Clean up lock-instrumentation and improve comments (#3499)

- Add a lockStat type to group counters
- Remove unnecessary helper functions
- Fix stats computation on force unlock
- Removed unnecessary checks and cleaned up comments

cmd/lock-instrument.go

@@ -17,7 +17,6 @@
 package cmd
 
 import (
-	"errors"
 	"fmt"
 	"time"
 )
@@ -36,59 +35,39 @@ const (
 	debugWLockStr lockType = "WLock"
 )
 
-// Struct containing information of status (ready/running/blocked) of an operation with given operation ID.
+// debugLockInfo - represents a single lock's information, uniquely identified by opsID.
+// See debugLockInfoPerVolumePath for more context.
 type debugLockInfo struct {
 	// "RLock" or "WLock".
 	lType lockType
-	// Contains the trace of the function which invoked the lock, obtained from runtime.
+	// Contains the backtrace of incl. the function which called (r)(un)lock.
 	lockSource string
-	// Status can be running/ready/blocked.
+	// Status can be running/blocked.
 	status statusType
-	// Time info of the since how long the status holds true.
+	// Time of last status update.
 	since time.Time
 }
 
-// debugLockInfo - container for storing locking information for unique copy
+// debugLockInfoPerVolumePath - lock state information on all locks held on (volume, path).
-// (volume,path) pair. ref variable holds the reference count for locks held for.
-// `ref` values helps us understand the n locks held for given <volume, path> pair.
-// `running` value helps us understand the total successful locks held (not blocked)
-// for given <volume, path> pair and the operation is under execution. `blocked`
-// value helps us understand the total number of operations blocked waiting on
-// locks for given <volume,path> pair.
 type debugLockInfoPerVolumePath struct {
-	ref      int64                    // running + blocked operations.
+	counters *lockStat                // Holds stats of lock held on (volume, path)
-	running  int64                    // count of successful lock acquire and running operations.
+	lockInfo map[string]debugLockInfo // Lock information per operation ID.
-	blocked  int64                    // count of number of operations blocked waiting on lock.
-	lockInfo map[string]debugLockInfo // map of [opsID] debugLockInfo{operation, status, since} .
 }
 
-// returns an instance of debugLockInfo.
+// LockInfoOriginMismatch - represents error when lock origin don't match.
-// need to create this for every unique pair of {volume,path}.
+type LockInfoOriginMismatch struct {
-// total locks, number of calls blocked on locks, and number of successful locks held but not unlocked yet.
-func newDebugLockInfoPerVolumePath() *debugLockInfoPerVolumePath {
-	return &debugLockInfoPerVolumePath{
-		lockInfo: make(map[string]debugLockInfo),
-		ref:      0,
-		blocked:  0,
-		running:  0,
-	}
-}
-
-// LockInfoOriginNotFound - While changing the state of the lock info its important that the entry for
-// lock at a given origin exists, if not `LockInfoOriginNotFound` is returned.
-type LockInfoOriginNotFound struct {
 	volume     string
 	path       string
 	opsID      string
 	lockSource string
 }
 
-func (l LockInfoOriginNotFound) Error() string {
+func (l LockInfoOriginMismatch) Error() string {
-	return fmt.Sprintf("No lock state stored for the lock origined at \"%s\", for <volume> %s, <path> %s, <opsID> %s",
+	return fmt.Sprintf("No lock state stored for the lock originated at \"%s\", for <volume> %s, <path> %s, <opsID> %s",
 		l.lockSource, l.volume, l.path, l.opsID)
 }
 
-// LockInfoVolPathMissing - Error interface. Returned when the info the
+// LockInfoVolPathMissing - represents error when lock information is missing for a given (volume, path).
 type LockInfoVolPathMissing struct {
 	volume string
 	path   string
@@ -98,8 +77,7 @@ func (l LockInfoVolPathMissing) Error() string {
 	return fmt.Sprintf("No entry in debug Lock Map for Volume: %s, path: %s", l.volume, l.path)
 }
 
