// And again (in read-only mode).
db1, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
ok(t, err)
defer db1.Close()
// Verify both read-only databases are accessible.
for _, db := range []*bolt.DB{db0, db1} {
// Verify is is in read only mode indeed.
assert(t, db.IsReadOnly(), "")
// Read-only databases should not allow updates.
assert(t,
bolt.ErrDatabaseReadOnly == db.Update(func(*bolt.Tx) error {
panic(`should never get here`)
}),
"")
// Read-only databases should not allow beginning writable txns.
_, err = db.Begin(true)
assert(t, bolt.ErrDatabaseReadOnly == err, "")
// Verify the data.
ok(t, db.View(func(tx *bolt.Tx) error {
b := tx.Bucket(bucket)
if b == nil {
return fmt.Errorf("expected bucket `%s`", string(bucket))
}
got := string(b.Get(key))
expected := string(value)
if got != expected {
return fmt.Errorf("expected `%s`, got `%s`", expected, got)
}
return nil
}))
}
}
// TODO(benbjohnson): Test corruption at every byte of the first two pages.
// Ensure that a database cannot open a transaction when it's not open.
func TestDB_Begin_DatabaseNotOpen(t *testing.T) {
var db bolt.DB
tx, err := db.Begin(false)
assert(t, tx == nil, "")
equals(t, err, bolt.ErrDatabaseNotOpen)
}
// Ensure that a read-write transaction can be retrieved.
func TestDB_BeginRW(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, err := db.Begin(true)
assert(t, tx != nil, "")
ok(t, err)
assert(t, tx.DB() == db.DB, "")
equals(t, tx.Writable(), true)
ok(t, tx.Commit())
}
// Ensure that opening a transaction while the DB is closed returns an error.
func TestDB_BeginRW_Closed(t *testing.T) {
var db bolt.DB
tx, err := db.Begin(true)
equals(t, err, bolt.ErrDatabaseNotOpen)
assert(t, tx == nil, "")
}
func TestDB_Close_PendingTx_RW(t *testing.T) { testDB_Close_PendingTx(t, true) }
func TestDB_Close_PendingTx_RO(t *testing.T) { testDB_Close_PendingTx(t, false) }
// Ensure that a database cannot close while transactions are open.
func testDB_Close_PendingTx(t *testing.T, writable bool) {
db := NewTestDB()
defer db.Close()
// Start transaction.
tx, err := db.Begin(true)
if err != nil {
t.Fatal(err)
}
// Open update in separate goroutine.
done := make(chan struct{})
go func() {
db.Close()
close(done)
}()
// Ensure database hasn't closed.
time.Sleep(100 * time.Millisecond)
select {
case <-done:
t.Fatal("database closed too early")
default:
}
// Commit transaction.
if err := tx.Commit(); err != nil {
t.Fatal(err)
}
// Ensure database closed now.
time.Sleep(100 * time.Millisecond)
select {
case <-done:
default:
t.Fatal("database did not close")
}
}
// Ensure a database can provide a transactional block.
func TestDB_Update(t *testing.T) {
db := NewTestDB()
defer db.Close()
err := db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
b := tx.Bucket([]byte("widgets"))
b.Put([]byte("foo"), []byte("bar"))
b.Put([]byte("baz"), []byte("bat"))
b.Delete([]byte("foo"))
return nil
})
ok(t, err)
err = db.View(func(tx *bolt.Tx) error {
assert(t, tx.Bucket([]byte("widgets")).Get([]byte("foo")) == nil, "")
equals(t, []byte("bat"), tx.Bucket([]byte("widgets")).Get([]byte("baz")))
return nil
})
ok(t, err)
}
// Ensure a closed database returns an error while running a transaction block
func TestDB_Update_Closed(t *testing.T) {
var db bolt.DB
err := db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
return nil
})
equals(t, err, bolt.ErrDatabaseNotOpen)
}
// Ensure a panic occurs while trying to commit a managed transaction.
func TestDB_Update_ManualCommit(t *testing.T) {
db := NewTestDB()
defer db.Close()
var ok bool
db.Update(func(tx *bolt.Tx) error {
func() {
defer func() {
if r := recover(); r != nil {
ok = true
}
}()
tx.Commit()
}()
return nil
})
assert(t, ok, "expected panic")
}
// Ensure a panic occurs while trying to rollback a managed transaction.
func TestDB_Update_ManualRollback(t *testing.T) {
db := NewTestDB()
defer db.Close()
var ok bool
db.Update(func(tx *bolt.Tx) error {
func() {
defer func() {
if r := recover(); r != nil {
ok = true
}
}()
tx.Rollback()
}()
return nil
})
assert(t, ok, "expected panic")
}
// Ensure a panic occurs while trying to commit a managed transaction.
func TestDB_View_ManualCommit(t *testing.T) {
db := NewTestDB()
defer db.Close()
var ok bool
db.Update(func(tx *bolt.Tx) error {
func() {
defer func() {
if r := recover(); r != nil {
ok = true
}
}()
tx.Commit()
}()
return nil
})
assert(t, ok, "expected panic")
}
// Ensure a panic occurs while trying to rollback a managed transaction.
func TestDB_View_ManualRollback(t *testing.T) {
db := NewTestDB()
defer db.Close()
var ok bool
db.Update(func(tx *bolt.Tx) error {
func() {
defer func() {
if r := recover(); r != nil {
ok = true
}
}()
tx.Rollback()
}()
return nil
})
assert(t, ok, "expected panic")
}
// Ensure a write transaction that panics does not hold open locks.
func TestDB_Update_Panic(t *testing.T) {
db := NewTestDB()
defer db.Close()
func() {
defer func() {
if r := recover(); r != nil {
t.Log("recover: update", r)
}
}()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
panic("omg")
})
}()
// Verify we can update again.
err := db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
ok(t, err)
// Verify that our change persisted.
err = db.Update(func(tx *bolt.Tx) error {
assert(t, tx.Bucket([]byte("widgets")) != nil, "")
return nil
})
}
// Ensure a database can return an error through a read-only transactional block.
func TestDB_View_Error(t *testing.T) {
db := NewTestDB()
defer db.Close()
err := db.View(func(tx *bolt.Tx) error {
return errors.New("xxx")
})
equals(t, errors.New("xxx"), err)
}
// Ensure a read transaction that panics does not hold open locks.
func TestDB_View_Panic(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
return nil
})
func() {
defer func() {
if r := recover(); r != nil {
t.Log("recover: view", r)
}
}()
db.View(func(tx *bolt.Tx) error {
assert(t, tx.Bucket([]byte("widgets")) != nil, "")
panic("omg")
})
}()
// Verify that we can still use read transactions.
db.View(func(tx *bolt.Tx) error {
assert(t, tx.Bucket([]byte("widgets")) != nil, "")
return nil
})
}
// Ensure that an error is returned when a database write fails.
func TestDB_Commit_WriteFail(t *testing.T) {
t.Skip("pending") // TODO(benbjohnson)
}
// Ensure that DB stats can be returned.
func TestDB_Stats(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
stats := db.Stats()
equals(t, 2, stats.TxStats.PageCount)
equals(t, 0, stats.FreePageN)
equals(t, 2, stats.PendingPageN)
}
// Ensure that database pages are in expected order and type.
func TestDB_Consistency(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
for i := 0; i < 10; i++ {
db.Update(func(tx *bolt.Tx) error {
ok(t, tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar")))
return nil
})
}
db.Update(func(tx *bolt.Tx) error {
p, _ := tx.Page(0)
assert(t, p != nil, "")
equals(t, "meta", p.Type)
p, _ = tx.Page(1)
assert(t, p != nil, "")
equals(t, "meta", p.Type)
p, _ = tx.Page(2)
assert(t, p != nil, "")
equals(t, "free", p.Type)
p, _ = tx.Page(3)
assert(t, p != nil, "")
equals(t, "free", p.Type)
p, _ = tx.Page(4)
assert(t, p != nil, "")
equals(t, "leaf", p.Type)
p, _ = tx.Page(5)
assert(t, p != nil, "")
equals(t, "freelist", p.Type)
p, _ = tx.Page(6)
assert(t, p == nil, "")
return nil
})
}
// Ensure that DB stats can be substracted from one another.
func TestDBStats_Sub(t *testing.T) {
var a, b bolt.Stats
a.TxStats.PageCount = 3
a.FreePageN = 4
b.TxStats.PageCount = 10
b.FreePageN = 14
diff := b.Sub(&a)
equals(t, 7, diff.TxStats.PageCount)
// free page stats are copied from the receiver and not subtracted
equals(t, 14, diff.FreePageN)
}
func ExampleDB_Update() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Execute several commands within a write transaction.
err := db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
if err != nil {
return err
}
if err := b.Put([]byte("foo"), []byte("bar")); err != nil {
return err
}
return nil
})
// If our transactional block didn't return an error then our data is saved.
if err == nil {
db.View(func(tx *bolt.Tx) error {
value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
fmt.Printf("The value of 'foo' is: %s\n", value)
return nil
})
}
// Output:
// The value of 'foo' is: bar
}
func ExampleDB_View() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Insert data into a bucket.
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("people"))
b := tx.Bucket([]byte("people"))
b.Put([]byte("john"), []byte("doe"))
b.Put([]byte("susy"), []byte("que"))
return nil
})
// Access data from within a read-only transactional block.
db.View(func(tx *bolt.Tx) error {
v := tx.Bucket([]byte("people")).Get([]byte("john"))
fmt.Printf("John's last name is %s.\n", v)
return nil
})
// Output:
// John's last name is doe.
}
func ExampleDB_Begin_ReadOnly() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Create a bucket.
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
// Create several keys in a transaction.
tx, _ := db.Begin(true)
b := tx.Bucket([]byte("widgets"))
b.Put([]byte("john"), []byte("blue"))
b.Put([]byte("abby"), []byte("red"))
b.Put([]byte("zephyr"), []byte("purple"))
tx.Commit()
// Iterate over the values in sorted key order.
tx, _ = db.Begin(false)
c := tx.Bucket([]byte("widgets")).Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("%s likes %s\n", k, v)
}
tx.Rollback()
// Output:
// abby likes red
// john likes blue
// zephyr likes purple
}
// TestDB represents a wrapper around a Bolt DB to handle temporary file
// creation and automatic cleanup on close.
type TestDB struct {
*bolt.DB
}
// NewTestDB returns a new instance of TestDB.
func NewTestDB() *TestDB {
db, err := bolt.Open(tempfile(), 0666, nil)
if err != nil {
panic("cannot open db: " + err.Error())
}
return &TestDB{db}
}
// MustView executes a read-only function. Panic on error.
func (db *TestDB) MustView(fn func(tx *bolt.Tx) error) {
if err := db.DB.View(func(tx *bolt.Tx) error {
return fn(tx)
}); err != nil {
panic(err.Error())
}
}
// MustUpdate executes a read-write function. Panic on error.
func (db *TestDB) MustUpdate(fn func(tx *bolt.Tx) error) {
if err := db.DB.View(func(tx *bolt.Tx) error {
return fn(tx)
}); err != nil {
panic(err.Error())
}
}
// MustCreateBucket creates a new bucket. Panic on error.
func (db *TestDB) MustCreateBucket(name []byte) {
if err := db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte(name))
return err
}); err != nil {
panic(err.Error())
}
}
// Close closes the database and deletes the underlying file.
func (db *TestDB) Close() {
// Log statistics.
if *statsFlag {
db.PrintStats()
}
// Check database consistency after every test.
db.MustCheck()
// Close database and remove file.
defer os.Remove(db.Path())
db.DB.Close()
}
// PrintStats prints the database stats
func (db *TestDB) PrintStats() {
var stats = db.Stats()
fmt.Printf("[db] %-20s %-20s %-20s\n",
fmt.Sprintf("pg(%d/%d)", stats.TxStats.PageCount, stats.TxStats.PageAlloc),
fmt.Sprintf("cur(%d)", stats.TxStats.CursorCount),
fmt.Sprintf("node(%d/%d)", stats.TxStats.NodeCount, stats.TxStats.NodeDeref),
)
fmt.Printf(" %-20s %-20s %-20s\n",
fmt.Sprintf("rebal(%d/%v)", stats.TxStats.Rebalance, truncDuration(stats.TxStats.RebalanceTime)),
fmt.Sprintf("spill(%d/%v)", stats.TxStats.Spill, truncDuration(stats.TxStats.SpillTime)),
fmt.Sprintf("w(%d/%v)", stats.TxStats.Write, truncDuration(stats.TxStats.WriteTime)),
)
}
// MustCheck runs a consistency check on the database and panics if any errors are found.
func (db *TestDB) MustCheck() {
db.Update(func(tx *bolt.Tx) error {
// Collect all the errors.
var errors []error
for err := range tx.Check() {
errors = append(errors, err)
if len(errors) > 10 {
break
}
}
// If errors occurred, copy the DB and print the errors.
if len(errors) > 0 {
var path = tempfile()
tx.CopyFile(path, 0600)
// Print errors.
fmt.Print("\n\n")
fmt.Printf("consistency check failed (%d errors)\n", len(errors))
for _, err := range errors {
fmt.Println(err)
}
fmt.Println("")
fmt.Println("db saved to:")
fmt.Println(path)
fmt.Print("\n\n")
os.Exit(-1)
}
return nil
})
}
// CopyTempFile copies a database to a temporary file.
func (db *TestDB) CopyTempFile() {
path := tempfile()
db.View(func(tx *bolt.Tx) error { return tx.CopyFile(path, 0600) })
fmt.Println("db copied to: ", path)
}
// tempfile returns a temporary file path.
func tempfile() string {
f, _ := ioutil.TempFile("", "bolt-")
f.Close()
os.Remove(f.Name())
return f.Name()
}
// mustContainKeys checks that a bucket contains a given set of keys.
func mustContainKeys(b *bolt.Bucket, m map[string]string) {
found := make(map[string]string)
b.ForEach(func(k, _ []byte) error {
found[string(k)] = ""
return nil
})
// Check for keys found in bucket that shouldn't be there.
var keys []string
for k, _ := range found {
if _, ok := m[string(k)]; !ok {
keys = append(keys, k)
}
}
if len(keys) > 0 {
sort.Strings(keys)
panic(fmt.Sprintf("keys found(%d): %s", len(keys), strings.Join(keys, ",")))
}
// Check for keys not found in bucket that should be there.
for k, _ := range m {
if _, ok := found[string(k)]; !ok {
keys = append(keys, k)
}
}
if len(keys) > 0 {
sort.Strings(keys)
panic(fmt.Sprintf("keys not found(%d): %s", len(keys), strings.Join(keys, ",")))
}
}
func trunc(b []byte, length int) []byte {
if length < len(b) {
return b[:length]
}
return b
}
func truncDuration(d time.Duration) string {
return regexp.MustCompile(`^(\d+)(\.\d+)`).ReplaceAllString(d.String(), "$1")
}
func fileSize(path string) int64 {
fi, err := os.Stat(path)
if err != nil {
return 0
}
return fi.Size()
}
func warn(v ...interface{}) { fmt.Fprintln(os.Stderr, v...) }
func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr, msg+"\n", v...) }
// u64tob converts a uint64 into an 8-byte slice.
func u64tob(v uint64) []byte {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, v)
return b
}
// btou64 converts an 8-byte slice into an uint64.
func btou64(b []byte) uint64 { return binary.BigEndian.Uint64(b) }

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/*
Package bolt implements a low-level key/value store in pure Go. It supports
fully serializable transactions, ACID semantics, and lock-free MVCC with
multiple readers and a single writer. Bolt can be used for projects that
want a simple data store without the need to add large dependencies such as
Postgres or MySQL.
