PHP Classes

File: example/GoogleClient/cache/Google_ApcCache.php

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  Classes of Vivek Muthal   Viv OAuth IMAP   example/GoogleClient/cache/Google_ApcCache.php   Download  
File: example/GoogleClient/cache/Google_ApcCache.php
Role: Example script
Content type: text/plain
Description: Example script
Class: Viv OAuth IMAP
Access messages in IMAP server using OAuth token
Author: By
Last change: Update of example/GoogleClient/cache/Google_ApcCache.php
Date: 2 months ago
Size: 2,759 bytes
 

Contents

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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 googleApcCache extends Google_Cache {

  public function
__construct() {
    if (!
function_exists('apc_add')) {
      throw new
Google_CacheException("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
Google_CacheException("Couldn't store data");
    }
  }

 
/**
   * @inheritDoc
   * @param String $key
   */
 
public function delete($key) {
    @
apc_delete($key);
  }
}