-// LockInfoOpsIDNotFound - Returned when the lock state info exists, but the entry for
+// LockInfoOpsIDNotFound - represents error when lock info entry for a given operation ID doesn't exist.
-// given operation ID doesn't exist.
 type LockInfoOpsIDNotFound struct {
 	volume string
 	path   string
@@ -110,8 +88,7 @@ func (l LockInfoOpsIDNotFound) Error() string {
 	return fmt.Sprintf("No entry in lock info for <Operation ID> %s, <volume> %s, <path> %s", l.opsID, l.volume, l.path)
 }
 
-// LockInfoStateNotBlocked - When an attempt to change the state of the lock form `blocked` to `running` is done,
+// LockInfoStateNotBlocked - represents error when lock info isn't in blocked state when it should be.
-// its necessary that the state before the transsition is "blocked", otherwise LockInfoStateNotBlocked returned.
 type LockInfoStateNotBlocked struct {
 	volume string
 	path   string
@@ -122,146 +99,126 @@ func (l LockInfoStateNotBlocked) Error() string {
 	return fmt.Sprintf("Lock state should be \"Blocked\" for <volume> %s, <path> %s, <opsID> %s", l.volume, l.path, l.opsID)
 }
 
-var errLockNotInitialized = errors.New("Debug lockMap not initialized")
+// Initialize lock info for given (volume, path).
-
-// Initialize lock info volume path.
 func (n *nsLockMap) initLockInfoForVolumePath(param nsParam) {
-	n.debugLockMap[param] = newDebugLockInfoPerVolumePath()
+	n.debugLockMap[param] = &debugLockInfoPerVolumePath{
+		lockInfo: make(map[string]debugLockInfo),
+		counters: &lockStat{},
+	}
 }
 
 // Change the state of the lock from Blocked to Running.
 func (n *nsLockMap) statusBlockedToRunning(param nsParam, lockSource, opsID string, readLock bool) error {
-	// This operation is not executed under the scope nsLockMap.mutex.Lock(), lock has to be explicitly held here.
+	// This function is called outside nsLockMap.mutex.Lock(), so must be held explicitly.
 	n.lockMapMutex.Lock()
 	defer n.lockMapMutex.Unlock()
-	// new state info to be set for the lock.
-	newLockInfo := debugLockInfo{
-		lockSource: lockSource,
-		status:     runningStatus,
-		since:      time.Now().UTC(),
-	}
 
-	// Set lock type.
+	// Check whether the lock info entry for <volume, path> pair already exists.
-	if readLock {
+	_, ok := n.debugLockMap[param]
-		newLockInfo.lType = debugRLockStr
-	} else {
-		newLockInfo.lType = debugWLockStr
-	}
-
-	// Check whether the lock info entry for <volume, path> pair already exists and its not `nil`.
-	debugLockMap, ok := n.debugLockMap[param]
 	if !ok {
-		// The lock state info foe given <volume, path> pair should already exist.
-		// If not return `LockInfoVolPathMissing`.
 		return traceError(LockInfoVolPathMissing{param.volume, param.path})
 	}
-	//  ``debugLockMap`` entry containing lock info for `param <volume, path>` is `nil`.
+
-	if debugLockMap == nil {
+	// Check whether lock info entry for the given `opsID` exists.
-		return traceError(errLockNotInitialized)
-	}
 	lockInfo, ok := n.debugLockMap[param].lockInfo[opsID]
 	if !ok {
-		// The lock info entry for given `opsID` should already exist for given <volume, path> pair.
-		// If not return `LockInfoOpsIDNotFound`.
 		return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
 	}
-	// The entry for the lock origined at `lockSource` should already exist. If not return `LockInfoOriginNotFound`.
+
+	// Check whether lockSource is same.
 	if lockInfo.lockSource != lockSource {
-		return traceError(LockInfoOriginNotFound{param.volume, param.path, opsID, lockSource})
+		return traceError(LockInfoOriginMismatch{param.volume, param.path, opsID, lockSource})
 	}
-	// Status of the lock should already be set to "Blocked". If not return `LockInfoStateNotBlocked`.
+
+	// Status of the lock should be set to "Blocked".
 	if lockInfo.status != blockedStatus {
 		return traceError(LockInfoStateNotBlocked{param.volume, param.path, opsID})
 	}
-	// All checks finished. Changing the status of the operation from blocked to running and updating the time.
+	// Change lock status to running and update the time.
-	n.debugLockMap[param].lockInfo[opsID] = newLockInfo
+	n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, runningStatus, readLock)
 
