static inline struct bufferevent_async *
upcast_write(struct event_overlapped *eo)
{
struct bufferevent_async *bev_a;
bev_a = EVUTIL_UPCAST(eo, struct bufferevent_async, write_overlapped);
EVUTIL_ASSERT(BEV_IS_ASYNC(&bev_a->bev.bev));
return bev_a;
}
int
bufferevent_async_can_connect(struct bufferevent *bev)
{
const struct win32_extension_fns *ext =
event_get_win32_extension_fns();
if (BEV_IS_ASYNC(bev) &&
event_base_get_iocp(bev->ev_base) &&
ext && ext->ConnectEx)
return 1;
return 0;
}
static void
bufferevent_writecb(evutil_socket_t fd, short event, void *arg)
{
struct bufferevent *bufev = arg;
struct bufferevent_private *bufev_p =
EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
int res = 0;
short what = BEV_EVENT_WRITING;
int connected = 0;
ev_ssize_t atmost = -1;
bufferevent_incref_and_lock_(bufev);
if (event == EV_TIMEOUT) {
/* Note that we only check for event==EV_TIMEOUT. If
* event==EV_TIMEOUT|EV_WRITE, we can safely ignore the
* timeout, since a read has occurred */
what |= BEV_EVENT_TIMEOUT;
goto error;
}
if (bufev_p->connecting) {
int c = evutil_socket_finished_connecting_(fd);
/* we need to fake the error if the connection was refused
* immediately - usually connection to localhost on BSD */
if (bufev_p->connection_refused) {
bufev_p->connection_refused = 0;
c = -1;
}
if (c == 0)
goto done;
bufev_p->connecting = 0;
if (c < 0) {
event_del(&bufev->ev_write);
event_del(&bufev->ev_read);
bufferevent_run_eventcb_(bufev, BEV_EVENT_ERROR);
goto done;
} else {
connected = 1;
#ifdef _WIN32
if (BEV_IS_ASYNC(bufev)) {
event_del(&bufev->ev_write);
bufferevent_async_set_connected_(bufev);
bufferevent_run_eventcb_(bufev,
BEV_EVENT_CONNECTED);
goto done;
}
#endif
bufferevent_run_eventcb_(bufev,
BEV_EVENT_CONNECTED);
if (!(bufev->enabled & EV_WRITE) ||
bufev_p->write_suspended) {
event_del(&bufev->ev_write);
goto done;
}
}
}
atmost = bufferevent_get_write_max_(bufev_p);
if (bufev_p->write_suspended)
goto done;
if (evbuffer_get_length(bufev->output)) {
evbuffer_unfreeze(bufev->output, 1);
res = evbuffer_write_atmost(bufev->output, fd, atmost);
evbuffer_freeze(bufev->output, 1);
if (res == -1) {
int err = evutil_socket_geterror(fd);
if (EVUTIL_ERR_RW_RETRIABLE(err))
goto reschedule;
what |= BEV_EVENT_ERROR;
} else if (res == 0) {
/* eof case
XXXX Actually, a 0 on write doesn't indicate
an EOF. An ECONNRESET might be more typical.
*/
what |= BEV_EVENT_EOF;
}
if (res <= 0)
goto error;
bufferevent_decrement_write_buckets_(bufev_p, res);
}
if (evbuffer_get_length(bufev->output) == 0) {
event_del(&bufev->ev_write);
}
/*
* Invoke the user callback if our buffer is drained or below the
* low watermark.
*/
if ((res || !connected) &&
evbuffer_get_length(bufev->output) <= bufev->wm_write.low) {
bufferevent_run_writecb_(bufev);
}
goto done;
reschedule:
if (evbuffer_get_length(bufev->output) == 0) {
event_del(&bufev->ev_write);
}
goto done;
error:
bufferevent_disable(bufev, EV_WRITE);
bufferevent_run_eventcb_(bufev, what);
done:
bufferevent_decref_and_unlock_(bufev);
}
int
bufferevent_socket_connect(struct bufferevent *bev,
struct sockaddr *sa, int socklen)
{
struct bufferevent_private *bufev_p =
EVUTIL_UPCAST(bev, struct bufferevent_private, bev);
evutil_socket_t fd;
int r = 0;
int result=-1;
int ownfd = 0;
bufferevent_incref_and_lock_(bev);
if (!bufev_p)
goto done;
fd = bufferevent_getfd(bev);
if (fd < 0) {
if (!sa)
goto done;
fd = evutil_socket_(sa->sa_family,
SOCK_STREAM|EVUTIL_SOCK_NONBLOCK, 0);
if (fd < 0)
goto done;
ownfd = 1;
}
if (sa) {
#ifdef _WIN32
if (bufferevent_async_can_connect_(bev)) {
bufferevent_setfd(bev, fd);
r = bufferevent_async_connect_(bev, fd, sa, socklen);
if (r < 0)
goto freesock;
bufev_p->connecting = 1;
result = 0;
goto done;
} else
#endif
r = evutil_socket_connect_(&fd, sa, socklen);
if (r < 0)
goto freesock;
}
#ifdef _WIN32
/* ConnectEx() isn't always around, even when IOCP is enabled.