Bolt is a single-level, zero-copy, B+tree data store. This means that Bolt is
optimized for fast read access and does not require recovery in the event of a
system crash. Transactions which have not finished committing will simply be
rolled back in the event of a crash.
The design of Bolt is based on Howard Chu's LMDB database project.
Bolt currently works on Windows, Mac OS X, and Linux.
Basics
There are only a few types in Bolt: DB, Bucket, Tx, and Cursor. The DB is
a collection of buckets and is represented by a single file on disk. A bucket is
a collection of unique keys that are associated with values.
Transactions provide either read-only or read-write access to the database.
Read-only transactions can retrieve key/value pairs and can use Cursors to
iterate over the dataset sequentially. Read-write transactions can create and
delete buckets and can insert and remove keys. Only one read-write transaction
is allowed at a time.
Caveats
The database uses a read-only, memory-mapped data file to ensure that
applications cannot corrupt the database, however, this means that keys and
values returned from Bolt cannot be changed. Writing to a read-only byte slice
will cause Go to panic.
Keys and values retrieved from the database are only valid for the life of
the transaction. When used outside the transaction, these byte slices can
point to different data or can point to invalid memory which will cause a panic.
*/
package bolt

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package bolt
import "errors"
// These errors can be returned when opening or calling methods on a DB.
var (
// ErrDatabaseNotOpen is returned when a DB instance is accessed before it
// is opened or after it is closed.
ErrDatabaseNotOpen = errors.New("database not open")
// ErrDatabaseOpen is returned when opening a database that is
// already open.
ErrDatabaseOpen = errors.New("database already open")
// ErrInvalid is returned when a data file is not a Bolt-formatted database.
ErrInvalid = errors.New("invalid database")
// ErrVersionMismatch is returned when the data file was created with a
// different version of Bolt.
ErrVersionMismatch = errors.New("version mismatch")
// ErrChecksum is returned when either meta page checksum does not match.
ErrChecksum = errors.New("checksum error")
// ErrTimeout is returned when a database cannot obtain an exclusive lock
// on the data file after the timeout passed to Open().
ErrTimeout = errors.New("timeout")
)
// These errors can occur when beginning or committing a Tx.
var (
// ErrTxNotWritable is returned when performing a write operation on a
// read-only transaction.
ErrTxNotWritable = errors.New("tx not writable")
// ErrTxClosed is returned when committing or rolling back a transaction
// that has already been committed or rolled back.
ErrTxClosed = errors.New("tx closed")
// ErrDatabaseReadOnly is returned when a mutating transaction is started on a
// read-only database.
ErrDatabaseReadOnly = errors.New("database is in read-only mode")
)
// These errors can occur when putting or deleting a value or a bucket.
var (
// ErrBucketNotFound is returned when trying to access a bucket that has
// not been created yet.
ErrBucketNotFound = errors.New("bucket not found")
// ErrBucketExists is returned when creating a bucket that already exists.
ErrBucketExists = errors.New("bucket already exists")
// ErrBucketNameRequired is returned when creating a bucket with a blank name.
ErrBucketNameRequired = errors.New("bucket name required")
// ErrKeyRequired is returned when inserting a zero-length key.
ErrKeyRequired = errors.New("key required")
// ErrKeyTooLarge is returned when inserting a key that is larger than MaxKeySize.
ErrKeyTooLarge = errors.New("key too large")
// ErrValueTooLarge is returned when inserting a value that is larger than MaxValueSize.
ErrValueTooLarge = errors.New("value too large")
// ErrIncompatibleValue is returned when trying create or delete a bucket
// on an existing non-bucket key or when trying to create or delete a
// non-bucket key on an existing bucket key.
ErrIncompatibleValue = errors.New("incompatible value")
)

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@ -0,0 +1,242 @@
package bolt
import (
"fmt"
"sort"
"unsafe"
)
// freelist represents a list of all pages that are available for allocation.
// It also tracks pages that have been freed but are still in use by open transactions.
type freelist struct {
ids []pgid // all free and available free page ids.
pending map[txid][]pgid // mapping of soon-to-be free page ids by tx.
cache map[pgid]bool // fast lookup of all free and pending page ids.
}
// newFreelist returns an empty, initialized freelist.
func newFreelist() *freelist {
return &freelist{
pending: make(map[txid][]pgid),
cache: make(map[pgid]bool),
}
}
// size returns the size of the page after serialization.
func (f *freelist) size() int {
return pageHeaderSize + (int(unsafe.Sizeof(pgid(0))) * f.count())
}
// count returns count of pages on the freelist
func (f *freelist) count() int {
return f.free_count() + f.pending_count()
}
// free_count returns count of free pages
func (f *freelist) free_count() int {
return len(f.ids)
}
// pending_count returns count of pending pages
func (f *freelist) pending_count() int {
var count int
for _, list := range f.pending {
count += len(list)
}
return count
}
// all returns a list of all free ids and all pending ids in one sorted list.
func (f *freelist) all() []pgid {
m := make(pgids, 0)
for _, list := range f.pending {
m = append(m, list...)
}
sort.Sort(m)
return pgids(f.ids).merge(m)
}
// allocate returns the starting page id of a contiguous list of pages of a given size.
// If a contiguous block cannot be found then 0 is returned.
func (f *freelist) allocate(n int) pgid {
if len(f.ids) == 0 {
return 0
}
var initial, previd pgid
for i, id := range f.ids {
if id <= 1 {
panic(fmt.Sprintf("invalid page allocation: %d", id))
}
// Reset initial page if this is not contiguous.
if previd == 0 || id-previd != 1 {
initial = id
}
// If we found a contiguous block then remove it and return it.
if (id-initial)+1 == pgid(n) {
// If we're allocating off the beginning then take the fast path
// and just adjust the existing slice. This will use extra memory
// temporarily but the append() in free() will realloc the slice
// as is necessary.
if (i + 1) == n {
f.ids = f.ids[i+1:]
} else {
copy(f.ids[i-n+1:], f.ids[i+1:])
f.ids = f.ids[:len(f.ids)-n]
}
// Remove from the free cache.
for i := pgid(0); i < pgid(n); i++ {
delete(f.cache, initial+i)
}
return initial
}
previd = id
}
return 0
}
// free releases a page and its overflow for a given transaction id.
// If the page is already free then a panic will occur.
func (f *freelist) free(txid txid, p *page) {
if p.id <= 1 {
panic(fmt.Sprintf("cannot free page 0 or 1: %d", p.id))
}
// Free page and all its overflow pages.
var ids = f.pending[txid]
for id := p.id; id <= p.id+pgid(p.overflow); id++ {
// Verify that page is not already free.
if f.cache[id] {
panic(fmt.Sprintf("page %d already freed", id))
}
// Add to the freelist and cache.
ids = append(ids, id)
f.cache[id] = true
}
f.pending[txid] = ids
}
// release moves all page ids for a transaction id (or older) to the freelist.
func (f *freelist) release(txid txid) {
m := make(pgids, 0)
for tid, ids := range f.pending {
if tid <= txid {
// Move transaction's pending pages to the available freelist.
// Don't remove from the cache since the page is still free.
m = append(m, ids...)
delete(f.pending, tid)
}
}
sort.Sort(m)
f.ids = pgids(f.ids).merge(m)
}
// rollback removes the pages from a given pending tx.
func (f *freelist) rollback(txid txid) {
// Remove page ids from cache.
for _, id := range f.pending[txid] {
delete(f.cache, id)
}
// Remove pages from pending list.
delete(f.pending, txid)
}
// freed returns whether a given page is in the free list.
func (f *freelist) freed(pgid pgid) bool {
return f.cache[pgid]
}
// read initializes the freelist from a freelist page.
func (f *freelist) read(p *page) {
// If the page.count is at the max uint16 value (64k) then it's considered
// an overflow and the size of the freelist is stored as the first element.
idx, count := 0, int(p.count)
if count == 0xFFFF {
idx = 1
count = int(((*[maxAllocSize]pgid)(unsafe.Pointer(&p.ptr)))[0])
}
// Copy the list of page ids from the freelist.
ids := ((*[maxAllocSize]pgid)(unsafe.Pointer(&p.ptr)))[idx:count]
f.ids = make([]pgid, len(ids))
copy(f.ids, ids)
// Make sure they're sorted.
sort.Sort(pgids(f.ids))
// Rebuild the page cache.
f.reindex()
}
// write writes the page ids onto a freelist page. All free and pending ids are
// saved to disk since in the event of a program crash, all pending ids will
// become free.
func (f *freelist) write(p *page) error {
// Combine the old free pgids and pgids waiting on an open transaction.
ids := f.all()
// Update the header flag.
p.flags |= freelistPageFlag
// The page.count can only hold up to 64k elements so if we overflow that
// number then we handle it by putting the size in the first element.
if len(ids) < 0xFFFF {
p.count = uint16(len(ids))
copy(((*[maxAllocSize]pgid)(unsafe.Pointer(&p.ptr)))[:], ids)
} else {
p.count = 0xFFFF
((*[maxAllocSize]pgid)(unsafe.Pointer(&p.ptr)))[0] = pgid(len(ids))
copy(((*[maxAllocSize]pgid)(unsafe.Pointer(&p.ptr)))[1:], ids)
}
return nil
}
// reload reads the freelist from a page and filters out pending items.
func (f *freelist) reload(p *page) {
f.read(p)
// Build a cache of only pending pages.
pcache := make(map[pgid]bool)
for _, pendingIDs := range f.pending {
for _, pendingID := range pendingIDs {
pcache[pendingID] = true
}
}
// Check each page in the freelist and build a new available freelist
// with any pages not in the pending lists.
var a []pgid
for _, id := range f.ids {
if !pcache[id] {
a = append(a, id)
}
}
f.ids = a
// Once the available list is rebuilt then rebuild the free cache so that
// it includes the available and pending free pages.
f.reindex()
}
// reindex rebuilds the free cache based on available and pending free lists.
func (f *freelist) reindex() {
f.cache = make(map[pgid]bool)
for _, id := range f.ids {
f.cache[id] = true
}
for _, pendingIDs := range f.pending {
for _, pendingID := range pendingIDs {
f.cache[pendingID] = true
}
}
}

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package bolt
import (
"math/rand"
"reflect"
"sort"
"testing"
"unsafe"
)
// Ensure that a page is added to a transaction's freelist.
func TestFreelist_free(t *testing.T) {
f := newFreelist()
f.free(100, &page{id: 12})
if !reflect.DeepEqual([]pgid{12}, f.pending[100]) {
t.Fatalf("exp=%v; got=%v", []pgid{12}, f.pending[100])
}
}
// Ensure that a page and its overflow is added to a transaction's freelist.
func TestFreelist_free_overflow(t *testing.T) {
f := newFreelist()
f.free(100, &page{id: 12, overflow: 3})
if exp := []pgid{12, 13, 14, 15}; !reflect.DeepEqual(exp, f.pending[100]) {
t.Fatalf("exp=%v; got=%v", exp, f.pending[100])
}
}
// Ensure that a transaction's free pages can be released.
func TestFreelist_release(t *testing.T) {
f := newFreelist()
f.free(100, &page{id: 12, overflow: 1})
f.free(100, &page{id: 9})
f.free(102, &page{id: 39})
f.release(100)
f.release(101)
if exp := []pgid{9, 12, 13}; !reflect.DeepEqual(exp, f.ids) {
t.Fatalf("exp=%v; got=%v", exp, f.ids)
}
f.release(102)
if exp := []pgid{9, 12, 13, 39}; !reflect.DeepEqual(exp, f.ids) {
t.Fatalf("exp=%v; got=%v", exp, f.ids)
}
}
// Ensure that a freelist can find contiguous blocks of pages.
