09.使用libevent来读取登录日志并监听

test.cpp

#include <iostream>
#include <thread>
#include <event2/event.h>
#include <event2/event.h>
#include <event2/thread.h>
#include<event2/listener.h>
#ifndef _WIN32
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#else
#endif
using namespace std;

void read_file(evutil_socket_t fd, short event, void* arg)
{
	char buf[1024] = { 0 };
	int len = read(fd, buf, sizeof(buf) - 1);
	if (len > 0)
	{
		cout << buf << endl;
	}
	else
	{
		cout << "." << flush;
		this_thread::sleep_for(500ms);
	}
}


int main(int argc, char** argv)
{
#ifdef _WIN32 
	//初始化socket库
	WSADATA wsa;
	WSAStartup(MAKEWORD(2, 2), &wsa);
#else
	//忽略管道信号，发送数据给已关闭的socket
	if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
		return 1;
#endif

	event_config* conf = event_config_new();

	//设置支持文件描述符
	event_config_require_features(conf, EV_FEATURE_FDS);
	event_base* base = event_base_new_with_config(conf);

	event_config_free(conf);

	if (!base)
	{
		cerr << "event_base_new_with_config" << endl;
		return -1;
	}
	
	//打开文件只读，非阻塞
	int sock = open("/var/log/auth.log", O_RDONLY | O_NONBLOCK, 0);
	if (sock<=0)
	{
		cerr << "open /var/log/auth.log failed!" << endl;
		return -2;
	}
	//文件指针移动到结尾处
	lseek(sock, 0, SEEK_END);


	//监听文件数据
	event* fev = event_new(base, sock, EV_READ | EV_PERSIST, read_file, 0);
	event_add(fev, NULL);


    //进入事件主循环
    event_base_dispatch(base);
    event_base_free(base);

    return 0;
}

linux下makefile

test:test.cpp
        g++ $^ -o $@ -levent
        ./$@
clean:
        rm -rf test
        rm -rf *.o