<?php

// 使用Memache 作為進程鎖 

class lock_processlock{
	
	
	// key 的前綴
	protected $sLockKeyPre;
	// 重試間隔
 protected $iLockRetryInterval;
	//重試次數(shù) 
 protected $iLockRetryCount;
	//鎖的過期時間
 protected $iLockCacheTimeout;
 // 鎖過期后的回調函數(shù)
 protected $onLockTimeoutFunc;
	// memache 的實例
 protected $oMemcache;
	// 存儲memcache失敗后重試次數(shù) 
 protected $iMemcacheRetryCount;
	
	
	
	
	 public function __construct ($onLockTimeoutFunc=NULL) {
  $aLockConfig = get_config('', 'lock');
  $this->sLockKeyPre = self::LOCK_KEY_PRE;
  $this->iLockRetryInterval = self::LOCK_RETRY_INTERVAL;
  $this->iLockRetryCount =self::LOCK_RETRY_COUNT;
  $this->iLockCacheTimeout = self::LOCK_CACHE_TIMEOUT;
  $this->iMemcacheRetryCount = self::LOCK_CACHE_TIMEOUT;
		if(!$onLockTimeoutFunc){
			// 如果加鎖不成功則調用回調函數(shù),如果沒有回調函數(shù),使用本類中所帶的 
			$onLockTimeoutFunc ='onLockTimeout' ; 
		}
  $this->onLockTimeoutFunc = $onLockTimeoutFunc;
 }
	
	
	/**
	連接memcache 服務器 
	*/
	public function connect() {
		if (! isset ( $this->oMemcache )) {
			$this->oMemcache = new Memcache ();
			$this->oMemcache->connect ( '127.0.0.1', 11211 );
		}
		return $this->oMemcache;
	}
	
	
	/*
	向MeMcache中添加 key
	*/
	public addMemcache($sKey, $sValue, $iTimeout){
		
		for($i= 0 ; $i<$this->iMemcacheRetryCount){
			$bRes = $this->oMemcache->add($sKey, $sValue, $iTimeout);
			if($bRes){
				return true ; 
			}
				// 如果加鎖不成功,sleep 之后,從新加鎖
			usleep($this->iLockRetryInterval*1000);
			
		}
		return false ; 
		
	}
	
	
	/*
	加鎖 
	*/
	public function lock($sLockID){
		
		$oMemcache = $this->connect();
	 $sKey = $this->sLockKeyPre . $sLockID;
		
		// 加鎖如果不成功可以多試幾次 
		
		for($i = 0 ; $i <$this->iLockRetryCount ; $i++){
			
			// 這里設置value 的值可以隨便設置 
			if($this->addMemcache($sKey,'1',$this->iLockCacheTimeout)){
				return true ; 
			}
			
			// 如果加鎖不成功,sleep 之后,從新加鎖
			usleep($this->iLockRetryInterval*1000);
			
		}
		
		// 若還不成功,則加鎖失敗,調用回調函數(shù),.也就是失敗后需要處理的操作 
		if(is_callable($this->onLockTimeoutFunc)){
			// 調用函數(shù) 
			call_user_func($this->onLockTimeoutFunc); 
		}
		
	}
	
	
	/*
	解鎖操作 
	*/
	public function unlock($sLockID){
		
		$oMemcache = $this->connect();
	 $sKey = $this->sLockKeyPre . $sLockID;
		// 刪除key
		return $this->oMemcache->delete($sKey);
		
	}
	
	
	/**
	如果加鎖不成功,則執(zhí)行如下操作 
	*/
	 public function onLockTimeout(){
		 
		 echo ("加鎖超時");
	 }
  
}



// 應用實例 

 $oLock = new lock_processlock();
 $lockResource = "test";
 // 加鎖
 $oLock->lock($lockResource);
 // 解鎖
 $oLock->unlock($lockResource);