C++ 并发专题 - 实现一个线程安全的队列

一：概述

        本文利用 C++ 标准库中的多线程、条件变量、互斥锁等工具来实现一个线程安全的队列，并且使用多个线程来向队列中添加和获取数据。 

二：实现过程：

#include <iostream>
#include <queue>
#include <mutex>
#include <condition_variable>
#include <thread>
#include <vector>template <typename T>
class ThreadSafeQueue {
public:// 向队列中添加元素void push(const T& value) {std::lock_guard<std::mutex> lock(mutex_);queue_.push(value);cond_var_.notify_one();  // 通知一个等待的线程}// 从队列中取出元素，如果队列为空，阻塞等待T pop() {std::unique_lock<std::mutex> lock(mutex_);cond_var_.wait(lock, [this] { return !queue_.empty(); });  // 等待直到队列非空T value = queue_.front();queue_.pop();return value;}// 判断队列是否为空bool empty() const {std::lock_guard<std::mutex> lock(mutex_);return queue_.empty();}private:mutable std::mutex mutex_;            // 互斥锁，保护队列std::queue<T> queue_;                 // 基础队列std::condition_variable cond_var_;   // 条件变量，用于队列为空时的等待
};// 示例：使用线程安全队列
void producer(ThreadSafeQueue<int>& queue, int numItems) {for (int i = 0; i < numItems; ++i) {queue.push(i);std::cout << "Produced: " << i << std::endl;}
}void consumer(ThreadSafeQueue<int>& queue, int numItems) {for (int i = 0; i < numItems; ++i) {int item = queue.pop();std::cout << "Consumed: " << item << std::endl;}
}int main() {ThreadSafeQueue<int> queue;const int numItems = 10;const int numProducers = 2;const int numConsumers = 2;std::vector<std::thread> threads;// 启动生产者线程for (int i = 0; i < numProducers; ++i) {threads.push_back(std::thread(producer, std::ref(queue), numItems / numProducers));}// 启动消费者线程for (int i = 0; i < numConsumers; ++i) {threads.push_back(std::thread(consumer, std::ref(queue), numItems / numConsumers));}// 等待所有线程完成for (auto& thr : threads) {thr.join();}return 0;
}