利用libevent编写服务端程序,主要有3部分
//创建主通知链base
1.base = event_base_new();
//创建要监听的事件,并将其加入到主通知链中。
2.listener_event = event_new(base, listener, EV_READ|EV_PERSIST, do_accept, (void*)base);
event_add(listener_event, NULL);
event_free( listener_event ); 释放由event_new申请的结构体
//主循环
3.event_base_dispatch(base)
相关网址:
以下为参考文档网址
下面的代码转自
下面程序重点:
因为do_read, do_write是异步的,所以下面的程序使用了state这个结构体变量将do_read和do_write联系起来。 解决了异步之间的问题。
- /* For sockaddr_in */
- #include <netinet/in.h>
- /* For socket functions */
- #include <sys/socket.h>
- /* For fcntl */
- #include <fcntl.h>
- #include <event2/event.h>
- #include <assert.h>
- #include <unistd.h>
- #include <string.h>
- #include <stdlib.h>
- #include <stdio.h>
- #include <errno.h>
- #define MAX_LINE 16384
- #define PORT 9999
- void do_read(evutil_socket_t fd, short events, void *arg);
- void do_write(evutil_socket_t fd, short events, void *arg);
- struct fd_state
- {
- char buffer[MAX_LINE];
- size_t buffer_used;
- size_t n_written;
- size_t write_upto;
- struct event *read_event;
- struct event *write_event;
- };
- struct fd_state *
- alloc_fd_state(struct event_base *base, evutil_socket_t fd)
- {
- struct fd_state *state = (struct fd_state *)malloc(sizeof(struct fd_state));
- if (!state)
- {
- return NULL;
- }
- state->read_event = event_new(base, fd, EV_READ|EV_PERSIST, do_read, state);
- if (!state->read_event)
- {
- free(state);
- return NULL;
- }
- state->write_event =
- event_new(base, fd, EV_WRITE|EV_PERSIST, do_write, state);
- if (!state->write_event)
- {
- event_free(state->read_event);
- free(state);
- return NULL;
- }
- assert(state->write_event);
- return state;
- }
- void
- free_fd_state(struct fd_state *state)
- {
- event_free(state->read_event);
- event_free(state->write_event);
- free(state);
- }
- void
- do_read(evutil_socket_t fd, short events, void *arg)
- {
- struct fd_state *state = arg;
- char buf[1024];
- int i;
- ssize_t result;
- while (1)
- {
- // assert(state->write_event);
- result = recv(fd, buf, sizeof(buf), 0);
- if (result <= 0)
- break;
- printf( "[%s][%d]buf=[%s]len=[%d]\n", __FILE__, __LINE__, buf, result );
- }
- memcpy( state->buffer, "reply", sizeof("reply") );
- assert(state->write_event);
- event_add(state->write_event, NULL);
- state->write_upto = state->buffer_used;
- if (result == 0)
- {
- free_fd_state(state);
- }
- else if (result < 0)
- {
- if (errno == EAGAIN) // XXXX use evutil macro
- return;
- perror("recv");
- free_fd_state(state);
- }
- }
- void
- do_write(evutil_socket_t fd, short events, void *arg)
- {
- struct fd_state *state = arg;
- printf( "[%d]\n", __LINE__ );
- // while (state->n_written < state->write_upto)
- {
- // ssize_t result = send(fd, state->buffer + state->n_written,
- // state->write_upto - state->n_written, 0);
- ssize_t result = send(fd, state->buffer, strlen(state->buffer), 0 );
- if (result < 0)
- {
- if (errno == EAGAIN) // XXX use evutil macro
- return;
- free_fd_state(state);
- return;
- }
- assert(result != 0);
- state->n_written += result;
- }
- // if (state->n_written == state->buffer_used)
- {
- state->n_written = state->write_upto = state->buffer_used = 1;
- }
- event_del(state->write_event);
- }
- void
- do_accept(evutil_socket_t listener, short event, void *arg)
- {
- struct event_base *base = arg;
- struct sockaddr_storage ss;
- socklen_t slen = sizeof(ss);
- int fd = accept(listener, (struct sockaddr*)&ss, &slen);
- if (fd < 0)
- { // XXXX eagain??
- perror("accept");
- }
- else if (fd > FD_SETSIZE)
- {
- close(fd); // XXX replace all closes with EVUTIL_CLOSESOCKET */
- }
- else
- {
- struct fd_state *state;
- evutil_make_socket_nonblocking(fd);
- state = alloc_fd_state(base, fd);
- assert(state); /*XXX err*/
- assert(state->write_event);
- event_add(state->read_event, NULL);
- }
- }
- void
- run(void)
- {
- evutil_socket_t listener;
- struct sockaddr_in sin;
- struct event_base *base;
- struct event *listener_event;
- base = event_base_new();
- if (!base)
- return; /*XXXerr*/
- sin.sin_family = AF_INET;
- sin.sin_addr.s_addr = 0;
- sin.sin_port = htons(PORT);
- listener = socket(AF_INET, SOCK_STREAM, 0);
- evutil_make_socket_nonblocking(listener);
- #ifndef WIN32
- {
- int one = 1;
- setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
- }
- #endif
- if (bind(listener, (struct sockaddr*)&sin, sizeof(sin)) < 0) {
- perror("bind");
- return;
- }
- if (listen(listener, 16)<0) {
- perror("listen");
- return;
- }
- //do_accept(evutil_socket_t listener, short event, void *arg)
- listener_event = event_new(base, listener, EV_READ|EV_PERSIST, do_accept, (void*)base);
- /*XXX check it */
- event_add(listener_event, NULL);
- event_base_dispatch(base);
- }
- int
- main(int c, char **v)
- {
- setvbuf(stdout, NULL, _IONBF, 0);
- run();
- return 0;
- }
阅读(7439) | 评论(0) | 转发(0) |