-	// After locking unblocks decrease the blocked counter.
+	// Update global lock stats.
-	n.blockedCounter--
+	n.counters.lockGranted()
-	// Increase the running counter.
+	// Update (volume, pair) lock stats.
-	n.runningLockCounter++
+	n.debugLockMap[param].counters.lockGranted()
-	n.debugLockMap[param].blocked--
-	n.debugLockMap[param].running++
 	return nil
 }
 
-// Change the state of the lock from Ready to Blocked.
+// newDebugLockInfo - Constructs a debugLockInfo value given lock source, status and type.
-func (n *nsLockMap) statusNoneToBlocked(param nsParam, lockSource, opsID string, readLock bool) error {
+func newDebugLockInfo(lockSource string, status statusType, readLock bool) debugLockInfo {
-	newLockInfo := debugLockInfo{
+	lType := debugRLockStr
+	if readLock {
+		lType = debugRLockStr
+	} else {
+		lType = debugWLockStr
+	}
+	return debugLockInfo{
 		lockSource: lockSource,
-		status:     blockedStatus,
+		lType:      lType,
+		status:     status,
 		since:      time.Now().UTC(),
 	}
-	if readLock {
-		newLockInfo.lType = debugRLockStr
-	} else {
-		newLockInfo.lType = debugWLockStr
 }
 
-	lockInfo, ok := n.debugLockMap[param]
+// Change the state of the lock to Blocked.
+func (n *nsLockMap) statusNoneToBlocked(param nsParam, lockSource, opsID string, readLock bool) error {
+	_, ok := n.debugLockMap[param]
 	if !ok {
-		// State info entry for the given <volume, pair> doesn't exist, initializing it.
+		// Lock info entry for (volume, pair) doesn't exist, initialize it.
-		n.initLockInfoForVolumePath(param)
-	}
-	if lockInfo == nil {
-		//  *lockInfo is nil, initialize here.
 		n.initLockInfoForVolumePath(param)
 	}
 
-	// lockInfo is a map[string]debugLockInfo, which holds map[OperationID]{status,time, origin} of the lock.
+	// Mark lock status blocked for given opsID.
-	if n.debugLockMap[param].lockInfo == nil {
+	n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, blockedStatus, readLock)
-		n.debugLockMap[param].lockInfo = make(map[string]debugLockInfo)
+	// Update global lock stats.
-	}
+	n.counters.lockWaiting()
-	// The status of the operation with the given operation ID is marked blocked till its gets unblocked from the lock.
+	// Update (volume, path) lock stats.
-	n.debugLockMap[param].lockInfo[opsID] = newLockInfo
+	n.debugLockMap[param].counters.lockWaiting()
-	// Increment the Global lock counter.
-	n.globalLockCounter++
-	// Increment the counter for number of blocked opertions, decrement it after the locking unblocks.
-	n.blockedCounter++
-	// increment the reference of the lock for the given <volume,path> pair.
-	n.debugLockMap[param].ref++
-	// increment the blocked counter for the given <volume, path> pair.
-	n.debugLockMap[param].blocked++
 	return nil
 }
 
-// deleteLockInfoEntry - Deletes the lock state information for given
+// deleteLockInfoEntry - Deletes the lock information for given (volume, path).
-// <volume, path> pair. Called when nsLk.ref count is 0.
+// Called when nsLk.ref count is 0.
 func (n *nsLockMap) deleteLockInfoEntryForVolumePath(param nsParam) error {
 	// delete the lock info for the given operation.
 	if _, found := n.debugLockMap[param]; !found {
 		return traceError(LockInfoVolPathMissing{param.volume, param.path})
 	}
-	// Remove from the map if there are no more references for the given (volume,path) pair.
+
+	// The following stats update is relevant only in case of a
+	// ForceUnlock. In case of the last unlock on a (volume,
+	// path), this would be a no-op.
+	volumePathLocks := n.debugLockMap[param]
+	for _, lockInfo := range volumePathLocks.lockInfo {
+		granted := lockInfo.status == runningStatus
+		// Update global and (volume, path) stats.
+		n.counters.lockRemoved(granted)
+		volumePathLocks.counters.lockRemoved(granted)
+	}
 	delete(n.debugLockMap, param)
 	return nil
 }
 
