How to implement multi-threaded programming in C++ using STL?

Using STL to implement multi-threaded programming in C++ involves: using std::thread to create threads. Protect shared resources using std::mutex and std::lock_guard. Use std::condition_variable to coordinate conditions between threads. This method supports concurrent tasks such as file copying, where multiple threads process file blocks in parallel.

How to use STL to implement multi-threaded programming in C++

STL (Standard Template Library) provides a powerful set of Concurrency primitives and containers can easily implement multi-threaded programming. This article demonstrates how to use key components in STL to create multi-threaded applications.

Using Threads

To create a thread, use std::thread Class:

std::thread t1(some_function);
t1.join(); // 等待线程完成

some_function is a function to be executed concurrently.

Mutexes and locks

Mutexes can be used to prevent multiple threads from accessing shared resources at the same time. Using std::mutex:

std::mutex m;
{
    std::lock_guard<std::mutex> lock(m);
    // 在此处访问共享资源
} // 解除 m 的锁定

Condition variable

Condition variable allows a thread to wait for a specific condition, such as when a shared resource is available. Using std::condition_variable:

std::condition_variable cv;
std::unique_lock<std::mutex> lock(m);
cv.wait(lock); // 等待 cv 信号
cv.notify_one(); // 唤醒一个等待线程

Practical case: multi-threaded file copy

The following code demonstrates how to use STL to implement multi-threaded file copy:

#include <fstream>
#include <iostream>
#include <thread>
#include <vector>

void copy_file(const std::string& src, const std::string& dst) {
    std::ifstream infile(src);
    std::ofstream outfile(dst);
    outfile << infile.rdbuf();
}

int main() {
    std::vector<std::thread> threads;
    const int num_threads = 4;

    // 创建线程池
    for (int i = 0; i < num_threads; ++i) {
        threads.emplace_back(copy_file, "input.txt", "output" + std::to_string(i) + ".txt");
    }

    // 等待所有线程完成
    for (auto& t : threads) {
        t.join();
    }

    std::cout << "Files copied successfully!" << std::endl;
    return 0;
}

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