func TestFreelist_allocate(t *testing.T) {
f := &freelist{ids: []pgid{3, 4, 5, 6, 7, 9, 12, 13, 18}}
if id := int(f.allocate(3)); id != 3 {
t.Fatalf("exp=3; got=%v", id)
}
if id := int(f.allocate(1)); id != 6 {
t.Fatalf("exp=6; got=%v", id)
}
if id := int(f.allocate(3)); id != 0 {
t.Fatalf("exp=0; got=%v", id)
}
if id := int(f.allocate(2)); id != 12 {
t.Fatalf("exp=12; got=%v", id)
}
if id := int(f.allocate(1)); id != 7 {
t.Fatalf("exp=7; got=%v", id)
}
if id := int(f.allocate(0)); id != 0 {
t.Fatalf("exp=0; got=%v", id)
}
if id := int(f.allocate(0)); id != 0 {
t.Fatalf("exp=0; got=%v", id)
}
if exp := []pgid{9, 18}; !reflect.DeepEqual(exp, f.ids) {
t.Fatalf("exp=%v; got=%v", exp, f.ids)
}
if id := int(f.allocate(1)); id != 9 {
t.Fatalf("exp=9; got=%v", id)
}
if id := int(f.allocate(1)); id != 18 {
t.Fatalf("exp=18; got=%v", id)
}
if id := int(f.allocate(1)); id != 0 {
t.Fatalf("exp=0; got=%v", id)
}
if exp := []pgid{}; !reflect.DeepEqual(exp, f.ids) {
t.Fatalf("exp=%v; got=%v", exp, f.ids)
}
}
// Ensure that a freelist can deserialize from a freelist page.
func TestFreelist_read(t *testing.T) {
// Create a page.
var buf [4096]byte
page := (*page)(unsafe.Pointer(&buf[0]))
page.flags = freelistPageFlag
page.count = 2
// Insert 2 page ids.
ids := (*[3]pgid)(unsafe.Pointer(&page.ptr))
ids[0] = 23
ids[1] = 50
// Deserialize page into a freelist.
f := newFreelist()
f.read(page)
// Ensure that there are two page ids in the freelist.
if exp := []pgid{23, 50}; !reflect.DeepEqual(exp, f.ids) {
t.Fatalf("exp=%v; got=%v", exp, f.ids)
}
}
// Ensure that a freelist can serialize into a freelist page.
func TestFreelist_write(t *testing.T) {
// Create a freelist and write it to a page.
var buf [4096]byte
f := &freelist{ids: []pgid{12, 39}, pending: make(map[txid][]pgid)}
f.pending[100] = []pgid{28, 11}
f.pending[101] = []pgid{3}
p := (*page)(unsafe.Pointer(&buf[0]))
f.write(p)
// Read the page back out.
f2 := newFreelist()
f2.read(p)
// Ensure that the freelist is correct.
// All pages should be present and in reverse order.
if exp := []pgid{3, 11, 12, 28, 39}; !reflect.DeepEqual(exp, f2.ids) {
t.Fatalf("exp=%v; got=%v", exp, f2.ids)
}
}
func Benchmark_FreelistRelease10K(b *testing.B) { benchmark_FreelistRelease(b, 10000) }
func Benchmark_FreelistRelease100K(b *testing.B) { benchmark_FreelistRelease(b, 100000) }
func Benchmark_FreelistRelease1000K(b *testing.B) { benchmark_FreelistRelease(b, 1000000) }
func Benchmark_FreelistRelease10000K(b *testing.B) { benchmark_FreelistRelease(b, 10000000) }
func benchmark_FreelistRelease(b *testing.B, size int) {
ids := randomPgids(size)
pending := randomPgids(len(ids) / 400)
b.ResetTimer()
for i := 0; i < b.N; i++ {
f := &freelist{ids: ids, pending: map[txid][]pgid{1: pending}}
f.release(1)
}
}
func randomPgids(n int) []pgid {
rand.Seed(42)
pgids := make(pgids, n)
for i := range pgids {
pgids[i] = pgid(rand.Int63())
}
sort.Sort(pgids)
return pgids
}

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package bolt
import (
"bytes"
"fmt"
"sort"
"unsafe"
)
// node represents an in-memory, deserialized page.
type node struct {
bucket *Bucket
isLeaf bool
unbalanced bool
spilled bool
key []byte
pgid pgid
parent *node
children nodes
inodes inodes
}
// root returns the top-level node this node is attached to.
func (n *node) root() *node {
if n.parent == nil {
return n
}
return n.parent.root()
}
// minKeys returns the minimum number of inodes this node should have.
func (n *node) minKeys() int {
if n.isLeaf {
return 1
}
return 2
}
// size returns the size of the node after serialization.
func (n *node) size() int {
sz, elsz := pageHeaderSize, n.pageElementSize()
for i := 0; i < len(n.inodes); i++ {
item := &n.inodes[i]
sz += elsz + len(item.key) + len(item.value)
}
return sz
}
// sizeLessThan returns true if the node is less than a given size.
// This is an optimization to avoid calculating a large node when we only need
// to know if it fits inside a certain page size.
func (n *node) sizeLessThan(v int) bool {
sz, elsz := pageHeaderSize, n.pageElementSize()
for i := 0; i < len(n.inodes); i++ {
item := &n.inodes[i]
sz += elsz + len(item.key) + len(item.value)
if sz >= v {
return false
}
}
return true
}
// pageElementSize returns the size of each page element based on the type of node.
func (n *node) pageElementSize() int {
if n.isLeaf {
return leafPageElementSize
}
return branchPageElementSize
}
// childAt returns the child node at a given index.
func (n *node) childAt(index int) *node {
if n.isLeaf {
panic(fmt.Sprintf("invalid childAt(%d) on a leaf node", index))
}
return n.bucket.node(n.inodes[index].pgid, n)
}
// childIndex returns the index of a given child node.
func (n *node) childIndex(child *node) int {
index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, child.key) != -1 })
return index
}
// numChildren returns the number of children.
func (n *node) numChildren() int {
return len(n.inodes)
}
// nextSibling returns the next node with the same parent.
func (n *node) nextSibling() *node {
if n.parent == nil {
return nil
}
index := n.parent.childIndex(n)
if index >= n.parent.numChildren()-1 {
return nil
}
return n.parent.childAt(index + 1)
}
// prevSibling returns the previous node with the same parent.
func (n *node) prevSibling() *node {
if n.parent == nil {
return nil
}
index := n.parent.childIndex(n)
if index == 0 {
return nil
}
return n.parent.childAt(index - 1)
}
// put inserts a key/value.
func (n *node) put(oldKey, newKey, value []byte, pgid pgid, flags uint32) {
if pgid >= n.bucket.tx.meta.pgid {
panic(fmt.Sprintf("pgid (%d) above high water mark (%d)", pgid, n.bucket.tx.meta.pgid))
} else if len(oldKey) <= 0 {
panic("put: zero-length old key")
} else if len(newKey) <= 0 {
panic("put: zero-length new key")
}
// Find insertion index.
index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, oldKey) != -1 })
// Add capacity and shift nodes if we don't have an exact match and need to insert.
exact := (len(n.inodes) > 0 && index < len(n.inodes) && bytes.Equal(n.inodes[index].key, oldKey))
if !exact {
n.inodes = append(n.inodes, inode{})
copy(n.inodes[index+1:], n.inodes[index:])
}
inode := &n.inodes[index]
inode.flags = flags
inode.key = newKey
inode.value = value
inode.pgid = pgid
_assert(len(inode.key) > 0, "put: zero-length inode key")
}
// del removes a key from the node.
func (n *node) del(key []byte) {
// Find index of key.
index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, key) != -1 })
// Exit if the key isn't found.
if index >= len(n.inodes) || !bytes.Equal(n.inodes[index].key, key) {
return
}
// Delete inode from the node.
n.inodes = append(n.inodes[:index], n.inodes[index+1:]...)
// Mark the node as needing rebalancing.
n.unbalanced = true
}
// read initializes the node from a page.
func (n *node) read(p *page) {
n.pgid = p.id
n.isLeaf = ((p.flags & leafPageFlag) != 0)
n.inodes = make(inodes, int(p.count))
for i := 0; i < int(p.count); i++ {
inode := &n.inodes[i]
if n.isLeaf {
elem := p.leafPageElement(uint16(i))
inode.flags = elem.flags
inode.key = elem.key()
inode.value = elem.value()
} else {
elem := p.branchPageElement(uint16(i))
inode.pgid = elem.pgid
inode.key = elem.key()
}
_assert(len(inode.key) > 0, "read: zero-length inode key")
}
// Save first key so we can find the node in the parent when we spill.
if len(n.inodes) > 0 {
n.key = n.inodes[0].key
_assert(len(n.key) > 0, "read: zero-length node key")
} else {
n.key = nil
}
}
// write writes the items onto one or more pages.
func (n *node) write(p *page) {
// Initialize page.
if n.isLeaf {
p.flags |= leafPageFlag
} else {
p.flags |= branchPageFlag
}
if len(n.inodes) >= 0xFFFF {
panic(fmt.Sprintf("inode overflow: %d (pgid=%d)", len(n.inodes), p.id))
}
p.count = uint16(len(n.inodes))
// Loop over each item and write it to the page.
b := (*[maxAllocSize]byte)(unsafe.Pointer(&p.ptr))[n.pageElementSize()*len(n.inodes):]
for i, item := range n.inodes {
_assert(len(item.key) > 0, "write: zero-length inode key")
// Write the page element.
if n.isLeaf {
elem := p.leafPageElement(uint16(i))
elem.pos = uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem)))
elem.flags = item.flags
elem.ksize = uint32(len(item.key))
elem.vsize = uint32(len(item.value))
} else {
elem := p.branchPageElement(uint16(i))
elem.pos = uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem)))
elem.ksize = uint32(len(item.key))
elem.pgid = item.pgid
_assert(elem.pgid != p.id, "write: circular dependency occurred")
}
// If the length of key+value is larger than the max allocation size
// then we need to reallocate the byte array pointer.
//
// See: https://github.com/boltdb/bolt/pull/335
klen, vlen := len(item.key), len(item.value)
if len(b) < klen+vlen {
b = (*[maxAllocSize]byte)(unsafe.Pointer(&b[0]))[:]
}
// Write data for the element to the end of the page.
copy(b[0:], item.key)
b = b[klen:]
copy(b[0:], item.value)
b = b[vlen:]
}
// DEBUG ONLY: n.dump()
}
// split breaks up a node into multiple smaller nodes, if appropriate.
// This should only be called from the spill() function.
func (n *node) split(pageSize int) []*node {
var nodes []*node
node := n
for {
// Split node into two.
a, b := node.splitTwo(pageSize)
nodes = append(nodes, a)
// If we can't split then exit the loop.
if b == nil {
break
}
// Set node to b so it gets split on the next iteration.
node = b
}
return nodes
}
// splitTwo breaks up a node into two smaller nodes, if appropriate.
// This should only be called from the split() function.
func (n *node) splitTwo(pageSize int) (*node, *node) {
// Ignore the split if the page doesn't have at least enough nodes for
// two pages or if the nodes can fit in a single page.
if len(n.inodes) <= (minKeysPerPage*2) || n.sizeLessThan(pageSize) {
return n, nil
}
// Determine the threshold before starting a new node.
var fillPercent = n.bucket.FillPercent
if fillPercent < minFillPercent {
fillPercent = minFillPercent
} else if fillPercent > maxFillPercent {
fillPercent = maxFillPercent
}
threshold := int(float64(pageSize) * fillPercent)
// Determine split position and sizes of the two pages.
splitIndex, _ := n.splitIndex(threshold)
// Split node into two separate nodes.
// If there's no parent then we'll need to create one.
if n.parent == nil {
n.parent = &node{bucket: n.bucket, children: []*node{n}}
}
// Create a new node and add it to the parent.
next := &node{bucket: n.bucket, isLeaf: n.isLeaf, parent: n.parent}
n.parent.children = append(n.parent.children, next)
// Split inodes across two nodes.
next.inodes = n.inodes[splitIndex:]
n.inodes = n.inodes[:splitIndex]
// Update the statistics.
n.bucket.tx.stats.Split++
return n, next
}
// splitIndex finds the position where a page will fill a given threshold.
// It returns the index as well as the size of the first page.
// This is only be called from split().
func (n *node) splitIndex(threshold int) (index, sz int) {
sz = pageHeaderSize
// Loop until we only have the minimum number of keys required for the second page.
for i := 0; i < len(n.inodes)-minKeysPerPage; i++ {
index = i
inode := n.inodes[i]
elsize := n.pageElementSize() + len(inode.key) + len(inode.value)
// If we have at least the minimum number of keys and adding another
// node would put us over the threshold then exit and return.
if i >= minKeysPerPage && sz+elsize > threshold {
break
}
// Add the element size to the total size.
sz += elsize
}
return
}
// spill writes the nodes to dirty pages and splits nodes as it goes.
