libevent使用

(sudo apt-get install libevent-dev)

１：安裝libevent

用wget指令直接下載libevent：# wget http://www.monkey.org/~provos/libevent-1.2.tar.gz

而後，在配置時須要指定一個安裝路徑，即./configure –prefix=/usr；而後make；而後make install；

詳細的方法以下：

 

# cd /tmp

# wget http://www.monkey.org/~provos/libevent-1.2.tar.gz

 

# tar zxvf libevent-1.2.tar.gz
# cd libevent-1.2
# ./configure –prefix=/usr
# make
# make install

（注：在這裏執行的時候出現錯誤：

1，no acceptable C compiler found in $PATH

因爲centos默認沒有安裝gcc，使用yum安裝

#yum install gcc* make*

）

測試libevent是否安裝成功：
# ls -al /usr/lib | grep libevent
lrwxrwxrwx 1 root root 21 11?? 12 17:38 libevent-1.2.so.1 -> libevent-1.2.so.1.0.3
-rwxr-xr-x 1 root root 263546 11?? 12 17:38 libevent-1.2.so.1.0.3
-rw-r–r– 1 root root 454156 11?? 12 17:38 libevent.a
-rwxr-xr-x 1 root root 811 11?? 12 17:38 libevent.la
lrwxrwxrwx 1 root root 21 11?? 12 17:38 libevent.so -> libevent-1.2.so.1.0.3
還不錯，都安裝上了。

 2:libevent的使用

-levent 使用

//#include <sys/socket.h>
//#include <sys/types.h>
//#include <netinet/in.h>
//#include <stdio.h>
//#include <event.h>
//struct event ev;
//struct timeval tv;
//void time_cb(int fd, short event, void *argc)
//{
// printf("timer wakeup/n");
// event_add(&ev, &tv); // reschedule timer
//}
//int main(void)
//{
// struct event_base *base = event_init();
// tv.tv_sec = 10; // 10s period
// tv.tv_usec = 0;
// evtimer_set(&ev,time_cb,NULL);
// event_add(&ev, &tv);
// event_base_dispatch(base);
// return 0;
//}
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <event.h>
#include <stdlib.h>

#define PORT 25341
#define BACKLOG 5
#define MEM_SIZE 1024

struct event_base* base;
struct sock_ev
{
struct event* read_ev;
struct event* write_ev;
char* buffer;
};

void release_sock_event(struct sock_ev* ev)
{
event_del(ev->read_ev);
free(ev->read_ev);
free(ev->write_ev);
free(ev->buffer);
free(ev);
}

void on_write(int sock, short event, void* arg)
{
char* buffer = (char*)arg;
printf("發送的%s\n",buffer);
send(sock, buffer, 1024, 0);
free(buffer);
}

void on_read(int sock, short event, void* arg)
{
printf("有鏈接可讀\n");
struct event* write_ev;
int size;
struct sock_ev* ev = (struct sock_ev*)arg;
ev->buffer = (char*)malloc(MEM_SIZE);
bzero(ev->buffer, MEM_SIZE);
size = recv(sock, ev->buffer, MEM_SIZE, 0);
printf("receive data:%s, size:%d\n", ev->buffer, size);
if (size <= 0)
{
release_sock_event(ev);
close(sock);
return;
}
bzero(ev->buffer, MEM_SIZE);
sprintf(ev->buffer,"hello every one");
event_set(ev->write_ev, sock, EV_WRITE, on_write, ev->buffer);
event_base_set(base, ev->write_ev);
event_add(ev->write_ev, NULL);
}

void on_accept(int sock, short event, void* arg)
{

struct sockaddr_in cli_addr;
int newfd, sin_size;
struct sock_ev* ev = (struct sock_ev*)malloc(sizeof(struct sock_ev));
ev->read_ev = (struct event*)malloc(sizeof(struct event));
ev->write_ev = (struct event*)malloc(sizeof(struct event));
sin_size = sizeof(struct sockaddr_in);
printf("監聽到可用sock\n");
newfd = accept(sock, (struct sockaddr*)&cli_addr, &sin_size);
//cli_addr.sin_addr.s_addr
event_set(ev->read_ev, newfd, EV_READ|EV_PERSIST, on_read, ev);//可讀
event_base_set(base, ev->read_ev);
event_add(ev->read_ev, NULL);
}

int main(int argc, char* argv[])
{
struct sockaddr_in my_addr;
int sock;

sock = socket(AF_INET, SOCK_STREAM, 0);
int yes = 1;
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(5000);
my_addr.sin_addr.s_addr = INADDR_ANY;
bind(sock, (struct sockaddr*)&my_addr, sizeof(struct sockaddr));
listen(sock, BACKLOG);
/*
* 建立一個事件處理的全局變量，能夠理解爲這是一個負責集中處理各類出入IO事件的總管家，
* 它負責接收和派發全部輸入輸出IO事件的信息，這裏調用的是函數event_base_new(),
* 不少程序裏這裏用的是event_init()，區別就是前者是線程安全的、然後者是非線程安全的
* 好比建議用event_base_dispatch代替event_dispatch
* 用event_assign代替event_set和event_base_set等
*/
struct event listen_ev;
base = event_base_new();//線程安全的版本

/*
* 在listen_en這個事件監聽sock這個描述字的讀操做，當讀消息到達是調用on_accept函數
* ，EV_PERSIST參數告訴系統持續的監聽sock上的讀事件，若是不加該參數，
* 每次要監聽該事件時就要重複的調用
*
* event_add函數，從前面的代碼可知，sock這個描述字是bind到本地的socket端口上
* ，所以其對應的可讀事件天然就是來自客戶端的鏈接到達，
* 咱們就能夠調用accept無阻塞的返回客戶的鏈接了。
*
* listen_ev註冊到base這個事件中，至關於告訴處理IO的管家請留意個人listen_ev上的事件
* 至關於告訴處理IO的管家，當有個人事件到達時你發給我(調用on_accept函數)，
* 至此對listen_ev的初始化完畢。
* 正式啓動libevent的事件處理機制，
* 使系統運行起來，運行程序的話會發現event_base_dispatch是一個無限循環。
*/
event_set(&listen_ev, sock, EV_READ|EV_PERSIST, on_accept, NULL);//當讀消息到達時調用On_accpet

event_base_set(base, &listen_ev);
event_add(&listen_ev, NULL);
event_base_dispatch(base);

return 0; }