From 6a330d76a0fd1c44b87ed9232f26f969e5b43af4 Mon Sep 17 00:00:00 2001
From: Ashvin Deodhar <ashvin.deodhar@gmail.com>
Date: Wed, 16 Jan 2019 14:48:30 -0800
Subject: [PATCH] Reset lock retry count if lock file timestamp changes (#290)

---
 store/json.go | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/store/json.go b/store/json.go
index 373ca74bb9..65f18b4d55 100644
--- a/store/json.go
+++ b/store/json.go
@@ -141,7 +141,10 @@ func (kvs *jsonFileStore) Lock(block bool) error {
 	lockPerm := os.FileMode(0664) + os.FileMode(os.ModeExclusive)
 
 	// Try to acquire the lock file.
-	for i := 0; ; i++ {
+	var lockRetryCount uint
+	var modTimeCur time.Time
+	var modTimePrev time.Time
+	for lockRetryCount < lockMaxRetries {
 		lockFile, err = os.OpenFile(lockName, os.O_CREATE|os.O_EXCL|os.O_RDWR, lockPerm)
 		if err == nil {
 			break
@@ -151,12 +154,24 @@ func (kvs *jsonFileStore) Lock(block bool) error {
 			return ErrNonBlockingLockIsAlreadyLocked
 		}
 
-		if i == lockMaxRetries {
-			return ErrTimeoutLockingStore
+		// Reset the lock retry count if the timestamp for the lock file changes.
+		if fileInfo, err := os.Stat(lockName); err == nil {
+			modTimeCur = fileInfo.ModTime()
+			if !modTimeCur.Equal(modTimePrev) {
+				lockRetryCount = 0
+			}
+			modTimePrev = modTimeCur
 		}
 
 		time.Sleep(lockRetryDelay)
+
+		lockRetryCount++
 	}
+
+	if lockRetryCount == lockMaxRetries {
+		return ErrTimeoutLockingStore
+	}
+
 	defer lockFile.Close()
 
 	// Write the process ID for easy identification.