使用 libevent 和 libev 提高网络应用性能的方法

#define SERVER_PORT 8080
int debug = 0;

struct client {
int fd;
struct bufferevent *buf_ev;
};

int setnonblock(int fd)
{
int flags;

flags = fcntl(fd, F_GETFL);
flags |= O_NONBLOCK;
fcntl(fd, F_SETFL, flags);
}

void buf_read_callback(struct bufferevent *incoming,
void *arg)
{
struct evbuffer *evreturn;
char *req;

req = evbuffer_readline(incoming->input);
if (req == NULL)
return;

evreturn = evbuffer_new();
evbuffer_add_printf(evreturn,"You said %sn",req);
bufferevent_write_buffer(incoming,evreturn);
evbuffer_free(evreturn);
free(req);
}

void buf_write_callback(struct bufferevent *bev,
void *arg)
{
}

void buf_error_callback(struct bufferevent *bev,
short what,
void *arg)
{
struct client *client = (struct client *)arg;
bufferevent_free(client->buf_ev);
close(client->fd);
free(client);
}

void accept_callback(int fd,
short ev,
void *arg)
{
int client_fd;
struct sockaddr_in client_addr;
socklen_t client_len = sizeof(client_addr);
struct client *client;

client_fd = accept(fd,
(struct sockaddr *)&client_addr,
&client_len);
if (client_fd < 0)
{
warn("Client: accept() failed");
return;
}

setnonblock(client_fd);

client = calloc(1, sizeof(*client));
if (client == NULL)
err(1, "malloc failed");
client->fd = client_fd;

client->buf_ev = bufferevent_new(client_fd,
buf_read_callback,
buf_write_callback,
buf_error_callback,
client);

bufferevent_enable(client->buf_ev, EV_READ);
}

int main(int argc,
char **argv)
{
int socketlisten;
struct sockaddr_in addresslisten;
struct event accept_event;
int reuse = 1;

event_init();

socketlisten = socket(AF_INET, SOCK_STREAM, 0);

if (socketlisten < 0)
{
fprintf(stderr,"Failed to create listen socket");
return 1;
}

memset(&addresslisten, 0, sizeof(addresslisten));

addresslisten.sin_family = AF_INET;
addresslisten.sin_addr.s_addr = INADDR_ANY;
addresslisten.sin_port = htons(SERVER_PORT);

if (bind(socketlisten,
(struct sockaddr *)&addresslisten,
sizeof(addresslisten)) < 0)
{
fprintf(stderr,"Failed to bind");
return 1;
}

if (listen(socketlisten, 5) < 0)
{
fprintf(stderr,"Failed to listen to socket");
return 1;
}

setsockopt(socketlisten,
SOL_SOCKET,
SO_REUSEADDR,
&reuse,
sizeof(reuse));

setnonblock(socketlisten);

event_set(&accept_event,
socketlisten,
EV_READ|EV_PERSIST,
accept_callback,
NULL);

event_add(&accept_event,
NULL);

event_dispatch();

close(socketlisten);

return 0;
}

下面讨论各个函数及其操作：

main()：主函数创建用来监听连接的套接字，然后创建 accept() 的回调函数以便通过事件处理函数处理每个连接。