用Memcache实现分布式的锁服务

gistfile1.php

<?php

/**
 * 锁服务(用Memcache模拟锁)
 */

class Lock{

	private $mc = null;
	private $key_prefix = "memcache_lock_service_key_";
	private $all_lock_names = array();
	private $expiration = 60; //one min
	private $max_block_time = 15; //最长的阻塞时间
	/**
	 * [__construct description]
	 */
	public function __construct(){
		if(function_exists('memcache_init')){
			$this->mc = memcache_connect('memcache_host', 11211);
		}
	}

	/**
	 * [get_key description]
	 * @param  [type] $name [description]
	 * @return [type]       [description]
	 */
	private function get_key($name){
		$key = $this->key_prefix.$name;
		return $key;
	}

	/**
	 * 捕获锁
	 * @param  [type] $name [description]
	 * @return [type]       [description]
	 */
	public  function begin($name, $block = true)
	{
		if(!$this->mc || !$name){
			return false;
		}
		$max_block_time = $this->max_block_time;
		$key = $this->get_key($name);
		do{	
			$re = memcache_add($this->mc, $key, 1, false, $this->expiration);
			if($re == true){
				$this->all_lock_names[$name] = 1;
				//$this->debug();
				break;
			}else{
				//dolog('Lock failed '.$name);
			}
			//echo '#'.PHP_EOL;
			//sleep(1);
		}while($block && $max_block_time-- && !sleep(1));
		return $re;
	}

	/**
	 * 释放锁
	 */
	public function release($name){
		if(!$this->mc || !$name){
			return false;
		}
		$key = $this->get_key($name);
		$re = memcache_delete($this->mc, $key);
		if($re == true){
			unset($this->all_lock_names[$name]);
		}
		return $re;
	}

	/**
	 * 释放所有的锁
	 */
	public function __destruct(){
		if(!$this->mc){
			return false;
		}
		foreach ($this->all_lock_names as $name => $value) {
			# code...
			$this->release($name);
		}
	}

	/**
	 * 调试
	 * @return [type] [description]
	 */
	public function debug(){
		var_dump($this->all_lock_names);
		foreach ($this->all_lock_names as $name => $value) {
			$key = $this->get_key($name);
			if($this->mc){
				$value = memcache_get($this->mc, $key);
			}else{
				$value = "no such lock ";
			}
			echo "Lock name:$key, value:{$value}".PHP_EOL;
		}
	}
}