PHP concurrent locking case analysis

<!--?php 
/** 
 * pay.php 
 * 
 * 支付没有应用锁
 * 
 * Copy right (c) 2016 
 * 
 * modification history: 
 * -------------------- 
 * 2016/9/10, by CleverCode, Create 
 * 
 */ 
//用户支付
function pay($userId,$money)
{
  
 if(false == is_int($userId) || false == is_int($money))
 {
  return false;
 } 
  
 //取出总额
 $total = getUserLeftMoney($userId);
  
 //花费大于剩余
 if($money --> $total)
 {
  return false; 
 }
  
 //余额
 $left = $total - $money;
  
 //更新余额
 return setUserLeftMoney($userId,$left);
 
}
 
//取出用户的余额
function getUserLeftMoney($userId)
{
 if(false == is_int($userId))
 {
  return 0;
 }
 $sql = "select account form user_account where userid = ${userId}";
  
 //$mysql = new mysql();//mysql数据库
 return $mysql->query($sql);
}
 
//更新用户余额
function setUserLeftMoney($userId,$money)
{
 if(false == is_int($userId) || false == is_int($money))
 {
  return false;
 }  
  
 $sql = "update user_account set account = ${money} where userid = ${userId}";
  
 //$mysql = new mysql();//mysql数据库
 return $mysql->execute($sql);
}
?>

<!--?php 
/** 
 * LockSystem.php 
 * 
 * php锁机制
 * 
 * Copy right (c) 2016
 * 
 * modification history: 
 * -------------------- 
 * 2016/9/10, by CleverCode, Create 
 * 
 */ 
class LockSystem
{
 const LOCK_TYPE_DB = &#39;SQLLock&#39;;
 const LOCK_TYPE_FILE = &#39;FileLock&#39;;
 const LOCK_TYPE_MEMCACHE = &#39;MemcacheLock&#39;;
  
 private $_lock = null;
 private static $_supportLocks = array(&#39;FileLock&#39;, &#39;SQLLock&#39;, &#39;MemcacheLock&#39;); 
  
 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(&#39;false == $this->_lock instanceof ILock&#39;);   
  } 
  $this->_lock->getLock($key, $timeout); 
 }
  
 public function releaseLock($key)
 {
  if (false == $this->_lock instanceof ILock) 
  {
   throw new Exception(&#39;false == $this->_lock instanceof ILock&#39;);   
  } 
  $this->_lock->releaseLock($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[&#39;path&#39;]) && is_dir($options[&#39;path&#39;]))
  {
   $this->_lockPath = $options[&#39;path&#39;].&#39;/&#39;;
  }
  else
  {
   $this->_lockPath = &#39;/tmp/&#39;;
  }
  
  $this->_single = isset($options[&#39;single&#39;])?$options[&#39;single&#39;]:false;
 }
 public function getLock($key, $timeout=self::EXPIRE)
 {
  $startTime = Timer::getTimeStamp();
 
  $file = md5(__FILE__.$key);
  $this->fp = fopen($this->_lockPath.$file.&#39;.lock&#39;, "w+");
  if (true || $this->_single)
  {
   $op = LOCK_EX + LOCK_NB;
  }
  else
  {
   $op = LOCK_EX;
  }
  if (false == flock($this->fp, $op, $a))
  {
   throw new Exception(&#39;failed&#39;);
  }
  
  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)
 {  
  $sql = "SELECT GET_LOCK(&#39;".$key."&#39;, &#39;".$timeout."&#39;)";
  $res = $this->_db->query($sql);
  return $res;
 }
 
 public function releaseLock($key)
 {
  $sql = "SELECT RELEASE_LOCK(&#39;".$key."&#39;)";
  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 >= $time)
   throw new Exception(&#39;can not get lock for waiting &#39;.$timeout.&#39;s.&#39;);
 
 }
 
 public function releaseLock($key)
 {
  $this->memcache->delete($key);
 }
}

<!--?php
 
/** 
 * pay.php 
 * 
 * 支付应用锁
 * 
 * Copy right (c) 2016 
 * 
 * modification history: 
 * -------------------- 
 * 2016/9/10, by CleverCode, Create 
 * 
 */ 
//用户支付
function pay($userId,$money)
{
  
 if(false == is_int($userId) || false == is_int($money))
 {
  return false;
 } 
  
 try
 {
  //创建锁(推荐使用MemcacheLock)
  $lockSystem = new LockSystem(LockSystem::LOCK_TYPE_MEMCACHE);    
   
  //获取锁
  $lockKey = &#39;pay&#39;.$userId;
  $lockSystem--->getLock($lockKey,8);
   
  //取出总额
  $total = getUserLeftMoney($userId);
   
  //花费大于剩余
  if($money > $total)
  {
   $ret = false; 
  }
  else
  { 
   //余额
   $left = $total - $money;
    
   //更新余额
   $ret = setUserLeftMoney($userId,$left);
  }
   
  //释放锁
  $lockSystem->releaseLock($lockKey); 
 }
 catch (Exception $e)
 {
  //释放锁
  $lockSystem->releaseLock($lockKey);  
 }
 
}
//取出用户的余额
function getUserLeftMoney($userId)
{
 if(false == is_int($userId))
 {
  return 0;
 }
 $sql = "select account form user_account where userid = ${userId}";
  
 //$mysql = new mysql();//mysql数据库
 return $mysql->query($sql);
}
 
//更新用户余额
function setUserLeftMoney($userId,$money)
{
 if(false == is_int($userId) || false == is_int($money))
 {
  return false;
 }  
  
 $sql = "update user_account set account = ${money} where userid = ${userId}";
  
 //$mysql = new mysql();//mysql数据库
 return $mysql->execute($sql);
}
?>