[Mesa-dev] [PATCH] vulkan/wsi/wayland: Respect non-blocking AcquireNextImage

[Eric Engestrom]

On Tuesday, 2018-10-30 12:56:53 +0000, Daniel Stone wrote:
> If the client has requested that AcquireNextImage not block at all, with
> a timeout of 0, then don't make any non-blocking calls.

Indeed; per spec:
> If timeout is zero, then vkAcquireNextImageKHR does not wait, and will
> either successfully acquire an image, or fail and return VK_NOT_READY
> if no image is available.

Reviewed-by: Eric Engestrom <eric.engestrom at intel.com>

> 
> This will still potentially block infinitely given a non-infinte
> timeout, but the fix for that is much more involved.

Maybe we should add a comment/debug message about this?

----8<----
diff --git a/src/vulkan/wsi/wsi_common_wayland.c b/src/vulkan/wsi/wsi_common_wayland.c
index 86b3acec94e8b98b3dbf..d9852f464f9af2a32ab9 100644
--- a/src/vulkan/wsi/wsi_common_wayland.c
+++ b/src/vulkan/wsi/wsi_common_wayland.c
@@ -681,6 +681,16 @@ wsi_wl_swapchain_acquire_next_image(struct wsi_swapchain *wsi_chain,
 {
    struct wsi_wl_swapchain *chain = (struct wsi_wl_swapchain *)wsi_chain;
 
+#ifdef DEBUG
+   /*
+    * TODO: We need to implement this
+    */
+   if (info->timeout != 0 && info->timeout != UINT64_MAX)
+   {
+      fprintf(stderr, "timeout not supported; ignoring");
+   }
+#endif
+
    int ret = wl_display_dispatch_queue_pending(chain->display->wl_display,
                                                chain->display->queue);
    /* XXX: I'm not sure if out-of-date is the right error here.  If
---->8----

> 
> Signed-off-by: Daniel Stone <daniels at collabora.com>
> Cc: mesa-stable at lists.freedesktop.org
> Cc: Chad Versace <chadversary at chromium.org>
> Cc: Jason Ekstrand <jason at jlekstrand.net>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108540
> ---
>  src/vulkan/wsi/wsi_common_wayland.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/src/vulkan/wsi/wsi_common_wayland.c b/src/vulkan/wsi/wsi_common_wayland.c
> index e9cc22ec603..981243d8b14 100644
> --- a/src/vulkan/wsi/wsi_common_wayland.c
> +++ b/src/vulkan/wsi/wsi_common_wayland.c
> @@ -699,9 +699,14 @@ wsi_wl_swapchain_acquire_next_image(struct wsi_swapchain *wsi_chain,
>           }
>        }
>  
> -      /* This time we do a blocking dispatch because we can't go
> -       * anywhere until we get an event.
> +      /* We now have to do a blocking dispatch, because all our images
> +       * are in use and we cannot return one until the server does. However,
> +       * if the client has requested non-blocking ANI, then we tell it up front
> +       * that we have nothing to return.
>         */
> +      if (info->timeout == 0)
> +         return VK_NOT_READY;
> +
>        int ret = wl_display_roundtrip_queue(chain->display->wl_display,
>                                             chain->display->queue);
>        if (ret < 0)
> -- 
> 2.19.1
> 
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