#ifndef _MESSAGEQUEUE_H_INCLUDED_
#define _MESSAGEQUEUE_H_INCLUDED_

#include "stdafx.h"
#include <Windows.h>
#include <queue>


/*
 * 描述： 用于实现一个线程安全的消息队列
 *
 * 注： MessageQueue当前并不支持指针类型，对于指针类型，后续需要进行偏特化
*/

template<typename T>
class MessageQueue当前并不支持指针类型{
public:
	MessageQueue当前并不支持指针类型(int limit){
		this->limit = limit;
		this->bStop = false;
		::InitializeCriticalSection(&queueCs);
		::InitializeConditionVariable(&queueNotEmpty);
	}

	~MessageQueue当前并不支持指针类型(){
		bStop = true;
		::WakeConditionVariable(&queueNotEmpty);
		DeleteCriticalSection(&queueCs);
	}

	bool Push(T &msg){
		bool result = true;

		::EnterCriticalSection(&queueCs);
		if (msg_queue.size() >= limit){
			result = false;
		}
		else{
			if (msg_queue.empty()){
				msg_queue.push(msg);
				::WakeConditionVariable(&queueNotEmpty);
			}
			else{
				msg_queue.push(msg);
			}
		}
		::LeaveCriticalSection(&queueCs);
		return result;
	}

	
	T Pop(){
		EnterCriticalSection(&queueCs);
		while (!bStop && msg_queue.empty()){
			::SleepConditionVariableCS(&queueNotEmpty, &queueCs, INFINITE);
		}

		if (!msg_queue.empty()){
			T t = msg_queue.front();
			msg_queue.pop();

			LeaveCriticalSection(&queueCs);
			return t;
		}

		LeaveCriticalSection(&queueCs);
		return T();
	}

	T Pop(DWORD dwMilliseconds){
		EnterCriticalSection(&queueCs);
		if (msg_queue.empty()){
			::SleepConditionVariableCS(&queueNotEmpty, &queueCs, dwMilliseconds);
		}
		if (!msg_queue.empty()){
			T t = msg_queue.front();
			msg_queue.pop();

			LeaveCriticalSection(&queueCs);
			return t;
		}

		LeaveCriticalSection(&queueCs);
		return T();
	}

	int GetLimit()const{
		return limit;
	}

	int GetCurrentSize(){
		int sz;

		EnterCriticalSection(&queueCs);
		sz = msg_queue.size();
		LeaveCriticalSection(&queueCs);

		return sz;
	}

	/*
	 * 说明：很多时候我们可能并不需要很精确的获取到当前队列中的元素个数，因此我们可以不加锁进行保护（非线程安全)
	 */
	int GetCurrentSize_unsafe(){
		return msg_queue.size();
	}

	
private:
	std::queue<T> msg_queue;
	size_t limit;
	bool bStop;

	CRITICAL_SECTION  queueCs;
	CONDITION_VARIABLE queueNotEmpty;
};




#endif