// Returns an error if dirty pages cannot be allocated.
func (n *node) spill() error {
var tx = n.bucket.tx
if n.spilled {
return nil
}
// Spill child nodes first. Child nodes can materialize sibling nodes in
// the case of split-merge so we cannot use a range loop. We have to check
// the children size on every loop iteration.
sort.Sort(n.children)
for i := 0; i < len(n.children); i++ {
if err := n.children[i].spill(); err != nil {
return err
}
}
// We no longer need the child list because it's only used for spill tracking.
n.children = nil
// Split nodes into appropriate sizes. The first node will always be n.
var nodes = n.split(tx.db.pageSize)
for _, node := range nodes {
// Add node's page to the freelist if it's not new.
if node.pgid > 0 {
tx.db.freelist.free(tx.meta.txid, tx.page(node.pgid))
node.pgid = 0
}
// Allocate contiguous space for the node.
p, err := tx.allocate((node.size() / tx.db.pageSize) + 1)
if err != nil {
return err
}
// Write the node.
if p.id >= tx.meta.pgid {
panic(fmt.Sprintf("pgid (%d) above high water mark (%d)", p.id, tx.meta.pgid))
}
node.pgid = p.id
node.write(p)
node.spilled = true
// Insert into parent inodes.
if node.parent != nil {
var key = node.key
if key == nil {
key = node.inodes[0].key
}
node.parent.put(key, node.inodes[0].key, nil, node.pgid, 0)
node.key = node.inodes[0].key
_assert(len(node.key) > 0, "spill: zero-length node key")
}
// Update the statistics.
tx.stats.Spill++
}
// If the root node split and created a new root then we need to spill that
// as well. We'll clear out the children to make sure it doesn't try to respill.
if n.parent != nil && n.parent.pgid == 0 {
n.children = nil
return n.parent.spill()
}
return nil
}
// rebalance attempts to combine the node with sibling nodes if the node fill
// size is below a threshold or if there are not enough keys.
func (n *node) rebalance() {
if !n.unbalanced {
return
}
n.unbalanced = false
// Update statistics.
n.bucket.tx.stats.Rebalance++
// Ignore if node is above threshold (25%) and has enough keys.
var threshold = n.bucket.tx.db.pageSize / 4
if n.size() > threshold && len(n.inodes) > n.minKeys() {
return
}
// Root node has special handling.
if n.parent == nil {
// If root node is a branch and only has one node then collapse it.
if !n.isLeaf && len(n.inodes) == 1 {
// Move root's child up.
child := n.bucket.node(n.inodes[0].pgid, n)
n.isLeaf = child.isLeaf
n.inodes = child.inodes[:]
n.children = child.children
// Reparent all child nodes being moved.
for _, inode := range n.inodes {
if child, ok := n.bucket.nodes[inode.pgid]; ok {
child.parent = n
}
}
// Remove old child.
child.parent = nil
delete(n.bucket.nodes, child.pgid)
child.free()
}
return
}
// If node has no keys then just remove it.
if n.numChildren() == 0 {
n.parent.del(n.key)
n.parent.removeChild(n)
delete(n.bucket.nodes, n.pgid)
n.free()
n.parent.rebalance()
return
}
_assert(n.parent.numChildren() > 1, "parent must have at least 2 children")
// Destination node is right sibling if idx == 0, otherwise left sibling.
var target *node
var useNextSibling = (n.parent.childIndex(n) == 0)
if useNextSibling {
target = n.nextSibling()
} else {
target = n.prevSibling()
}
// If target node has extra nodes then just move one over.
if target.numChildren() > target.minKeys() {
if useNextSibling {
// Reparent and move node.
if child, ok := n.bucket.nodes[target.inodes[0].pgid]; ok {
child.parent.removeChild(child)
child.parent = n
child.parent.children = append(child.parent.children, child)
}
n.inodes = append(n.inodes, target.inodes[0])
target.inodes = target.inodes[1:]
// Update target key on parent.
target.parent.put(target.key, target.inodes[0].key, nil, target.pgid, 0)
target.key = target.inodes[0].key
_assert(len(target.key) > 0, "rebalance(1): zero-length node key")
} else {
// Reparent and move node.
if child, ok := n.bucket.nodes[target.inodes[len(target.inodes)-1].pgid]; ok {
child.parent.removeChild(child)
child.parent = n
child.parent.children = append(child.parent.children, child)
}
n.inodes = append(n.inodes, inode{})
copy(n.inodes[1:], n.inodes)
n.inodes[0] = target.inodes[len(target.inodes)-1]
target.inodes = target.inodes[:len(target.inodes)-1]
}
// Update parent key for node.
n.parent.put(n.key, n.inodes[0].key, nil, n.pgid, 0)
n.key = n.inodes[0].key
_assert(len(n.key) > 0, "rebalance(2): zero-length node key")
return
}
// If both this node and the target node are too small then merge them.
if useNextSibling {
// Reparent all child nodes being moved.
for _, inode := range target.inodes {
if child, ok := n.bucket.nodes[inode.pgid]; ok {
child.parent.removeChild(child)
child.parent = n
child.parent.children = append(child.parent.children, child)
}
}
// Copy over inodes from target and remove target.
n.inodes = append(n.inodes, target.inodes...)
n.parent.del(target.key)
n.parent.removeChild(target)
delete(n.bucket.nodes, target.pgid)
target.free()
} else {
// Reparent all child nodes being moved.
for _, inode := range n.inodes {
if child, ok := n.bucket.nodes[inode.pgid]; ok {
child.parent.removeChild(child)
child.parent = target
child.parent.children = append(child.parent.children, child)
}
}
// Copy over inodes to target and remove node.
target.inodes = append(target.inodes, n.inodes...)
n.parent.del(n.key)
n.parent.removeChild(n)
delete(n.bucket.nodes, n.pgid)
n.free()
}
// Either this node or the target node was deleted from the parent so rebalance it.
n.parent.rebalance()
}
// removes a node from the list of in-memory children.
// This does not affect the inodes.
func (n *node) removeChild(target *node) {
for i, child := range n.children {
if child == target {
n.children = append(n.children[:i], n.children[i+1:]...)
return
}
}
}
// dereference causes the node to copy all its inode key/value references to heap memory.
// This is required when the mmap is reallocated so inodes are not pointing to stale data.
func (n *node) dereference() {
if n.key != nil {
key := make([]byte, len(n.key))
copy(key, n.key)
n.key = key
_assert(n.pgid == 0 || len(n.key) > 0, "dereference: zero-length node key on existing node")
}
for i := range n.inodes {
inode := &n.inodes[i]
key := make([]byte, len(inode.key))
copy(key, inode.key)
inode.key = key
_assert(len(inode.key) > 0, "dereference: zero-length inode key")
value := make([]byte, len(inode.value))
copy(value, inode.value)
inode.value = value
}
// Recursively dereference children.
for _, child := range n.children {
child.dereference()
}
// Update statistics.
n.bucket.tx.stats.NodeDeref++
}
// free adds the node's underlying page to the freelist.
func (n *node) free() {
if n.pgid != 0 {
n.bucket.tx.db.freelist.free(n.bucket.tx.meta.txid, n.bucket.tx.page(n.pgid))
n.pgid = 0
}
}
// dump writes the contents of the node to STDERR for debugging purposes.
/*
func (n *node) dump() {
// Write node header.
var typ = "branch"
if n.isLeaf {
typ = "leaf"
}
warnf("[NODE %d {type=%s count=%d}]", n.pgid, typ, len(n.inodes))
// Write out abbreviated version of each item.
for _, item := range n.inodes {
if n.isLeaf {
if item.flags&bucketLeafFlag != 0 {
bucket := (*bucket)(unsafe.Pointer(&item.value[0]))
warnf("+L %08x -> (bucket root=%d)", trunc(item.key, 4), bucket.root)
} else {
warnf("+L %08x -> %08x", trunc(item.key, 4), trunc(item.value, 4))
}
} else {
warnf("+B %08x -> pgid=%d", trunc(item.key, 4), item.pgid)
}
}
warn("")
}
*/
type nodes []*node
func (s nodes) Len() int { return len(s) }
func (s nodes) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s nodes) Less(i, j int) bool { return bytes.Compare(s[i].inodes[0].key, s[j].inodes[0].key) == -1 }
// inode represents an internal node inside of a node.
// It can be used to point to elements in a page or point
// to an element which hasn't been added to a page yet.
type inode struct {
flags uint32
pgid pgid
key []byte
value []byte
}
type inodes []inode

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package bolt
import (
"testing"
"unsafe"
)
// Ensure that a node can insert a key/value.
func TestNode_put(t *testing.T) {
n := &node{inodes: make(inodes, 0), bucket: &Bucket{tx: &Tx{meta: &meta{pgid: 1}}}}
n.put([]byte("baz"), []byte("baz"), []byte("2"), 0, 0)
n.put([]byte("foo"), []byte("foo"), []byte("0"), 0, 0)
n.put([]byte("bar"), []byte("bar"), []byte("1"), 0, 0)
n.put([]byte("foo"), []byte("foo"), []byte("3"), 0, leafPageFlag)
if len(n.inodes) != 3 {
t.Fatalf("exp=3; got=%d", len(n.inodes))
}
if k, v := n.inodes[0].key, n.inodes[0].value; string(k) != "bar" || string(v) != "1" {
t.Fatalf("exp=<bar,1>; got=<%s,%s>", k, v)
}
if k, v := n.inodes[1].key, n.inodes[1].value; string(k) != "baz" || string(v) != "2" {
t.Fatalf("exp=<baz,2>; got=<%s,%s>", k, v)
}
if k, v := n.inodes[2].key, n.inodes[2].value; string(k) != "foo" || string(v) != "3" {
t.Fatalf("exp=<foo,3>; got=<%s,%s>", k, v)
}
if n.inodes[2].flags != uint32(leafPageFlag) {
t.Fatalf("not a leaf: %d", n.inodes[2].flags)
}
}
// Ensure that a node can deserialize from a leaf page.
func TestNode_read_LeafPage(t *testing.T) {
// Create a page.
var buf [4096]byte
page := (*page)(unsafe.Pointer(&buf[0]))
page.flags = leafPageFlag
page.count = 2
// Insert 2 elements at the beginning. sizeof(leafPageElement) == 16
nodes := (*[3]leafPageElement)(unsafe.Pointer(&page.ptr))
nodes[0] = leafPageElement{flags: 0, pos: 32, ksize: 3, vsize: 4} // pos = sizeof(leafPageElement) * 2
nodes[1] = leafPageElement{flags: 0, pos: 23, ksize: 10, vsize: 3} // pos = sizeof(leafPageElement) + 3 + 4
// Write data for the nodes at the end.
data := (*[4096]byte)(unsafe.Pointer(&nodes[2]))
copy(data[:], []byte("barfooz"))
copy(data[7:], []byte("helloworldbye"))
// Deserialize page into a leaf.
n := &node{}
n.read(page)
// Check that there are two inodes with correct data.
if !n.isLeaf {
t.Fatal("expected leaf")
}
if len(n.inodes) != 2 {
t.Fatalf("exp=2; got=%d", len(n.inodes))
}
if k, v := n.inodes[0].key, n.inodes[0].value; string(k) != "bar" || string(v) != "fooz" {
t.Fatalf("exp=<bar,fooz>; got=<%s,%s>", k, v)
}
if k, v := n.inodes[1].key, n.inodes[1].value; string(k) != "helloworld" || string(v) != "bye" {
t.Fatalf("exp=<helloworld,bye>; got=<%s,%s>", k, v)
}
}
// Ensure that a node can serialize into a leaf page.
func TestNode_write_LeafPage(t *testing.T) {
// Create a node.
n := &node{isLeaf: true, inodes: make(inodes, 0), bucket: &Bucket{tx: &Tx{db: &DB{}, meta: &meta{pgid: 1}}}}
n.put([]byte("susy"), []byte("susy"), []byte("que"), 0, 0)
n.put([]byte("ricki"), []byte("ricki"), []byte("lake"), 0, 0)
n.put([]byte("john"), []byte("john"), []byte("johnson"), 0, 0)
// Write it to a page.
var buf [4096]byte
p := (*page)(unsafe.Pointer(&buf[0]))
n.write(p)
// Read the page back in.
n2 := &node{}
n2.read(p)
// Check that the two pages are the same.
if len(n2.inodes) != 3 {
t.Fatalf("exp=3; got=%d", len(n2.inodes))
}
if k, v := n2.inodes[0].key, n2.inodes[0].value; string(k) != "john" || string(v) != "johnson" {
t.Fatalf("exp=<john,johnson>; got=<%s,%s>", k, v)
}
if k, v := n2.inodes[1].key, n2.inodes[1].value; string(k) != "ricki" || string(v) != "lake" {
t.Fatalf("exp=<ricki,lake>; got=<%s,%s>", k, v)
}
if k, v := n2.inodes[2].key, n2.inodes[2].value; string(k) != "susy" || string(v) != "que" {
t.Fatalf("exp=<susy,que>; got=<%s,%s>", k, v)
}
}
// Ensure that a node can split into appropriate subgroups.
func TestNode_split(t *testing.T) {
// Create a node.
n := &node{inodes: make(inodes, 0), bucket: &Bucket{tx: &Tx{db: &DB{}, meta: &meta{pgid: 1}}}}
n.put([]byte("00000001"), []byte("00000001"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000002"), []byte("00000002"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000003"), []byte("00000003"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000004"), []byte("00000004"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000005"), []byte("00000005"), []byte("0123456701234567"), 0, 0)
// Split between 2 & 3.
n.split(100)
var parent = n.parent
if len(parent.children) != 2 {
t.Fatalf("exp=2; got=%d", len(parent.children))
}
if len(parent.children[0].inodes) != 2 {
t.Fatalf("exp=2; got=%d", len(parent.children[0].inodes))
}
if len(parent.children[1].inodes) != 3 {
t.Fatalf("exp=3; got=%d", len(parent.children[1].inodes))
}
}
// Ensure that a page with the minimum number of inodes just returns a single node.
func TestNode_split_MinKeys(t *testing.T) {
// Create a node.
n := &node{inodes: make(inodes, 0), bucket: &Bucket{tx: &Tx{db: &DB{}, meta: &meta{pgid: 1}}}}
n.put([]byte("00000001"), []byte("00000001"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000002"), []byte("00000002"), []byte("0123456701234567"), 0, 0)
// Split.
n.split(20)
if n.parent != nil {
t.Fatalf("expected nil parent")
}
}
// Ensure that a node that has keys that all fit on a page just returns one leaf.
