STL 线程安全

是的，所有的 STL 容器都不是线程安全的。当多个线程并发访问同一个 STL 容器时，如果有至少一个线程对容器进行了修改（插入、删除、更新等操作），则必须使用同步机制（如锁）来确保线程安全。以下是一些常见的 STL 容器以及使用互斥锁进行线程同步的示例。

示例 1：`std::vector` 的线程安全操作

#include <iostream>
#include <vector>
#include <thread>
#include <pthread.h>

std::vector<int> shared_vector;
pthread_mutex_t vec_mutex = PTHREAD_MUTEX_INITIALIZER;

void thread_safe_push_back(int value) {
    pthread_mutex_lock(&vec_mutex);
    shared_vector.push_back(value);
    pthread_mutex_unlock(&vec_mutex);
}

void thread_function() {
    for (int i = 0; i < 100; ++i) {
        thread_safe_push_back(i);
    }
}

int main() {
    std::thread t1(thread_function);
    std::thread t2(thread_function);

    t1.join();
    t2.join();

    std::cout << "Vector size: " << shared_vector.size() << std::endl;

    pthread_mutex_destroy(&vec_mutex);

    return 0;
}

示例 2：`std::map` 的线程安全操作

#include <iostream>
#include <map>
#include <thread>
#include <pthread.h>

std::map<int, int> shared_map;
pthread_mutex_t map_mutex = PTHREAD_MUTEX_INITIALIZER;

void thread_safe_insert(int key, int value) {
    pthread_mutex_lock(&map_mutex);
    shared_map[key] = value;
    pthread_mutex_unlock(&map_mutex);
}

void thread_function() {
    for (int i = 0; i < 100; ++i) {
        thread_safe_insert(i, i * 10);
    }
}

int main() {
    std::thread t1(thread_function);
    std::thread t2(thread_function);

    t1.join();
    t2.join();

    std::cout << "Map size: " << shared_map.size() << std::endl;

    pthread_mutex_destroy(&map_mutex);

    return 0;
}

示例 3：`std::queue` 的线程安全操作

#include <iostream>
#include <queue>
#include <thread>
#include <pthread.h>

std::queue<int> shared_queue;
pthread_mutex_t queue_mutex = PTHREAD_MUTEX_INITIALIZER;

void thread_safe_enqueue(int value) {
    pthread_mutex_lock(&queue_mutex);
    shared_queue.push(value);
    pthread_mutex_unlock(&queue_mutex);
}

void thread_function() {
    for (int i = 0; i < 100; ++i) {
        thread_safe_enqueue(i);
    }
}

int main() {
    std::thread t1(thread_function);
    std::thread t2(thread_function);

    t1.join();
    t2.join();

    std::cout << "Queue size: " << shared_queue.size() << std::endl;

    pthread_mutex_destroy(&queue_mutex);

    return 0;
}