libev事件库使用笔记

源码下载地址：http://dist.schmorp.de/libev/

libev是一个高性能的事件循环库，比libevent库的性能要好。

安装：

tar -zxf libev-4.15.tar.gz
cd libev-4.15
./configure
make
make install

设置环境变量：

设置一下环境变量(在文件/etc/profile中添加)。然后才可以运行。

1 export LIBDIR=/usr/local/lib
2 export LD_LIBRARY_PATH=/usr/local/lib
3 export LD_RUN_PATH=/usr/local/lib

添加完成后运行：source  /etc/profile   使设置生效；

没有接触过libev的新手一般对概念也是比较蒙的，我也不多做介绍，教你如何快速上手

对比说明吧！

示例一：不使用libev

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
#define DAEMON_PORT                8888
#define MAX_LISTEN                1024

char get_manager_ip[16];

int adminserver();
void pthread_adminserver(int client_sd);

int main(int argc, char** argv){
    strcpy(get_manager_ip, argv[1]);
    adminserver();
}
int adminserver()
{
    int ret = 0;
    int i = 0;
    int max = 0;
    int nCurrentSocket = 0;
    FILE *fp;
    int res;
    int client_sd;
    int server_sd;
    int reuse_addr;
    pthread_t p_tcpserver;
    int client_addr_size ;

    struct sockaddr_in client_addr;
    struct sockaddr_in server_addr;
    char line[128];
    char listen_ip[16];
    char cmd_ip[128];
    
    char *pt;
    char *edit;


    sprintf(cmd_ip,"ifconfig %s |grep 'addr:' >/get_manager_ip",get_manager_ip);
    system(cmd_ip);

    fp = fopen("/get_manager_ip","rb");
    if (fp == NULL) 
    {
        printf("Cann't open get_manger_ip file!
");  
        exit(-1);    
    }
    
    memset(line,0,128);
    fgets(line,128,fp);
    fclose(fp);

    pt=strstr(line, "addr:");
    if (pt != NULL)    
    {
        pt+=5;
        edit=strtok(pt," ");
        strcpy(listen_ip,edit);
    }

    server_sd=socket( AF_INET, SOCK_STREAM, 0 );
    
    if (server_sd < 0)
    {
        printf("ERROR: Cann't create socket!!!
");
        exit(-1);
    }
    
    bzero(&server_addr, sizeof(struct sockaddr));
    server_addr.sin_family = AF_INET;  
    server_addr.sin_addr.s_addr=inet_addr(listen_ip);
    server_addr.sin_port   = htons(DAEMON_PORT);  
    
    reuse_addr = 1;
    if (setsockopt (server_sd, SOL_SOCKET, SO_REUSEADDR, &reuse_addr, sizeof(reuse_addr)) < 0 )
    {
        printf("setsockopt error
");
        close(server_sd);
           return -1;
    }
    
    res = bind(server_sd, (struct sockaddr *)&server_addr, sizeof(server_addr));
    if (res < 0 )
    {  
        printf("Cann't bind!res = %d,erro:%d, reason:%s.
",res, errno, strerror(errno));  
        close(server_sd);
        exit(-1);
    }  
    
    if (listen( server_sd, MAX_LISTEN ) != 0 ) {  
        printf("Cann't listen!
"); 
        close(server_sd);
        exit(-1);  
    }

    while(1)
    {
        
        client_addr_size = sizeof(client_addr);
        client_sd = accept( server_sd, (struct sockaddr *)&client_addr, (socklen_t *)&client_addr_size);
        if (pthread_create(&p_tcpserver, NULL, (void *)&pthread_adminserver, client_sd)!=0)
        {
            printf("Could not create thread check_work_time
");
            return ;
        } 
    }
    close(server_sd);
    exit(1);    
}

void pthread_adminserver(int client_sd)
{
    int sockfd = 0;
    int rc;
    char buffer[4096];
     while(1)
        {             //线程处理某个客户端的连接
            memset(buffer,0,4096);
            rc=read(client_sd,buffer,4096);
            if(strlen(buffer) == 0){
            close(client_sd);  //关闭线程处理的客户端连接
            pthread_exit(0);//终止该线程
            }
            printf("read date:"%s"
",buffer);
            
        }
        close(client_sd);  //关闭线程处理的客户端连接
        pthread_exit(0);//终止该线程
}

说明：这是一个处理多并发的socket服务端，通过while接收多条连接，然后通过线程去处理每条连接，简单易懂，但是 使用两个while(1),是一件很浪费系统资源是事情；

示例二：通过示例一改动，添加libev

先对比两个示例先用起来吧，欢迎大神指导。

 