func TestNode_split_SinglePage(t *testing.T) {
// Create a node.
n := &node{inodes: make(inodes, 0), bucket: &Bucket{tx: &Tx{db: &DB{}, meta: &meta{pgid: 1}}}}
n.put([]byte("00000001"), []byte("00000001"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000002"), []byte("00000002"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000003"), []byte("00000003"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000004"), []byte("00000004"), []byte("0123456701234567"), 0, 0)
n.put([]byte("00000005"), []byte("00000005"), []byte("0123456701234567"), 0, 0)
// Split.
n.split(4096)
if n.parent != nil {
t.Fatalf("expected nil parent")
}
}

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package bolt
import (
"fmt"
"os"
"sort"
"unsafe"
)
const pageHeaderSize = int(unsafe.Offsetof(((*page)(nil)).ptr))
const minKeysPerPage = 2
const branchPageElementSize = int(unsafe.Sizeof(branchPageElement{}))
const leafPageElementSize = int(unsafe.Sizeof(leafPageElement{}))
const (
branchPageFlag = 0x01
leafPageFlag = 0x02
metaPageFlag = 0x04
freelistPageFlag = 0x10
)
const (
bucketLeafFlag = 0x01
)
type pgid uint64
type page struct {
id pgid
flags uint16
count uint16
overflow uint32
ptr uintptr
}
// typ returns a human readable page type string used for debugging.
func (p *page) typ() string {
if (p.flags & branchPageFlag) != 0 {
return "branch"
} else if (p.flags & leafPageFlag) != 0 {
return "leaf"
} else if (p.flags & metaPageFlag) != 0 {
return "meta"
} else if (p.flags & freelistPageFlag) != 0 {
return "freelist"
}
return fmt.Sprintf("unknown<%02x>", p.flags)
}
// meta returns a pointer to the metadata section of the page.
func (p *page) meta() *meta {
return (*meta)(unsafe.Pointer(&p.ptr))
}
// leafPageElement retrieves the leaf node by index
func (p *page) leafPageElement(index uint16) *leafPageElement {
n := &((*[0x7FFFFFF]leafPageElement)(unsafe.Pointer(&p.ptr)))[index]
return n
}
// leafPageElements retrieves a list of leaf nodes.
func (p *page) leafPageElements() []leafPageElement {
return ((*[0x7FFFFFF]leafPageElement)(unsafe.Pointer(&p.ptr)))[:]
}
// branchPageElement retrieves the branch node by index
func (p *page) branchPageElement(index uint16) *branchPageElement {
return &((*[0x7FFFFFF]branchPageElement)(unsafe.Pointer(&p.ptr)))[index]
}
// branchPageElements retrieves a list of branch nodes.
func (p *page) branchPageElements() []branchPageElement {
return ((*[0x7FFFFFF]branchPageElement)(unsafe.Pointer(&p.ptr)))[:]
}
// dump writes n bytes of the page to STDERR as hex output.
func (p *page) hexdump(n int) {
buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:n]
fmt.Fprintf(os.Stderr, "%x\n", buf)
}
type pages []*page
func (s pages) Len() int { return len(s) }
func (s pages) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s pages) Less(i, j int) bool { return s[i].id < s[j].id }
// branchPageElement represents a node on a branch page.
type branchPageElement struct {
pos uint32
ksize uint32
pgid pgid
}
// key returns a byte slice of the node key.
func (n *branchPageElement) key() []byte {
buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
}
// leafPageElement represents a node on a leaf page.
type leafPageElement struct {
flags uint32
pos uint32
ksize uint32
vsize uint32
}
// key returns a byte slice of the node key.
func (n *leafPageElement) key() []byte {
buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
}
// value returns a byte slice of the node value.
func (n *leafPageElement) value() []byte {
buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos+n.ksize]))[:n.vsize]
}
// PageInfo represents human readable information about a page.
type PageInfo struct {
ID int
Type string
Count int
OverflowCount int
}
type pgids []pgid
func (s pgids) Len() int { return len(s) }
func (s pgids) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s pgids) Less(i, j int) bool { return s[i] < s[j] }
// merge returns the sorted union of a and b.
func (a pgids) merge(b pgids) pgids {
// Return the opposite slice if one is nil.
if len(a) == 0 {
return b
} else if len(b) == 0 {
return a
}
// Create a list to hold all elements from both lists.
merged := make(pgids, 0, len(a)+len(b))
// Assign lead to the slice with a lower starting value, follow to the higher value.
lead, follow := a, b
if b[0] < a[0] {
lead, follow = b, a
}
// Continue while there are elements in the lead.
for len(lead) > 0 {
// Merge largest prefix of lead that is ahead of follow[0].
n := sort.Search(len(lead), func(i int) bool { return lead[i] > follow[0] })
merged = append(merged, lead[:n]...)
if n >= len(lead) {
break
}
// Swap lead and follow.
lead, follow = follow, lead[n:]
}
// Append what's left in follow.
merged = append(merged, follow...)
return merged
}

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package bolt
import (
"reflect"
"sort"
"testing"
"testing/quick"
)
// Ensure that the page type can be returned in human readable format.
func TestPage_typ(t *testing.T) {
if typ := (&page{flags: branchPageFlag}).typ(); typ != "branch" {
t.Fatalf("exp=branch; got=%v", typ)
}
if typ := (&page{flags: leafPageFlag}).typ(); typ != "leaf" {
t.Fatalf("exp=leaf; got=%v", typ)
}
if typ := (&page{flags: metaPageFlag}).typ(); typ != "meta" {
t.Fatalf("exp=meta; got=%v", typ)
}
if typ := (&page{flags: freelistPageFlag}).typ(); typ != "freelist" {
t.Fatalf("exp=freelist; got=%v", typ)
}
if typ := (&page{flags: 20000}).typ(); typ != "unknown<4e20>" {
t.Fatalf("exp=unknown<4e20>; got=%v", typ)
}
}
// Ensure that the hexdump debugging function doesn't blow up.
func TestPage_dump(t *testing.T) {
(&page{id: 256}).hexdump(16)
}
func TestPgids_merge(t *testing.T) {
a := pgids{4, 5, 6, 10, 11, 12, 13, 27}
b := pgids{1, 3, 8, 9, 25, 30}
c := a.merge(b)
if !reflect.DeepEqual(c, pgids{1, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 25, 27, 30}) {
t.Errorf("mismatch: %v", c)
}
a = pgids{4, 5, 6, 10, 11, 12, 13, 27, 35, 36}
b = pgids{8, 9, 25, 30}
c = a.merge(b)
if !reflect.DeepEqual(c, pgids{4, 5, 6, 8, 9, 10, 11, 12, 13, 25, 27, 30, 35, 36}) {
t.Errorf("mismatch: %v", c)
}
}
func TestPgids_merge_quick(t *testing.T) {
if err := quick.Check(func(a, b pgids) bool {
// Sort incoming lists.
sort.Sort(a)
sort.Sort(b)
// Merge the two lists together.
got := a.merge(b)
// The expected value should be the two lists combined and sorted.
exp := append(a, b...)
sort.Sort(exp)
if !reflect.DeepEqual(exp, got) {
t.Errorf("\nexp=%+v\ngot=%+v\n", exp, got)
return false
}
return true
}, nil); err != nil {
t.Fatal(err)
}
}

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package bolt_test
import (
"bytes"
"flag"
"fmt"
"math/rand"
"os"
"reflect"
"testing/quick"
"time"
)
// testing/quick defaults to 5 iterations and a random seed.
// You can override these settings from the command line:
//
// -quick.count The number of iterations to perform.
// -quick.seed The seed to use for randomizing.
// -quick.maxitems The maximum number of items to insert into a DB.
// -quick.maxksize The maximum size of a key.
// -quick.maxvsize The maximum size of a value.
//
var qcount, qseed, qmaxitems, qmaxksize, qmaxvsize int
func init() {
flag.IntVar(&qcount, "quick.count", 5, "")
flag.IntVar(&qseed, "quick.seed", int(time.Now().UnixNano())%100000, "")
flag.IntVar(&qmaxitems, "quick.maxitems", 1000, "")
flag.IntVar(&qmaxksize, "quick.maxksize", 1024, "")
flag.IntVar(&qmaxvsize, "quick.maxvsize", 1024, "")
flag.Parse()
fmt.Fprintln(os.Stderr, "seed:", qseed)
fmt.Fprintf(os.Stderr, "quick settings: count=%v, items=%v, ksize=%v, vsize=%v\n", qcount, qmaxitems, qmaxksize, qmaxvsize)
}
func qconfig() *quick.Config {
return &quick.Config{
MaxCount: qcount,
Rand: rand.New(rand.NewSource(int64(qseed))),
}
}
type testdata []testdataitem
func (t testdata) Len() int { return len(t) }
func (t testdata) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
func (t testdata) Less(i, j int) bool { return bytes.Compare(t[i].Key, t[j].Key) == -1 }
func (t testdata) Generate(rand *rand.Rand, size int) reflect.Value {
n := rand.Intn(qmaxitems-1) + 1
items := make(testdata, n)
for i := 0; i < n; i++ {
item := &items[i]
item.Key = randByteSlice(rand, 1, qmaxksize)
item.Value = randByteSlice(rand, 0, qmaxvsize)
}
return reflect.ValueOf(items)
}
type revtestdata []testdataitem
func (t revtestdata) Len() int { return len(t) }
func (t revtestdata) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
func (t revtestdata) Less(i, j int) bool { return bytes.Compare(t[i].Key, t[j].Key) == 1 }
type testdataitem struct {
Key []byte
Value []byte
}
func randByteSlice(rand *rand.Rand, minSize, maxSize int) []byte {
n := rand.Intn(maxSize-minSize) + minSize
b := make([]byte, n)
for i := 0; i < n; i++ {
b[i] = byte(rand.Intn(255))
}
return b
}

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package bolt_test
import (
"bytes"
"fmt"
"math/rand"
"sync"
"testing"
"github.com/boltdb/bolt"
)
func TestSimulate_1op_1p(t *testing.T) { testSimulate(t, 100, 1) }
func TestSimulate_10op_1p(t *testing.T) { testSimulate(t, 10, 1) }
func TestSimulate_100op_1p(t *testing.T) { testSimulate(t, 100, 1) }
func TestSimulate_1000op_1p(t *testing.T) { testSimulate(t, 1000, 1) }
func TestSimulate_10000op_1p(t *testing.T) { testSimulate(t, 10000, 1) }
func TestSimulate_10op_10p(t *testing.T) { testSimulate(t, 10, 10) }
func TestSimulate_100op_10p(t *testing.T) { testSimulate(t, 100, 10) }
func TestSimulate_1000op_10p(t *testing.T) { testSimulate(t, 1000, 10) }
func TestSimulate_10000op_10p(t *testing.T) { testSimulate(t, 10000, 10) }
func TestSimulate_100op_100p(t *testing.T) { testSimulate(t, 100, 100) }
func TestSimulate_1000op_100p(t *testing.T) { testSimulate(t, 1000, 100) }
func TestSimulate_10000op_100p(t *testing.T) { testSimulate(t, 10000, 100) }
func TestSimulate_10000op_1000p(t *testing.T) { testSimulate(t, 10000, 1000) }
// Randomly generate operations on a given database with multiple clients to ensure consistency and thread safety.
func testSimulate(t *testing.T, threadCount, parallelism int) {
if testing.Short() {
t.Skip("skipping test in short mode.")
}
rand.Seed(int64(qseed))
// A list of operations that readers and writers can perform.
var readerHandlers = []simulateHandler{simulateGetHandler}
var writerHandlers = []simulateHandler{simulateGetHandler, simulatePutHandler}
var versions = make(map[int]*QuickDB)
versions[1] = NewQuickDB()
db := NewTestDB()
defer db.Close()
var mutex sync.Mutex
// Run n threads in parallel, each with their own operation.
var wg sync.WaitGroup
var threads = make(chan bool, parallelism)
var i int
for {
threads <- true
wg.Add(1)
writable := ((rand.Int() % 100) < 20) // 20% writers
// Choose an operation to execute.
var handler simulateHandler
if writable {
handler = writerHandlers[rand.Intn(len(writerHandlers))]
} else {
handler = readerHandlers[rand.Intn(len(readerHandlers))]
}
// Execute a thread for the given operation.
go func(writable bool, handler simulateHandler) {
defer wg.Done()
// Start transaction.
tx, err := db.Begin(writable)
if err != nil {
t.Fatal("tx begin: ", err)
}
// Obtain current state of the dataset.
mutex.Lock()
var qdb = versions[tx.ID()]
if writable {
qdb = versions[tx.ID()-1].Copy()
}
mutex.Unlock()
// Make sure we commit/rollback the tx at the end and update the state.
if writable {
defer func() {
mutex.Lock()
versions[tx.ID()] = qdb
mutex.Unlock()
ok(t, tx.Commit())
}()
} else {
defer tx.Rollback()
}
// Ignore operation if we don't have data yet.
if qdb == nil {
return
}
// Execute handler.
handler(tx, qdb)
// Release a thread back to the scheduling loop.
