Visual Studio 2017开发linux程序之libevent使用实例

下载源码编译安装后，samle里面有个hello-world.c就是最简单的一个tcp server端程序了

/*
This example program provides a trivial server program that listens for TCP
connections on port 9995. When they arrive, it writes a short message to
each client connection, and closes each connection once it is flushed.

Where possible, it exits cleanly in response to a SIGINT (ctrl-c).
*/

#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#ifndef _WIN32
#include <netinet/in.h>
# ifdef _XOPEN_SOURCE_EXTENDED
# include <arpa/inet.h>
# endif
#include <sys/socket.h>
#endif

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

static const char MESSAGE[] = "Hello, World!\n";

static const int PORT = 9995;

static void listener_cb(struct evconnlistener *, evutil_socket_t,
struct sockaddr *, int socklen, void *);
static void conn_writecb(struct bufferevent *, void *);
static void conn_eventcb(struct bufferevent *, short, void *);
static void signal_cb(evutil_socket_t, short, void *);

int
main(int argc, char **argv)
{
struct event_base *base;
struct evconnlistener *listener;
struct event *signal_event;

struct sockaddr_in sin;
#ifdef _WIN32
WSADATA wsa_data;
WSAStartup(0x0201, &wsa_data);
#endif

base = event_base_new();
if (!base) {
fprintf(stderr, "Could not initialize libevent!\n");
return 1;
}

memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(PORT);

listener = evconnlistener_new_bind(base, listener_cb, (void *)base,
LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE, -1,
(struct sockaddr*)&sin,
sizeof(sin));

if (!listener) {
fprintf(stderr, "Could not create a listener!\n");
return 1;
}

signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);

if (!signal_event || event_add(signal_event, NULL)<0) {
fprintf(stderr, "Could not create/add a signal event!\n");
return 1;
}

event_base_dispatch(base);

evconnlistener_free(listener);
event_free(signal_event);
event_base_free(base);

printf("done\n");
return 0;
}

static void
listener_cb(struct evconnlistener *listener, evutil_socket_t fd,
struct sockaddr *sa, int socklen, void *user_data)
{
struct event_base *base = user_data;
struct bufferevent *bev;

bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
if (!bev) {
fprintf(stderr, "Error constructing bufferevent!");
event_base_loopbreak(base);
return;
}
bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL);
bufferevent_enable(bev, EV_WRITE);
bufferevent_disable(bev, EV_READ);

bufferevent_write(bev, MESSAGE, strlen(MESSAGE));
}

static void
conn_writecb(struct bufferevent *bev, void *user_data)
{
struct evbuffer *output = bufferevent_get_output(bev);
if (evbuffer_get_length(output) == 0) {
printf("flushed answer\n");
bufferevent_free(bev);
}
}

static void
conn_eventcb(struct bufferevent *bev, short events, void *user_data)
{
if (events & BEV_EVENT_EOF) {
printf("Connection closed.\n");
} else if (events & BEV_EVENT_ERROR) {
printf("Got an error on the connection: %s\n",
strerror(errno));/*XXX win32*/
}
/* None of the other events can happen here, since we haven't enabled
* timeouts */
bufferevent_free(bev);
}

static void
signal_cb(evutil_socket_t sig, short events, void *user_data)
{
struct event_base *base = user_data;
struct timeval delay = { 2, 0 };

printf("Caught an interrupt signal; exiting cleanly in two seconds.\n");

event_base_loopexit(base, &delay);
}

设置好链接库的路径和链接库





写一个简单的client端，代码如下：

// sample_tcpclient.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include <stdio.h>
#include <Winsock2.h>
#include <mstcpip.h>

#pragma comment(lib,"ws2_32.lib")

#define _WINSOCK_DEPRECATED_NO_WARNINGS

int main(int argc, char* argv[])
{
WORD wVersionRequested;
WSADATA wsaData;
int err;

wVersionRequested = MAKEWORD(1, 1);

err = WSAStartup(wVersionRequested, &wsaData);
if (err != 0) {
printf("WSAStartup failed:%d\n", err);
getchar();
exit(0);
}

if (LOBYTE(wsaData.wVersion) != 1 ||
HIBYTE(wsaData.wVersion) != 1) {
WSACleanup();
printf("version error\n");
getchar();
exit(0);
}
lab_start:
SOCKET sockClient = socket(AF_INET, SOCK_STREAM, 0);

SOCKADDR_IN addrSrv;
addrSrv.sin_addr.S_un.S_addr = inet_addr("192.168.2.41");
addrSrv.sin_family = AF_INET;
addrSrv.sin_port = htons(9995);
int ret = connect(sockClient, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));
if (ret != 0)
{
printf("connect failed:%d\n", ret);
return -1;
}

// 开启KeepAlive
BOOL bKeepAlive = TRUE;
int nRet = ::setsockopt(sockClient, SOL_SOCKET, SO_KEEPALIVE, (char*)&bKeepAlive, sizeof(bKeepAlive));
if (nRet == SOCKET_ERROR)
{
printf("setsockopt error:%d\n", nRet);
return -1;
}
// 设置KeepAlive参数
tcp_keepalive alive_in = { 0 };
tcp_keepalive alive_out = { 0 };
alive_in.keepalivetime = 5000; // 开始首次KeepAlive探测前的TCP空闭时间
alive_in.keepaliveinterval = 1000; // 两次KeepAlive探测间的时间间隔
alive_in.onoff = TRUE;

unsigned long ulBytesReturn = 0;
nRet = WSAIoctl(sockClient, SIO_KEEPALIVE_VALS, &alive_in, sizeof(alive_in),
&alive_out, sizeof(alive_out), &ulBytesReturn, NULL, NULL);
if (nRet == SOCKET_ERROR)
{
printf("WSAIoctl error:%d\n", nRet);
return -1;
}

//disable nagle
int on = 1;
/* make socket here */
#ifdef WIN32
setsockopt(sockClient, IPPROTO_TCP, TCP_NODELAY, (const char *)&on, sizeof(on));
#else
setsockopt(sockClient, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on));
#endif

const char *data_str = "hello world, i am client";
int data_len = strlen(data_str)+1;
for (int i = 0; i < 10; i++)
{
ret = send(sockClient, data_str + (data_len - data_len % 1024), data_len % 1024, 0);
if (ret < 0)
{
printf("send error:%d\n", ret);
break;
}
printf("data_len:%d count:%d ret:%d\n", data_len, i, ret);

char recvBuf[256];
ret = ::recv(sockClient, recvBuf, 256, 0);
if (ret < 0)
{
printf("recv error:%d\n", ret);
break;
}
recvBuf[ret] = '\0';
printf("ret:%d recv:%s\n", ret, recvBuf);

Sleep(3000);
}

closesocket(sockClient);
getchar();

closesocket(sockClient);
WSACleanup();
}


然后就是连接成功了：