[游戏开发]thread_local关键字

????????thread_local是C++11为了线程安全引入的变量声明符，跟gcc内置的线程局部存储设备__thread功能类似。thread_local声明的对象的存储在每个线程开始时分配，在线程结束是销毁。每一个thread_local变量在每个线程有一份独立实体，各个线程的变量互不干扰。

????????__thread只能用于修饰POD类型，不能修饰class类型因为无法自动调用构造函数和析构函数，而thread_local可以修饰class类型，在线程结束时，会调用class的析构函数。

例：

#include <iostream>
#include <thread>


class Test1
{
public:
	Test1(int _id):id(_id){}
	~Test1(){ std::cout << "del t: " << std::this_thread::get_id() << " Id: " << getId() << std::endl; }
	const int getId() const { return id; }
	void setId(int val) { id = val; }
	void add() { id++; }
	void add(int val) { id += val; }
private:
	int id;
};

thread_local int tVal = 1;
thread_local Test1 tClass(1);

void mainFunc()
{
	tVal++;
	tClass.add();
	std::cout << "main: " << std::this_thread::get_id() << " tVal:" << tVal <<" tClass.Id: "<< tClass.getId()<<std::endl;
}

void Func1(const std::string&thread_name)
{
	tVal += 10;
	tClass.add(10);
	std::cout << thread_name.c_str() <<": " << std::this_thread::get_id() << " tVal: " << tVal << " tClass.Id: " << tClass.getId() << std::endl;
}

void Func2(const std::string&thread_name)
{
	tVal += 20;
	tClass.add(20);
	std::cout << thread_name.c_str() << ": " << std::this_thread::get_id() << " tVal:" << tVal << " tClass.Id: " << tClass.getId() << std::endl;
}

int main()
{
	mainFunc();
	std::thread t1(Func1,"t1");
	std::thread t2(Func2, "t2");
	t1.join();
	t2.join();

	mainFunc();

	std::thread t3([=]()
	{
		tVal += 30;
		tClass.add(30);
		std::cout << "t3: " << std::this_thread::get_id() << " tVal:" << tVal << " tClass.Id: " << tClass.getId() << std::endl;
	});
	t3.join();

	mainFunc();

	return 0;
}

运行结果：

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