<-threads
}(writable, handler)
i++
if i > threadCount {
break
}
}
// Wait until all threads are done.
wg.Wait()
}
type simulateHandler func(tx *bolt.Tx, qdb *QuickDB)
// Retrieves a key from the database and verifies that it is what is expected.
func simulateGetHandler(tx *bolt.Tx, qdb *QuickDB) {
// Randomly retrieve an existing exist.
keys := qdb.Rand()
if len(keys) == 0 {
return
}
// Retrieve root bucket.
b := tx.Bucket(keys[0])
if b == nil {
panic(fmt.Sprintf("bucket[0] expected: %08x\n", trunc(keys[0], 4)))
}
// Drill into nested buckets.
for _, key := range keys[1 : len(keys)-1] {
b = b.Bucket(key)
if b == nil {
panic(fmt.Sprintf("bucket[n] expected: %v -> %v\n", keys, key))
}
}
// Verify key/value on the final bucket.
expected := qdb.Get(keys)
actual := b.Get(keys[len(keys)-1])
if !bytes.Equal(actual, expected) {
fmt.Println("=== EXPECTED ===")
fmt.Println(expected)
fmt.Println("=== ACTUAL ===")
fmt.Println(actual)
fmt.Println("=== END ===")
panic("value mismatch")
}
}
// Inserts a key into the database.
func simulatePutHandler(tx *bolt.Tx, qdb *QuickDB) {
var err error
keys, value := randKeys(), randValue()
// Retrieve root bucket.
b := tx.Bucket(keys[0])
if b == nil {
b, err = tx.CreateBucket(keys[0])
if err != nil {
panic("create bucket: " + err.Error())
}
}
// Create nested buckets, if necessary.
for _, key := range keys[1 : len(keys)-1] {
child := b.Bucket(key)
if child != nil {
b = child
} else {
b, err = b.CreateBucket(key)
if err != nil {
panic("create bucket: " + err.Error())
}
}
}
// Insert into database.
if err := b.Put(keys[len(keys)-1], value); err != nil {
panic("put: " + err.Error())
}
// Insert into in-memory database.
qdb.Put(keys, value)
}
// QuickDB is an in-memory database that replicates the functionality of the
// Bolt DB type except that it is entirely in-memory. It is meant for testing
// that the Bolt database is consistent.
type QuickDB struct {
sync.RWMutex
m map[string]interface{}
}
// NewQuickDB returns an instance of QuickDB.
func NewQuickDB() *QuickDB {
return &QuickDB{m: make(map[string]interface{})}
}
// Get retrieves the value at a key path.
func (db *QuickDB) Get(keys [][]byte) []byte {
db.RLock()
defer db.RUnlock()
m := db.m
for _, key := range keys[:len(keys)-1] {
value := m[string(key)]
if value == nil {
return nil
}
switch value := value.(type) {
case map[string]interface{}:
m = value
case []byte:
return nil
}
}
// Only return if it's a simple value.
if value, ok := m[string(keys[len(keys)-1])].([]byte); ok {
return value
}
return nil
}
// Put inserts a value into a key path.
func (db *QuickDB) Put(keys [][]byte, value []byte) {
db.Lock()
defer db.Unlock()
// Build buckets all the way down the key path.
m := db.m
for _, key := range keys[:len(keys)-1] {
if _, ok := m[string(key)].([]byte); ok {
return // Keypath intersects with a simple value. Do nothing.
}
if m[string(key)] == nil {
m[string(key)] = make(map[string]interface{})
}
m = m[string(key)].(map[string]interface{})
}
// Insert value into the last key.
m[string(keys[len(keys)-1])] = value
}
// Rand returns a random key path that points to a simple value.
func (db *QuickDB) Rand() [][]byte {
db.RLock()
defer db.RUnlock()
if len(db.m) == 0 {
return nil
}
var keys [][]byte
db.rand(db.m, &keys)
return keys
}
func (db *QuickDB) rand(m map[string]interface{}, keys *[][]byte) {
i, index := 0, rand.Intn(len(m))
for k, v := range m {
if i == index {
*keys = append(*keys, []byte(k))
if v, ok := v.(map[string]interface{}); ok {
db.rand(v, keys)
}
return
}
i++
}
panic("quickdb rand: out-of-range")
}
// Copy copies the entire database.
func (db *QuickDB) Copy() *QuickDB {
db.RLock()
defer db.RUnlock()
return &QuickDB{m: db.copy(db.m)}
}
func (db *QuickDB) copy(m map[string]interface{}) map[string]interface{} {
clone := make(map[string]interface{}, len(m))
for k, v := range m {
switch v := v.(type) {
case map[string]interface{}:
clone[k] = db.copy(v)
default:
clone[k] = v
}
}
return clone
}
func randKey() []byte {
var min, max = 1, 1024
n := rand.Intn(max-min) + min
b := make([]byte, n)
for i := 0; i < n; i++ {
b[i] = byte(rand.Intn(255))
}
return b
}
func randKeys() [][]byte {
var keys [][]byte
var count = rand.Intn(2) + 2
for i := 0; i < count; i++ {
keys = append(keys, randKey())
}
return keys
}
func randValue() []byte {
n := rand.Intn(8192)
b := make([]byte, n)
for i := 0; i < n; i++ {
b[i] = byte(rand.Intn(255))
}
return b
}

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@ -0,0 +1,611 @@
package bolt
import (
"fmt"
"io"
"os"
"sort"
"time"
"unsafe"
)
// txid represents the internal transaction identifier.
type txid uint64
// Tx represents a read-only or read/write transaction on the database.
// Read-only transactions can be used for retrieving values for keys and creating cursors.
// Read/write transactions can create and remove buckets and create and remove keys.
//
// IMPORTANT: You must commit or rollback transactions when you are done with
// them. Pages can not be reclaimed by the writer until no more transactions
// are using them. A long running read transaction can cause the database to
// quickly grow.
type Tx struct {
writable bool
managed bool
db *DB
meta *meta
root Bucket
pages map[pgid]*page
stats TxStats
commitHandlers []func()
}
// init initializes the transaction.
func (tx *Tx) init(db *DB) {
tx.db = db
tx.pages = nil
// Copy the meta page since it can be changed by the writer.
tx.meta = &meta{}
db.meta().copy(tx.meta)
// Copy over the root bucket.
tx.root = newBucket(tx)
tx.root.bucket = &bucket{}
*tx.root.bucket = tx.meta.root
// Increment the transaction id and add a page cache for writable transactions.
if tx.writable {
tx.pages = make(map[pgid]*page)
tx.meta.txid += txid(1)
}
}
// ID returns the transaction id.
func (tx *Tx) ID() int {
return int(tx.meta.txid)
}
// DB returns a reference to the database that created the transaction.
func (tx *Tx) DB() *DB {
return tx.db
}
// Size returns current database size in bytes as seen by this transaction.
func (tx *Tx) Size() int64 {
return int64(tx.meta.pgid) * int64(tx.db.pageSize)
}
// Writable returns whether the transaction can perform write operations.
func (tx *Tx) Writable() bool {
return tx.writable
}
// Cursor creates a cursor associated with the root bucket.
// All items in the cursor will return a nil value because all root bucket keys point to buckets.
// The cursor is only valid as long as the transaction is open.
// Do not use a cursor after the transaction is closed.
func (tx *Tx) Cursor() *Cursor {
return tx.root.Cursor()
}
// Stats retrieves a copy of the current transaction statistics.
func (tx *Tx) Stats() TxStats {
return tx.stats
}
// Bucket retrieves a bucket by name.
// Returns nil if the bucket does not exist.
func (tx *Tx) Bucket(name []byte) *Bucket {
return tx.root.Bucket(name)
}
// CreateBucket creates a new bucket.
// Returns an error if the bucket already exists, if the bucket name is blank, or if the bucket name is too long.
func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) {
return tx.root.CreateBucket(name)
}
// CreateBucketIfNotExists creates a new bucket if it doesn't already exist.
// Returns an error if the bucket name is blank, or if the bucket name is too long.
func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) {
return tx.root.CreateBucketIfNotExists(name)
}
// DeleteBucket deletes a bucket.
// Returns an error if the bucket cannot be found or if the key represents a non-bucket value.
func (tx *Tx) DeleteBucket(name []byte) error {
return tx.root.DeleteBucket(name)
}
// ForEach executes a function for each bucket in the root.
// If the provided function returns an error then the iteration is stopped and
// the error is returned to the caller.
func (tx *Tx) ForEach(fn func(name []byte, b *Bucket) error) error {
return tx.root.ForEach(func(k, v []byte) error {
if err := fn(k, tx.root.Bucket(k)); err != nil {
return err
}
return nil
})
}
// OnCommit adds a handler function to be executed after the transaction successfully commits.
func (tx *Tx) OnCommit(fn func()) {
tx.commitHandlers = append(tx.commitHandlers, fn)
}
// Commit writes all changes to disk and updates the meta page.
// Returns an error if a disk write error occurs, or if Commit is
// called on a read-only transaction.
func (tx *Tx) Commit() error {
_assert(!tx.managed, "managed tx commit not allowed")
if tx.db == nil {
return ErrTxClosed
} else if !tx.writable {
return ErrTxNotWritable
}
// TODO(benbjohnson): Use vectorized I/O to write out dirty pages.
// Rebalance nodes which have had deletions.
var startTime = time.Now()
tx.root.rebalance()
if tx.stats.Rebalance > 0 {
tx.stats.RebalanceTime += time.Since(startTime)
}
// spill data onto dirty pages.
startTime = time.Now()
if err := tx.root.spill(); err != nil {
tx.rollback()
return err
}
tx.stats.SpillTime += time.Since(startTime)
// Free the old root bucket.
tx.meta.root.root = tx.root.root
// Free the freelist and allocate new pages for it. This will overestimate
// the size of the freelist but not underestimate the size (which would be bad).
tx.db.freelist.free(tx.meta.txid, tx.db.page(tx.meta.freelist))
p, err := tx.allocate((tx.db.freelist.size() / tx.db.pageSize) + 1)
if err != nil {
tx.rollback()
return err
}
if err := tx.db.freelist.write(p); err != nil {
tx.rollback()
return err
}
tx.meta.freelist = p.id
// Write dirty pages to disk.
startTime = time.Now()
if err := tx.write(); err != nil {
tx.rollback()
return err
}
// If strict mode is enabled then perform a consistency check.
// Only the first consistency error is reported in the panic.
if tx.db.StrictMode {
if err, ok := <-tx.Check(); ok {
panic("check fail: " + err.Error())
}
}
// Write meta to disk.
if err := tx.writeMeta(); err != nil {
tx.rollback()
return err
}
tx.stats.WriteTime += time.Since(startTime)
// Finalize the transaction.
tx.close()
// Execute commit handlers now that the locks have been removed.
for _, fn := range tx.commitHandlers {
fn()
}
return nil
}
// Rollback closes the transaction and ignores all previous updates. Read-only
// transactions must be rolled back and not committed.
func (tx *Tx) Rollback() error {
_assert(!tx.managed, "managed tx rollback not allowed")
if tx.db == nil {
return ErrTxClosed
}
tx.rollback()
return nil
}
func (tx *Tx) rollback() {
if tx.db == nil {
return
}
if tx.writable {
tx.db.freelist.rollback(tx.meta.txid)
tx.db.freelist.reload(tx.db.page(tx.db.meta().freelist))
}
tx.close()
}
func (tx *Tx) close() {
if tx.db == nil {
return
}
if tx.writable {
// Grab freelist stats.
var freelistFreeN = tx.db.freelist.free_count()
var freelistPendingN = tx.db.freelist.pending_count()
var freelistAlloc = tx.db.freelist.size()
// Remove writer lock.
tx.db.rwlock.Unlock()
// Merge statistics.
tx.db.statlock.Lock()
tx.db.stats.FreePageN = freelistFreeN
tx.db.stats.PendingPageN = freelistPendingN
tx.db.stats.FreeAlloc = (freelistFreeN + freelistPendingN) * tx.db.pageSize
tx.db.stats.FreelistInuse = freelistAlloc
tx.db.stats.TxStats.add(&tx.stats)
tx.db.statlock.Unlock()
} else {
tx.db.removeTx(tx)
}
tx.db = nil
}
// Copy writes the entire database to a writer.
// This function exists for backwards compatibility. Use WriteTo() in
func (tx *Tx) Copy(w io.Writer) error {
_, err := tx.WriteTo(w)
return err
}
// WriteTo writes the entire database to a writer.
// If err == nil then exactly tx.Size() bytes will be written into the writer.
func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) {
// Attempt to open reader directly.
var f *os.File
if f, err = os.OpenFile(tx.db.path, os.O_RDONLY|odirect, 0); err != nil {
// Fallback to a regular open if that doesn't work.
if f, err = os.OpenFile(tx.db.path, os.O_RDONLY, 0); err != nil {
return 0, err
}
}
// Copy the meta pages.
tx.db.metalock.Lock()
n, err = io.CopyN(w, f, int64(tx.db.pageSize*2))
tx.db.metalock.Unlock()
if err != nil {
_ = f.Close()
return n, fmt.Errorf("meta copy: %s", err)
}
// Copy data pages.
wn, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2))
n += wn
if err != nil {
_ = f.Close()
return n, err
}
return n, f.Close()
}
// CopyFile copies the entire database to file at the given path.
// A reader transaction is maintained during the copy so it is safe to continue
// using the database while a copy is in progress.
func (tx *Tx) CopyFile(path string, mode os.FileMode) error {
f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
if err != nil {
return err
}
err = tx.Copy(f)
if err != nil {
_ = f.Close()
return err
}
return f.Close()
}
// Check performs several consistency checks on the database for this transaction.
// An error is returned if any inconsistency is found.
