Merge pull request googleapis#475 from kylefarris/patch-1

flock() not getting file handle all the time

Author: ianbarber

src/Google/Cache/File.php

@@ -170,6 +170,13 @@ private function acquireLock($type, $storageFile)
   {
     $mode = $type == LOCK_EX ? "w" : "r";
     $this->fh = fopen($storageFile, $mode);
+    if (!$this->fh) {
+      $this->client->getLogger()->error(
+        'Failed to open file during lock acquisition',
+        array('file' => $storageFile)
+      );
+      return false;
+    }
     $count = 0;
     while (!flock($this->fh, $type | LOCK_NB)) {
       // Sleep for 10ms.