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moby--moby/distribution/xfer/transfer_test.go
Aaron Lehmann 3e2b50ccaa Fix watching a released transfer
Things could go wrong if Watch was called after the last existing
watcher was released. The call to Watch would succeed even though it was
not really adding a watcher, and the corresponding call to Release would
close hasWatchers a second time.

The fix for this is twofold:

1. We allow transfers to gain new watchers after the watcher count has
touched zero. This means that the channel returned by Released should
not be closed until all watchers have been released AND the transfer is
no longer tracked by the transfer manager, meaning it won't be possible
for additional calls to Watch to race with closing the channel returned
by Released.

The Transfer interface has a new method called Close so the transfer can
know when the transfer manager no longer references it.

Remove the Cancel method. It's not used and should not be exported.

2. Even though (1) makes it possible to add watchers after all the
previous watchers have been released, we want to avoid doing this in
practice. A transfer that has had all its watchers released is in the
process of being cancelled, and attaching to one of these will never be
the correct behavior. Add a check if a watcher is attaching to a
cancelled transfer.  In this case, wait for the transfer to be removed
from the map and try again. This will ensure correct behavior when a
watcher tries to attach during the race window.

Either (1) or (2) should be sufficient to fix the race involved here,
but the combination is the most correct approach. (1) fixes the
low-level plumbing to be resilient to the race condition, and (2) avoids
using it in a racy way.

