struct bufferevent *
bufferevent_socket_new(struct event_base *base, evutil_socket_t fd,
int options)
{
struct bufferevent_private *bufev_p;
struct bufferevent *bufev;
#ifdef WIN32
if (base && event_base_get_iocp(base))
return bufferevent_async_new(base, fd, options);
#endif
if ((bufev_p = mm_calloc(1, sizeof(struct bufferevent_private)))== NULL)
return NULL;
if (bufferevent_init_common(bufev_p, base, &bufferevent_ops_socket,
options) < 0) {
mm_free(bufev_p);
return NULL;
}
bufev = &bufev_p->bev;
event_assign(&bufev->ev_read, bufev->ev_base, fd,
EV_READ|EV_PERSIST, bufferevent_readcb, bufev);
event_assign(&bufev->ev_write, bufev->ev_base, fd,
EV_WRITE|EV_PERSIST, bufferevent_writecb, bufev);
evbuffer_add_cb(bufev->output, bufferevent_socket_outbuf_cb, bufev);
evbuffer_freeze(bufev->input, 0);
evbuffer_freeze(bufev->output, 1);
return bufev;
}
struct bufferevent *
bufferevent_async_new(struct event_base *base,
evutil_socket_t fd, int options)
{
struct bufferevent_async *bev_a;
struct bufferevent *bev;
struct event_iocp_port *iocp;
options |= BEV_OPT_THREADSAFE;
if (!(iocp = event_base_get_iocp(base)))
return NULL;
if (fd >= 0 && event_iocp_port_associate(iocp, fd, 1)<0) {
int err = GetLastError();
/* We may have alrady associated this fd with a port.
* Let's hope it's this port, and that the error code
* for doing this neer changes. */
if (err != ERROR_INVALID_PARAMETER)
return NULL;
}
if (!(bev_a = mm_calloc(1, sizeof(struct bufferevent_async))))
return NULL;
bev = &bev_a->bev.bev;
if (!(bev->input = evbuffer_overlapped_new(fd))) {
mm_free(bev_a);
return NULL;
}
if (!(bev->output = evbuffer_overlapped_new(fd))) {
evbuffer_free(bev->input);
mm_free(bev_a);
return NULL;
}
if (bufferevent_init_common(&bev_a->bev, base, &bufferevent_ops_async,
options)<0)
goto err;
evbuffer_add_cb(bev->input, be_async_inbuf_callback, bev);
evbuffer_add_cb(bev->output, be_async_outbuf_callback, bev);
event_overlapped_init(&bev_a->connect_overlapped, connect_complete);
event_overlapped_init(&bev_a->read_overlapped, read_complete);
event_overlapped_init(&bev_a->write_overlapped, write_complete);
bev_a->ok = fd >= 0;
if (bev_a->ok)
_bufferevent_init_generic_timeout_cbs(bev);
return bev;
err:
bufferevent_free(&bev_a->bev.bev);
return NULL;
}
struct bufferevent *
bufferevent_socket_new(struct event_base *base, evutil_socket_t fd,
int options)
{
struct bufferevent_private *bufev_p;
struct bufferevent *bufev;
#ifdef WIN32
if (base && event_base_get_iocp(base))
return bufferevent_async_new(base, fd, options);
#endif
if ((bufev_p = mm_calloc(1, sizeof(struct bufferevent_private)))== NULL)
return NULL;
if (bufferevent_init_common(bufev_p, base, &bufferevent_ops_socket,
options) < 0) {
mm_free(bufev_p);
return NULL;
}
bufev = &bufev_p->bev;
//设置将evbuffer的数据向fd传
evbuffer_set_flags(bufev->output, EVBUFFER_FLAG_DRAINS_TO_FD);
//设置读写回调
event_assign(&bufev->ev_read, bufev->ev_base, fd,
EV_READ|EV_PERSIST, bufferevent_readcb, bufev);
event_assign(&bufev->ev_write, bufev->ev_base, fd,
EV_WRITE|EV_PERSIST, bufferevent_writecb, bufev);
//设置evbuffer的回调函数，使得外界给写缓冲区添加数据时，能触发
//写操作，这个回调对于写事件的监听是很重要的
evbuffer_add_cb(bufev->output, bufferevent_socket_outbuf_cb, bufev);
/* 虽然这里冻结了，但实际上Libevent在读数据或者写数据之前会解冻的读完或者写完数据后，又会马上冻结。
* 这主要防止数据被意外修改。用户一般不会直接调用evbuffer_freeze或者evbuffer_unfreeze函数。
* 一切的冻结和解冻操作都由Libevent内部完成。还有一点要注意，因为这里只是把写缓冲区的头部冻结了。
* 所以还是可以往写缓冲区的尾部追加数据。同样，此时也是可以从读缓冲区读取数据。这个是必须的。
* 因为在Libevent内部不解冻的时候，用户需要从读缓冲区中获取数据(这相当于从socket fd中读取数据)，
* 用户也需要把数据写到写缓冲区中(这相当于把数据写入到socket fd中)。*/
//冻结读缓冲区的尾部，未解冻之前不能往读缓冲区追加数据
//也就是说不能从socket fd中读取数据
evbuffer_freeze(bufev->input, 0);
//冻结写缓冲区的头部，未解冻之前不能把写缓冲区的头部数据删除
//也就是说不能把数据写到socket fd
evbuffer_freeze(bufev->output, 1);
return bufev;
}
