多線程編程需要實現一個線程安全的隊列,上鎖,避免多個線程同時讀寫
代碼:
/**
* 線程安全的隊列
*/
#ifndef __THREAD_SAFE_QUEUE__
#define __THREAD_SAFE_QUEUE__
#include <iostream>
#include <queue>
#include <mutex>
#include <condition_variable>
template <class T>
class thread_safe_queue
{
private:
mutable mutex mut; //鎖
queue<T> data_queue; //隊列
condition_variable data_cond; //條件變量
public:
//構造函數
thread_safe_queue();
thread_safe_queue &operator=(const thread_safe_queue&)=delete;
//可以多傳遞一個額外的條件
bool wait_and_pop(T &value,atomic_bool &bl);
bool try_pop(T &value);
void push(T new_value);
bool empty() const;
void notify_all()
{
data_cond.notify_all();
}
};
template <class T>
thread_safe_queue<T>::thread_safe_queue(){}
template <class T>
bool thread_safe_queue<T>::empty() const
{
lock_guard<mutex> lock(mut);
return data_queue.empty();
}
template <class T>
void thread_safe_queue<T>::push(T new_value)
{
lock_guard<mutex> lock(mut);
data_queue.push(new_value);
data_cond.notify_one();
}
template <class T>
bool thread_safe_queue<T>::wait_and_pop(T &value,atomic_bool &bl)
{
unique_lock<mutex> lock(mut);
//避免隊列爲空時一直等待
data_cond.wait(lock,[this,&bl](){return (!this->data_queue.empty())||bl; });
if(bl&&data_queue.empty())
return false;
value=data_queue.front();
data_queue.pop();
return true;
}
template<class T>
bool thread_safe_queue<T>::try_pop(T &value)
{
lock_guard<mutex> lock(mut);
if(empty())
return false;
value=data_queue.front();
data_queue.pop();
return true;
}
#endif
對於mutex我的理解是在同一個mutex的lock、unlock之間的代碼不能同時運行。