[Xcb] [PATCH 1/1] read from connection when polling special events and replies

[Uli Schlachter]

On 19.04.2017 04:58, David McFarland wrote:
> Using the mesa vulkan driver, if you acquire an image from a
> swapchain using a finite timeout (x11_acquire_next_image_poll_x11),
> it will occasionally lock, calling xcb_poll_for_special_event in
> a loop until the timeout expires.
> 
> Call _xcb_in_read() once from the polling functions for special
> events and replies, in the same way as xcb_poll_for_event.
> 
> Signed-off-by: David McFarland <corngood at gmail.com>
> ---
>  src/xcb_in.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/src/xcb_in.c b/src/xcb_in.c
> index bab4bc7..73209e0 100644
> --- a/src/xcb_in.c
> +++ b/src/xcb_in.c
> @@ -661,6 +661,8 @@ int xcb_poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply,
>      assert(reply != 0);
>      pthread_mutex_lock(&c->iolock);
>      ret = poll_for_reply(c, widen(c, request), reply, error);
> +    if(!ret && c->in.reading == 0 && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
> +        ret = poll_for_reply(c, widen(c, request), reply, error);
>      pthread_mutex_unlock(&c->iolock);
>      return ret;
>  }
> @@ -678,6 +680,8 @@ int xcb_poll_for_reply64(xcb_connection_t *c, uint64_t request, void **reply, xc
>      assert(reply != 0);
>      pthread_mutex_lock(&c->iolock);
>      ret = poll_for_reply(c, request, reply, error);
> +    if(!ret && c->in.reading == 0 && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
> +        ret = poll_for_reply(c, request, reply, error);
>      pthread_mutex_unlock(&c->iolock);
>      return ret;
>  }
> @@ -768,6 +772,8 @@ xcb_generic_event_t *xcb_poll_for_special_event(xcb_connection_t *c,
>          return 0;
>      pthread_mutex_lock(&c->iolock);
>      event = get_special_event(c, se);
> +    if(!event && c->in.reading == 0 && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
> +        event = get_special_event(c, se);
>      pthread_mutex_unlock(&c->iolock);
>      return event;
>  }
> 

Reviewed-by: Uli Schlachter <psychon at znc.in>

(Anyone wants to guess how long it takes for the patch adding the
`_queued`-variant of these function to appear?)

-- 
- Captain, I think I should tell you I've never
  actually landed a starship before.
- That's all right, Lieutenant, neither have I.