php/src/common/sample/CacheStorageFile.php

   1 <?php
   2 /**
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing,
  14  * software distributed under the License is distributed on an
  15  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  16  * KIND, either express or implied.  See the License for the
  17  * specific language governing permissions and limitations
  18  * under the License.
  19  */
  20
  21 class CacheStorageFile extends CacheStorage {
  22   private $prefix = null;
  23
  24   public function __construct($name) {
  25     $this->prefix = $name;
  26   }
  27
  28   public function store($key, $value) {
  29     $cacheDir = CacheStorageFile::getCacheDir($key);
  30     $cacheFile = CacheStorageFile::getCacheFile($key);
  31     if (! is_dir($cacheDir)) {
  32       if (! @mkdir($cacheDir, 0755, true)) {
  33         throw new CacheException("Could not create cache directory");
  34       }
  35     }
  36
  37     return file_put_contents($cacheFile, $value);
  38   }
  39
  40   public function fetch($key) {
  41     $cacheFile = CacheStorageFile::getCacheFile($key);
  42     if (File::exists($cacheFile) && File::readable($cacheFile)) {
  43       return @file_get_contents($cacheFile);
  44     }
  45     return false;
  46   }
  47
  48   public function delete($key) {
  49     $cacheFile = CacheStorageFile::getCacheFile($key);
  50     if (! @unlink($cacheFile)) {
  51       throw new CacheException("Cache file could not be deleted");
  52     }
  53   }
  54
  55   public function isLocked($key) {
  56     // our lock file convention is simple: /the/file/path.lock
  57     clearstatcache();
  58     return file_exists($key . '.lock');
  59   }
  60
  61   public function lock($key) {
  62     $cacheDir = CacheStorageFile::getCacheDir($key);
  63     $cacheFile = CacheStorageFile::getCacheFile($key);
  64     if (! is_dir($cacheDir)) {
  65       if (! @mkdir($cacheDir, 0755, true)) {
  66         // make sure the failure isn't because of a concurency issue
  67         if (! is_dir($cacheDir)) {
  68           throw new CacheException("Could not create cache directory");
  69         }
  70       }
  71     }
  72     @touch($cacheFile . '.lock');
  73   }
  74
  75   public function unlock($key) {
  76     // suppress all warnings, if some other process removed it that's ok too
  77     $cacheFile = CacheStorageFile::getCacheFile($key);
  78     @unlink($cacheFile . '.lock');
  79   }
  80
  81   private function getCacheDir($key) {
  82     // use the first 2 characters of the hash as a directory prefix
  83     // this should prevent slowdowns due to huge directory listings
  84     // and thus give some basic amount of scalability
  85     return Config::get('cache_root') . '/' . $this->prefix . '/' .
  86         substr($key, 0, 2);
  87   }
  88
  89   private function getCacheFile($key) {
  90     return $this->getCacheDir($key) . '/' . $key;
  91   }
  92 }