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libevent学习之三:简单的服务器和客户端


1.服务器

#include <stdio.h>
#include <time.h>

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

const int PORT = 2500;
const int BUFFER_SIZE = 1024;

void listener_cb(struct evconnlistener *, evutil_socket_t,
struct sockaddr *, int socklen, void *);
void conn_writecb(struct bufferevent *, void *);
void conn_readcb(struct bufferevent *, void *);
void conn_eventcb(struct bufferevent *, short, void *);
void delay(int ms);

int main(int argc, char **argv)
{
printf("I am server\n");
#ifdef WIN32
WSAData wsaData;
WSAStartup(MAKEWORD(2, 0), &wsaData);
#endif
struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(PORT);

struct evconnlistener *listener;
struct event_base *base = event_base_new();
if (!base)
{
printf("Could not initialize libevent\n");
return 1;
}
listener = evconnlistener_new_bind(base, listener_cb, (void *)base,
LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE, -1,
(struct sockaddr*)&sin,
sizeof(sin));

if (!listener)
{
printf("Could not create a listener\n");
return 1;
}

event_base_dispatch(base);
evconnlistener_free(listener);
event_base_free(base);

printf("done\n");
return 0;
}

void listener_cb(struct evconnlistener *listener, evutil_socket_t fd,
struct sockaddr *sa, int socklen, void *user_data)
{
printf("Detect an connection\n");
struct event_base *base = (struct event_base *)user_data;
struct bufferevent *bev;

bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
if (!bev)
{
printf("Could not create a bufferevent\n");
event_base_loopbreak(base);
return;
}
bufferevent_setcb(bev, conn_readcb, conn_writecb, conn_eventcb, NULL);
bufferevent_enable(bev, EV_READ|EV_WRITE);
//服务器监听到连接时,给客户端发送第一条消息
char *reply_msg = "I receive a message from server";
bufferevent_write(bev, reply_msg, strlen(reply_msg));
}

//conn_writecwritecb函数将在bufferevent中的output evbuffer缓冲区发送完成后被调用。
//此时evbuffer_get_length(output) = 0,说明output evbuffer缓冲区被清空。
//假设发现有10000条记录要发送出去,1次发送10000条将占用大量内存,所以,我们要分批发送
//先发送100条数据,假设每条数据为1024字节bufferevent_write(bev,buf,1024 *100);
//系统在这100条记录发送完成后将调用conn_writecbb回调函数,然后在该函数中循环发送剩下的
//数据
void conn_writecb(struct bufferevent *bev, void *user_data)
{
// struct evbuffer *output = bufferevent_get_output(bev);
// if (evbuffer_get_length(output) == 0)
// {
// printf("Output evbuffer is flushed\n");
// bufferevent_free(bev);
// }
//delay 1 second
delay(1000);
static int msg_num = 1;
char reply_msg[1000] = {'\0'};
char *str = "I receive a message from server ";
memcpy(reply_msg,str,strlen(str));
sprintf(reply_msg+strlen(str),"%d",msg_num);
bufferevent_write(bev, reply_msg, strlen(reply_msg));
msg_num++;
}

void conn_readcb(struct bufferevent *bev, void *user_data)
{
struct evbuffer *input =bufferevent_get_input(bev);
size_t sz=evbuffer_get_length(input);
if (sz > 0)
{
char msg[BUFFER_SIZE] = {'\0'};
bufferevent_read(bev, msg, sz);
printf("%s\n", msg);
}
}

void conn_eventcb(struct bufferevent *bev, short events, void *user_data)
{
if (events & BEV_EVENT_EOF)
{
printf("Connection closed\n");
}
else if (events & BEV_EVENT_ERROR)
{
printf("Got an error on the connection: %s\n",strerror(errno));
}

bufferevent_free(bev);
}

void delay(int ms)
{
clock_t start = clock();
while(clock() - start < ms);
}

2.客户端

#include <stdio.h>
#include <time.h>

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

const int PORT = 2500;
const int BUFFER_SIZE = 1024;

