From 0184227828b90cc170541073fc2a1b718ffede63 Mon Sep 17 00:00:00 2001
From: Tiru Srikantha <tiru@playfab.com>
Date: Fri, 5 Jun 2015 13:23:23 -0700
Subject: [PATCH] Check to see why a lock acquisition failed

---
 api/lock.go | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/api/lock.go b/api/lock.go
index 4b694789c..a76685f04 100644
--- a/api/lock.go
+++ b/api/lock.go
@@ -183,11 +183,23 @@ WAIT:
 
 	// Handle the case of not getting the lock
 	if !locked {
-		select {
-		case <-time.After(DefaultLockRetryTime):
+		// Determine why the lock failed
+		qOpts.WaitIndex = 0
+		pair, meta, err = kv.Get(l.opts.Key, qOpts)
+		if pair != nil && pair.Session != "" {
+			//If the session is not null, this means that a wait can safely happen
+			//using a long poll
+			qOpts.WaitIndex = meta.LastIndex
 			goto WAIT
-		case <-stopCh:
-			return nil, nil
+		} else {
+			// If the session is empty and the lock failed to acquire, then it means
+			// a lock-delay is in effect and a timed wait must be used
+			select {
+			case <-time.After(DefaultLockRetryTime):
+				goto WAIT
+			case <-stopCh:
+				return nil, nil
+			}
 		}
 	}