[ci skip] Merge pull request #5708 from mchobbylong/develop

Resolve race condition in redis driven session key get_lock

1 files changed, 7 insertions, 5 deletions

diff --git a/system/libraries/Session/drivers/Session_redis_driver.php b/system/libraries/Session/drivers/Session_redis_driver.php
index 07511e555..c90e94bd3 100644
--- a/system/libraries/Session/drivers/Session_redis_driver.php
+++ b/system/libraries/Session/drivers/Session_redis_driver.php
@@ -383,11 +383,13 @@ class CI_Session_redis_driver extends CI_Session_driver implements SessionHandle
 				continue;
 			}
 
-			$result = ($ttl === -2)
-				? $this->_redis->set($lock_key, time(), array('nx', 'ex' => 300))
-				: $this->_redis->setex($lock_key, 300, time());
-
-			if ( ! $result)
+			if ($ttl === -2 && ! $this->_redis->set($lock_key, time(), array('nx', 'ex' => 300)))
+			{
+				// Sleep for 1s to wait for lock releases.
+				sleep(1);
+				continue;
+			}
+			elseif ( ! $this->_redis->setex($lock_key, 300, time()))
 			{
 				log_message('error', 'Session: Error while trying to obtain lock for '.$this->_key_prefix.$session_id);
 				return FALSE;