一个对异步IO的小小的介绍 (4)
一个对异步IO的小小的介绍 (1)
一个对异步IO的小小的介绍 (2)
一个对异步IO的小小的介绍 (3)
这里是ROT13 server的最后一个实现，它使用 bufferevents API。
Example: A simpler ROT13 server with Libevent
/* For sockaddr_in */
#include <netinet/in.h>
/* For socket functions */
#include <sys/socket.h>
/* For fcntl */
#include <fcntl.h>
#include <event2/event.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#define MAX_LINE 16384void do_read(evutil_socket_t fd, short events, void *arg);void do_write(evutil_socket_t fd, short events, void *arg);charrot13_char(char c)
{ /* We don't want to use isalpha here; setting the locale would change * which characters are considered alphabetical. */
if ((c >= 'a' && c <= 'm') || (c >= 'A' && c <= 'M'))
return c + 13;
else if ((c >= 'n' && c <= 'z') || (c >= 'N' && c <= 'Z'))
return c - 13;
else
return c;
}
void readcb(struct bufferevent *bev, void *ctx)
{
struct evbuffer *input, *output; char *line;
size_t n; int i;
input = bufferevent_get_input(bev);
output = bufferevent_get_output(bev);
while ((line = evbuffer_readln(input, &n, EVBUFFER_EOL_LF)))
{
for (i = 0; i < n; ++i)
line[i] = rot13_char(line[i]);
evbuffer_add(output, line, n);
evbuffer_add(output, "\n", 1);
free(line);
}
if (evbuffer_get_length(input) >= MAX_LINE)
{
/* Too long; just process what there is and go on so that the buffer * doesn't grow infinitely long. */
char buf[1024];
while (evbuffer_get_length(input))
{
int n = evbuffer_remove(input, buf, sizeof(buf));
for (i = 0; i < n; ++i)
buf[i] = rot13_char(buf[i]);
evbuffer_add(output, buf, n);
}
evbuffer_add(output, "\n", 1);
}
}
void errorcb(struct bufferevent *bev, short error, void *ctx)
{
if (error & BEV_EVENT_EOF)
{
/* connection has been closed, do any clean up here */ /* ... */
}
else if (error & BEV_EVENT_ERROR)
{
/* check errno to see what error occurred */
/* ... */
}
else if (error & BEV_EVENT_TIMEOUT)
{
/* must be a timeout event handle, handle it */
/* ... */
}
bufferevent_free(bev);
}
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)
{
perror("accept");
}
else if (fd > FD_SETSIZE)
{
close(fd);
}
else
{
struct bufferevent *bev;
evutil_make_socket_nonblocking(fd);
bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
bufferevent_setcb(bev, readcb, NULL, errorcb, NULL);
bufferevent_setwatermark(bev, EV_READ, 0, MAX_LINE);
bufferevent_enable(bev, EV_READ|EV_WRITE);
}
}
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(40713);
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;
}
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;
}
（完）