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180 lines
5.8 KiB
180 lines
5.8 KiB
<?php |
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/** |
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* @link http://www.yiiframework.com/ |
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* @copyright Copyright (c) 2008 Yii Software LLC |
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* @license http://www.yiiframework.com/license/ |
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*/ |
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namespace yii\mutex; |
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use Yii; |
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use yii\base\InvalidConfigException; |
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use yii\helpers\FileHelper; |
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/** |
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* FileMutex implements mutex "lock" mechanism via local file system files. |
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* |
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* This component relies on PHP `flock()` function. |
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* |
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* Application configuration example: |
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* |
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* ```php |
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* [ |
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* 'components' => [ |
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* 'mutex' => [ |
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* 'class' => 'yii\mutex\FileMutex' |
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* ], |
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* ], |
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* ] |
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* ``` |
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* |
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* > Note: this component can maintain the locks only for the single web server, |
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* > it probably will not suffice in case you are using cloud server solution. |
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* |
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* > Warning: due to `flock()` function nature this component is unreliable when |
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* > using a multithreaded server API like ISAPI. |
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* |
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* @see Mutex |
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* |
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* @author resurtm <resurtm@gmail.com> |
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* @since 2.0 |
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*/ |
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class FileMutex extends Mutex |
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{ |
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/** |
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* @var string the directory to store mutex files. You may use [path alias](guide:concept-aliases) here. |
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* Defaults to the "mutex" subdirectory under the application runtime path. |
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*/ |
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public $mutexPath = '@runtime/mutex'; |
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/** |
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* @var int the permission to be set for newly created mutex files. |
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* This value will be used by PHP chmod() function. No umask will be applied. |
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* If not set, the permission will be determined by the current environment. |
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*/ |
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public $fileMode; |
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/** |
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* @var int the permission to be set for newly created directories. |
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* This value will be used by PHP chmod() function. No umask will be applied. |
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* Defaults to 0775, meaning the directory is read-writable by owner and group, |
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* but read-only for other users. |
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*/ |
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public $dirMode = 0775; |
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/** |
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* @var resource[] stores all opened lock files. Keys are lock names and values are file handles. |
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*/ |
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private $_files = []; |
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/** |
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* Initializes mutex component implementation dedicated for UNIX, GNU/Linux, Mac OS X, and other UNIX-like |
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* operating systems. |
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* @throws InvalidConfigException |
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*/ |
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public function init() |
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{ |
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parent::init(); |
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$this->mutexPath = Yii::getAlias($this->mutexPath); |
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if (!is_dir($this->mutexPath)) { |
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FileHelper::createDirectory($this->mutexPath, $this->dirMode, true); |
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} |
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} |
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/** |
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* Acquires lock by given name. |
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* @param string $name of the lock to be acquired. |
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* @param int $timeout time (in seconds) to wait for lock to become released. |
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* @return bool acquiring result. |
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*/ |
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protected function acquireLock($name, $timeout = 0) |
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{ |
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$filePath = $this->getLockFilePath($name); |
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$waitTime = 0; |
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while (true) { |
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$file = fopen($filePath, 'w+'); |
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if ($file === false) { |
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return false; |
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} |
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if ($this->fileMode !== null) { |
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@chmod($filePath, $this->fileMode); |
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} |
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if (!flock($file, LOCK_EX | LOCK_NB)) { |
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fclose($file); |
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if (++$waitTime > $timeout) { |
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return false; |
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} |
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sleep(1); |
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continue; |
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} |
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// Under unix we delete the lock file before releasing the related handle. Thus it's possible that we've acquired a lock on |
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// a non-existing file here (race condition). We must compare the inode of the lock file handle with the inode of the actual lock file. |
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// If they do not match we simply continue the loop since we can assume the inodes will be equal on the next try. |
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// Example of race condition without inode-comparison: |
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// Script A: locks file |
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// Script B: opens file |
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// Script A: unlinks and unlocks file |
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// Script B: locks handle of *unlinked* file |
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// Script C: opens and locks *new* file |
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// In this case we would have acquired two locks for the same file path. |
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if (DIRECTORY_SEPARATOR !== '\\' && fstat($file)['ino'] !== @fileinode($filePath)) { |
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clearstatcache(true, $filePath); |
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flock($file, LOCK_UN); |
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fclose($file); |
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continue; |
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} |
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$this->_files[$name] = $file; |
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return true; |
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} |
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// Should not be reached normally. |
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return false; |
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} |
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/** |
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* Releases lock by given name. |
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* @param string $name of the lock to be released. |
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* @return bool release result. |
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*/ |
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protected function releaseLock($name) |
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{ |
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if (!isset($this->_files[$name])) { |
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return false; |
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} |
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if (DIRECTORY_SEPARATOR === '\\') { |
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// Under windows it's not possible to delete a file opened via fopen (either by own or other process). |
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// That's why we must first unlock and close the handle and then *try* to delete the lock file. |
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flock($this->_files[$name], LOCK_UN); |
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fclose($this->_files[$name]); |
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@unlink($this->getLockFilePath($name)); |
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} else { |
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// Under unix it's possible to delete a file opened via fopen (either by own or other process). |
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// That's why we must unlink (the currently locked) lock file first and then unlock and close the handle. |
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unlink($this->getLockFilePath($name)); |
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flock($this->_files[$name], LOCK_UN); |
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fclose($this->_files[$name]); |
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} |
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unset($this->_files[$name]); |
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return true; |
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} |
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/** |
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* Generate path for lock file. |
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* @param string $name |
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* @return string |
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* @since 2.0.10 |
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*/ |
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protected function getLockFilePath($name) |
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{ |
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return $this->mutexPath . DIRECTORY_SEPARATOR . md5($name) . '.lock'; |
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} |
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}
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