added google xoauth2 support + fixed a journaling issue

webui/google-api/cache/apiFileCache.php

@@ -0,0 +1,135 @@
+<?php
+/*
+ * Copyright 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * This class implements a basic on disk storage. While that does
+ * work quite well it's not the most elegant and scalable solution.
+ * It will also get you into a heap of trouble when you try to run
+ * this in a clustered environment. In those cases please use the
+ * MySql back-end
+ *
+ * @author Chris Chabot <chabotc@google.com>
+ */
+class apiFileCache extends apiCache {
+  private $path;
+
+  public function __construct() {
+    global $apiConfig;
+    $this->path = $apiConfig['ioFileCache_directory'];
+  }
+
+  private function isLocked($storageFile) {
+    // our lock file convention is simple: /the/file/path.lock
+    return file_exists($storageFile . '.lock');
+  }
+
+  private function createLock($storageFile) {
+    $storageDir = dirname($storageFile);
+    if (! is_dir($storageDir)) {
+      if (! @mkdir($storageDir, 0755, true)) {
+        // make sure the failure isn't because of a concurrency issue
+        if (! is_dir($storageDir)) {
+          throw new apiCacheException("Could not create storage directory: $storageDir");
+        }
+      }
+    }
+    @touch($storageFile . '.lock');
+  }
+
+  private function removeLock($storageFile) {
+    // suppress all warnings, if some other process removed it that's ok too
+    @unlink($storageFile . '.lock');
+  }
+
+  private function waitForLock($storageFile) {
+    // 20 x 250 = 5 seconds
+    $tries = 20;
+    $cnt = 0;
+    do {
+      // make sure PHP picks up on file changes. This is an expensive action but really can't be avoided
+      clearstatcache();
+      // 250 ms is a long time to sleep, but it does stop the server from burning all resources on polling locks..
+      usleep(250);
+      $cnt ++;
+    } while ($cnt <= $tries && $this->isLocked($storageFile));
+    if ($this->isLocked($storageFile)) {
+      // 5 seconds passed, assume the owning process died off and remove it
+      $this->removeLock($storageFile);
+    }
+  }
+
+  private function getCacheDir($hash) {
+    // use the first 2 characters of the hash as a directory prefix
+    // this should prevent slowdowns due to huge directory listings
+    // and thus give some basic amount of scalability
+    return $this->path . '/' . substr($hash, 0, 2);
+  }
+
+  private function getCacheFile($hash) {
+    return $this->getCacheDir($hash) . '/' . $hash;
+  }
+
+  public function get($key, $expiration = false) {
+    $storageFile = $this->getCacheFile(md5($key));
+    // See if this storage file is locked, if so we wait upto 5 seconds for the lock owning process to
+    // complete it's work. If the lock is not released within that time frame, it's cleaned up.
+    // This should give us a fair amount of 'Cache Stampeding' protection
+    if ($this->isLocked($storageFile)) {
+      $this->waitForLock($storageFile);
+    }
+    if (file_exists($storageFile) && is_readable($storageFile)) {
+      $now = time();
+      if (! $expiration || (($mtime = @filemtime($storageFile)) !== false && ($now - $mtime) < $expiration)) {
+        if (($data = @file_get_contents($storageFile)) !== false) {
+          $data = unserialize($data);
+          return $data;
+        }
+      }
+    }
+    return false;
+  }
+
+  public function set($key, $value) {
+    $storageDir = $this->getCacheDir(md5($key));
+    $storageFile = $this->getCacheFile(md5($key));
+    if ($this->isLocked($storageFile)) {
+      // some other process is writing to this file too, wait until it's done to prevent hickups
+      $this->waitForLock($storageFile);
+    }
+    if (! is_dir($storageDir)) {
+      if (! @mkdir($storageDir, 0755, true)) {
+        throw new apiCacheException("Could not create storage directory: $storageDir");
+      }
+    }
+    // we serialize the whole request object, since we don't only want the
+    // responseContent but also the postBody used, headers, size, etc
+    $data = serialize($value);
+    $this->createLock($storageFile);
+    if (! @file_put_contents($storageFile, $data)) {
+      $this->removeLock($storageFile);
+      throw new apiCacheException("Could not store data in the file");
+    }
+    $this->removeLock($storageFile);
+  }
+
+  public function delete($key) {
+    $file = $this->getCacheFile(md5($key));
+    if (! @unlink($file)) {
+      throw new apiCacheException("Cache file could not be deleted");
+    }
+  }
+}