libevent库简单使用

创建一个事件处理框架并显示系统中可以用那些io转接函数，以及现在使用的是哪种，并消除该事件

#include <iostream>
#include <event2/event.h>

using namespace std;

int main()
{
	struct event_base* base = NULL;
	base = event_base_new();//创建新的事件框架
	const char** meths = event_get_supported_methods();//显示系统中可以使用哪些io转接函数
	for (int i=0; meths[i] != NULL; ++i)
	{
		cout<<meths[i];
	}
	cout<<"\ncurrent = "<<event_base_get_method(base);//显示当前使用的是哪一种转接函数
	event_base_free(base);//释放事件框架
	return 0;
}

用libevent库写有名管道通信

读端程序

#include <iostream>
#include <event2/event.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

using namespace std;

void cb(evutil_socket_t fd, short what, void * arg)
{
	char buf[256];
	int n=read(fd, buf, sizeof(buf));
	if (n==-1)
	{
		cout<<"read is error!\n";
		exit(1);
	}
	cout<<"the buf is "<<buf<<endl;
}

int main()
{
	unlink("myfifo");
	mkfifo("myfifo", 0664);
	int fd=open("myfifo", O_RDONLY | O_NONBLOCK);

	struct event_base* base=NULL;
	base=event_base_new();
	
	struct event *ev=NULL;
	ev=event_new(base, fd, EV_READ | EV_PERSIST, cb, NULL);

	event_add(ev, NULL);

	event_base_dispatch(base);

	event_free(ev);

	event_base_free(base);

	close(fd);
}

写端程序

#include <iostream>
#include <event2/event.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h> 
#include <string.h>

using namespace std;

void cb(evutil_socket_t fd, short what, void * arg)
{
	char buf[256]="hello world";
	static int num=0;
	sleep(1);
	//printf(buf, "hello world! %d\n", ++num);
	cout<<buf<<endl;
	write(fd, buf, strlen(buf));
}

int main()
{
	int fd=open("myfifo", O_WRONLY | O_NONBLOCK);

	struct event_base* base=NULL;
	base=event_base_new();
	
	struct event *ev=NULL;
	ev=event_new(base, fd, EV_WRITE | EV_PERSIST, cb, NULL);

	event_add(ev, NULL);

	event_base_dispatch(base);

	event_free(ev);

	event_base_free(base);

	close(fd);
}