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128 lines
3.8 KiB
PHP
128 lines
3.8 KiB
PHP
<?php
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/**
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* @link https://www.yiiframework.com/
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* @copyright Copyright (c) 2008 Yii Software LLC
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* @license https://www.yiiframework.com/license/
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*/
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namespace yii\mutex;
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use yii\base\Component;
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/**
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* The Mutex component allows mutual execution of concurrent processes in order to prevent "race conditions".
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*
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* This is achieved by using a "lock" mechanism. Each possibly concurrent thread cooperates by acquiring
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* a lock before accessing the corresponding data.
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*
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* Usage example:
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*
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* ```
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* if ($mutex->acquire($mutexName)) {
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* // business logic execution
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* } else {
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* // execution is blocked!
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* }
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* ```
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*
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* This is a base class, which should be extended in order to implement the actual lock mechanism.
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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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abstract class Mutex extends Component
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{
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/**
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* @var bool whether all locks acquired in this process (i.e. local locks) must be released automatically
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* before finishing script execution. Defaults to true. Setting this property to true means that all locks
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* acquired in this process must be released (regardless of errors or exceptions).
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*/
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public $autoRelease = true;
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/**
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* @var string[] names of the locks acquired by the current PHP process.
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*/
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private $_locks = [];
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/**
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* Initializes the Mutex component.
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*/
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public function init()
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{
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if ($this->autoRelease) {
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$locks = &$this->_locks;
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register_shutdown_function(function () use (&$locks) {
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foreach ($locks as $lock) {
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$this->release($lock);
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}
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});
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}
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}
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/**
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* Acquires a lock by name.
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* @param string $name of the lock to be acquired. Must be unique.
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* @param int $timeout time (in seconds) to wait for lock to be released. Defaults to zero meaning that method will return
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* false immediately in case lock was already acquired.
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* @return bool lock acquiring result.
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*/
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public function acquire($name, $timeout = 0)
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{
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if (!in_array($name, $this->_locks, true) && $this->acquireLock($name, $timeout)) {
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$this->_locks[] = $name;
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return true;
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}
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return false;
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}
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/**
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* Releases acquired lock. This method will return false in case the lock was not found.
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* @param string $name of the lock to be released. This lock must already exist.
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* @return bool lock release result: false in case named lock was not found..
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*/
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public function release($name)
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{
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if ($this->releaseLock($name)) {
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$index = array_search($name, $this->_locks);
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if ($index !== false) {
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unset($this->_locks[$index]);
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}
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return true;
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}
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return false;
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}
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/**
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* Checks if a lock is acquired by the current process.
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* Note that it returns false if the mutex is acquired in another process.
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*
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* @param string $name of the lock to check.
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* @return bool Returns true if currently acquired.
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* @since 2.0.36
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*/
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public function isAcquired($name)
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{
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return in_array($name, $this->_locks, true);
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}
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/**
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* This method should be extended by a concrete Mutex implementations. Acquires lock by name.
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* @param string $name of the lock to be acquired.
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* @param int $timeout time (in seconds) to wait for the lock to be released.
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* @return bool acquiring result.
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*/
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abstract protected function acquireLock($name, $timeout = 0);
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/**
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* This method should be extended by a concrete Mutex implementations. Releases lock by given name.
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* @param string $name of the lock to be released.
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* @return bool release result.
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*/
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abstract protected function releaseLock($name);
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}
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