基于Libevent的HTTP Serve

简单的Http Server

使用Libevent内置的http相关接口，可以很容易的构建一个Http Server，一个简单的Http Server如下：

#include

#include

#include

#include

#include

#include

int init_win_socket()

{

WSADATA wsaData;

if(WSAStartup(MAKEWORD(2,2) , &wsaData) != 0)

{

return -1;

}

return0;

}

void generic_handler(struct evhttp_request *req, void *arg)

{

struct evbuffer *buf = evbuffer_new();

if(!buf)

{

puts("failed to create response buffer \n");

return;

}

evbuffer_add_printf(buf, "Server Responsed. Requested: %s\n",

evhttp_request_get_uri(req));

evhttp_send_reply(req, HTTP_OK, "OK", buf);

evbuffer_free(buf);

}

int main(int argc, char* argv[])

{

#ifdef WIN32

init_win_socket();#endif

short http_port = 8081;

char *http_addr = "127.0.0.1";

struct event_base * base = event_base_new();

struct evhttp * http_server = evhttp_new(base);

if(!http_server)

{

return -1;

}

int ret = evhttp_bind_socket(http_server,http_addr,http_port);

if(ret!=0)

{

return -1;

}

evhttp_set_gencb(http_server, generic_handler, NULL);

printf("http server start OK! \n");

event_base_dispatch(base);

evhttp_free(http_server);

WSACleanup();

return0;

}

通过Libevent的接口构建一个Http Server的过程如下：

（1）初始化：在event_base上新建一个evhttp，将这个evhttp绑定到监听的IP和端口号。

（2）设置Http回调函数：使用evhttp_set_gencb设置Http Server的处理请求的回调函数。

（3）启动Http Server：等待请求进入事件循环。

在Http Server中使用定时器提供更新服务

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define DEFAULT_FILE "F:\\Libevent\\LibeventTest\\Debug\\sample.txt"

char *filedata;

time_t lasttime = 0;char filename[80];int counter = 0;

struct event *loadfile_event;struct timeval tv;

void read_file()

unsigned long size = 0;

char *data;

struct stat buf;

if(stat(filename,&buf)<0)

{

printf("Read file error! \n");

return;

}

if (buf.st_mtime > lasttime)

{

if (counter++)

fprintf(stderr,"Reloading file: %s",filename);

else

fprintf(stderr,"Loading file: %s",filename);

FILE *f = fopen(filename, "rb");

if (f == NULL)

{

fprintf(stderr,"Couldn't open file\n");

return;

}

size = buf.st_size;

filedata = (char *)malloc(size+1);

memset(filedata,0,size+1);

fread(filedata, sizeof(char), size, f);

fclose(f);

fprintf(stderr," (%d bytes)\n",size);

lasttime = buf.st_mtime;

}

}

void read_file_timer_cb(evutil_socket_t listener, short event, void *arg) {

if (!evtimer_pending(loadfile_event, NULL))

{

event_del(loadfile_event);

evtimer_add(loadfile_event, &tv);

}

read_file();