//
// It can be safely run concurrently on a writable transaction. However, this
// incurs a high cost for large databases and databases with a lot of subbuckets
// because of caching. This overhead can be removed if running on a read-only
// transaction, however, it is not safe to execute other writer transactions at
// the same time.
func (tx *Tx) Check() <-chan error {
ch := make(chan error)
go tx.check(ch)
return ch
}
func (tx *Tx) check(ch chan error) {
// Check if any pages are double freed.
freed := make(map[pgid]bool)
for _, id := range tx.db.freelist.all() {
if freed[id] {
ch <- fmt.Errorf("page %d: already freed", id)
}
freed[id] = true
}
// Track every reachable page.
reachable := make(map[pgid]*page)
reachable[0] = tx.page(0) // meta0
reachable[1] = tx.page(1) // meta1
for i := uint32(0); i <= tx.page(tx.meta.freelist).overflow; i++ {
reachable[tx.meta.freelist+pgid(i)] = tx.page(tx.meta.freelist)
}
// Recursively check buckets.
tx.checkBucket(&tx.root, reachable, freed, ch)
// Ensure all pages below high water mark are either reachable or freed.
for i := pgid(0); i < tx.meta.pgid; i++ {
_, isReachable := reachable[i]
if !isReachable && !freed[i] {
ch <- fmt.Errorf("page %d: unreachable unfreed", int(i))
}
}
// Close the channel to signal completion.
close(ch)
}
func (tx *Tx) checkBucket(b *Bucket, reachable map[pgid]*page, freed map[pgid]bool, ch chan error) {
// Ignore inline buckets.
if b.root == 0 {
return
}
// Check every page used by this bucket.
b.tx.forEachPage(b.root, 0, func(p *page, _ int) {
if p.id > tx.meta.pgid {
ch <- fmt.Errorf("page %d: out of bounds: %d", int(p.id), int(b.tx.meta.pgid))
}
// Ensure each page is only referenced once.
for i := pgid(0); i <= pgid(p.overflow); i++ {
var id = p.id + i
if _, ok := reachable[id]; ok {
ch <- fmt.Errorf("page %d: multiple references", int(id))
}
reachable[id] = p
}
// We should only encounter un-freed leaf and branch pages.
if freed[p.id] {
ch <- fmt.Errorf("page %d: reachable freed", int(p.id))
} else if (p.flags&branchPageFlag) == 0 && (p.flags&leafPageFlag) == 0 {
ch <- fmt.Errorf("page %d: invalid type: %s", int(p.id), p.typ())
}
})
// Check each bucket within this bucket.
_ = b.ForEach(func(k, v []byte) error {
if child := b.Bucket(k); child != nil {
tx.checkBucket(child, reachable, freed, ch)
}
return nil
})
}
// allocate returns a contiguous block of memory starting at a given page.
func (tx *Tx) allocate(count int) (*page, error) {
p, err := tx.db.allocate(count)
if err != nil {
return nil, err
}
// Save to our page cache.
tx.pages[p.id] = p
// Update statistics.
tx.stats.PageCount++
tx.stats.PageAlloc += count * tx.db.pageSize
return p, nil
}
// write writes any dirty pages to disk.
func (tx *Tx) write() error {
// Sort pages by id.
pages := make(pages, 0, len(tx.pages))
for _, p := range tx.pages {
pages = append(pages, p)
}
sort.Sort(pages)
// Write pages to disk in order.
for _, p := range pages {
size := (int(p.overflow) + 1) * tx.db.pageSize
offset := int64(p.id) * int64(tx.db.pageSize)
// Write out page in "max allocation" sized chunks.
ptr := (*[maxAllocSize]byte)(unsafe.Pointer(p))
for {
// Limit our write to our max allocation size.
sz := size
if sz > maxAllocSize-1 {
sz = maxAllocSize - 1
}
// Write chunk to disk.
buf := ptr[:sz]
if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
return err
}
// Update statistics.
tx.stats.Write++
// Exit inner for loop if we've written all the chunks.
size -= sz
if size == 0 {
break
}
// Otherwise move offset forward and move pointer to next chunk.
offset += int64(sz)
ptr = (*[maxAllocSize]byte)(unsafe.Pointer(&ptr[sz]))
}
}
// Ignore file sync if flag is set on DB.
if !tx.db.NoSync || IgnoreNoSync {
if err := fdatasync(tx.db); err != nil {
return err
}
}
// Clear out page cache.
tx.pages = make(map[pgid]*page)
return nil
}
// writeMeta writes the meta to the disk.
func (tx *Tx) writeMeta() error {
// Create a temporary buffer for the meta page.
buf := make([]byte, tx.db.pageSize)
p := tx.db.pageInBuffer(buf, 0)
tx.meta.write(p)
// Write the meta page to file.
if _, err := tx.db.ops.writeAt(buf, int64(p.id)*int64(tx.db.pageSize)); err != nil {
return err
}
if !tx.db.NoSync || IgnoreNoSync {
if err := fdatasync(tx.db); err != nil {
return err
}
}
// Update statistics.
tx.stats.Write++
return nil
}
// page returns a reference to the page with a given id.
// If page has been written to then a temporary bufferred page is returned.
func (tx *Tx) page(id pgid) *page {
// Check the dirty pages first.
if tx.pages != nil {
if p, ok := tx.pages[id]; ok {
return p
}
}
// Otherwise return directly from the mmap.
return tx.db.page(id)
}
// forEachPage iterates over every page within a given page and executes a function.
func (tx *Tx) forEachPage(pgid pgid, depth int, fn func(*page, int)) {
p := tx.page(pgid)
// Execute function.
fn(p, depth)
// Recursively loop over children.
if (p.flags & branchPageFlag) != 0 {
for i := 0; i < int(p.count); i++ {
elem := p.branchPageElement(uint16(i))
tx.forEachPage(elem.pgid, depth+1, fn)
}
}
}
// Page returns page information for a given page number.
// This is only safe for concurrent use when used by a writable transaction.
func (tx *Tx) Page(id int) (*PageInfo, error) {
if tx.db == nil {
return nil, ErrTxClosed
} else if pgid(id) >= tx.meta.pgid {
return nil, nil
}
// Build the page info.
p := tx.db.page(pgid(id))
info := &PageInfo{
ID: id,
Count: int(p.count),
OverflowCount: int(p.overflow),
}
// Determine the type (or if it's free).
if tx.db.freelist.freed(pgid(id)) {
info.Type = "free"
} else {
info.Type = p.typ()
}
return info, nil
}
// TxStats represents statistics about the actions performed by the transaction.
type TxStats struct {
// Page statistics.
PageCount int // number of page allocations
PageAlloc int // total bytes allocated
// Cursor statistics.
CursorCount int // number of cursors created
// Node statistics
NodeCount int // number of node allocations
NodeDeref int // number of node dereferences
// Rebalance statistics.
Rebalance int // number of node rebalances
RebalanceTime time.Duration // total time spent rebalancing
// Split/Spill statistics.
Split int // number of nodes split
Spill int // number of nodes spilled
SpillTime time.Duration // total time spent spilling
// Write statistics.
Write int // number of writes performed
WriteTime time.Duration // total time spent writing to disk
}
func (s *TxStats) add(other *TxStats) {
s.PageCount += other.PageCount
s.PageAlloc += other.PageAlloc
s.CursorCount += other.CursorCount
s.NodeCount += other.NodeCount
s.NodeDeref += other.NodeDeref
s.Rebalance += other.Rebalance
s.RebalanceTime += other.RebalanceTime
s.Split += other.Split
s.Spill += other.Spill
s.SpillTime += other.SpillTime
s.Write += other.Write
s.WriteTime += other.WriteTime
}
// Sub calculates and returns the difference between two sets of transaction stats.
// This is useful when obtaining stats at two different points and time and
// you need the performance counters that occurred within that time span.
func (s *TxStats) Sub(other *TxStats) TxStats {
var diff TxStats
diff.PageCount = s.PageCount - other.PageCount
diff.PageAlloc = s.PageAlloc - other.PageAlloc
diff.CursorCount = s.CursorCount - other.CursorCount
diff.NodeCount = s.NodeCount - other.NodeCount
diff.NodeDeref = s.NodeDeref - other.NodeDeref
diff.Rebalance = s.Rebalance - other.Rebalance
diff.RebalanceTime = s.RebalanceTime - other.RebalanceTime
diff.Split = s.Split - other.Split
diff.Spill = s.Spill - other.Spill
diff.SpillTime = s.SpillTime - other.SpillTime
diff.Write = s.Write - other.Write
diff.WriteTime = s.WriteTime - other.WriteTime
return diff
}

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@ -0,0 +1,456 @@
package bolt_test
import (
"errors"
"fmt"
"os"
"testing"
"github.com/boltdb/bolt"
)
// Ensure that committing a closed transaction returns an error.
func TestTx_Commit_Closed(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, _ := db.Begin(true)
tx.CreateBucket([]byte("foo"))
ok(t, tx.Commit())
equals(t, tx.Commit(), bolt.ErrTxClosed)
}
// Ensure that rolling back a closed transaction returns an error.
func TestTx_Rollback_Closed(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, _ := db.Begin(true)
ok(t, tx.Rollback())
equals(t, tx.Rollback(), bolt.ErrTxClosed)
}
// Ensure that committing a read-only transaction returns an error.
func TestTx_Commit_ReadOnly(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, _ := db.Begin(false)
equals(t, tx.Commit(), bolt.ErrTxNotWritable)
}
// Ensure that a transaction can retrieve a cursor on the root bucket.
func TestTx_Cursor(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.CreateBucket([]byte("woojits"))
c := tx.Cursor()
k, v := c.First()
equals(t, "widgets", string(k))
assert(t, v == nil, "")
k, v = c.Next()
equals(t, "woojits", string(k))
assert(t, v == nil, "")
k, v = c.Next()
assert(t, k == nil, "")
assert(t, v == nil, "")
return nil
})
}
// Ensure that creating a bucket with a read-only transaction returns an error.
func TestTx_CreateBucket_ReadOnly(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.View(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("foo"))
assert(t, b == nil, "")
equals(t, bolt.ErrTxNotWritable, err)
return nil
})
}
// Ensure that creating a bucket on a closed transaction returns an error.
func TestTx_CreateBucket_Closed(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, _ := db.Begin(true)
tx.Commit()
b, err := tx.CreateBucket([]byte("foo"))
assert(t, b == nil, "")
equals(t, bolt.ErrTxClosed, err)
}
// Ensure that a Tx can retrieve a bucket.
func TestTx_Bucket(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
b := tx.Bucket([]byte("widgets"))
assert(t, b != nil, "")
return nil
})
}
// Ensure that a Tx retrieving a non-existent key returns nil.
func TestTx_Get_Missing(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
value := tx.Bucket([]byte("widgets")).Get([]byte("no_such_key"))
assert(t, value == nil, "")
return nil
})
}
// Ensure that a bucket can be created and retrieved.
func TestTx_CreateBucket(t *testing.T) {
db := NewTestDB()
defer db.Close()
// Create a bucket.
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
assert(t, b != nil, "")
ok(t, err)
return nil
})
// Read the bucket through a separate transaction.
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
assert(t, b != nil, "")
return nil
})
}
// Ensure that a bucket can be created if it doesn't already exist.
func TestTx_CreateBucketIfNotExists(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucketIfNotExists([]byte("widgets"))
assert(t, b != nil, "")
ok(t, err)
b, err = tx.CreateBucketIfNotExists([]byte("widgets"))
assert(t, b != nil, "")
ok(t, err)
b, err = tx.CreateBucketIfNotExists([]byte{})
assert(t, b == nil, "")
equals(t, bolt.ErrBucketNameRequired, err)
b, err = tx.CreateBucketIfNotExists(nil)
assert(t, b == nil, "")
equals(t, bolt.ErrBucketNameRequired, err)
return nil
})
// Read the bucket through a separate transaction.
db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("widgets"))
assert(t, b != nil, "")
return nil
})
}
// Ensure that a bucket cannot be created twice.
func TestTx_CreateBucket_Exists(t *testing.T) {
db := NewTestDB()
defer db.Close()
// Create a bucket.
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
assert(t, b != nil, "")
ok(t, err)
return nil
})
// Create the same bucket again.
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket([]byte("widgets"))
assert(t, b == nil, "")
equals(t, bolt.ErrBucketExists, err)
return nil
})
}
// Ensure that a bucket is created with a non-blank name.
func TestTx_CreateBucket_NameRequired(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
b, err := tx.CreateBucket(nil)
assert(t, b == nil, "")
equals(t, bolt.ErrBucketNameRequired, err)
return nil
})
}
// Ensure that a bucket can be deleted.
func TestTx_DeleteBucket(t *testing.T) {
db := NewTestDB()
defer db.Close()
// Create a bucket and add a value.
