Linux网络编程之多线程

多线程模型

在多线程模型下，注意共享数据的同步，mutex/condition_variable/rw_lock等的使用，local thread storage的使用，另外，可以搭配线程池处理异步计算任务。在C++11中的线程库中已经提供了future相关的工具，合理地使用线程模型减少资源的同时，能获得不错的性能

//thread server
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <netdb.h>
#include <pthread.h>
#include <unistd.h>

#define MAX_READ_CHUNK 2*1024*1024
#define KEEP_ALIVE 0
void run();

int main(int argc, char *argv[])
{
    run();
    return 0;
}

void error_exit()
{
    perror("error");
    exit(EXIT_FAILURE);
}

int do_read_and_write(int clientfd)
{
    char read[MAX_READ_CHUNK];
    ssize_t result;
    result = recv(clientfd, read, sizeof(read), 0);
    if (result<=0){
        perror("error recv data");
        return -1;
    }

    //write back
    result = send(clientfd, read, result, 0);

    if (result<=0){
        perror("error send data");
        return -1;
    }

    if(!KEEP_ALIVE)
        close(clientfd);
    return 0;
}

void *handle_client_socket(void *clientfd)
{
    if (pthread_detach(pthread_self())!=0){
        error_exit();
    }
    int client = *(int *)clientfd;
    if (clientfd!=NULL){
        free(clientfd);
        clientfd = NULL;
    }
    if (do_read_and_write(client)<0){
        error_exit();
    }
    //we set the thread detach,so no need call pthread_exit
    //pthread_exit(NULL);
}

void run()
{
    struct hostent *h;
    h = gethostbyname("localhost");
    if (!h){
        error_exit();
    }

    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_addr = *(struct in_addr*)h->h_addr;
    sin.sin_port = htons(8000);

    int serverfd = socket(AF_INET, SOCK_STREAM, 0);
    if (serverfd<0){
        error_exit();
    }
    int reuse = 1;
    if (setsockopt(serverfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse))){
        error_exit();
    }

    socklen_t slen = sizeof(sin);
    if (bind(serverfd, (struct sockaddr *)&sin, slen)<0){
        error_exit();
    }

    if (listen(serverfd, 20)<0){
        error_exit();
    }

    struct sockaddr_in client;
    socklen_t slen_client = sizeof(client);
    int clientfd;
    pthread_t pt;

    while(1){

        clientfd = accept(serverfd, (struct sockaddr *)&client, &slen_client);
        if (clientfd<0){
            error_exit();
        }

        int *temp = (int *) malloc(sizeof(int));
        *temp = clientfd;
        if(pthread_create(&pt, NULL, handle_client_socket, temp)!=0){
            error_exit();
        }

    }

}