基于Libevent的HTTP Server

1、基于Libevent的HTTP Server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 <event2/event.h>#include <event2/buffer.h>#include <event2/http.h>#include <Winsock2.h>#include <stdlib.h>#include <stdio.h>int init_win_socket() WSADATA ws

2、aData; if(WSAStartup(MAKEWORD(2,2) , &wsaData) != 0) return -1; return 0;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. Requ

3、ested: %sn", 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 = "" struct event_base * base = event_base_new(); str

4、uct 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

5、_server); WSACleanup(); return 0;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 <event2/event.h>#include <event2/buffer.h>#include &

6、lt;event2/http.h>#include <sys/stat.h>#include <Winsock2.h>#include <assert.h>#include <string.h>#include <stdlib.h>#include <stdio.h>#define DEFAULT_FILE "F:LibeventLibeventTestDebugsample.txt"char *filedata;time_t lasttime = 0;char filename80;int co

7、unter = 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",

8、filename); else fprintf(stderr,"Loading file: %s",filename); FILE *f = fopen(filename, "rb"); if (f = NULL) fprintf(stderr,"Couldn't open filen"); return; size = buf.st_size; filedata = (char *)malloc(size+1); memset(filedata,0,size+1); fread(filedata, sizeof(char),

9、 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();void load_fi

10、le(struct event_base * base) tv.tv_sec = 5; tv.tv_usec = 0; /loadfile_event = malloc(sizeof(struct event); loadfile_event = evtimer_new(base,read_file_timer_cb,NULL); /evtimer_set(loadfile_event,load_file,loadfile_event); evtimer_add(loadfile_event,&tv);void generic_handler(struct evhttp_request

11、 *req, void *arg) struct evbuffer *buf = evbuffer_new(); if(!buf) puts("failed to create response buffer n"); return; evbuffer_add_printf(buf,"%s",filedata); evhttp_send_reply(req, HTTP_OK, "OK", buf); evbuffer_free(buf);int init_win_socket() WSADATA wsaData; if(WSAStar

12、tup(MAKEWORD(2,2) , &wsaData) != 0) return -1; return 0;int main(int argc, char* argv)#ifdef WIN32 init_win_socket();#endif short http_port = 8081; char *http_addr = "" if (argc > 1) strcpy(filename,argv1); printf("Using %sn",filename); else strcpy(filename,DEFAUL

13、T_FILE); 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); read_file(); load_file(base); p

14、rintf("http server start OK! n"); event_base_dispatch(base); evhttp_free(http_server); WSACleanup(); return 0;在这个Http Server中提供了一个每5秒触发一次的定时器，读取一个文件，如果这个文件被更新过，则读取更新后的内容。当访问这个Http Server时，提供这个文件中最新的内容。多线程的Http Server在上面的Http Server中，处理Http请求的回调函数generic_handler和定时器读取文件的回调函数read_file_timer_

15、cb都在同一个event_base的dispatch中，并且都在同一个进程中，使用多线程可以改善程序的性能，下面是一个来自网络的多线程Http Server：#include <event.h>#include <evhttp.h>#include <pthread.h>#include <errno.h>#include <string.h>#include <fcntl.h>#include <sys/socket.h>#include <sys/types.h>#include <net

16、inet/in.h> int httpserver_bindsocket(int port, int backlog);int httpserver_start(int port, int nthreads, int backlog);void* httpserver_Dispatch(void *arg);void httpserver_GenericHandler(struct evhttp_request *req, void *arg);void httpserver_ProcessRequest(struct evhttp_request *req); int httpserv

17、er_bindsocket(int port, int backlog) int r; int nfd; nfd = socket(AF_INET, SOCK_STREAM, 0); if (nfd < 0) return -1; int one = 1; r = setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (char *)&one, sizeof(int); struct sockaddr_in addr; memset(&addr, 0, sizeof(addr); addr.sin_family = AF_INET; addr

18、.sin_addr.s_addr = INADDR_ANY; addr.sin_port = htons(port); r = bind(nfd, (struct sockaddr*)&addr, sizeof(addr); if (r < 0) return -1; r = listen(nfd, backlog); if (r < 0) return -1; int flags; if (flags = fcntl(nfd, F_GETFL, 0) < 0 | fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) retu

19、rn -1; return nfd; int httpserver_start(int port, int nthreads, int backlog) int r, i; int nfd = httpserver_bindsocket(port, backlog); if (nfd < 0) return -1; pthread_t thsnthreads; for (i = 0; i < nthreads; i+) struct event_base *base = event_init(); if (base = NULL) return -1; struct evhttp *httpd = evhttp_new(base); if (httpd = NULL) return -1; r = evhttp_accept_socket(httpd, nfd); if (r != 0) return -1; evhttp_set_gencb(httpd, httpserver_GenericHandler, NULL); r = pthread_create(&t