-// deleteLockInfoEntry - Deletes the entry for given opsID in the lock state information
+// deleteLockInfoEntry - Deletes lock info entry for given opsID.
-// of given <volume, path> pair. Called when the nsLk ref count for the given
+// Called when the nsLk ref count for the given (volume, path) is
-// <volume, path> pair is not 0.
+// not 0.
 func (n *nsLockMap) deleteLockInfoEntryForOps(param nsParam, opsID string) error {
 	// delete the lock info for the given operation.
 	infoMap, found := n.debugLockMap[param]
 	if !found {
 		return traceError(LockInfoVolPathMissing{param.volume, param.path})
 	}
-	// The opertion finished holding the lock on the resource, remove
+	// The operation finished holding the lock on the resource, remove
 	// the entry for the given operation with the operation ID.
-	_, foundInfo := infoMap.lockInfo[opsID]
+	opsIDLock, foundInfo := infoMap.lockInfo[opsID]
 	if !foundInfo {
-		// Unlock request with invalid opertion ID not accepted.
+		// Unlock request with invalid operation ID not accepted.
 		return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
 	}
-	// Decrease the global running and lock reference counter.
+	// Update global and (volume, path) lock status.
-	n.runningLockCounter--
+	granted := opsIDLock.status == runningStatus
-	n.globalLockCounter--
+	n.counters.lockRemoved(granted)
-	// Decrease the lock referee counter for the lock info for given <volume,path> pair.
+	infoMap.counters.lockRemoved(granted)
-	// Decrease the running operation number. Its assumed that the operation is over
-	// once an attempt to release the lock is made.
-	infoMap.running--
-	// Decrease the total reference count of locks jeld on <volume,path> pair.
-	infoMap.ref--
 	delete(infoMap.lockInfo, opsID)
 	return nil
 }

cmd/lock-instrument_test.go

@@ -124,19 +124,19 @@ func verifyGlobalLockStats(l lockStateCase, t *testing.T, testNum int) {
 	globalNSMutex.lockMapMutex.Lock()
 
 	// Verifying the lock stats.
-	if globalNSMutex.globalLockCounter != int64(l.expectedGlobalLockCount) {
+	if globalNSMutex.counters.total != int64(l.expectedGlobalLockCount) {
 		t.Errorf("Test %d: Expected the global lock counter to be %v, but got %v", testNum, int64(l.expectedGlobalLockCount),
-			globalNSMutex.globalLockCounter)
+			globalNSMutex.counters.total)
 	}
 	// verify the count for total blocked locks.
-	if globalNSMutex.blockedCounter != int64(l.expectedBlockedLockCount) {
+	if globalNSMutex.counters.blocked != int64(l.expectedBlockedLockCount) {
 		t.Errorf("Test %d: Expected the total blocked lock counter to be %v, but got %v", testNum, int64(l.expectedBlockedLockCount),
-			globalNSMutex.blockedCounter)
+			globalNSMutex.counters.blocked)
 	}
 	// verify the count for total running locks.
-	if globalNSMutex.runningLockCounter != int64(l.expectedRunningLockCount) {
+	if globalNSMutex.counters.granted != int64(l.expectedRunningLockCount) {
 		t.Errorf("Test %d: Expected the total running lock counter to be %v, but got %v", testNum, int64(l.expectedRunningLockCount),
-			globalNSMutex.runningLockCounter)
+			globalNSMutex.counters.granted)
 	}
 	globalNSMutex.lockMapMutex.Unlock()
 	// Verifying again with the JSON response of the lock info.
@@ -169,19 +169,19 @@ func verifyLockStats(l lockStateCase, t *testing.T, testNum int) {
 	param := nsParam{l.volume, l.path}
 
