Revert "Make localLocker lock attempts cancellable (#16510)" (#16884)

cmd/local-locker.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"fmt"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/minio/minio/internal/dsync"
@@ -50,7 +51,7 @@ func isWriteLock(lri []lockRequesterInfo) bool {
 
 // localLocker implements Dsync.NetLocker
 type localLocker struct {
-	mutex   chan struct{}
+	mutex   sync.Mutex
 	lockMap map[string][]lockRequesterInfo
 	lockUID map[string]string // UUID -> resource map.
 }
@@ -69,41 +70,13 @@ func (l *localLocker) canTakeLock(resources ...string) bool {
 	return true
 }
 
-// lockMu locks the "mutex" of the local locker.
-// If "ctx" is canceled before the lock can be obtained false is returned.
-// If "true" is returned unlockMu MUST be called.
-// Behavior is similar to sync.Mutex.
-func (l *localLocker) lockMu(ctx context.Context) (ok bool) {
-	select {
-	case l.mutex <- struct{}{}:
-		return true
-	case <-ctx.Done():
-		return false
-	}
-}
-
-// lockMuBlock will block while getting the mutex.
-// When returned unlockMu *must* be called.
-// Behavior is similar to sync.Mutex.
-func (l *localLocker) lockMuBlock() {
-	l.mutex <- struct{}{}
-}
-
-// unlockMu unlocks an acquired mutex.
-// This may only be called once after successfully getting a mutex.
-func (l *localLocker) unlockMu() {
-	<-l.mutex
-}
-
 func (l *localLocker) Lock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
 	if len(args.Resources) > maxDeleteList {
 		return false, fmt.Errorf("internal error: localLocker.Lock called with more than %d resources", maxDeleteList)
 	}
 
-	if !l.lockMu(ctx) {
-		return false, ctx.Err()
-	}
-	defer l.unlockMu()
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 
 	if !l.canTakeLock(args.Resources...) {
 		// Not all locks can be taken on resources,
@@ -142,9 +115,8 @@ func (l *localLocker) Unlock(_ context.Context, args dsync.LockArgs) (reply bool
 		return false, fmt.Errorf("internal error: localLocker.Unlock called with more than %d resources", maxDeleteList)
 	}
 
-	l.lockMuBlock()
-	defer l.unlockMu()
-
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 	err = nil
 
 	for _, resource := range args.Resources {
@@ -191,11 +163,8 @@ func (l *localLocker) RLock(ctx context.Context, args dsync.LockArgs) (reply boo
 		return false, fmt.Errorf("internal error: localLocker.RLock called with more than one resource")
 	}
 
-	if !l.lockMu(ctx) {
-		return false, ctx.Err()
-	}
-	defer l.unlockMu()
-
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 	resource := args.Resources[0]
 	lrInfo := lockRequesterInfo{
 		Name:            resource,
@@ -227,9 +196,8 @@ func (l *localLocker) RUnlock(_ context.Context, args dsync.LockArgs) (reply boo
 		return false, fmt.Errorf("internal error: localLocker.RUnlock called with more than one resource")
 	}
 
-	l.lockMuBlock()
-	defer l.unlockMu()
-
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 	var lri []lockRequesterInfo
 
 	resource := args.Resources[0]
@@ -246,8 +214,8 @@ func (l *localLocker) RUnlock(_ context.Context, args dsync.LockArgs) (reply boo
 }
 
 func (l *localLocker) DupLockMap() map[string][]lockRequesterInfo {
-	l.lockMuBlock()
-	defer l.unlockMu()
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 
 	lockCopy := make(map[string][]lockRequesterInfo, len(l.lockMap))
 	for k, v := range l.lockMap {
@@ -271,9 +239,12 @@ func (l *localLocker) IsLocal() bool {
 }
 
 func (l *localLocker) ForceUnlock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	l.lockMuBlock()
-	defer l.unlockMu()
-
+	select {
+	case <-ctx.Done():
+		return false, ctx.Err()
+	default:
+		l.mutex.Lock()
+		defer l.mutex.Unlock()
 		if len(args.UID) == 0 {
 			for _, resource := range args.Resources {
 				lris, ok := l.lockMap[resource]
@@ -324,13 +295,16 @@ func (l *localLocker) ForceUnlock(ctx context.Context, args dsync.LockArgs) (rep
 			l.removeEntry(resource, dsync.LockArgs{UID: args.UID}, &lris)
 			idx++
 		}
+	}
 }
 
 func (l *localLocker) Refresh(ctx context.Context, args dsync.LockArgs) (refreshed bool, err error) {
-	if !l.lockMu(ctx) {
+	select {
+	case <-ctx.Done():
 		return false, ctx.Err()
-	}
-	defer l.unlockMu()
+	default:
+		l.mutex.Lock()
+		defer l.mutex.Unlock()
 
 		// Check whether uid is still active.
 		resource, ok := l.lockUID[formatUUID(args.UID, 0)]
@@ -357,13 +331,14 @@ func (l *localLocker) Refresh(ctx context.Context, args dsync.LockArgs) (refresh
 				return true, nil
 			}
 		}
+	}
 }
 
 // Similar to removeEntry but only removes an entry only if the lock entry exists in map.
 // Caller must hold 'l.mutex' lock.
 func (l *localLocker) expireOldLocks(interval time.Duration) {
-	l.lockMuBlock()
-	defer l.unlockMu()
+	l.mutex.Lock()
+	defer l.mutex.Unlock()
 
 	for k, lris := range l.lockMap {
 		modified := false
@@ -394,7 +369,6 @@ func (l *localLocker) expireOldLocks(interval time.Duration) {
 
 func newLocker() *localLocker {
 	return &localLocker{
-		mutex:   make(chan struct{}, 1),
 		lockMap: make(map[string][]lockRequesterInfo, 1000),
 		lockUID: make(map[string]string, 1000),
 	}

cmd/lock-rest-server-common_test.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"os"
 	"reflect"
+	"sync"
 	"testing"
 
 	"github.com/minio/minio/internal/dsync"
@@ -37,7 +38,10 @@ func createLockTestServer(ctx context.Context, t *testing.T) (string, *lockRESTS
 	}
 
 	locker := &lockRESTServer{
-		ll: newLocker(),
+		ll: &localLocker{
+			mutex:   sync.Mutex{},
+			lockMap: make(map[string][]lockRequesterInfo),
+		},
 	}
 	creds := globalActiveCred
 	token, err := authenticateNode(creds.AccessKey, creds.SecretKey, "")