Fixes #19606

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2016-01-25 13:28:02 -08:00

423 lines
11 KiB
Go

package xfer
import (
"sync/atomic"
"testing"
"time"
"github.com/docker/docker/pkg/progress"
)
func TestTransfer(t *testing.T) {
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
select {
case <-start:
default:
t.Fatalf("transfer function not started even though concurrency limit not reached")
}
xfer := NewTransfer()
go func() {
for i := 0; i <= 10; i++ {
progressChan <- progress.Progress{ID: id, Action: "testing", Current: int64(i), Total: 10}
time.Sleep(10 * time.Millisecond)
}
close(progressChan)
}()
return xfer
}
}
tm := NewTransferManager(5)
progressChan := make(chan progress.Progress)
progressDone := make(chan struct{})
receivedProgress := make(map[string]int64)
go func() {
for p := range progressChan {
val, present := receivedProgress[p.ID]
if !present {
if p.Current != 0 {
t.Fatalf("got unexpected progress value: %d (expected 0)", p.Current)
}
} else if p.Current == 10 {
// Special case: last progress output may be
// repeated because the transfer finishing
// causes the latest progress output to be
// written to the channel (in case the watcher
// missed it).
if p.Current != 9 && p.Current != 10 {
t.Fatalf("got unexpected progress value: %d (expected %d)", p.Current, val+1)
}
} else if p.Current != val+1 {
t.Fatalf("got unexpected progress value: %d (expected %d)", p.Current, val+1)
}
receivedProgress[p.ID] = p.Current
}
close(progressDone)
}()
// Start a few transfers
ids := []string{"id1", "id2", "id3"}
xfers := make([]Transfer, len(ids))
watchers := make([]*Watcher, len(ids))
for i, id := range ids {
xfers[i], watchers[i] = tm.Transfer(id, makeXferFunc(id), progress.ChanOutput(progressChan))
}
for i, xfer := range xfers {
<-xfer.Done()
xfer.Release(watchers[i])
}
close(progressChan)
<-progressDone
for _, id := range ids {
if receivedProgress[id] != 10 {
t.Fatalf("final progress value %d instead of 10", receivedProgress[id])
}
}
}
func TestConcurrencyLimit(t *testing.T) {
concurrencyLimit := 3
var runningJobs int32
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
xfer := NewTransfer()
go func() {
<-start
totalJobs := atomic.AddInt32(&runningJobs, 1)
if int(totalJobs) > concurrencyLimit {
t.Fatalf("too many jobs running")
}
for i := 0; i <= 10; i++ {
progressChan <- progress.Progress{ID: id, Action: "testing", Current: int64(i), Total: 10}
time.Sleep(10 * time.Millisecond)
}
atomic.AddInt32(&runningJobs, -1)
close(progressChan)
}()
return xfer
}
}
tm := NewTransferManager(concurrencyLimit)
progressChan := make(chan progress.Progress)
progressDone := make(chan struct{})
receivedProgress := make(map[string]int64)
go func() {
for p := range progressChan {
receivedProgress[p.ID] = p.Current
}
close(progressDone)
}()
// Start more transfers than the concurrency limit
ids := []string{"id1", "id2", "id3", "id4", "id5", "id6", "id7", "id8"}
xfers := make([]Transfer, len(ids))
watchers := make([]*Watcher, len(ids))
for i, id := range ids {
xfers[i], watchers[i] = tm.Transfer(id, makeXferFunc(id), progress.ChanOutput(progressChan))
}
for i, xfer := range xfers {
<-xfer.Done()
xfer.Release(watchers[i])
}
close(progressChan)
<-progressDone
for _, id := range ids {
if receivedProgress[id] != 10 {
t.Fatalf("final progress value %d instead of 10", receivedProgress[id])
}
}
}
func TestInactiveJobs(t *testing.T) {
concurrencyLimit := 3
var runningJobs int32
testDone := make(chan struct{})
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
xfer := NewTransfer()
go func() {
<-start
totalJobs := atomic.AddInt32(&runningJobs, 1)
if int(totalJobs) > concurrencyLimit {
t.Fatalf("too many jobs running")
}
for i := 0; i <= 10; i++ {
progressChan <- progress.Progress{ID: id, Action: "testing", Current: int64(i), Total: 10}
time.Sleep(10 * time.Millisecond)
}
atomic.AddInt32(&runningJobs, -1)
close(inactive)
<-testDone
close(progressChan)
}()
return xfer
}
}
tm := NewTransferManager(concurrencyLimit)
progressChan := make(chan progress.Progress)
progressDone := make(chan struct{})
receivedProgress := make(map[string]int64)
go func() {
for p := range progressChan {
receivedProgress[p.ID] = p.Current
}
close(progressDone)
}()
// Start more transfers than the concurrency limit
ids := []string{"id1", "id2", "id3", "id4", "id5", "id6", "id7", "id8"}
xfers := make([]Transfer, len(ids))
watchers := make([]*Watcher, len(ids))
for i, id := range ids {
xfers[i], watchers[i] = tm.Transfer(id, makeXferFunc(id), progress.ChanOutput(progressChan))
}
close(testDone)
for i, xfer := range xfers {
<-xfer.Done()
xfer.Release(watchers[i])
}
close(progressChan)
<-progressDone
for _, id := range ids {
if receivedProgress[id] != 10 {
t.Fatalf("final progress value %d instead of 10", receivedProgress[id])
}
}
}
func TestWatchRelease(t *testing.T) {
ready := make(chan struct{})
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
