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social/src/cache/apiApcCache.php 2.66 KB
42868d70   andryeyev   Создал GIT
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  <?php
  /*
   * Copyright 2010 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.
   */
  
  /**
   * A persistent storage class based on the APC cache, which is not
   * really very persistent, as soon as you restart your web server
   * the storage will be wiped, however for debugging and/or speed
   * it can be useful, kinda, and cache is a lot cheaper then storage.
   *
   * @author Chris Chabot <chabotc@google.com>
   */
  class apiApcCache extends apiCache {
  
    public function __construct() {
      if (! function_exists('apc_add')) {
        throw new apiCacheException("Apc functions not available");
      }
    }
  
    private function isLocked($key) {
      if ((@apc_fetch($key . '.lock')) === false) {
        return false;
      }
      return true;
    }
  
    private function createLock($key) {
      // the interesting thing is that this could fail if the lock was created in the meantime..
      // but we'll ignore that out of convenience
      @apc_add($key . '.lock', '', 5);
    }
  
    private function removeLock($key) {
      // suppress all warnings, if some other process removed it that's ok too
      @apc_delete($key . '.lock');
    }
  
    private function waitForLock($key) {
      // 20 x 250 = 5 seconds
      $tries = 20;
      $cnt = 0;
      do {
        // 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 && $this->isLocked($key));
      if ($this->isLocked($key)) {
        // 5 seconds passed, assume the owning process died off and remove it
        $this->removeLock($key);
      }
    }
  
     /**
     * @inheritDoc
     */
    public function get($key, $expiration = false) {
  
      if (($ret = @apc_fetch($key)) === false) {
        return false;
      }
      if (!$expiration || (time() - $ret['time'] > $expiration)) {
        $this->delete($key);
        return false;
      }
      return unserialize($ret['data']);
    }
  
    /**
     * @inheritDoc
     */
    public function set($key, $value) {
      if (@apc_store($key, array('time' => time(), 'data' => serialize($value))) == false) {
        throw new apiCacheException("Couldn't store data");
      }
    }
  
    /**
     * @inheritDoc
     */
    public function delete($key) {
      @apc_delete($key);
    }
  }