C++并发编程练习13 “线程安全栈设计”

使用mutex锁，设计一个线程安全的stack，示例如下

#include 
#include 
#include 
#include 

struct empty_stack : std::exception
{
    const char* what() const throw();
};

template
class threadsafe_stack
{
private:
	std::stack data;
	std::mutex m;
public:
	threadsafe_stack()
	{
	}

	threadsafe_stack(const threadsafe_stack& other)
	{
		std::lock_guard lock(other.m);
		data = other.data; //copy in the constructor function
	}

	threadsafe_stack& operator=(const threadsafe_stack& other) = delete;
	
	void push(T new_value)
	{
		std::lock_guard lock(m);
		data.push(new_value);
	}

	size_t size()
	{
		std::lock_guard lock(m);
		return data.size();
	}

	std::shared_ptr pop() //get stack top data, then pop up it
	{
		std::lock_guard lock(m);
		if (data.empty())  //check if it is empty
		{
			throw empty_stack(); //throw an exception
		}

		std::shared_ptr const res(std::make_shared(data.top()));
		data.pop();
		return res;
	}

	void pop(T& value)
	{
		std::lock_guard lock(m);
		if (data.empty())
			throw empty_stack();

		value  = data.top();
		data.pop();
	}

	bool empty() const
	{	
		std::lock_guard lock(m);
		return data.empty();
	}
};

测试代码：

#include 
#include 
#include 

#include "safeStack.hxx"

void func(threadsafe_stack* dat)
{
	for (int i = 0; i < 12000; i++)
	{
		dat->push(i);
		std::this_thread::yield();
	}
}

int main()
{
	threadsafe_stack datas;
	std::thread th(func, &datas);
	th.detach();

	do
	{
		size_t sz = datas.size();
		std::cout << sz << std::endl;
		if (sz < 12000)
		{
			std::this_thread::yield();
			continue;
		}

		break;
	}while(true);
	
	return 0;
}