void conn_writecb(struct bufferevent *, void *);
void conn_readcb(struct bufferevent *, void *);
void conn_eventcb(struct bufferevent *, short, void *);
void delay(int ms);

int main()
{
printf("I am client\n");
#ifdef WIN32
WSAData wsaData;
WSAStartup(MAKEWORD(2, 0), &wsaData);
#endif
struct sockaddr_in srv;
memset(&srv, 0, sizeof(srv));
srv.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");
srv.sin_family = AF_INET;
srv.sin_port = htons(PORT);

struct event_base *base = event_base_new();
if (!base)
{
printf("Could not initialize libevent\n");
return 1;
}

struct bufferevent* bev = bufferevent_socket_new(base, -1,
BEV_OPT_CLOSE_ON_FREE);
bufferevent_setcb(bev, conn_readcb, conn_writecb, conn_eventcb, NULL);
int flag=bufferevent_socket_connect(bev, (struct sockaddr *)&srv,sizeof(srv));
bufferevent_enable(bev, EV_READ | EV_WRITE);
if(-1==flag)
{
printf("Connect failed\n");
return 1;
}

event_base_dispatch(base);
event_base_free(base);

printf("done\n");
return 0;
}

//conn_writecwritecb函数将在bufferevent中的output evbuffer缓冲区发送完成后被调用。
//此时evbuffer_get_length(output) = 0,说明output evbuffer缓冲区被清空。
//假设发现有10000条记录要发送出去,1次发送10000条将占用大量内存,所以,我们要分批发送
//先发送100条数据,假设每条数据为1024字节bufferevent_write(bev,buf,1024 *100);
//系统在这100条记录发送完成后将调用conn_writecbb回调函数,然后在该函数中循环发送剩下的
//数据
void conn_writecb(struct bufferevent *bev, void *user_data)
{
// struct evbuffer *output = bufferevent_get_output(bev);
// if (evbuffer_get_length(output) == 0)
// {
// printf("Output evbuffer is flushed\n");
// bufferevent_free(bev);
// }
//delay 1 second
delay(1000);
static int msg_num = 1;
char reply_msg[1000] = {'\0'};
char *str = "I receive a message from client ";
memcpy(reply_msg,str,strlen(str));
sprintf(reply_msg+strlen(str),"%d",msg_num);
bufferevent_write(bev, reply_msg, strlen(reply_msg));
msg_num++;
}

void conn_readcb(struct bufferevent *bev, void *user_data)
{
struct evbuffer *input =bufferevent_get_input(bev);
size_t sz=evbuffer_get_length(input);
if (sz > 0)
{
char msg[BUFFER_SIZE] = {'\0'};
bufferevent_read(bev, msg, sz);
printf("%s\n", msg);
}
}

void conn_eventcb(struct bufferevent *bev, short events, void *user_data)
{
if (events & BEV_EVENT_EOF)
{
printf("Connection closed\n");
}
else if (events & BEV_EVENT_ERROR)
{
printf("Got an error on the connection: %s\n",strerror(errno));
}
else if( events & BEV_EVENT_CONNECTED)
{
printf("Connect succeed\n");
//客户端链接成功后,给服务器发送第一条消息
char *reply_msg = "I receive a message from client";
bufferevent_write(bev, reply_msg, strlen(reply_msg));
return ;
}

bufferevent_free(bev);
}

void delay(int ms)
{
clock_t start = clock();
while(clock() - start < ms);
}

3.运行效果

先启动服务器,然后启动客户端,效果如下图所示。

服务器

libevent学习之三:简单的服务器和客户端_数据


客户端

libevent学习之三:简单的服务器和客户端_数据_02

4.源码

源码默认使用的是MingW版本的libevent头文件和库,也包含Windows版本的libevent头文件和库,后缀为_win。

libevent的编译和使用可以参考:​​libevent学习之二:Windows7(Win7)下编译libevent​​

如何调试libevent可参考:​​libevent学习之四:vs2012编译libevent-2.1.8-stable源码 可调试​​



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