Added a check to prevent non-CLI calls from failing.

Author: im-bryan

src/RedisSimpleLock.php

@@ -33,7 +33,10 @@ public function __construct($identifier, Client $client, $ttl = 10000, LoggerInt
         $this->logger     = $logger ?: new NullLogger;
         $this->id         = mt_rand();
         register_shutdown_function($closure = $this->releaseClosure());
-        pcntl_signal(SIGINT, $closure);
+
+        if (php_sapi_name() === 'cli') {
+            pcntl_signal(SIGINT, $closure);
+        }
     }
 
     public function acquire()