On 9/3/21 12:27 PM, Yann Ylavic wrote:
> On Tue, Aug 31, 2021 at 9:29 AM Ruediger Pluem <rpl...@apache.org> wrote:
>>
>> On 8/30/21 8:04 PM, yla...@apache.org wrote:
>>> +
>>> + /* Flush any pending input data now, we don't know when
>>> + * the next POLLIN will trigger and retaining data
>>> might
>>> + * deadlock the underlying protocol. We don't check for
>>> + * pending data first with ap_filter_input_pending()
>>> since
>>> + * the read from proxy_tunnel_forward() is nonblocking
>>> + * anyway and returning OK if there's no data.
>>> + */
>>> + rc = proxy_tunnel_forward(tunnel, in);
>>> + if (rc != OK) {
>>> + return rc;
>>> + }
>>
>> Don't we do all of this already a few lines above if
>> ap_filter_input_pending(in->c) == OK?
>> Why doing it again?
>
> With whatever tc (client or origin connection), here on tc->rtnevents
> & POLLOUT we have out == tc and in == tc->other, so we forward
> potential pending input data from tc->other to tc (without waiting
> tc->other to become readable).
>
> Below with the same tc (same loop), if tc->rtnevents & POLLIN we
> forward from tc to tc->other, thus the opposite direction.
I still don't get it. Starting at line 4941 in proxy_util.c we have
/* Flush any pending input data now, we don't know when
* the next POLLIN will trigger and retaining data might
* block the protocol.
*/
if (ap_filter_input_pending(in->c) == OK) {
rc = proxy_tunnel_forward(tunnel, in);
if (rc != OK) {
return rc;
}
}
/* Flush any pending input data now, we don't know when
* the next POLLIN will trigger and retaining data might
* deadlock the underlying protocol. We don't check for
* pending data first with ap_filter_input_pending() since
* the read from proxy_tunnel_forward() is nonblocking
* anyway and returning OK if there's no data.
*/
rc = proxy_tunnel_forward(tunnel, in);
if (rc != OK) {
return rc;
}
We execute the same code
rc = proxy_tunnel_forward(tunnel, in);
if (rc != OK) {
return rc;
}
twice if ap_filter_input_pending(in->c) == OK. Even the comments above these
two executions
start with the same wording. I still ask me why we need to do it twice.
Regards
Rüdiger
