MySQLConnectionPool::MySQLConnectionPool()
{
	if (!loadConfigFile())
	{
		return;
	}
	for (int i = 0; i < _initSize; ++i)
	{
		Connection* p = new Connection();
		p->connect(_ip, _port, _username, _password, _dbname);
		p->refreshAliveTime(); 
		_connectionQue.push(p);
		_connectionCnt++;
	}

	thread produce(std::bind(&MySQLConnectionPool::produceConnectionTask, this));
	produce.detach();

	thread scanner(std::bind(&MySQLConnectionPool::scannerConnectionTask, this));
	scanner.detach();
}

void MySQLConnectionPool::produceConnectionTask()
{
	for (;;)
	{
		unique_lock<mutex> lock(_queueMutex);
    // queue队列中的连接不为空 即不需要创建新连接，当前线程进入阻塞状态
		while (!_connectionQue.empty())
		{
			cv.wait(lock); 
		}
		if (_connectionCnt < _maxSize)
		{
			Connection* p = new Connection();
			p->connect(_ip, _port, _username, _password, _dbname);
			p->refreshAliveTime();
			_connectionQue.push(p);
			_connectionCnt++;
		}
		cv.notify_all();
	}
}

shared_ptr<Connection> MySQLConnectionPool::getConnection()
{
	unique_lock<mutex> lock(_queueMutex);
	while (_connectionQue.empty())
	{
		if (cv_status::timeout == cv.wait_for(lock, chrono::milliseconds(_connectionTimeout)))
		{
			if (_connectionQue.empty())
			{
				LOG("getConnection Timeout !");
				return nullptr;
			}
		}
	}
   // lambda 实现shared_ptr删除器
  // Conn析构时，再次将conn添加到队列中。
	shared_ptr<Connection> ptr(_connectionQue.front(),
		[&](Connection* conn)->void {
			unique_lock<mutex> lock(_queueMutex);
            conn->refreshAliveTime();
			_connectionQue.push(conn);
		});

    _connectionQue.pop();
   	// 如果当前队列中的连接为空 唤醒produce线程
    if (_connectionQue.empty()) cv.notify_all();
	return ptr;
}

void MySQLConnectionPool::scannerConnectionTask()
{
	for (;;)
	{

		this_thread::sleep_for(chrono::seconds(_maxIdleTime));

		unique_lock<mutex> lock(_queueMutex);
		while (_connectionCnt > _initSize)
		{
			Connection* p = _connectionQue.front();
			if (p->getAliveeTime() >= (_maxIdleTime * 1000))
			{
				_connectionQue.pop();
				_connectionCnt--;
				delete p;
			}
			else
			{
				break;
			}
		}
	}
}