* Here, we borrow the socket object's write handler to fall back
* on a non-blocking connect() when ConnectEx() is unavailable. */
if (BEV_IS_ASYNC(bev)) {
event_assign(&bev->ev_write, bev->ev_base, fd,
EV_WRITE|EV_PERSIST, bufferevent_writecb, bev);
}
#endif
bufferevent_setfd(bev, fd);
if (r == 0) {
if (! be_socket_enable(bev, EV_WRITE)) {
bufev_p->connecting = 1;
result = 0;
goto done;
}
} else if (r == 1) {
/* The connect succeeded already. How very BSD of it. */
result = 0;
bufev_p->connecting = 1;
event_active(&bev->ev_write, EV_WRITE, 1);
} else {
/* The connect failed already. How very BSD of it. */
bufev_p->connection_refused = 1;
bufev_p->connecting = 1;
result = 0;
event_active(&bev->ev_write, EV_WRITE, 1);
}
goto done;
freesock:
bufferevent_run_eventcb_(bev, BEV_EVENT_ERROR);
if (ownfd)
evutil_closesocket(fd);
/* do something about the error? */
done:
bufferevent_decref_and_unlock_(bev);
return result;
}
static void
bufferevent_writecb(evutil_socket_t fd, short event, void *arg)
{
struct bufferevent *bufev = arg;
struct bufferevent_private *bufev_p =
EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
int res = 0;
short what = BEV_EVENT_WRITING;
int connected = 0;
ev_ssize_t atmost = -1;
_bufferevent_incref_and_lock(bufev);
if (event == EV_TIMEOUT) {
/* Note that we only check for event==EV_TIMEOUT. If
* event==EV_TIMEOUT|EV_WRITE, we can safely ignore the
* timeout, since a read has occurred */
what |= BEV_EVENT_TIMEOUT;
goto error;
}
//正在连接服务器...
if (bufev_p->connecting) {
int c = evutil_socket_finished_connecting(fd);
/* we need to fake the error if the connection was refused
* immediately - usually connection to localhost on BSD */
if (bufev_p->connection_refused) { //在bufferevent_socket_connect中被设置
bufev_p->connection_refused = 0;
c = -1;
}
if (c == 0) //正在连接，继续监听可写。
goto done;
bufev_p->connecting = 0;
if (c < 0) { //连接发生错误
event_del(&bufev->ev_write);
event_del(&bufev->ev_read);
_bufferevent_run_eventcb(bufev, BEV_EVENT_ERROR);
goto done;
} else { //连接成功
connected = 1;
#ifdef WIN32
if (BEV_IS_ASYNC(bufev)) {
event_del(&bufev->ev_write);
bufferevent_async_set_connected(bufev);
_bufferevent_run_eventcb(bufev,
BEV_EVENT_CONNECTED);
goto done;
}
#endif
//连接成功，调用用户错误处理函数。比较奇怪。
_bufferevent_run_eventcb(bufev,
BEV_EVENT_CONNECTED);
if (!(bufev->enabled & EV_WRITE) ||
bufev_p->write_suspended) {
event_del(&bufev->ev_write);
goto done;
}
}
}
atmost = _bufferevent_get_write_max(bufev_p);
//写被挂起
if (bufev_p->write_suspended)
goto done;
//存在可写数据
if (evbuffer_get_length(bufev->output)) {
evbuffer_unfreeze(bufev->output, 1);
//将缓冲区数据写入socket。
res = evbuffer_write_atmost(bufev->output, fd, atmost);
evbuffer_freeze(bufev->output, 1);
if (res == -1) { //写发生错误
int err = evutil_socket_geterror(fd);
if (EVUTIL_ERR_RW_RETRIABLE(err)) //socket缓冲区满，一次未写完，继续监听可写事件，等待下次写入。
goto reschedule;
what |= BEV_EVENT_ERROR; //写发生异常错误
} else if (res == 0) {
/* eof case
XXXX Actually, a 0 on write doesn't indicate
an EOF. An ECONNRESET might be more typical.
*/
what |= BEV_EVENT_EOF;
}
if (res <= 0)
goto error;
_bufferevent_decrement_write_buckets(bufev_p, res);
}
//缓冲区数据已写完，删除写事件。
if (evbuffer_get_length(bufev->output) == 0) {
event_del(&bufev->ev_write);
}
/* 低于写低水位，调用用户回调。
*/
if ((res || !connected) &&
evbuffer_get_length(bufev->output) <= bufev->wm_write.low) {
_bufferevent_run_writecb(bufev);
}
goto done;
reschedule:
if (evbuffer_get_length(bufev->output) == 0) {
event_del(&bufev->ev_write);
}
goto done;
error:
bufferevent_disable(bufev, EV_WRITE);
_bufferevent_run_eventcb(bufev, what);
done:
_bufferevent_decref_and_unlock(bufev);
}
