先来说一下使用套路:
1. 创建一个事件处理框架
2. 创建一事件
3. 事件添加到事件处理框架上
4. 开始事件循环
5. 释放资源
重要函数讲解:
消息循环:
未决 && 非未决
- 未决:有资格被处理但是还没有被处理
- 非未决:没有资格被处理
事件的状态转换
例子:
read
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <event2/buffer event.h>
//读操作处理函数
void read_cb(evutil_socket_t fd,short what,void *arg)
{
//读管道
char buf[1024] = {0};
int len = read(fd,buf,sizeof(buf));
printf("data len = %d,buf = %s\n", len, buf);
//判断是否有读事件发生
printf("read event: %s",what & EV_READ ? "YES" : "NO");
}
int main(int argc,const char* argv[])
{
unlink("myfifo");
//创建有名管道,默认管道是堵塞的
mkfifo("myfifo",0664);
int fd = open("myfifo",O_RDONLY | O_NONBLOCK);
if(fd == -1)
{
perror("open error");
exit(1);
}
//读管道
struct event_base* base = NULL;
base = event_base_new();
//创建事件
struct event* ev = NULL;
ev = event_new(base,fd,EV_READ | EV_PERSIST,read_cb,NULL);
//添加事件,NULL事件触发时产生回调
event_add(ev,NULL);
//事件循环
event_base_dispatch(base);
//释放资源
event_free(ev);
event_base_free(base);
close(fd);
return 0;
}
write
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <event2/event.h>
//写操作处理函数
void write_cb(evutil_socket_t fd,short what,void *arg)
{
//写管道
char buf[1024] = {0};
static int num = 0;
sprintf(buf,"hello,world == %d\n",num++);
write(fd,buf,strlen(buf)+1);
}
int main(int argc,const char* argv[])
{
//创建有名管道,默认管道是堵塞的
mkfifo("myfifo",0664);
int fd = open("myfifo",O_WRONLY | O_NONBLOCK);
if(fd == -1)
{
perror("open error");
exit(1);
}
//写管道
struct event_base* base = NULL;
base = event_base_new();
//创建事件
struct event* ev = NULL;
//检测的写缓冲区是否有空间写
ev = event_new(base,fd,EV_WRITE | EV_PERSIST,write_cb,NULL);
//添加事件,NULL事件触发时产生回调
event_add(ev,NULL);
//事件循环
event_base_dispatch(base);
//释放资源
event_free(ev);
event_base_free(base);
close(fd);
return 0;
}
BufferEvent
链接监听器:
例子:
server.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <event2/event.h>
#include <event2/listener.h>
#include <event2/bufferevent.h>
// 读缓冲区回调
void read_cb(struct bufferevent *bev, void *arg)
{
char buf[1024] = {0};
bufferevent_read(bev, buf, sizeof(buf));
printf("client say: %s\n", p);
// 发数据给客户端
char* p = "我已经收到了你发送的数据!";
bufferevent_write(bev, p, strlen(p)+1);
printf("====== send buf: %s\n", p);
}
// 写缓冲区回调,数据被成功发送出去之后会调用该函数
void write_cb(struct bufferevent *bev, void *arg)
{
printf("我是写缓冲区的回调函数...\n");
}
// 事件
void event_cb(struct bufferevent *bev, short events, void *arg)
{
if (events & BEV_EVENT_EOF)
{
printf("connection closed\n");
}
else if(events & BEV_EVENT_ERROR)
{
printf("some other error\n");
}
bufferevent_free(bev);
printf("buffevent 资源已经被释放...\n");
}
//连接完成后,对应通信操作
void cb_listener(
struct evconnlistener *listener,
evutil_socket_t fd,
struct sockaddr *addr,
int len, void *ptr)
{
printf("connect new client\n");
//获取传经来的Base
struct event_base* base = (struct event_base*)ptr;
// 通信操作
// 添加新事件
struct bufferevent *bev;
bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
// 给bufferevent缓冲区设置回调,默认写回调是可用的
bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
bufferevent_enable(bev, EV_READ);
}
int main(int argc, const char* argv[])
{
// init server
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(9876);
serv.sin_addr.s_addr = htonl(INADDR_ANY);
struct event_base* base;
base = event_base_new();
// 创建套接字
// 绑定
// 接收连接请求
struct evconnlistener* listener;
listener = evconnlistener_new_bind(base, cb_listener, base,
LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE,
36, (struct sockaddr*)&serv, sizeof(serv));
event_base_dispatch(base);
evconnlistener_free(listener);
event_base_free(base);
return 0;
}
client.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
void read_cb(struct bufferevent *bev, void *arg)
{
char buf[1024] = {0};
bufferevent_read(bev, buf, sizeof(buf));
printf("Server say: %s\n", buf);
}
void write_cb(struct bufferevent *bev, void *arg)
{
printf("I am Write_cb function....\n");
}
void event_cb(struct bufferevent *bev, short events, void *arg)
{
if (events & BEV_EVENT_EOF)
{
printf("connection closed\n");
}
else if(events & BEV_EVENT_ERROR)
{
printf("some other error\n");
}
else if(events & BEV_EVENT_CONNECTED)
{
printf("成功连接到服务器, O(∩_∩)O哈哈~\n");
return;
}
bufferevent_free(bev);
printf("free bufferevent...\n");
}
void send_cb(evutil_socket_t fd, short what, void *arg)
{
char buf[1024] = {0};
struct bufferevent* bev = (struct bufferevent*)arg;
printf("请输入要发送的数据: \n");
read(fd, buf, sizeof(buf));
bufferevent_write(bev, buf, strlen(buf)+1);
}
int main(int argc, const char* argv[])
{
struct event_base* base;
base = event_base_new();
struct bufferevent* bev;
bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
// 连接服务器
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(9876);
evutil_inet_pton(AF_INET, "127.0.0.1", &serv.sin_addr.s_addr);
bufferevent_socket_connect(bev, (struct sockaddr*)&serv, sizeof(serv));
// 设置回调
bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
bufferevent_enable(bev, EV_READ | EV_PERSIST);
// 创建一个事件
struct event* ev = event_new(base, STDIN_FILENO,
EV_READ | EV_PERSIST,
send_cb, bev);
event_add(ev, NULL);
event_base_dispatch(base);
event_base_free(base);
return 0;
}