阻塞

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

#define PORT 8080
#define BUFFER_SIZE 1024

void *handle_client(void *arg) {
    int client_fd = *((int *)arg);
    free(arg);
    
    char buffer[BUFFER_SIZE];
    
    // 阻塞式读取 - 线程会在这里等待数据
    while (1) {
        int bytes_read = read(client_fd, buffer, BUFFER_SIZE);
        if (bytes_read <= 0) {
            break;
        }
        
        // 简单的回显服务
        write(client_fd, buffer, bytes_read);
    }
    
    close(client_fd);
    pthread_exit(NULL);
}

int main() {
    int server_fd;
    struct sockaddr_in address;
    int addrlen = sizeof(address);
    
    // 创建socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("Socket creation failed");
        exit(EXIT_FAILURE);
    }
    
    // 设置socket选项
    int opt = 1;
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
        perror("Setsockopt failed");
        exit(EXIT_FAILURE);
    }
    
    // 绑定地址和端口
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);
    
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("Bind failed");
        exit(EXIT_FAILURE);
    }
    
    // 监听连接
    if (listen(server_fd, 10) < 0) {
        perror("Listen failed");
        exit(EXIT_FAILURE);
    }
    
    printf("Server listening on port %d\n", PORT);
    
    // 接受连接并为每个客户端创建新线程
    while (1) {
        int *client_fd = malloc(sizeof(int));
        // accept是阻塞调用 - 会等待新连接
        if ((*client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
            perror("Accept failed");
            free(client_fd);
            continue;
        }
        
        pthread_t thread_id;
        if (pthread_create(&thread_id, NULL, handle_client, client_fd) != 0) {
            perror("Thread creation failed");
            close(*client_fd);
            free(client_fd);
            continue;
        }
        
        // 分离线程以便自动回收资源
        pthread_detach(thread_id);
    }
    
    return 0;
}