store: Improved locking API and added mocks.

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

pkg/store/consul.go

@@ -302,13 +302,16 @@ func (s *Consul) WatchTree(prefix string, stopCh <-chan struct{}) (<-chan []*KVP
 	return watchCh, nil
 }
 
-// CreateLock returns a handle to a lock struct which can be used
-// to acquire and release the mutex.
-func (s *Consul) CreateLock(key string, value []byte) (Locker, error) {
-	l, err := s.client.LockOpts(&api.LockOptions{
-		Key:   s.normalize(key),
-		Value: value,
-	})
+// NewLock returns a handle to a lock struct which can be used to acquire and
+// release the mutex.
+func (s *Consul) NewLock(key string, options *LockOptions) (Locker, error) {
+	consulOpts := &api.LockOptions{
+		Key: s.normalize(key),
+	}
+	if options != nil {
+		consulOpts.Value = options.Value
+	}
+	l, err := s.client.LockOpts(consulOpts)
 	if err != nil {
 		return nil, err
 	}

pkg/store/etcd.go

@@ -277,8 +277,8 @@ func (s *Etcd) DeleteTree(prefix string) error {
 	return nil
 }
 
-// CreateLock returns a handle to a lock struct which can be used
-// to acquire and release the mutex.
-func (s *Etcd) CreateLock(key string, value []byte) (Locker, error) {
+// NewLock returns a handle to a lock struct which can be used to acquire and
+// release the mutex.
+func (s *Etcd) NewLock(key string, options *LockOptions) (Locker, error) {
 	return nil, ErrNotImplemented
 }

pkg/store/mock.go

@@ -56,9 +56,9 @@ func (s *Mock) WatchTree(prefix string, stopCh <-chan struct{}) (<-chan []*KVPai
 	return args.Get(0).(chan []*KVPair), args.Error(1)
 }
 
-// CreateLock mock
-func (s *Mock) CreateLock(key string, value []byte) (Locker, error) {
-	args := s.Mock.Called(key, value)
+// NewLock mock
+func (s *Mock) NewLock(key string, options *LockOptions) (Locker, error) {
+	args := s.Mock.Called(key, options)
 	return args.Get(0).(Locker), args.Error(1)
 }
 
@@ -85,3 +85,20 @@ func (s *Mock) AtomicDelete(key string, previous *KVPair) (bool, error) {
 	args := s.Mock.Called(key, previous)
 	return args.Bool(0), args.Error(1)
 }
+
+// MockLock mock implementation of Locker
+type MockLock struct {
+	mock.Mock
+}
+
+// Lock mock
+func (l *MockLock) Lock() (<-chan struct{}, error) {
+	args := l.Mock.Called()
+	return args.Get(0).(<-chan struct{}), args.Error(1)
+}
+
+// Unlock mock
+func (l *MockLock) Unlock() error {
+	args := l.Mock.Called()
+	return args.Error(0)
+}

pkg/store/store.go

@@ -78,7 +78,7 @@ type Store interface {
 	// CreateLock for a given key.
 	// The returned Locker is not held and must be acquired with `.Lock`.
 	// value is optional.
-	CreateLock(key string, value []byte) (Locker, error)
+	NewLock(key string, options *LockOptions) (Locker, error)
 
 	// List the content of a given prefix
 	List(prefix string) ([]*KVPair, error)
@@ -106,6 +106,11 @@ type WriteOptions struct {
 	Ephemeral bool
 }
 
+// LockOptions contains optional request parameters
+type LockOptions struct {
+	Value []byte // Optional, value to associate with the lock
+}
+
 // WatchCallback is used for watch methods on keys
 // and is triggered on key change
 type WatchCallback func(entries ...*KVPair)
@@ -130,7 +135,7 @@ var (
 	}
 )
 
-// CreateStore creates a an instance of store
+// NewStore creates a an instance of store
 func NewStore(backend Backend, addrs []string, options *Config) (Store, error) {
 	if init, exists := initializers[backend]; exists {
 		log.WithFields(log.Fields{"backend": backend}).Debug("Initializing store service")

pkg/store/zookeeper.go

@@ -222,10 +222,11 @@ func (s *Zookeeper) AtomicDelete(key string, previous *KVPair) (bool, error) {
 	return false, ErrNotImplemented
 }
 
-// CreateLock returns a handle to a lock struct which can be used
-// to acquire and release the mutex.
-func (s *Zookeeper) CreateLock(key string, value []byte) (Locker, error) {
-	// FIXME: `value` is not being used since there is no support in zk.NewLock().
+// NewLock returns a handle to a lock struct which can be used to acquire and
+// release the mutex.
+func (s *Zookeeper) NewLock(key string, options *LockOptions) (Locker, error) {
+	// FIXME: `options.Value` is not being used since there is no support in
+	// zk.NewLock().
 	return &zookeeperLock{
 		lock: zk.NewLock(s.client, normalize(key), zk.WorldACL(zk.PermAll)),
 	}, nil