C++实现对象池的具体方法

    /// <summary>
	/// 对象池
	/// </summary>
	class ObjectPool
	{
	public:		
		/// <summary>
		/// 构造方法
		/// </summary>
		/// <param name="bufferArray">对象池的缓冲区，由外部指定，可以理解为一个数组。数组大小需满足bufferSize>=elementSize*arraySize</param>
		/// <param name="elementSize">数组元素大小</param>
		/// <param name="arraySize">数组长度或元素个数</param>
		ObjectPool(void* bufferArray, int elementSize, int arraySize );		
		/// <summary>
		/// 申请对象
		/// 如果池里对象不足,则会等待，直到有对象才返回。
		/// </summary>
		/// <returns>返回申请的对象指针</returns>
		void* Applicate();
		/// <summary>
		/// 申请对象
		/// </summary>
		/// <param name="timeout">超时时间，超时后返回null</param>
		/// <returns>返回申请的对象指针</returns>
		void* Applicate(int timeout);	
		/// <summary>
		/// 归还对象
		/// </summary>
		/// <param name="element">需归还的对象</param>
		void ReturnBack(void* element);	
	};

#ifndef OBJECTPOOL_H
#define OBJECTPOOL_H

#include<unordered_map>
#include<vector>
#include<mutex>
#include<condition_variable>
namespace AC {
	/// <summary>
	/// 对象池
	/// </summary>
	class ObjectPool
	{
	public:		
		/// <summary>
		/// 构造方法
		/// </summary>
		/// <param name="bufferArray">对象池的缓冲区，由外部指定，可以理解为一个数组。数组大小需满足bufferSize>=elementSize*arraySize</param>
		/// <param name="elementSize">数组元素大小</param>
		/// <param name="arraySize">数组长度或元素个数</param>
		ObjectPool(void* bufferArray, int elementSize, int arraySize );
		/// <summary>
		/// 析构方法
		/// </summary>
		~ObjectPool();
		/// <summary>
		/// 申请对象
		/// 如果池里对象不足,则会等待，直到有对象才返回。
		/// </summary>
		/// <returns>返回申请的对象指针</returns>
		void* Applicate();
		/// <summary>
		/// 申请对象
		/// </summary>
		/// <param name="timeout">超时时间，超时后返回null</param>
		/// <returns>返回申请的对象指针</returns>
		void* Applicate(int timeout);	
		/// <summary>
		/// 归还对象
		/// </summary>
		/// <param name="element">需归还的对象</param>
		void ReturnBack(void* element);	
		/// <summary>
		/// 获取对象池的缓冲区，即构造方法中的bufferArray
		/// </summary>
		/// <returns>缓冲区的指针</returns>
		void* GetPoolBuffer();
		/// <summary>
		/// 获取对象的大小，即构造方法中的elementSize
		/// </summary>
		/// <returns>对象的大小</returns>
		int GetObjectSize();
		/// <summary>
		/// 获取总的对象数量，即构造方法中的arraySize
		/// </summary>
		/// <returns>总的对象数量</returns>
		int GetObjectCount();
	private:
		void*_buffer = NULL;
		int _elementSize;
		int _arraySize;
		std::vector<void*> _unusedUnits;
		std::unordered_map<void*, int> _usedUnits;
		std::mutex _mutex;
		std::condition_variable _cond;
	};

	/// <summary>
	/// 泛型对象池
	/// </summary>
	/// <typeparam name="T">对象类型</typeparam>
	template<typename T>
	class ObjectPoolGeneric:private ObjectPool
	{
	public:
		/// <summary>
		/// 构造方法
		/// </summary>
		/// <param name="array">对象数组</param>
		/// <param name="size">数组大小</param>
		/// <returns></returns>
		ObjectPoolGeneric(T*array,int size) :ObjectPool(array, sizeof(T), size)
		{
		}
		/// <summary>
		/// 析构方法
		/// </summary>
		~ObjectPoolGeneric() {}
		/// <summary>
		/// 申请对象
		/// 如果池里对象不足,则会等待，直到有对象才返回。
		/// </summary>
		/// <returns>返回申请的对象指针</returns>
		T* Applicate() {
			return (T*)ObjectPool::Applicate();
		}
		/// <summary>
		/// 申请对象
		/// </summary>
		/// <param name="timeout">超时时间，超时后返回null</param>
		/// <returns>返回申请的对象指针</returns>
		T* Applicate(int timeout) {
			return (T*)ObjectPool::Applicate(timeout);
		}
		/// <summary>
		/// 归还对象
		/// </summary>
		/// <param name="element">需归还的对象</param>
		void ReturnBack(T* element)
		{
			ObjectPool::ReturnBack(element);
		}
		/// <summary>
		/// 获取对象池的缓冲区，即构造方法中的bufferArray
		/// </summary>
		/// <returns>缓冲区的指针</returns>
		T* GetPoolBuffer() {
			return (T*)ObjectPool::GetPoolBuffer();
		}
	};
}
#endif 

