/src/storage/buzzFileStorage.php
PHP | 135 lines | 84 code | 11 blank | 40 comment | 18 complexity | 387781b9200d502f2bcf11e72b0bcf49 MD5 | raw file
Possible License(s): Apache-2.0
- <?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
- */
- class buzzFileStorage extends buzzStorage {
- private $path;
- public function __construct($path)
- {
- $this->path = $path;
- }
- private function isLocked($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 concurency issue
- if (! is_dir($storageDir)) {
- throw new buzzStorageException("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 getStorageDir($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 getStorageFile($hash) {
- return $this->getStorageDir($hash) . '/' . $hash;
- }
- public function get($key, $expiration = false) {
- $storageFile = $this->getStorageFile(md5($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 'Storage 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 = $this->getStorageDir(md5($key));
- $storageFile = $this->getStorageFile(md5($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 buzzStorageException("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 buzzStorageException("Could not store data in the file");
- }
- $this->removeLock($storageFile);
- }
- public function delete($key) {
- $file = $this->getStorageFile(md5($key));
- if (! @unlink($file)) {
- throw new buzzStorageException("Storage file could not be deleted");
- }
- }
- }