From ef791764e07c34bfda2a9c8c2bc995060f3b0929 Mon Sep 17 00:00:00 2001
From: Krishna Srinivas <634494+krishnasrinivas@users.noreply.github.com>
Date: Tue, 2 Apr 2019 12:27:20 -0700
Subject: [PATCH] Do no access nsLockMap.lockMap when using dsync (#7464)

There is no need to access nsLockMap.lockMap when using dsync
---
 cmd/namespace-lock.go | 82 ++++++++++++++++++++++++++++++-------------
 1 file changed, 58 insertions(+), 24 deletions(-)

diff --git a/cmd/namespace-lock.go b/cmd/namespace-lock.go
index eb188c2a4..024b2a2c7 100644
--- a/cmd/namespace-lock.go
+++ b/cmd/namespace-lock.go
@@ -51,14 +51,6 @@ type RWLocker interface {
 	RUnlock()
 }
 
-// RWLockerSync - internal locker interface.
-type RWLockerSync interface {
-	GetLock(id, source string, timeout time.Duration) bool
-	Unlock()
-	GetRLock(id, source string, timeout time.Duration) bool
-	RUnlock()
-}
-
 // Initialize distributed locking only in case of distributed setup.
 // Returns lock clients and the node index for the current server.
 func newDsyncNodes(endpoints EndpointList) (clnts []dsync.NetLocker, myNode int) {
@@ -101,8 +93,11 @@ func newDsyncNodes(endpoints EndpointList) (clnts []dsync.NetLocker, myNode int)
 func newNSLock(isDistXL bool) *nsLockMap {
 	nsMutex := nsLockMap{
 		isDistXL: isDistXL,
-		lockMap:  make(map[nsParam]*nsLock),
 	}
+	if isDistXL {
+		return &nsMutex
+	}
+	nsMutex.lockMap = make(map[nsParam]*nsLock)
 	return &nsMutex
 }
 
@@ -119,7 +114,7 @@ type nsParam struct {
 
 // nsLock - provides primitives for locking critical namespace regions.
 type nsLock struct {
-	RWLockerSync
+	*lsync.LRWMutex
 	ref uint
 }
 
@@ -141,13 +136,8 @@ func (n *nsLockMap) lock(volume, path string, lockSource, opsID string, readLock
 	nsLk, found := n.lockMap[param]
 	if !found {
 		n.lockMap[param] = &nsLock{
-			RWLockerSync: func() RWLockerSync {
-				if n.isDistXL {
-					return dsync.NewDRWMutex(pathJoin(volume, path), globalDsync)
-				}
-				return &lsync.LRWMutex{}
-			}(),
-			ref: 1,
+			LRWMutex: &lsync.LRWMutex{},
+			ref:      1,
 		}
 		nsLk = n.lockMap[param]
 	} else {
@@ -259,8 +249,49 @@ func (n *nsLockMap) ForceUnlock(volume, path string) {
 	delete(n.lockMap, nsParam{volume, path})
 }
 
-// lockInstance - frontend/top-level interface for namespace locks.
-type lockInstance struct {
+// dsync's distributed lock instance.
+type distLockInstance struct {
+	rwMutex             *dsync.DRWMutex
+	volume, path, opsID string
+}
+
+// Lock - block until write lock is taken or timeout has occurred.
+func (di *distLockInstance) GetLock(timeout *dynamicTimeout) (timedOutErr error) {
+	lockSource := getSource()
+	start := UTCNow()
+
+	if !di.rwMutex.GetLock(di.opsID, lockSource, timeout.Timeout()) {
+		timeout.LogFailure()
+		return OperationTimedOut{Path: di.path}
+	}
+	timeout.LogSuccess(UTCNow().Sub(start))
+	return nil
+}
+
+// Unlock - block until write lock is released.
+func (di *distLockInstance) Unlock() {
+	di.rwMutex.Unlock()
+}
+
+// RLock - block until read lock is taken or timeout has occurred.
+func (di *distLockInstance) GetRLock(timeout *dynamicTimeout) (timedOutErr error) {
+	lockSource := getSource()
+	start := UTCNow()
+	if !di.rwMutex.GetRLock(di.opsID, lockSource, timeout.Timeout()) {
+		timeout.LogFailure()
+		return OperationTimedOut{Path: di.path}
+	}
+	timeout.LogSuccess(UTCNow().Sub(start))
+	return nil
+}
+
+// RUnlock - block until read lock is released.
+func (di *distLockInstance) RUnlock() {
+	di.rwMutex.RUnlock()
+}
+
+// localLockInstance - frontend/top-level interface for namespace locks.
+type localLockInstance struct {
 	ns                  *nsLockMap
 	volume, path, opsID string
 }
@@ -270,11 +301,14 @@ type lockInstance struct {
 // volume, path and operation ID.
 func (n *nsLockMap) NewNSLock(volume, path string) RWLocker {
 	opsID := mustGetUUID()
-	return &lockInstance{n, volume, path, opsID}
+	if n.isDistXL {
+		return &distLockInstance{dsync.NewDRWMutex(pathJoin(volume, path), globalDsync), volume, path, opsID}
+	}
+	return &localLockInstance{n, volume, path, opsID}
 }
 
 // Lock - block until write lock is taken or timeout has occurred.
-func (li *lockInstance) GetLock(timeout *dynamicTimeout) (timedOutErr error) {
+func (li *localLockInstance) GetLock(timeout *dynamicTimeout) (timedOutErr error) {
 	lockSource := getSource()
 	start := UTCNow()
 	readLock := false
@@ -287,13 +321,13 @@ func (li *lockInstance) GetLock(timeout *dynamicTimeout) (timedOutErr error) {
 }
 
 // Unlock - block until write lock is released.
-func (li *lockInstance) Unlock() {
+func (li *localLockInstance) Unlock() {
 	readLock := false
 	li.ns.unlock(li.volume, li.path, li.opsID, readLock)
 }
 
 // RLock - block until read lock is taken or timeout has occurred.
-func (li *lockInstance) GetRLock(timeout *dynamicTimeout) (timedOutErr error) {
+func (li *localLockInstance) GetRLock(timeout *dynamicTimeout) (timedOutErr error) {
 	lockSource := getSource()
 	start := UTCNow()
 	readLock := true
@@ -306,7 +340,7 @@ func (li *lockInstance) GetRLock(timeout *dynamicTimeout) (timedOutErr error) {
 }
 
 // RUnlock - block until read lock is released.
-func (li *lockInstance) RUnlock() {
+func (li *localLockInstance) RUnlock() {
 	readLock := true
 	li.ns.unlock(li.volume, li.path, li.opsID, readLock)
 }