文章标题

利用libevent和多线程 实现多并发的服务器的设计。主进程监听连接的到来使用一个base,进行事件循环。每当 一个连接进来时，创建一个新的线程实现与客户端之间的通信，子线程建立一个base,进行事件循环

客户端（多线程）：
主线程->连接描述符（socket_fd = connectServer(ip, port);）
-》创建子进程（init_read_event_thread(socket_fd);）
-》 pthread_create(&thread,NULL,init_read_event,(void*)sock);
-》创建base,并且建立事件循环（
void* init_read_event(void* arg)
->事件的回调函数

    -》写数据给服务端

服务器（多线程）（base)： ( 主要是一个线程一个base)
主线程-》listen(fd, 10);
-》设置事件循环

         event_set(&listen_ev, fd, EV_READ|EV_PERSIST, on_accept, NULL);（等待连接的到来）            -》得到连接描述符子线程 (base)：     accept_new_thread(new_fd);         pthread_create(&thread,NULL,process_in_new_thread_when_accepted,(void*)sock);            -》process_in_new_thread_when_accepted(void* arg)                ->设置事件循环

服务器端程序：

#include <iostream>#include <sys/select.h>#include <sys/socket.h>#include <stdio.h>#include <unistd.h>#include <pthread.h>#include <stdio.h>#include <sys/types.h>#include <netinet/in.h>#include <arpa/inet.h>#include <string>#include <string.h>#include <event.h>#include <stdlib.h>using namespace std;#define SERVER_IP "127.0.0.1"#define SERVER_PORT 9090#define BUF_SIZE 1024struct sock_ev_write{//用户写事件完成后的销毁，在on_write()中执行    struct event* write_ev;    char* buffer;};struct sock_ev {//用于读事件终止（socket断开）后的销毁    struct event_base* base;//因为socket断掉后，读事件的loop要终止，所以要有base指针    struct event* read_ev;};/** * 销毁写事件用到的结构体 */void destroy_sock_ev_write(struct sock_ev_write* sock_ev_write_struct){    if(NULL != sock_ev_write_struct){//        event_del(sock_ev_write_struct->write_ev);//因为写事件没用EV_PERSIST，故不用event_del        if(NULL != sock_ev_write_struct->write_ev){            free(sock_ev_write_struct->write_ev);        }        if(NULL != sock_ev_write_struct->buffer){            delete[]sock_ev_write_struct->buffer;        }        free(sock_ev_write_struct);    }}/** * 读事件结束后，用于销毁相应的资源 */void destroy_sock_ev(struct sock_ev* sock_ev_struct){   if(NULL == sock_ev_struct){        return;    }    event_del(sock_ev_struct->read_ev);    event_base_loopexit(sock_ev_struct->base, NULL);//停止loop循环    if(NULL != sock_ev_struct->read_ev){        free(sock_ev_struct->read_ev);    cout<<"free read_ev succeed"<<endl;    }/*    if(NULL !=sock_ev_struct->base)    {        event_base_free(sock_ev_struct->base);        cout<<"free base succeed"<<endl;    }*///    destroy_sock_ev_write(sock_ev_struct->sock_ev_write_struct);    if(NULL !=sock_ev_struct)    {        free(sock_ev_struct);        cout<<"free sock_ev_struct"<<endl;    }}int getSocket(){    int fd =socket( AF_INET, SOCK_STREAM, 0 );    if(-1 == fd){        cout<<"Error, fd is -1"<<endl;    }    return fd;}void on_write(int sock, short event, void* arg){    cout<<"on_write() called, sock="<<sock<<endl;    if(NULL == arg){        cout<<"Error! void* arg is NULL in on_write()"<<endl;        return;    }    struct sock_ev_write* sock_ev_write_struct = (struct sock_ev_write*)arg;    char buffer[BUF_SIZE];    sprintf(buffer, "fd=%d, received[%s]", sock, sock_ev_write_struct->buffer);//    int write_num0 = write(sock, sock_ev_write_struct->buffer, strlen(sock_ev_write_struct->buffer));//    int write_num = write(sock, sock_ev_write_struct->buffer, strlen(sock_ev_write_struct->buffer));    int write_num = write(sock, buffer, strlen(buffer));    destroy_sock_ev_write(sock_ev_write_struct);    cout<<"on_write() finished, sock="<<sock<<endl;}void on_read(int sock, short event, void* arg){    cout<<"on_read() called, sock="<<sock<<endl;    if(NULL == arg){        return;    }    struct sock_ev* event_struct = (struct sock_ev*) arg;//获取传进来的参数    char* buffer = new char[BUF_SIZE];    memset(buffer, 0, sizeof(char)*BUF_SIZE);    //--本来应该用while一直循环，但由于用了libevent，只在可以读的时候才触发on_read(),故不必用while了    int size = read(sock, buffer, BUF_SIZE);    if(0 == size){//说明socket关闭        cout<<"read size is 0 for socket:"<<sock<<endl;        destroy_sock_ev(event_struct);        close(sock);        return;    }    struct sock_ev_write* sock_ev_write_struct = (struct sock_ev_write*)malloc(sizeof(struct sock_ev_write));    sock_ev_write_struct->buffer = buffer;    struct event* write_ev = (struct event*)malloc(sizeof(struct event));//发生写事件（也就是只要socket缓冲区可写）时，就将反馈数据通过socket写回客户端    sock_ev_write_struct->write_ev = write_ev;    event_set(write_ev, sock, EV_WRITE, on_write, sock_ev_write_struct);    event_base_set(event_struct->base, write_ev);    event_add(write_ev, NULL);    cout<<"on_read() finished, sock="<<sock<<endl;}/** * main执行accept()得到新socket_fd的时候，执行这个方法 * 创建一个新线程，在新线程里反馈给client收到的信息 */void* process_in_new_thread_when_accepted(void* arg){    long long_fd = (long)arg;    int fd = (int)long_fd;    if(fd<0){        cout<<"process_in_new_thread_when_accepted() quit!"<<endl;        return 0;    }    //-------初始化base,写事件和读事件--------    struct event_base* base = event_base_new();    struct event* read_ev = (struct event*)malloc(sizeof(struct event));//发生读事件后，从socket中取出数据    //-------将base，read_ev,write_ev封装到一个event_struct对象里，便于销毁---------    struct sock_ev* event_struct = (struct sock_ev*)malloc(sizeof(struct sock_ev));    event_struct->base = base;    event_struct->read_ev = read_ev;    //-----对读事件进行相应的设置------------    event_set(read_ev, fd, EV_READ|EV_PERSIST, on_read, event_struct);    event_base_set(base, read_ev);    event_add(read_ev, NULL);    //--------开始libevent的loop循环-----------    event_base_dispatch(base);    cout<<"event_base_dispatch() stopped for sock("<<fd<<")"<<" in process_in_new_thread_when_accepted()"<<endl;    event_base_free(base);   //必须在此删除子线程的base    return 0;}/** * 每当accept出一个新的socket_fd时，调用这个方法。 * 创建一个新线程，在新线程里与client做交互 */void accept_new_thread(int sock){    pthread_t thread;    pthread_create(&thread,NULL,process_in_new_thread_when_accepted,(void*)sock);    pthread_detach(thread);}/** * 每当有新连接连到server时，就通过libevent调用此函数。 *    每个连接对应一个新线程 */void on_accept(int sock, short event, void* arg){    struct sockaddr_in remote_addr;    int sin_size=sizeof(struct sockaddr_in);    int new_fd = accept(sock,  (struct sockaddr*) &remote_addr, (socklen_t*)&sin_size);    if(new_fd < 0){        cout<<"Accept error in on_accept()"<<endl;        return;    }    cout<<"new_fd accepted is "<<new_fd<<endl;    accept_new_thread(new_fd);    cout<<"on_accept() finished for fd="<<new_fd<<endl;}int main(){    int fd = getSocket();    if(fd<0){        cout<<"Error in main(), fd<0"<<endl;    }    cout<<"main() fd="<<fd<<endl;    //----为服务器主线程绑定ip和port------------------------------    struct sockaddr_in local_addr; //服务器端网络地址结构体    memset(&local_addr,0,sizeof(local_addr)); //数据初始化--清零    local_addr.sin_family=AF_INET; //设置为IP通信    local_addr.sin_addr.s_addr=inet_addr(SERVER_IP);//服务器IP地址    local_addr.sin_port=htons(SERVER_PORT); //服务器端口号    int bind_result = bind(fd, (struct sockaddr*) &local_addr, sizeof(struct sockaddr));    if(bind_result < 0){        cout<<"Bind Error in main()"<<endl;        return -1;    }    cout<<"bind_result="<<bind_result<<endl;    listen(fd, 10);    //-----设置libevent事件，每当socket出现可读事件，就调用on_accept()------------    struct event_base* base = event_base_new();    struct event listen_ev;    event_set(&listen_ev, fd, EV_READ|EV_PERSIST, on_accept, NULL);    event_base_set(base, &listen_ev);    event_add(&listen_ev, NULL);    event_base_dispatch(base);    //------以下语句理论上是不会走到的---------------------------    cout<<"event_base_dispatch() in main() finished"<<endl;    //----销毁资源-------------    event_del(&listen_ev);    event_base_free(base);    cout<<"main() finished"<<endl;}

