php异步锁
时间:2021-09-16 17:16:54 +0800 CST 浏览:1036

文件锁,memcache锁,SQL锁。推荐使用memcache锁。

异步锁

<?php

class LockSystem
{
    const LOCK_TYPE_DB = 'SQLLock';
    const LOCK_TYPE_FILE = 'FileLock';
    const LOCK_TYPE_MEMCACHE = 'MemcacheLock';
  
    private $_lock = null;
    private static $_supportLocks = array('FileLock', 'SQLLock', 'MemcacheLock');  
  
    public function __construct($type, $options = array()) 
    {
        if(false == empty($type))
        {
            $this->createLock($type, $options);
        }
    }   

    public function createLock($type, $options=array())
    {
        if (false == in_array($type, self::$_supportLocks))
        {
            throw new Exception("not support lock of ${type}");
        }
        $this->_lock = new $type($options);
    }
  
    public function getLock($key, $timeout = ILock::EXPIRE)
    {
        if (false == $this->_lock instanceof ILock)  
        {
            throw new Exception('false == $this->_lock instanceof ILock');        
        }  
        $this->_lock->getLock($key, $timeout);   
    }
  
    public function releaseLock($key)
    {
        if (false == $this->_lock instanceof ILock)  
        {
            throw new Exception('false == $this->_lock instanceof ILock');        
        }  
        $this->_lock->releaseLock($key);       
    }   
}

interface ILock
{
    const EXPIRE = 5;
    public function getLock($key, $timeout=self::EXPIRE);
    public function releaseLock($key);
}

class FileLock implements ILock
{
    private $_fp;
    private $_single;

    public function __construct($options)
    {
        if (isset($options['path']) && is_dir($options['path']))
        {
            $this->_lockPath = $options['path'].'/';
        }
        else
        {
            $this->_lockPath = '/tmp/';
        }
     
        $this->_single = isset($options['single'])?$options['single']:false;
    }

    public function getLock($key, $timeout=self::EXPIRE)
    {
        $startTime = Timer::getTimeStamp();

        $file = md5(__FILE__.$key);
        $this->fp = fopen($this->_lockPath.$file.'.lock', "w+");
        if (true || $this->_single)
        {
            $op = LOCK_EX + LOCK_NB;
        }
        else
        {
            $op = LOCK_EX;
        }
        if (false == flock($this->fp, $op, $a))
        {
            throw new Exception('failed');
        }
     
	    return true;
    }

    public function releaseLock($key)
    {
        flock($this->fp, LOCK_UN);
        fclose($this->fp);
    }
}

class SQLLock implements ILock
{
    public function __construct($options)
    {
        $this->_db = new mysql(); 
    }

    public function getLock($key, $timeout=self::EXPIRE)
    {     
        $sql = "SELECT GET_LOCK('".$key."', '".$timeout."')";
        $res =  $this->_db->query($sql);
        return $res;
    }

    public function releaseLock($key)
    {
        $sql = "SELECT RELEASE_LOCK('".$key."')";
        return $this->_db->query($sql);
    }
}

class MemcacheLock implements ILock
{
    public function __construct($options)
    {
      
        $this->memcache = new Memcache();
    }

    public function getLock($key, $timeout=self::EXPIRE)
    {   
        $waitime = 20000;
        $totalWaitime = 0;
        $time = $timeout*1000000;
        while ($totalWaitime < $time && false == $this->memcache->add($key, 1, $timeout)) 
        {
            usleep($waitime);
            $totalWaitime += $waitime;
        }
        if ($totalWaitime >= $time)
            throw new Exception('can not get lock for waiting '.$timeout.'s.');

    }

    public function releaseLock($key)
    {
        $this->memcache->delete($key);
    }
}

应用锁

 try
    {
        //创建锁(推荐使用MemcacheLock)
        $lockSystem = new LockSystem(LockSystem::LOCK_TYPE_MEMCACHE);           
      
        //获取锁
        $lockKey = 'key';
        $lockSystem->getLock($lockKey,8);
      
        //业务逻辑
        ...
      
        //释放锁
        $lockSystem->releaseLock($lockKey); 
    }
    catch (Exception $e)
    {
        //释放锁
        $lockSystem->releaseLock($lockKey);   
    }

说明

参考:

https://blog.csdn.net/clevercode/article/details/52493568



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