用linux写的多线程聊天

基础概念

多线程聊天是指在一个聊天应用程序中，使用多个线程来处理并发连接和消息传递。Linux操作系统提供了强大的多线程支持，主要通过POSIX线程（pthread）库来实现。

类型

客户端-服务器模型：服务器端创建一个主线程用于监听客户端连接，每当有新的客户端连接时，服务器会创建一个新的线程来处理该客户端的请求。
P2P模型：每个节点既是客户端也是服务器，可以直接与其他节点进行通信。

应用场景

即时通讯软件：如微信、QQ等。
在线游戏：多人在线角色扮演游戏（MMORPG）。
分布式系统：如分布式计算任务的分发和处理。

示例代码

以下是一个简单的Linux多线程聊天服务器的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <pthread.h>

#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024

int client_sockets[MAX_CLIENTS] = {0};
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

void *handle_client(void *arg) {
    int client_socket = *(int*)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = recv(client_socket, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            break;
        }
        pthread_mutex_lock(&mutex);
        for (int i = 0; i < MAX_CLIENTS; i++) {
            if (client_sockets[i] != 0 && client_sockets[i] != client_socket) {
                send(client_sockets[i], buffer, bytes_received, 0);
            }
        }
        pthread_mutex_unlock(&mutex);
    }
    close(client_socket);
    pthread_mutex_lock(&mutex);
    for (int i = 0; i < MAX_CLIENTS; i++) {
        if (client_sockets[i] == client_socket) {
            client_sockets[i] = 0;
            break;
        }
    }
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
    int server_socket, client_socket;
    struct sockaddr_in server_addr, client_addr;
    socklen_t addr_len = sizeof(client_addr);

    server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1) {
        perror("Socket creation failed");
        exit(EXIT_FAILURE);
    }

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(8888);

    if (bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1) {
        perror("Bind failed");
        close(server_socket);
        exit(EXIT_FAILURE);
    }

    if (listen(server_socket, 5) == -1) {
        perror("Listen failed");
        close(server_socket);
        exit(EXIT_FAILURE);
    }

    printf("Server listening on port 8888\n");

    while (1) {
        client_socket = accept(server_socket, (struct sockaddr*)&client_addr, &addr_len);
        if (client_socket == -1) {
            perror("Accept failed");
            continue;
        }

        pthread_mutex_lock(&mutex);
        for (int i = 0; i < MAX_CLIENTS; i++) {
            if (client_sockets[i] == 0) {
                client_sockets[i] = client_socket;
                break;
            }
        }
        pthread_mutex_unlock(&mutex);

        pthread_t thread;
        pthread_create(&thread, NULL, handle_client, &client_socket);
        pthread_detach(thread);
    }

    close(server_socket);
    return 0;
}