客户端程序：

#include <iostream>#include <sys/select.h>#include <sys/socket.h>#include <unistd.h>#include <pthread.h>#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <netinet/in.h>#include <arpa/inet.h>#include <string>#include <string.h>#include <event.h>using namespace std;#define BUF_SIZE 1024/** * 连接到server端，如果成功，返回fd，如果失败返回-1 */int connectServer(char* ip, int port){    int fd = socket( AF_INET, SOCK_STREAM, 0 );    cout<<"fd= "<<fd<<endl;    if(-1 == fd){        cout<<"Error, connectServer() quit"<<endl;        return -1;    }    struct sockaddr_in remote_addr; //服务器端网络地址结构体    memset(&remote_addr,0,sizeof(remote_addr)); //数据初始化--清零    remote_addr.sin_family=AF_INET; //设置为IP通信    remote_addr.sin_addr.s_addr=inet_addr(ip);//服务器IP地址    remote_addr.sin_port=htons(port); //服务器端口号    int con_result = connect(fd, (struct sockaddr*) &remote_addr, sizeof(struct sockaddr));    if(con_result < 0){        cout<<"Connect Error!"<<endl;        close(fd);        return -1;    }    cout<<"con_result="<<con_result<<endl;    return fd;}void on_read(int sock, short event, void* arg){    char* buffer = new char[BUF_SIZE];    memset(buffer, 0, sizeof(char)*BUF_SIZE);    //--本来应该用while一直循环，但由于用了libevent，只在可以读的时候才触发on_read(),故不必用while了    int size = read(sock, buffer, BUF_SIZE);    if(0 == size){//说明socket关闭        cout<<"read size is 0 for socket:"<<sock<<endl;        struct event* read_ev = (struct event*)arg;        if(NULL != read_ev){            event_del(read_ev);            free(read_ev);        }        close(sock);        return;    }    cout<<"Received from server---"<<buffer<<endl;    delete[]buffer;}void* init_read_event(void* arg){    long long_sock = (long)arg;    int sock = (int)long_sock;    //-----初始化libevent，设置回调函数on_read()------------    struct event_base* base = event_base_new();    struct event* read_ev = (struct event*)malloc(sizeof(struct event));//发生读事件后，从socket中取出数据    event_set(read_ev, sock, EV_READ|EV_PERSIST, on_read, read_ev);    event_base_set(base, read_ev);    event_add(read_ev, NULL);    event_base_dispatch(base);    //--------------    event_base_free(base);}/** * 创建一个新线程，在新线程里初始化libevent读事件的相关设置，并开启event_base_dispatch */void init_read_event_thread(int sock){    pthread_t thread;    pthread_create(&thread,NULL,init_read_event,(void*)sock);    pthread_detach(thread);}int main() {    cout << "main started" << endl; // prints Hello World!!!    cout << "Please input server IP:"<<endl;    char ip[16];    cin >> ip;    cout << "Please input port:"<<endl;    int port;    cin >> port;    cout << "ServerIP is "<<ip<<" ,port="<<port<<endl;    int socket_fd = connectServer(ip, port);    cout << "socket_fd="<<socket_fd<<endl;    init_read_event_thread(socket_fd);    //--------------------------    char buffer[BUF_SIZE];    bool isBreak = false;    while(!isBreak){        cout << "Input your data to server(\'q\' or \"quit\" to exit)"<<endl;        //cin >> buffer;        cin.getline(buffer,BUF_SIZE);        if(strcmp("q", buffer)==0 || strcmp("quit", buffer)==0){            isBreak=true;            close(socket_fd);            break;        }        cout << "Your input is "<<buffer<<endl;        int write_num = write(socket_fd, buffer, strlen(buffer));        cout << write_num <<" characters written"<<endl;        sleep(2);    }    cout<<"main finished"<<endl;    return 0;}