libevent的TCP server、定时、信号的应用

libevent实现信号处理

/*
 * Compile with:
 * cc -I/usr/local/include -o signal-test \
 *   signal-test.c -L/usr/local/lib -levent
 */

#include <sys/types.h>

#include <event2/event-config.h>

#include <sys/stat.h>
#ifndef _WIN32
#include <sys/queue.h>
#include <unistd.h>
#include <sys/time.h>
#else
#include <winsock2.h>
#include <windows.h>
#endif
#include <signal.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <event2/event.h>

int called = 0;

/************************************
@ Brief:		捕获信号事件的回调
@ Author:		
@ Created:		
@ Return:            
************************************/
static void signal_cb(evutil_socket_t fd, short event, void *arg)
{
	struct event *signal = arg;

	printf("signal_cb: got signal %d\n", event_get_signal(signal));

	if (called >= 2)
		event_del(signal);

	called++;
}

int main(int argc, char **argv)
{
	struct event *signal_int;
	struct event_base* base;
#ifdef _WIN32
	WORD wVersionRequested;
	WSADATA wsaData;

	wVersionRequested = MAKEWORD(2, 2);

	(void) WSAStartup(wVersionRequested, &wsaData);
#endif

	/* Initalize the event library */
	//初始化信号集合，管理base
	base = event_base_new();

	/* Initalize one event */
	//创建这个事件处理，也可以使用event_new处理
	signal_int = evsignal_new(base, SIGINT, signal_cb, event_self_cbarg());

	//绑定集合里面
	event_add(signal_int, NULL);

	//进入事件循环处理
	event_base_dispatch(base);
	
FREE:
	event_free(signal_int);
	event_base_free(base);

	return (0);
}

libevent实现定时的处理

/*
 * XXX This sample code was once meant to show how to use the basic Libevent
 * interfaces, but it never worked on non-Unix platforms, and some of the
 * interfaces have changed since it was first written.  It should probably
 * be removed or replaced with something better.
 *
 * Compile with:
 * cc -I/usr/local/include -o time-test time-test.c -L/usr/local/lib -levent
 */

#include <sys/types.h>

#include <event2/event-config.h>

#include <sys/stat.h>
#ifndef _WIN32
#include <sys/queue.h>
#include <unistd.h>
#endif
#include <time.h>
#ifdef EVENT__HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <event2/event.h>
#include <event2/event_struct.h>
#include <event2/util.h>

#ifdef _WIN32
#include <winsock2.h>
#endif

struct timeval lasttime;

int event_is_persistent;

static void
timeout_cb(evutil_socket_t fd, short event, void *arg)
{
	struct timeval newtime, difference;
	struct event *timeout = arg;
	double elapsed;

	evutil_gettimeofday(&newtime, NULL);
	evutil_timersub(&newtime, &lasttime, &difference);
	elapsed = difference.tv_sec +
	    (difference.tv_usec / 1.0e6);

	printf("timeout_cb called at %d: %.3f seconds elapsed.\n",
	    (int)newtime.tv_sec, elapsed);
	lasttime = newtime;

	if (! event_is_persistent) {
		struct timeval tv;
		evutil_timerclear(&tv);
		tv.tv_sec = 2;
		event_add(timeout, &tv);
	}
}

int main(int argc, char **argv)
{
	struct event timeout;
	struct timeval tv;
	struct event_base *base;
	int flags;

#ifdef _WIN32
	WORD wVersionRequested;
	WSADATA wsaData;

	wVersionRequested = MAKEWORD(2, 2);

	(void)WSAStartup(wVersionRequested, &wsaData);
#endif

	if (argc == 2 && !strcmp(argv[1], "-p")) {
		event_is_persistent = 1;
		flags = EV_PERSIST;
	} else {
		event_is_persistent = 0;
		flags = 0;
	}

	/* Initalize the event library */
	base = event_base_new();

	/* Initalize one event */
	//创建这个事件处理
	event_assign(&timeout, base, -1, flags, timeout_cb, (void*) &timeout);

	evutil_timerclear(&tv);
	tv.tv_sec = 2;
	event_add(&timeout, &tv);

	evutil_gettimeofday(&lasttime, NULL);

	setbuf(stdout, NULL);
	setbuf(stderr, NULL);

	event_base_dispatch(base);

	return (0);
}

libevent实现Tcp Server基于bufferevent实现

#include <iostream>
#include <string.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/listener.h>
 
#ifdef _WIN32
#include <windows.h>
#include <time.h>
#include <ws2tcpip.h>
#else
#include <unistd.h>
#include <arpa/inet.h>
#endif
 
#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "wsock32.lib")
#pragma comment(lib, "libevent.lib")
#pragma comment(lib, "libevent_core.lib")
#pragma comment(lib, "libevent_extras.lib")
 
using namespace std;
 
/************************************
@ Brief:		读缓冲区回调
@ Author:		
@ Created:		
@ Return:            
************************************/
void read_cb(struct bufferevent *bev, void *arg)
{
	char buf[1024] = {0};
	char* ip = (char*)arg;
 
	bufferevent_read(bev, buf, sizeof(buf));
	
	cout << "client " << ip << " say:" << buf << endl;
    
 
	//写数据给客户端
	const char *p = "i am server, i received your msg!" ;
	bufferevent_write(bev, p, strlen(p)+1);
}
 
 
/************************************
@ Brief:		写缓冲区回调
@ Author:		
@ Created:		
@ Return:            
************************************/
void write_cb(struct bufferevent *bev, void *arg)
{
	cout << "I'm 服务器，成功写数据给客户端，写缓冲回调函数被调用..." << endl;
}
 
/************************************
@ Brief:		事件回调
@ Author:		
@ Created:		
@ Return:            
************************************/
void event_cb(struct bufferevent *bev, short events, void *arg)
{
	char* ip = (char*)arg;
	if (events & BEV_EVENT_EOF)
	{
		cout << "connection closed:" << ip << endl;
	}
	else if (events & BEV_EVENT_ERROR)
	{
		cout << "some other error !" << endl;
	}
 
	bufferevent_free(bev);
	cout << "bufferevent 资源已经被释放..." << endl;
}
 
/************************************
@ Brief:		监听回调
@ Author:		
@ Created:		
@ Return:            
************************************/
void cb_listener(struct evconnlistener *listener, evutil_socket_t fd, struct sockaddr *addr, int len, void *ptr)
{
	struct sockaddr_in* client = (sockaddr_in*)addr ;
	cout << "connect new client: " << inet_ntoa(client->sin_addr) << "::"<< ntohs(client->sin_port)<< endl;
 
	struct event_base *base = (struct event_base*)ptr;
 
	//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
	bufferevent_setcb(bev, read_cb, write_cb, event_cb, inet_ntoa(client->sin_addr));
 
	//启动 bufferevent的 读缓冲区。默认是disable 的
	bufferevent_enable(bev, EV_READ);
}
 
int main()
{
#ifdef WIN32
	WORD wVersionRequested;
	WSADATA wsaData;
	wVersionRequested = MAKEWORD(2, 2);
	(void)WSAStartup(wVersionRequested, &wsaData);
#endif
	//init server
	struct sockaddr_in serv;
 
	memset(&serv, 0, sizeof(serv));
	serv.sin_family = AF_INET;
	serv.sin_port = htons(8888);
	serv.sin_addr.s_addr = htonl(INADDR_ANY);
 
	//创建 event_base
	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));
 
	//启动循环监听
	event_base_dispatch(base);
	evconnlistener_free(listener);
	event_base_free(base);
	return 0;
}