add distributed lock manager

weed/cluster/lock_manager/lock_manager.go

@@ -0,0 +1,118 @@
+package lock_manager
+
+import (
+	"fmt"
+	"github.com/google/uuid"
+	"github.com/puzpuzpuz/xsync/v2"
+	"time"
+)
+
+// LockManager lock manager
+type LockManager struct {
+	locks *xsync.MapOf[string, *Lock]
+}
+type Lock struct {
+	Token        string
+	ExpirationNs int64
+	Key          string // only used for moving locks
+}
+
+func NewLockManager() *LockManager {
+	t := &LockManager{
+		locks: xsync.NewMapOf[*Lock](),
+	}
+	go t.CleanUp()
+	return t
+}
+
+func (lm *LockManager) Lock(path string, ttlDuration time.Duration, token string) (renewToken string, err error) {
+	lm.locks.Compute(path, func(oldValue *Lock, loaded bool) (newValue *Lock, delete bool) {
+		if oldValue != nil {
+			now := time.Now()
+			if oldValue.ExpirationNs > 0 && oldValue.ExpirationNs < now.UnixNano() {
+				// lock is expired, set to a new lock
+				expirationNs := time.Now().Add(ttlDuration).UnixNano()
+				return &Lock{Token: token, ExpirationNs: expirationNs}, false
+			}
+			if oldValue.Token == token {
+				expirationNs := time.Now().Add(ttlDuration).UnixNano()
+				return &Lock{Token: token, ExpirationNs: expirationNs}, false
+			} else {
+				err = fmt.Errorf("lock: token mismatch")
+				return oldValue, false
+			}
+		} else {
+			expirationNs := time.Now().Add(ttlDuration).UnixNano()
+			if token == "" {
+				renewToken = uuid.New().String()
+				return &Lock{Token: renewToken, ExpirationNs: expirationNs}, false
+			} else {
+				err = fmt.Errorf("lock: non-empty token on a new lock")
+				return nil, false
+			}
+			return &Lock{Token: token, ExpirationNs: expirationNs}, false
+		}
+	})
+	return
+}
+
+func (lm *LockManager) Unlock(path string, token string) (isUnlocked bool, err error) {
+	lm.locks.Compute(path, func(oldValue *Lock, loaded bool) (newValue *Lock, delete bool) {
+		if oldValue != nil {
+			now := time.Now()
+			if oldValue.ExpirationNs > 0 && oldValue.ExpirationNs < now.UnixNano() {
+				// lock is expired, delete it
+				isUnlocked = true
+				return nil, true
+			}
+			if oldValue.Token == token {
+				if oldValue.ExpirationNs <= now.UnixNano() {
+					isUnlocked = true
+					return nil, true
+				}
+				return oldValue, false
+			} else {
+				isUnlocked = false
+				err = fmt.Errorf("unlock: token mismatch")
+				return oldValue, false
+			}
+		} else {
+			isUnlocked = true
+			return nil, true
+		}
+	})
+	return
+}
+
+func (lm *LockManager) CleanUp() {
+	for {
+		time.Sleep(1 * time.Minute)
+		now := time.Now().UnixNano()
+		lm.locks.Range(func(key string, value *Lock) bool {
+			if now > value.ExpirationNs {
+				lm.locks.Delete(key)
+				return true
+			}
+			return true
+		})
+	}
+}
+
+// TakeOutLocksByKey takes out locks by key
+// if keyFn return true, the lock will be taken out
+func (lm *LockManager) TakeOutLocksByKey(keyFn func(key string) bool) (locks []*Lock) {
+	now := time.Now().UnixNano()
+	lm.locks.Range(func(key string, lock *Lock) bool {
+		if now > lock.ExpirationNs {
+			lm.locks.Delete(key)
+			return true
+		}
+		if keyFn(key) {
+			lm.locks.Delete(key)
+			lock.Key = key
+			locks = append(locks, lock)
+		}
+		return true
+	})
+	return
+}

weed/cluster/lock_manager/lock_ring.go

@@ -2,6 +2,7 @@ package lock_manager
 
 import (
 	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/util"
 	"sort"
 	"sync"
 	"time"
@@ -22,14 +23,19 @@ type LockRing struct {
 	onTakeSnapshot   func(snapshot []pb.ServerAddress)
 }
 
-func NewLockRing(snapshotInterval time.Duration, onTakeSnapshot func(snapshot []pb.ServerAddress)) *LockRing {
+func NewLockRing(snapshotInterval time.Duration) *LockRing {
 	return &LockRing{
 		snapshotInterval: snapshotInterval,
 		candidateServers: make(map[pb.ServerAddress]struct{}),
-		onTakeSnapshot:   onTakeSnapshot,
 	}
 }
 
+func (r *LockRing) SetTakeSnapshotCallback(onTakeSnapshot func(snapshot []pb.ServerAddress)) {
+	r.Lock()
+	defer r.Unlock()
+	r.onTakeSnapshot = onTakeSnapshot
+}
+
 // AddServer adds a server to the ring
 // if the previous snapshot passed the snapshot interval, create a new snapshot
 func (r *LockRing) AddServer(server pb.ServerAddress) {
@@ -144,3 +150,25 @@ func (r *LockRing) getSortedServers() []pb.ServerAddress {
 	})
 	return sortedServers
 }
+
+func (r *LockRing) GetSnapshot() (servers []pb.ServerAddress) {
+	r.RLock()
+	defer r.RUnlock()
+
+	if len(r.snapshots) == 0 {
+		return
+	}
+	return r.snapshots[0].servers
+}
+
+func HashKeyToServer(key string, servers []pb.ServerAddress) pb.ServerAddress {
+	if len(servers) == 0 {
+		return ""
+	}
+	x := util.HashStringToLong(key)
+	if x < 0 {
+		x = -x
+	}
+	x = x % int64(len(servers))
+	return servers[x]
+}

weed/cluster/lock_manager/lock_ring_test.go

@@ -8,15 +8,7 @@ import (
 )
 
 func TestAddServer(t *testing.T) {
-	counter := 0
-	r := NewLockRing(100*time.Millisecond, func(snapshot []pb.ServerAddress) {
-		counter++
-		if counter == 1 {
-			assert.Equal(t, 1, len(snapshot))
-		} else if counter == 2 {
-			assert.Equal(t, 2, len(snapshot))
-		}
-	})
+	r := NewLockRing(100 * time.Millisecond)
 	r.AddServer("localhost:8080")
 	assert.Equal(t, 1, len(r.snapshots))
 	r.AddServer("localhost:8081")
@@ -36,7 +28,7 @@ func TestAddServer(t *testing.T) {
 }
 
 func TestLockRing(t *testing.T) {
-	r := NewLockRing(100*time.Millisecond, nil)
+	r := NewLockRing(100 * time.Millisecond)
 	r.SetSnapshot([]pb.ServerAddress{"localhost:8080", "localhost:8081"})
 	assert.Equal(t, 1, len(r.snapshots))
 	r.SetSnapshot([]pb.ServerAddress{"localhost:8080", "localhost:8081", "localhost:8082"})