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
return nil
})
// Delete the bucket and make sure we can't get the value.
db.Update(func(tx *bolt.Tx) error {
ok(t, tx.DeleteBucket([]byte("widgets")))
assert(t, tx.Bucket([]byte("widgets")) == nil, "")
return nil
})
db.Update(func(tx *bolt.Tx) error {
// Create the bucket again and make sure there's not a phantom value.
b, err := tx.CreateBucket([]byte("widgets"))
assert(t, b != nil, "")
ok(t, err)
assert(t, tx.Bucket([]byte("widgets")).Get([]byte("foo")) == nil, "")
return nil
})
}
// Ensure that deleting a bucket on a closed transaction returns an error.
func TestTx_DeleteBucket_Closed(t *testing.T) {
db := NewTestDB()
defer db.Close()
tx, _ := db.Begin(true)
tx.Commit()
equals(t, tx.DeleteBucket([]byte("foo")), bolt.ErrTxClosed)
}
// Ensure that deleting a bucket with a read-only transaction returns an error.
func TestTx_DeleteBucket_ReadOnly(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.View(func(tx *bolt.Tx) error {
equals(t, tx.DeleteBucket([]byte("foo")), bolt.ErrTxNotWritable)
return nil
})
}
// Ensure that nothing happens when deleting a bucket that doesn't exist.
func TestTx_DeleteBucket_NotFound(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
equals(t, bolt.ErrBucketNotFound, tx.DeleteBucket([]byte("widgets")))
return nil
})
}
// Ensure that no error is returned when a tx.ForEach function does not return
// an error.
func TestTx_ForEach_NoError(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
equals(t, nil, tx.ForEach(func(name []byte, b *bolt.Bucket) error {
return nil
}))
return nil
})
}
// Ensure that an error is returned when a tx.ForEach function returns an error.
func TestTx_ForEach_WithError(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
err := errors.New("foo")
equals(t, err, tx.ForEach(func(name []byte, b *bolt.Bucket) error {
return err
}))
return nil
})
}
// Ensure that Tx commit handlers are called after a transaction successfully commits.
func TestTx_OnCommit(t *testing.T) {
var x int
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.OnCommit(func() { x += 1 })
tx.OnCommit(func() { x += 2 })
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
equals(t, 3, x)
}
// Ensure that Tx commit handlers are NOT called after a transaction rolls back.
func TestTx_OnCommit_Rollback(t *testing.T) {
var x int
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.OnCommit(func() { x += 1 })
tx.OnCommit(func() { x += 2 })
tx.CreateBucket([]byte("widgets"))
return errors.New("rollback this commit")
})
equals(t, 0, x)
}
// Ensure that the database can be copied to a file path.
func TestTx_CopyFile(t *testing.T) {
db := NewTestDB()
defer db.Close()
var dest = tempfile()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte("bat"))
return nil
})
ok(t, db.View(func(tx *bolt.Tx) error { return tx.CopyFile(dest, 0600) }))
db2, err := bolt.Open(dest, 0600, nil)
ok(t, err)
defer db2.Close()
db2.View(func(tx *bolt.Tx) error {
equals(t, []byte("bar"), tx.Bucket([]byte("widgets")).Get([]byte("foo")))
equals(t, []byte("bat"), tx.Bucket([]byte("widgets")).Get([]byte("baz")))
return nil
})
}
type failWriterError struct{}
func (failWriterError) Error() string {
return "error injected for tests"
}
type failWriter struct {
// fail after this many bytes
After int
}
func (f *failWriter) Write(p []byte) (n int, err error) {
n = len(p)
if n > f.After {
n = f.After
err = failWriterError{}
}
f.After -= n
return n, err
}
// Ensure that Copy handles write errors right.
func TestTx_CopyFile_Error_Meta(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte("bat"))
return nil
})
err := db.View(func(tx *bolt.Tx) error { return tx.Copy(&failWriter{}) })
equals(t, err.Error(), "meta copy: error injected for tests")
}
// Ensure that Copy handles write errors right.
func TestTx_CopyFile_Error_Normal(t *testing.T) {
db := NewTestDB()
defer db.Close()
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte("bat"))
return nil
})
err := db.View(func(tx *bolt.Tx) error { return tx.Copy(&failWriter{3 * db.Info().PageSize}) })
equals(t, err.Error(), "error injected for tests")
}
func ExampleTx_Rollback() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Create a bucket.
db.Update(func(tx *bolt.Tx) error {
_, err := tx.CreateBucket([]byte("widgets"))
return err
})
// Set a value for a key.
db.Update(func(tx *bolt.Tx) error {
return tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
})
// Update the key but rollback the transaction so it never saves.
tx, _ := db.Begin(true)
b := tx.Bucket([]byte("widgets"))
b.Put([]byte("foo"), []byte("baz"))
tx.Rollback()
// Ensure that our original value is still set.
db.View(func(tx *bolt.Tx) error {
value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
fmt.Printf("The value for 'foo' is still: %s\n", value)
return nil
})
// Output:
// The value for 'foo' is still: bar
}
func ExampleTx_CopyFile() {
// Open the database.
db, _ := bolt.Open(tempfile(), 0666, nil)
defer os.Remove(db.Path())
defer db.Close()
// Create a bucket and a key.
db.Update(func(tx *bolt.Tx) error {
tx.CreateBucket([]byte("widgets"))
tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte("bar"))
return nil
})
// Copy the database to another file.
toFile := tempfile()
db.View(func(tx *bolt.Tx) error { return tx.CopyFile(toFile, 0666) })
defer os.Remove(toFile)
// Open the cloned database.
db2, _ := bolt.Open(toFile, 0666, nil)
defer db2.Close()
// Ensure that the key exists in the copy.
db2.View(func(tx *bolt.Tx) error {
value := tx.Bucket([]byte("widgets")).Get([]byte("foo"))
fmt.Printf("The value for 'foo' in the clone is: %s\n", value)
return nil
})
// Output:
// The value for 'foo' in the clone is: bar
}

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package boltdb
import (
"bytes"
"encoding/binary"
"errors"
"os"
"path/filepath"
"sync/atomic"
"github.com/boltdb/bolt"
"github.com/docker/libkv"
"github.com/docker/libkv/store"
)
var (
// ErrMultipleEndpointsUnsupported is thrown when multiple endpoints specified for
// BoltDB. Endpoint has to be a local file path
ErrMultipleEndpointsUnsupported = errors.New("boltdb supports one endpoint and should be a file path")
// ErrBoltBucketNotFound is thrown when specified BoltBD bucket doesn't exist in the DB
ErrBoltBucketNotFound = errors.New("boltdb bucket doesn't exist")
// ErrBoltBucketOptionMissing is thrown when boltBcuket config option is missing
ErrBoltBucketOptionMissing = errors.New("boltBucket config option missing")
// ErrBoltAPIUnsupported is thrown when an APIs unsupported by BoltDB backend is called
ErrBoltAPIUnsupported = errors.New("API not supported by BoltDB backend")
)
//BoltDB type implements the Store interface
type BoltDB struct {
client *bolt.DB
boltBucket []byte
dbIndex uint64
}
const (
libkvmetadatalen = 8
)
// Register registers boltdb to libkv
func Register() {
libkv.AddStore(store.BOLTDB, New)
}
// New opens a new BoltDB connection to the specified path and bucket
func New(endpoints []string, options *store.Config) (store.Store, error) {
if len(endpoints) > 1 {
return nil, ErrMultipleEndpointsUnsupported
}
if (options == nil) || (len(options.Bucket) == 0) {
return nil, ErrBoltBucketOptionMissing
}
dir, _ := filepath.Split(endpoints[0])
if err := os.MkdirAll(dir, 0750); err != nil {
return nil, err
}
db, err := bolt.Open(endpoints[0], 0644, nil)
if err != nil {
return nil, err
}
b := &BoltDB{}
b.client = db
b.boltBucket = []byte(options.Bucket)
return b, nil
}
// Get the value at "key". BoltDB doesn't provide an inbuilt last modified index with every kv pair. Its implemented by
// by a atomic counter maintained by the libkv and appened to the value passed by the client.
func (b *BoltDB) Get(key string) (*store.KVPair, error) {
var val []byte
db := b.client
err := db.View(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return (ErrBoltBucketNotFound)
}
val = bucket.Get([]byte(key))
return nil
})
if len(val) == 0 {
return nil, store.ErrKeyNotFound
}
if err != nil {
return nil, err
}
dbIndex := binary.LittleEndian.Uint64(val[:libkvmetadatalen])
val = val[libkvmetadatalen:]
return &store.KVPair{Key: key, Value: val, LastIndex: (dbIndex)}, nil
}
//Put the key, value pair. index number metadata is prepended to the value
func (b *BoltDB) Put(key string, value []byte, opts *store.WriteOptions) error {
var dbIndex uint64
db := b.client
dbval := make([]byte, libkvmetadatalen)
err := db.Update(func(tx *bolt.Tx) error {
bucket, err := tx.CreateBucketIfNotExists(b.boltBucket)
if err != nil {
return err
}
dbIndex = atomic.AddUint64(&b.dbIndex, 1)
binary.LittleEndian.PutUint64(dbval, dbIndex)
dbval = append(dbval, value...)
err = bucket.Put([]byte(key), dbval)
if err != nil {
return err
}
return nil
})
return err
}
//Delete the value for the given key.
func (b *BoltDB) Delete(key string) error {
db := b.client
err := db.Update(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return (ErrBoltBucketNotFound)
}
err := bucket.Delete([]byte(key))
return err
})
return err
}
// Exists checks if the key exists inside the store
func (b *BoltDB) Exists(key string) (bool, error) {
var val []byte
db := b.client
err := db.View(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return (ErrBoltBucketNotFound)
}
val = bucket.Get([]byte(key))
return nil
})
if len(val) == 0 {
return false, err
}
return true, err
}
// List returns the range of keys starting with the passed in prefix
func (b *BoltDB) List(keyPrefix string) ([]*store.KVPair, error) {
kv := []*store.KVPair{}
db := b.client
err := db.View(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return (ErrBoltBucketNotFound)
}
cursor := bucket.Cursor()
prefix := []byte(keyPrefix)
for key, val := cursor.Seek(prefix); bytes.HasPrefix(key, prefix); key, val = cursor.Next() {
dbIndex := binary.LittleEndian.Uint64(val[:libkvmetadatalen])
val = val[libkvmetadatalen:]
kv = append(kv, &store.KVPair{
Key: string(key),
Value: val,
LastIndex: dbIndex,
})
}
return nil
})
if len(kv) == 0 {
return nil, store.ErrKeyNotFound
}
return kv, err
}
// AtomicDelete deletes a value at "key" if the key
// has not been modified in the meantime, throws an
// error if this is the case
func (b *BoltDB) AtomicDelete(key string, previous *store.KVPair) (bool, error) {
var val []byte
var dbIndex uint64
if previous == nil {
return false, store.ErrPreviousNotSpecified
}
db := b.client
err := db.Update(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return ErrBoltBucketNotFound
}
val = bucket.Get([]byte(key))
dbIndex = binary.LittleEndian.Uint64(val[:libkvmetadatalen])
if dbIndex != previous.LastIndex {
return store.ErrKeyModified
}
err := bucket.Delete([]byte(key))
return err
})
if err != nil {
return false, err
}
return true, err
}
// AtomicPut puts a value at "key" if the key has not been
// modified since the last Put, throws an error if this is the case
func (b *BoltDB) AtomicPut(key string, value []byte, previous *store.KVPair, options *store.WriteOptions) (bool, *store.KVPair, error) {
var val []byte
var dbIndex uint64
dbval := make([]byte, libkvmetadatalen)
db := b.client
err := db.Update(func(tx *bolt.Tx) error {
var err error
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
if previous != nil {
return ErrBoltBucketNotFound
}
bucket, err = tx.CreateBucket(b.boltBucket)
if err != nil {
return err
}
}
// AtomicPut is equivalent to Put if previous is nil and the Ky
// doesn't exist in the DB.
val = bucket.Get([]byte(key))
if previous == nil && len(val) != 0 {
return store.ErrKeyModified
}
if previous != nil {
dbIndex = binary.LittleEndian.Uint64(val[:libkvmetadatalen])
if dbIndex != previous.LastIndex {
return store.ErrKeyModified
}
}
dbIndex = atomic.AddUint64(&b.dbIndex, 1)
binary.LittleEndian.PutUint64(dbval, b.dbIndex)
dbval = append(dbval, value...)
return (bucket.Put([]byte(key), dbval))
})
if err != nil {
return false, nil, err
}
updated := &store.KVPair{
Key: key,
Value: value,
LastIndex: dbIndex,
}
return true, updated, nil
}
// Close the db connection to the BoltDB
func (b *BoltDB) Close() {
db := b.client
db.Close()
}
// DeleteTree deletes a range of keys with a given prefix
func (b *BoltDB) DeleteTree(keyPrefix string) error {
db := b.client
err := db.Update(func(tx *bolt.Tx) error {
bucket := tx.Bucket(b.boltBucket)
if bucket == nil {
return (ErrBoltBucketNotFound)
}
cursor := bucket.Cursor()
prefix := []byte(keyPrefix)
for key, _ := cursor.Seek(prefix); bytes.HasPrefix(key, prefix); key, _ = cursor.Next() {
_ = bucket.Delete([]byte(key))
}
return nil
})
return err
}
// NewLock has to implemented at the library level since its not supported by BoltDB
func (b *BoltDB) NewLock(key string, options *store.LockOptions) (store.Locker, error) {
return nil, ErrBoltAPIUnsupported
}
// Watch has to implemented at the library level since its not supported by BoltDB
func (b *BoltDB) Watch(key string, stopCh <-chan struct{}) (<-chan *store.KVPair, error) {
return nil, ErrBoltAPIUnsupported
}
// WatchTree has to implemented at the library level since its not supported by BoltDB
func (b *BoltDB) WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*store.KVPair, error) {
return nil, ErrBoltAPIUnsupported
}

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package boltdb
import (
"os"
"testing"
"github.com/docker/libkv"
"github.com/docker/libkv/store"
"github.com/docker/libkv/testutils"
"github.com/stretchr/testify/assert"
)
func makeBoltDBClient(t *testing.T) store.Store {
kv, err := New([]string{"/tmp/not_exist_dir/__boltdbtest"}, &store.Config{Bucket: "boltDBTest"})
if err != nil {
t.Fatalf("cannot create store: %v", err)
}
return kv
}
func TestRegister(t *testing.T) {
Register()
kv, err := libkv.NewStore(
store.BOLTDB,
[]string{"/tmp/not_exist_dir/__boltdbtest"},
&store.Config{Bucket: "boltDBTest"},
)
assert.NoError(t, err)
assert.NotNil(t, kv)
if _, ok := kv.(*BoltDB); !ok {
t.Fatal("Error registering and initializing boltDB")
}
_ = os.Remove("/tmp/not_exist_dir/__boltdbtest")
}
func TestBoldDBStore(t *testing.T) {
kv := makeBoltDBClient(t)
testutils.RunTestCommon(t, kv)
testutils.RunTestAtomic(t, kv)
_ = os.Remove("/tmp/not_exist_dir/__boltdbtest")
}