add distributed lock manager

weed/cluster/lock_manager/distributed_lock_manager.go

@@ -0,0 +1,50 @@
+package lock_manager
+
+import (
+	"github.com/seaweedfs/seaweedfs/weed/pb"
+)
+
+type DistributedLockManager struct {
+	lockManager *LockManager
+}
+
+func NewDistributedLockManager() *DistributedLockManager {
+	return &DistributedLockManager{
+		lockManager: NewLockManager(),
+	}
+}
+
+func (dlm *DistributedLockManager) Lock(host pb.ServerAddress, key string, expiredAtNs int64, token string, servers []pb.ServerAddress) (renewToken string, movedTo pb.ServerAddress, err error) {
+	server := HashKeyToServer(key, servers)
+	if server != host {
+		movedTo = server
+		return
+	}
+	renewToken, err = dlm.lockManager.Lock(key, expiredAtNs, token)
+	return
+}
+
+func (dlm *DistributedLockManager) Unlock(host pb.ServerAddress, key string, token string, servers []pb.ServerAddress) (movedTo pb.ServerAddress, err error) {
+	server := HashKeyToServer(key, servers)
+	if server != host {
+		movedTo = server
+		return
+	}
+	_, err = dlm.lockManager.Unlock(key, token)
+	return
+}
+
+// InsertLock is used to insert a lock to a server unconditionally
+// It is used when a server is down and the lock is moved to another server
+func (dlm *DistributedLockManager) InsertLock(key string, expiredAtNs int64, token string) {
+	dlm.lockManager.InsertLock(key, expiredAtNs, token)
+}
+func (dlm *DistributedLockManager) SelectNotOwnedLocks(host pb.ServerAddress, servers []pb.ServerAddress) (locks []*Lock) {
+	return dlm.lockManager.SelectLocks(func(key string) bool {
+		server := HashKeyToServer(key, servers)
+		return server != host
+	})
+}
+func (dlm *DistributedLockManager) CalculateTargetServer(key string, servers []pb.ServerAddress) pb.ServerAddress {
+	return HashKeyToServer(key, servers)
+}