 	// Verify the total locks (blocked+running) for given <vol,path> pair.
-	if globalNSMutex.debugLockMap[param].ref != int64(l.expectedVolPathLockCount) {
+	if globalNSMutex.debugLockMap[param].counters.total != int64(l.expectedVolPathLockCount) {
 		t.Errorf("Test %d: Expected the total lock count for volume: \"%s\", path: \"%s\" to be %v, but got %v", testNum,
-			param.volume, param.path, int64(l.expectedVolPathLockCount), globalNSMutex.debugLockMap[param].ref)
+			param.volume, param.path, int64(l.expectedVolPathLockCount), globalNSMutex.debugLockMap[param].counters.total)
 	}
 	// Verify the total running locks for given <volume, path> pair.
-	if globalNSMutex.debugLockMap[param].running != int64(l.expectedVolPathRunningCount) {
+	if globalNSMutex.debugLockMap[param].counters.granted != int64(l.expectedVolPathRunningCount) {
 		t.Errorf("Test %d: Expected the total running locks for volume: \"%s\", path: \"%s\" to be %v, but got %v", testNum, param.volume, param.path,
-			int64(l.expectedVolPathRunningCount), globalNSMutex.debugLockMap[param].running)
+			int64(l.expectedVolPathRunningCount), globalNSMutex.debugLockMap[param].counters.granted)
 	}
 	// Verify the total blocked locks for givne <volume, path> pair.
-	if globalNSMutex.debugLockMap[param].blocked != int64(l.expectedVolPathBlockCount) {
+	if globalNSMutex.debugLockMap[param].counters.blocked != int64(l.expectedVolPathBlockCount) {
 		t.Errorf("Test %d:  Expected the total blocked locks for volume: \"%s\", path: \"%s\"  to be %v, but got %v", testNum, param.volume, param.path,
-			int64(l.expectedVolPathBlockCount), globalNSMutex.debugLockMap[param].blocked)
+			int64(l.expectedVolPathBlockCount), globalNSMutex.debugLockMap[param].counters.blocked)
 	}
 }
 
@@ -230,16 +230,19 @@ func verifyLockState(l lockStateCase, t *testing.T, testNum int) {
 
 // TestNewDebugLockInfoPerVolumePath -  Validates the values initialized by newDebugLockInfoPerVolumePath().
 func TestNewDebugLockInfoPerVolumePath(t *testing.T) {
-	lockInfo := newDebugLockInfoPerVolumePath()
+	lockInfo := &debugLockInfoPerVolumePath{
+		lockInfo: make(map[string]debugLockInfo),
+		counters: &lockStat{},
+	}
 
-	if lockInfo.ref != 0 {
+	if lockInfo.counters.total != 0 {
-		t.Errorf("Expected initial reference value of total locks to be 0, got %d", lockInfo.ref)
+		t.Errorf("Expected initial reference value of total locks to be 0, got %d", lockInfo.counters.total)
 	}
-	if lockInfo.blocked != 0 {
+	if lockInfo.counters.blocked != 0 {
-		t.Errorf("Expected initial reference of blocked locks to be 0, got %d", lockInfo.blocked)
+		t.Errorf("Expected initial reference of blocked locks to be 0, got %d", lockInfo.counters.blocked)
 	}
-	if lockInfo.running != 0 {
+	if lockInfo.counters.granted != 0 {
-		t.Errorf("Expected initial reference value of held locks to be 0, got %d", lockInfo.running)
+		t.Errorf("Expected initial reference value of held locks to be 0, got %d", lockInfo.counters.granted)
 	}
 }
 