#include <ev.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <unistd.h>

#define PORT 8080
#define BUFFER_SIZE 1024
#define MAX_CONNECTIONS 10

struct ev_io *libevlist[MAX_CONNECTIONS] = {NULL};

void socket_accept_callback(struct ev_loop *loop, struct ev_io *watcher, int revents);
void socket_read_callback(struct ev_loop *loop, struct ev_io *watcher, int revents);
/*
    Server                  Client


    socket                  socket
      |                       |
      v                       v
    bind                    connect
      |                       |
      v                       v
    listen                  write
      |                       |
      v                       v
    accept                  read
      |                       |
      v                       v
    read                    close
      |
      v
    write
      |
      v
    close
*/

int main() {
    struct ev_loop *loop = ev_default_loop(0);

    /* socket start */
    int sd;
    struct sockaddr_in addr;
    int addr_len = sizeof(addr);

    struct ev_io *socket_watcher = (struct ev_io*)malloc(sizeof(struct ev_io));
    struct ev_timer *timeout_watcher = (struct ev_timer*)malloc(sizeof(struct ev_timer));

    // socket
    sd = socket(PF_INET, SOCK_STREAM, 0);
    if (sd < 0) {
        printf("socket error
");
        return -1;
    }
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(PORT);
    addr.sin_addr.s_addr = INADDR_ANY;

    // bind
    if (bind(sd, (struct sockaddr*) &addr, sizeof(addr)) != 0) {
        printf("bind error
");
        return -1;
    }
    // listen
    if (listen(sd, SOMAXCONN) < 0) {
        printf("listen error
");
        return -1;
    }
    // set sd reuseful
    int bReuseaddr = 1;
    if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, (const char*) &bReuseaddr, sizeof(bReuseaddr)) != 0) {
        printf("setsockopt error in reuseaddr[%d]
", sd);
        return -1;
    }
    /* socket end */

    ev_io_init(socket_watcher, socket_accept_callback, sd, EV_READ);
    ev_io_start(loop, socket_watcher);

//     while(1) {
        ev_run(loop, 0);
//     }

    return 1;
}

void socket_accept_callback(struct ev_loop *loop, struct ev_io *watcher, int revents) {
    printf("I am: %d
", getpid());

    struct sockaddr_in client_addr;
    socklen_t client_len = sizeof(client_addr);
    int client_sd;

    if (EV_ERROR & revents) {
        printf("error event in accept
");
        return;
    }

    // socket accept: get file description
    client_sd = accept(watcher->fd, (struct sockaddr*) &client_addr, &client_len);
    if (client_sd < 0) {
        printf("accept error
");
        return;
    }
    // too much connections
    if (client_sd > MAX_CONNECTIONS) {
        printf("fd too large[%d]
", client_sd);
        close(client_sd);
        return;
    }

    if (libevlist[client_sd] != NULL) {
        printf("client_sd not NULL fd is [%d]
", client_sd);
        return;
    }

    printf("client connected
");
    // ev_io watcher for client
    struct ev_io *client_watcher = (struct ev_io*) malloc(sizeof(struct ev_io));
    if (client_watcher == NULL) {
        printf("malloc error in accept_cb
");
        return;
    }
    // listen new client
    ev_io_init(client_watcher, socket_read_callback, client_sd, EV_READ);
    ev_io_start(loop, client_watcher);

    libevlist[client_sd] = client_watcher;
}

void socket_read_callback(struct ev_loop *loop, struct ev_io *watcher, int revents) {
    char buffer[BUFFER_SIZE];
    ssize_t read;

    if (EV_ERROR & revents) {
        printf("error event in read
");
        return;
    }
    // socket recv
    read = recv(watcher->fd, buffer, BUFFER_SIZE, 0); // read stream to buffer
    if (read < 0) {
        printf("read error
");
        return;
    }

    if (read == 0) {
        printf("client disconnected.
");

        if (libevlist[watcher->fd] == NULL) {
            printf("the fd already freed[%d]
", watcher->fd);
        }
        else {
            printf("fd:%d will be closed!
",watcher->fd);
            close(watcher->fd);
            ev_io_stop(loop, libevlist[watcher->fd]);
            free(libevlist[watcher->fd]);
            libevlist[watcher->fd] = NULL;
        }
        return;
    }
    else {
        printf("receive message[%d]says:%s
",watcher->fd, buffer);
        if(memcmp(buffer,"quit",strlen("quit")) == 0)
        {
            printf("recv quit cmd,fd:%d will be closed!
",watcher->fd);
            close(watcher->fd);
            ev_io_stop(loop, libevlist[watcher->fd]);
            free(libevlist[watcher->fd]);
            libevlist[watcher->fd] = NULL;
            return ;
        }
    }

    // socket send to client
    send(watcher->fd, buffer, read, 0);
    bzero(buffer, sizeof(buffer));
}