Update Godeps

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/Godeps/Godeps.json

@@ -120,6 +120,11 @@
 			"Comment": "docs-v1.12.0-rc4-2016-07-15-1316-g426a0af",
 			"Rev": "426a0af0759798d8e3332b38236ee40df6d14798"
 		},
+		{
+			"ImportPath": "github.com/docker/docker/pkg/locker",
+			"Comment": "docs-v1.12.0-rc4-2016-07-15-1316-g426a0af",
+			"Rev": "426a0af0759798d8e3332b38236ee40df6d14798"
+		},
 		{
 			"ImportPath": "github.com/docker/docker/pkg/longpath",
 			"Comment": "docs-v1.12.0-rc4-2016-07-15-1316-g426a0af",

libnetwork/Godeps/_workspace/src/github.com/docker/docker/pkg/locker/README.md

@@ -0,0 +1,65 @@
+Locker
+=====
+
+locker provides a mechanism for creating finer-grained locking to help
+free up more global locks to handle other tasks.
+
+The implementation looks close to a sync.Mutex, however the user must provide a
+reference to use to refer to the underlying lock when locking and unlocking,
+and unlock may generate an error.
+
+If a lock with a given name does not exist when `Lock` is called, one is
+created.
+Lock references are automatically cleaned up on `Unlock` if nothing else is
+waiting for the lock.
+
+
+## Usage
+
+```go
+package important
+
+import (
+	"sync"
+	"time"
+
+	"github.com/docker/docker/pkg/locker"
+)
+
+type important struct {
+	locks *locker.Locker
+	data  map[string]interface{}
+	mu    sync.Mutex
+}
+
+func (i *important) Get(name string) interface{} {
+	i.locks.Lock(name)
+	defer i.locks.Unlock(name)
+	return data[name]
+}
+
+func (i *important) Create(name string, data interface{}) {
+	i.locks.Lock(name)
+	defer i.locks.Unlock(name)
+
+	i.createImportant(data)
+
+	s.mu.Lock()
+	i.data[name] = data
+	s.mu.Unlock()
+}
+
+func (i *important) createImportant(data interface{}) {
+	time.Sleep(10 * time.Second)
+}
+```
+
+For functions dealing with a given name, always lock at the beginning of the
+function (or before doing anything with the underlying state), this ensures any
+other function that is dealing with the same name will block.
+
+When needing to modify the underlying data, use the global lock to ensure nothing
+else is modfying it at the same time.
+Since name lock is already in place, no reads will occur while the modification
+is being performed.
+

libnetwork/Godeps/_workspace/src/github.com/docker/docker/pkg/locker/locker.go

@@ -0,0 +1,112 @@
+/*
+Package locker provides a mechanism for creating finer-grained locking to help
+free up more global locks to handle other tasks.
+
+The implementation looks close to a sync.Mutex, however the user must provide a
+reference to use to refer to the underlying lock when locking and unlocking,
+and unlock may generate an error.
+
+If a lock with a given name does not exist when `Lock` is called, one is
+created.
+Lock references are automatically cleaned up on `Unlock` if nothing else is
+waiting for the lock.
+*/
+package locker
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+)
+
+// ErrNoSuchLock is returned when the requested lock does not exist
+var ErrNoSuchLock = errors.New("no such lock")
+
+// Locker provides a locking mechanism based on the passed in reference name
+type Locker struct {
+	mu    sync.Mutex
+	locks map[string]*lockCtr
+}
+
+// lockCtr is used by Locker to represent a lock with a given name.
+type lockCtr struct {
+	mu sync.Mutex
+	// waiters is the number of waiters waiting to acquire the lock
+	// this is int32 instead of uint32 so we can add `-1` in `dec()`
+	waiters int32
+}
+
+// inc increments the number of waiters waiting for the lock
+func (l *lockCtr) inc() {
+	atomic.AddInt32(&l.waiters, 1)
+}
+
+// dec decrements the number of waiters waiting on the lock
+func (l *lockCtr) dec() {
+	atomic.AddInt32(&l.waiters, -1)
+}
+
+// count gets the current number of waiters
+func (l *lockCtr) count() int32 {
+	return atomic.LoadInt32(&l.waiters)
+}
+
+// Lock locks the mutex
+func (l *lockCtr) Lock() {
+	l.mu.Lock()
+}
+
+// Unlock unlocks the mutex
+func (l *lockCtr) Unlock() {
+	l.mu.Unlock()
+}
+
+// New creates a new Locker
+func New() *Locker {
+	return &Locker{
+		locks: make(map[string]*lockCtr),
+	}
+}
+
+// Lock locks a mutex with the given name. If it doesn't exist, one is created
+func (l *Locker) Lock(name string) {
+	l.mu.Lock()
+	if l.locks == nil {
+		l.locks = make(map[string]*lockCtr)
+	}
+
+	nameLock, exists := l.locks[name]
+	if !exists {
+		nameLock = &lockCtr{}
+		l.locks[name] = nameLock
+	}
+
+	// increment the nameLock waiters while inside the main mutex
+	// this makes sure that the lock isn't deleted if `Lock` and `Unlock` are called concurrently
+	nameLock.inc()
+	l.mu.Unlock()
+
+	// Lock the nameLock outside the main mutex so we don't block other operations
+	// once locked then we can decrement the number of waiters for this lock
+	nameLock.Lock()
+	nameLock.dec()
+}
+
+// Unlock unlocks the mutex with the given name
+// If the given lock is not being waited on by any other callers, it is deleted
+func (l *Locker) Unlock(name string) error {
+	l.mu.Lock()
+	nameLock, exists := l.locks[name]
+	if !exists {
+		l.mu.Unlock()
+		return ErrNoSuchLock
+	}
+
+	if nameLock.count() == 0 {
+		delete(l.locks, name)
+	}
+	nameLock.Unlock()
+
+	l.mu.Unlock()
+	return nil
+}