@@ -300,7 +303,7 @@ func TestNsLockMapStatusBlockedToRunning(t *testing.T) {
 			readLock:   true,
 			setBlocked: false,
 			// expected metrics.
-			expectedErr: LockInfoOriginNotFound{"my-bucket", "my-object", "abcd1234", "Bad Origin"},
+			expectedErr: LockInfoOriginMismatch{"my-bucket", "my-object", "abcd1234", "Bad Origin"},
 		},
 		// Test case - 5.
 		// Test case with write lock.
@@ -332,21 +335,11 @@ func TestNsLockMapStatusBlockedToRunning(t *testing.T) {
 		debugLockMap: make(map[nsParam]*debugLockInfoPerVolumePath),
 		lockMap:      make(map[nsParam]*nsLock),
 	}
-	// Entry for <volume, path> pair is set to nil. Should fail with `errLockNotInitialized`.
-	globalNSMutex.debugLockMap[param] = nil
-	actualErr = globalNSMutex.statusBlockedToRunning(param, testCases[0].lockSource,
-		testCases[0].opsID, testCases[0].readLock)
-
-	if errorCause(actualErr) != errLockNotInitialized {
-		t.Fatalf("Errors mismatch: Expected \"%s\", got \"%s\"", errLockNotInitialized, actualErr)
-	}
 
 	// Setting the lock info the be `nil`.
 	globalNSMutex.debugLockMap[param] = &debugLockInfoPerVolumePath{
 		lockInfo: nil, // setting the lockinfo to nil.
-		ref:      0,
+		counters: &lockStat{},
-		blocked:  0,
-		running:  0,
 	}
 
 	actualErr = globalNSMutex.statusBlockedToRunning(param, testCases[0].lockSource,
@@ -361,9 +354,7 @@ func TestNsLockMapStatusBlockedToRunning(t *testing.T) {
 	// but the initial state if already "Running". Such an attempt should fail
 	globalNSMutex.debugLockMap[param] = &debugLockInfoPerVolumePath{
 		lockInfo: make(map[string]debugLockInfo),
-		ref:      0,
+		counters: &lockStat{},
-		blocked:  0,
-		running:  0,
 	}
 
 	// Setting the status of the lock to be "Running".
@@ -610,14 +601,14 @@ func TestNsLockMapDeleteLockInfoEntryForOps(t *testing.T) {
 	} else {
 		t.Fatalf("Entry for <volume> %s, <path> %s should have existed. ", param.volume, param.path)
 	}
-	if globalNSMutex.runningLockCounter != int64(0) {
+	if globalNSMutex.counters.granted != int64(0) {
-		t.Errorf("Expected the count of total running locks to be %v, but got %v", int64(0), globalNSMutex.runningLockCounter)
+		t.Errorf("Expected the count of total running locks to be %v, but got %v", int64(0), globalNSMutex.counters.granted)
 	}
-	if globalNSMutex.blockedCounter != int64(0) {
+	if globalNSMutex.counters.blocked != int64(0) {
-		t.Errorf("Expected the count of total blocked locks to be %v, but got %v", int64(0), globalNSMutex.blockedCounter)
+		t.Errorf("Expected the count of total blocked locks to be %v, but got %v", int64(0), globalNSMutex.counters.blocked)
 	}
-	if globalNSMutex.globalLockCounter != int64(0) {
+	if globalNSMutex.counters.total != int64(0) {
-		t.Errorf("Expected the count of all locks to be %v, but got %v", int64(0), globalNSMutex.globalLockCounter)
+		t.Errorf("Expected the count of all locks to be %v, but got %v", int64(0), globalNSMutex.counters.total)
 	}
 }
 
