How to use mutex yii

How to use mutex yii? Mutex

Mutex component of Yii source code analysis allows concurrent processes to execute each other to prevent "race conditions". This is achieved through the use of a "locking" mechanism. Each potentially concurrent thread cooperates by acquiring a lock before accessing the corresponding data.

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Usage example:

if ($mutex->acquire($mutexName)) {
    // business logic execution
} else {
    // execution is blocked!
}

This is a base class and should be extended to implement the actual locking mechanism.

Let’s take a look at its source code implementation:

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */
 
namespace yii\mutex;
 
use yii\base\Component;
 
/**
 * The Mutex component allows mutual execution of concurrent processes in order to prevent "race conditions".
 *
 * This is achieved by using a "lock" mechanism. Each possibly concurrent thread cooperates by acquiring
 * a lock before accessing the corresponding data.
 *
 * Usage example:
 *
 * ```
 * if ($mutex->acquire($mutexName)) {
 *     // business logic execution
 * } else {
 *     // execution is blocked!
 * }
 * ```
 *
 * This is a base class, which should be extended in order to implement the actual lock mechanism.
 *
 * @author resurtm <resurtm@gmail.com>
 * @since 2.0
 */
abstract class Mutex extends Component
{
    /**
     * @var bool whether all locks acquired in this process (i.e. local locks) must be released automatically
     * before finishing script execution. Defaults to true. Setting this property to true means that all locks
     * acquired in this process must be released (regardless of errors or exceptions).
     */
    public $autoRelease = true;//是否自动释放锁
 
    /**
     * @var string[] names of the locks acquired by the current PHP process.
     */
    private $_locks = [];//当前进程拥有的锁信息
 
 
    /**
     * 初始化Mutex组件
     */
    public function init()
    {
        if ($this->autoRelease) {//如果是自动释放锁
            $locks = &$this->_locks;
            //注册shutdown回调函数，在这里做锁的释放动作
            register_shutdown_function(function () use (&$locks) {
                foreach ($locks as $lock) {
                    $this->release($lock);
                }
            });
        }
    }
 
    /**
     * Acquires a lock by name.
     * @param string $name of the lock to be acquired. Must be unique.
     * @param int $timeout time (in seconds) to wait for lock to be released. Defaults to zero meaning that method will return
     * false immediately in case lock was already acquired.
     * @return bool lock acquiring result.
     */
    public function acquire($name, $timeout = 0)//按名称获取锁
    {
        if ($this->acquireLock($name, $timeout)) {
            $this->_locks[] = $name;
 
            return true;
        }
 
        return false;
    }
 
    /**
     * Releases acquired lock. This method will return false in case the lock was not found.
     * @param string $name of the lock to be released. This lock must already exist.
     * @return bool lock release result: false in case named lock was not found..
     */
    public function release($name)//按名称释放锁
    {
        if ($this->releaseLock($name)) {
            $index = array_search($name, $this->_locks);
            if ($index !== false) {
                unset($this->_locks[$index]);
            }
 
            return true;
        }
 
        return false;
    }
 
    /**
     * This method should be extended by a concrete Mutex implementations. Acquires lock by name.
     * @param string $name of the lock to be acquired.
     * @param int $timeout time (in seconds) to wait for the lock to be released.
     * @return bool acquiring result.
     */
    abstract protected function acquireLock($name, $timeout = 0);//抽象函数，按名称获取锁
 
    /**
     * This method should be extended by a concrete Mutex implementations. Releases lock by given name.
     * @param string $name of the lock to be released.
     * @return bool release result.
     */
    abstract protected function releaseLock($name);//抽象函数，按名称释放锁
}

As a base class, subclasses need to implement the acquireLock and releaseLock methods, that is, specific locking and unlocking strategies.

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