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<?php |
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/* |
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* Copyright 2008 Google Inc. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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|
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require_once ANALYTIFY_LIB_PATH . "Google/Cache/Abstract.php"; |
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require_once ANALYTIFY_LIB_PATH . "Google/Cache/Exception.php"; |
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|
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/* |
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* This class implements a basic on disk storage. While that does |
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* work quite well it's not the most elegant and scalable solution. |
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* It will also get you into a heap of trouble when you try to run |
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* this in a clustered environment. |
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* |
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* @author Chris Chabot <chabotc@google.com> |
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*/ |
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class Analytify_Google_Cache_File extends Analytify_Google_Cache_Abstract |
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{ |
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const MAX_LOCK_RETRIES = 10; |
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private $path; |
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private $fh; |
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|
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public function __construct(Analytify_Google_Client $client) |
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{ |
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$this->path = $client->getClassConfig($this, 'directory'); |
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} |
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|
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public function get($key, $expiration = false) |
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{ |
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$storageFile = $this->getCacheFile($key); |
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$data = false; |
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|
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if (!file_exists($storageFile)) { |
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return false; |
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} |
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|
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if ($expiration) { |
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$mtime = filemtime($storageFile); |
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if ((time() - $mtime) >= $expiration) { |
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$this->delete($key); |
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return false; |
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} |
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} |
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|
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if ($this->acquireReadLock($storageFile)) { |
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$data = fread($this->fh, filesize($storageFile)); |
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$data = unserialize($data); |
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$this->unlock($storageFile); |
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} |
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|
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return $data; |
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} |
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|
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public function set($key, $value) |
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{ |
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$storageFile = $this->getWriteableCacheFile($key); |
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if ($this->acquireWriteLock($storageFile)) { |
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// We serialize the whole request object, since we don't only want the |
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// responseContent but also the postBody used, headers, size, etc. |
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$data = serialize($value); |
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$result = fwrite($this->fh, $data); |
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$this->unlock($storageFile); |
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} |
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} |
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|
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public function delete($key) |
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{ |
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$file = $this->getCacheFile($key); |
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if (file_exists($file) && !unlink($file)) { |
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throw new Analytify_Google_Cache_Exception("Cache file could not be deleted"); |
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} |
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} |
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|
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private function getWriteableCacheFile($file) |
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{ |
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return $this->getCacheFile($file, true); |
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} |
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|
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private function getCacheFile($file, $forWrite = false) |
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{ |
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return $this->getCacheDir($file, $forWrite) . '/' . md5($file); |
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} |
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|
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private function getCacheDir($file, $forWrite) |
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{ |
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// use the first 2 characters of the hash as a directory prefix |
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// this should prevent slowdowns due to huge directory listings |
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// and thus give some basic amount of scalability |
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$storageDir = $this->path . '/' . substr(md5($file), 0, 2); |
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if ($forWrite && ! is_dir($storageDir)) { |
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if (! mkdir($storageDir, 0755, true)) { |
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throw new Analytify_Google_Cache_Exception("Could not create storage directory: $storageDir"); |
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} |
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} |
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return $storageDir; |
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} |
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|
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private function acquireReadLock($storageFile) |
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{ |
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return $this->acquireLock(LOCK_SH, $storageFile); |
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} |
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|
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private function acquireWriteLock($storageFile) |
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{ |
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$rc = $this->acquireLock(LOCK_EX, $storageFile); |
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if (!$rc) { |
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$this->delete($storageFile); |
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} |
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return $rc; |
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} |
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|
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private function acquireLock($type, $storageFile) |
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{ |
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$mode = $type == LOCK_EX ? "w" : "r"; |
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$this->fh = fopen($storageFile, $mode); |
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$count = 0; |
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while (!flock($this->fh, $type | LOCK_NB)) { |
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// Sleep for 10ms. |
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usleep(10000); |
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if (++$count < self::MAX_LOCK_RETRIES) { |
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return false; |
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} |
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} |
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return true; |
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} |
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|
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public function unlock($storageFile) |
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{ |
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if ($this->fh) { |
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flock($this->fh, LOCK_UN); |
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} |
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} |
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} |
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|
