store: Add a channel to lock that is closed if our lock is lost or an error.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

pkg/store/consul.go

@@ -257,10 +257,9 @@ func (s *Consul) CreateLock(key string, value []byte) (Locker, error) {
 }
 
 // Lock attempts to acquire the lock and blocks while doing so.
-func (l *consulLock) Lock() error {
-	// FIXME: Locks may be lost and we should watch for the returned channel.
-	_, err := l.lock.Lock(nil)
-	return err
+// Returns a channel that is closed if our lock is lost or an error.
+func (l *consulLock) Lock() (<-chan struct{}, error) {
+	return l.lock.Lock(nil)
 }
 
 // Unlock released the lock. It is an error to call this

pkg/store/store.go

@@ -70,7 +70,7 @@ type KVEntry interface {
 // Locker provides locking mechanism on top of the store.
 // Similar to `sync.Lock` except it may return errors.
 type Locker interface {
-	Lock() error
+	Lock() (<-chan struct{}, error)
 	Unlock() error
 }
 

pkg/store/zookeeper.go

@@ -212,8 +212,12 @@ func (s *Zookeeper) CreateLock(key string, value []byte) (Locker, error) {
 }
 
 // Lock attempts to acquire the lock and blocks while doing so.
-func (l *zookeeperLock) Lock() error {
-	return l.lock.Lock()
+// Returns a channel that is closed if our lock is lost or an error.
+func (l *zookeeperLock) Lock() (<-chan struct{}, error) {
+	if err := l.lock.Lock(); err != nil {
+		return nil, err
+	}
+	return make(<-chan struct{}), nil
 }
 
 // Unlock released the lock. It is an error to call this