@@ -680,13 +671,13 @@ func TestNsLockMapDeleteLockInfoEntryForVolumePath(t *testing.T) {
 		t.Fatalf("Entry for <volume> %s, <path> %s should have been deleted. ", param.volume, param.path)
 	}
 	// The lock count values should be 0.
-	if globalNSMutex.runningLockCounter != int64(0) {
+	if globalNSMutex.counters.granted != int64(0) {
-		t.Errorf("Expected the count of total running locks to be %v, but got %v", int64(0), globalNSMutex.runningLockCounter)
+		t.Errorf("Expected the count of total running locks to be %v, but got %v", int64(0), globalNSMutex.counters.granted)
 	}
-	if globalNSMutex.blockedCounter != int64(0) {
+	if globalNSMutex.counters.blocked != int64(0) {
-		t.Errorf("Expected the count of total blocked locks to be %v, but got %v", int64(0), globalNSMutex.blockedCounter)
+		t.Errorf("Expected the count of total blocked locks to be %v, but got %v", int64(0), globalNSMutex.counters.blocked)
 	}
-	if globalNSMutex.globalLockCounter != int64(0) {
+	if globalNSMutex.counters.total != int64(0) {
-		t.Errorf("Expected the count of all locks to be %v, but got %v", int64(0), globalNSMutex.globalLockCounter)
+		t.Errorf("Expected the count of all locks to be %v, but got %v", int64(0), globalNSMutex.counters.total)
 	}
 }

cmd/lock-stat.go

@@ -0,0 +1,49 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+// lockStat - encapsulates total, blocked and granted lock counts.
+type lockStat struct {
+	total   int64
+	blocked int64
+	granted int64
+}
+
+// lockWaiting - updates lock stat when a lock becomes blocked.
+func (ls *lockStat) lockWaiting() {
+	ls.blocked++
+	ls.total++
+}
+
+// lockGranted - updates lock stat when a lock is granted.
+func (ls *lockStat) lockGranted() {
+	ls.blocked--
+	ls.granted++
+}
+
+// lockRemoved - updates lock stat when a lock is removed, by Unlock
+// or ForceUnlock.
+func (ls *lockStat) lockRemoved(granted bool) {
+	if granted {
+		ls.granted--
+		ls.total--
+
+	} else {
+		ls.blocked--
+		ls.total--
+	}
+}

cmd/lockinfo-handlers.go

@@ -66,17 +66,17 @@ func getSystemLockState() (SystemLockState, error) {
 
 	lockState := SystemLockState{}
 
-	lockState.TotalBlockedLocks = globalNSMutex.blockedCounter
+	lockState.TotalBlockedLocks = globalNSMutex.counters.blocked
-	lockState.TotalLocks = globalNSMutex.globalLockCounter
+	lockState.TotalLocks = globalNSMutex.counters.total
-	lockState.TotalAcquiredLocks = globalNSMutex.runningLockCounter
+	lockState.TotalAcquiredLocks = globalNSMutex.counters.granted
 
 	for param, debugLock := range globalNSMutex.debugLockMap {
 		volLockInfo := VolumeLockInfo{}
 		volLockInfo.Bucket = param.volume
 		volLockInfo.Object = param.path
-		volLockInfo.LocksOnObject = debugLock.ref
+		volLockInfo.LocksOnObject = debugLock.counters.total
-		volLockInfo.TotalBlockedLocks = debugLock.blocked
+		volLockInfo.TotalBlockedLocks = debugLock.counters.blocked
-		volLockInfo.LocksAcquiredOnObject = debugLock.running
+		volLockInfo.LocksAcquiredOnObject = debugLock.counters.granted
 		for opsID, lockInfo := range debugLock.lockInfo {
 			volLockInfo.LockDetailsOnObject = append(volLockInfo.LockDetailsOnObject, OpsLockState{
 				OperationID: opsID,

cmd/namespace-lock.go

@@ -61,6 +61,7 @@ func initNSLock(isDistXL bool) {
 	globalNSMutex = &nsLockMap{
 		isDistXL: isDistXL,
 		lockMap:  make(map[nsParam]*nsLock),
+		counters: &lockStat{},
 	}
 
 	// Initialize nsLockMap with entry for instrumentation information.
@@ -91,9 +92,7 @@ type nsLock struct {
 // Unlock, RLock and RUnlock.
 type nsLockMap struct {
 	// Lock counter used for lock debugging.
-	globalLockCounter  int64                                   // Total locks held.
+	counters     *lockStat
-	blockedCounter     int64                                   // Total operations blocked waiting for locks.
-	runningLockCounter int64                                   // Total locks held but not released yet.
 	debugLockMap map[nsParam]*debugLockInfoPerVolumePath // Info for instrumentation on locks.
 
 	// Indicates whether the locking service is part