PHP中利用Redis实现分布式锁

protected function lock($lock_key, $expire_time = 5)
{
    $redis = new Redis();
    $redis->connect('localhost', 6379); // 连接Redis
    $micro_second = 1000000;
    $timeout = 10 * $micro_second; //等待锁超时时间

    while($timeout >= 0)
    {
        $microtime = microtime(true);
        $timeout -= $micro_second;
        $current_lock_time = $microtime + $expire_time + 1; //锁过期时间

        if($redis->setnx($lock_key, $current_lock_time)) //获取锁成功
        {
            $redis->expire($lock_key, $expire_time); //设置过期时间，防止死锁
            return $current_lock_time;
        }

        //检查锁是否过期
        $lock_time = $redis->get($lock_key);
        if($lock_time < $microtime)
        {
            $new_lock_time = $microtime + $expire_time + 1; //设置新的过期时间
            $old_lock_time = $redis->getset($lock_key, $new_lock_time); //获取旧的过期时间并设置新的过期时间
            if($old_lock_time < $microtime) //锁已经过期，获取锁成功
            {
                $redis->expire($lock_key, $expire_time); //设置过期时间，防止死锁
                return $new_lock_time;
            }
        }

        //等待一段时间后再次尝试获取锁
        usleep(10000); //等待10毫秒
    }

    return false;
}

protected function unlock($lock_key, $current_lock_time)
{
    $redis = new Redis();
    $redis->connect('localhost', 6379); // 连接Redis
    
    $lock_time = $redis->get($lock_key);
    if($lock_time == $current_lock_time) //判断是否为当前持有锁的客户端
        $redis->del($lock_key); //释放锁
}