#include "ObjectPool.h"
#include <chrono> 
namespace AC {
	ObjectPool::ObjectPool(void* bufferArray, int elementSize, int arraySize)
	{
		if (elementSize < 1 || arraySize < 1)
			return;
		_buffer = bufferArray;
		_elementSize = elementSize;
		_arraySize = arraySize;
		char* firstAdress = (char*)bufferArray;
		//记录未使用的索引
		for (int i = 0; i < arraySize; i++)
		{
			_unusedUnits.push_back(&(firstAdress[i * elementSize]));
		}
	}
	ObjectPool::~ObjectPool()
	{
	}
	void* ObjectPool::Applicate()
	{
		return Applicate(-1);
	}
	void* ObjectPool::Applicate(int timeout) {
		void* resource = NULL;
		std::unique_lock<std::mutex> l(_mutex);
		while (_unusedUnits.size() < 1)
		{
			if (timeout == -1)
			{
				_cond.wait(l);
			}
			else if (_cond.wait_for(l, std::chrono::microseconds(timeout)) == std::cv_status::timeout)
			{
				return nullptr;
			}
		}
		resource = _unusedUnits.back();
		_usedUnits[resource] = 1;
		_unusedUnits.pop_back();
		return resource;
	}
	void ObjectPool::ReturnBack(void* element) {
		_mutex.lock();
		auto iter = _usedUnits.find(element);
		if (iter != _usedUnits.end())
		{
			_unusedUnits.push_back(element);
			_usedUnits.erase(iter);
			_cond.notify_one();
		}
		_mutex.unlock();
	}
	void* ObjectPool::GetPoolBuffer()
	{
		return _buffer;
	}
	int ObjectPool::GetObjectSize()
	{
		return _elementSize;
	}
	int ObjectPool::GetObjectCount()
	{
		return _arraySize;
	}
}

#include "ObjectPool.h"
class A {
public:
	A() {
		printf("%p\n", this);
	}
};
int main(int arGC, char** argv) {
	//初始化对象池，2个对象
	AC::ObjectPool objectPool(new char[sizeof(A) * 2], sizeof(A), 2);
	A* a, * b, * c;
	//申请对象，使用定位new初始化对象
	a = new (objectPool.Applicate())A;
	b = new (objectPool.Applicate())A;
	//归还对象
	a->~A();//返初始化对象
	objectPool.ReturnBack(a);
	c = new (objectPool.Applicate())A;
	b->~A();
	c->~A();
	//使用结束，删除缓存
	delete	objectPool.GetPoolBuffer();
	return 0;
}

#include <thread>
#include <chrono>
#include <mutex>
#include <condition_variable>
#include "ObjectPool.h"
class ThreadInfo {
public:
	std::thread* pThread;
	std::mutex _mutext;
	std::condition_variable _cv;
	std::function<void()> _threadPoc;
};
//线程信息数组，数组长度即线程池的线程数
ThreadInfo _threadArray[3];
//对象池，使用线程信息数组初始化
AC::ObjectPoolGeneric<ThreadInfo>_threadPool(_threadArray, 3);
bool _exitThreadPool = false;
//在线程池中运行方法
void RunInThreadPool(std::function<void()> f) {
	//申请线程
	auto threadInfo = _threadPool.Applicate();
	threadInfo->_threadPoc = f; 
	if (threadInfo->pThread)
		//复用线程
	{
		threadInfo->_cv.notify_one();
	}
	else
		//创建线程
	{
		threadInfo->pThread = new std::thread([=]() {
			while (!_exitThreadPool)
			{
				printf("thread %d run\n", threadInfo->pThread->get_id());
				if (threadInfo->_threadPoc)
				{	//执行线程操作
					threadInfo->_threadPoc();
				}
				printf("thread %d stop\n", threadInfo->pThread->get_id());
				//归还线程
				_threadPool.ReturnBack(threadInfo);
				std::unique_lock<std::mutex>lck(threadInfo->_mutext);
				threadInfo->_cv.wait(lck);
			}
		});
	}
}
int main(int argc, char** argv) {
	while(true)
	{   //在线程池中运行方法
		RunInThreadPool([]() {		
			std::this_thread::sleep_for(std::chrono::milliseconds(1000));	
		});
	}
    return 0;
}