xfer := NewTransfer()
go func() {
defer func() {
close(progressChan)
}()
<-ready
for i := int64(0); ; i++ {
select {
case <-time.After(10 * time.Millisecond):
case <-xfer.Context().Done():
return
}
progressChan <- progress.Progress{ID: id, Action: "testing", Current: i, Total: 10}
}
}()
return xfer
}
}
tm := NewTransferManager(5)
type watcherInfo struct {
watcher *Watcher
progressChan chan progress.Progress
progressDone chan struct{}
receivedFirstProgress chan struct{}
}
progressConsumer := func(w watcherInfo) {
first := true
for range w.progressChan {
if first {
close(w.receivedFirstProgress)
}
first = false
}
close(w.progressDone)
}
// Start a transfer
watchers := make([]watcherInfo, 5)
var xfer Transfer
watchers[0].progressChan = make(chan progress.Progress)
watchers[0].progressDone = make(chan struct{})
watchers[0].receivedFirstProgress = make(chan struct{})
xfer, watchers[0].watcher = tm.Transfer("id1", makeXferFunc("id1"), progress.ChanOutput(watchers[0].progressChan))
go progressConsumer(watchers[0])
// Give it multiple watchers
for i := 1; i != len(watchers); i++ {
watchers[i].progressChan = make(chan progress.Progress)
watchers[i].progressDone = make(chan struct{})
watchers[i].receivedFirstProgress = make(chan struct{})
watchers[i].watcher = xfer.Watch(progress.ChanOutput(watchers[i].progressChan))
go progressConsumer(watchers[i])
}
// Now that the watchers are set up, allow the transfer goroutine to
// proceed.
close(ready)
// Confirm that each watcher gets progress output.
for _, w := range watchers {
<-w.receivedFirstProgress
}
// Release one watcher every 5ms
for _, w := range watchers {
xfer.Release(w.watcher)
<-time.After(5 * time.Millisecond)
}
// Now that all watchers have been released, Released() should
// return a closed channel.
<-xfer.Released()
// Done() should return a closed channel because the xfer func returned
// due to cancellation.
<-xfer.Done()
for _, w := range watchers {
close(w.progressChan)
<-w.progressDone
}
}
func TestWatchFinishedTransfer(t *testing.T) {
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
xfer := NewTransfer()
go func() {
// Finish immediately
close(progressChan)
}()
return xfer
}
}
tm := NewTransferManager(5)
// Start a transfer
watchers := make([]*Watcher, 3)
var xfer Transfer
xfer, watchers[0] = tm.Transfer("id1", makeXferFunc("id1"), progress.ChanOutput(make(chan progress.Progress)))
// Give it a watcher immediately
watchers[1] = xfer.Watch(progress.ChanOutput(make(chan progress.Progress)))
// Wait for the transfer to complete
<-xfer.Done()
// Set up another watcher
watchers[2] = xfer.Watch(progress.ChanOutput(make(chan progress.Progress)))
// Release the watchers
for _, w := range watchers {
xfer.Release(w)
}
// Now that all watchers have been released, Released() should
// return a closed channel.
<-xfer.Released()
}
func TestDuplicateTransfer(t *testing.T) {
ready := make(chan struct{})
var xferFuncCalls int32
makeXferFunc := func(id string) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
atomic.AddInt32(&xferFuncCalls, 1)
xfer := NewTransfer()
go func() {
defer func() {
close(progressChan)
}()
<-ready
for i := int64(0); ; i++ {
select {
case <-time.After(10 * time.Millisecond):
case <-xfer.Context().Done():
return
}
progressChan <- progress.Progress{ID: id, Action: "testing", Current: i, Total: 10}
}
}()
return xfer
}
}
tm := NewTransferManager(5)
type transferInfo struct {
xfer Transfer
watcher *Watcher
progressChan chan progress.Progress
progressDone chan struct{}
receivedFirstProgress chan struct{}
}
progressConsumer := func(t transferInfo) {
first := true
for range t.progressChan {
if first {
close(t.receivedFirstProgress)
}
first = false
}
close(t.progressDone)
}
// Try to start multiple transfers with the same ID
transfers := make([]transferInfo, 5)
for i := range transfers {
t := &transfers[i]
t.progressChan = make(chan progress.Progress)
t.progressDone = make(chan struct{})
t.receivedFirstProgress = make(chan struct{})
t.xfer, t.watcher = tm.Transfer("id1", makeXferFunc("id1"), progress.ChanOutput(t.progressChan))
go progressConsumer(*t)
}
// Allow the transfer goroutine to proceed.
close(ready)
// Confirm that each watcher gets progress output.
for _, t := range transfers {
<-t.receivedFirstProgress
}
// Confirm that the transfer function was called exactly once.
if xferFuncCalls != 1 {
t.Fatal("transfer function wasn't called exactly once")
}
// Release one watcher every 5ms
for _, t := range transfers {
t.xfer.Release(t.watcher)
<-time.After(5 * time.Millisecond)
}
for _, t := range transfers {
// Now that all watchers have been released, Released() should
// return a closed channel.
<-t.xfer.Released()
// Done() should return a closed channel because the xfer func returned
// due to cancellation.
<-t.xfer.Done()
}
for _, t := range transfers {
close(t.progressChan)
<-t.progressDone
}
}