From 6039916631c0767348711257bb6cd10deb6e7178 Mon Sep 17 00:00:00 2001
From: Raph Levien <raph.levien@gmail.com>
Date: Tue, 19 Oct 2021 17:25:08 -0700
Subject: [PATCH] Wait on in-flight command buffers on exit

If there is a command buffer in flight on exit from the winit app, wait
on it so that the resources get destroyed cleanly.

There may be a more aggressive strategy to quick-exit, but this is
probably the most reliable approach and I see it in other code bases.
---
 piet-gpu/bin/winit.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/piet-gpu/bin/winit.rs b/piet-gpu/bin/winit.rs
index c5f9bef..19db3c2 100644
--- a/piet-gpu/bin/winit.rs
+++ b/piet-gpu/bin/winit.rs
@@ -1,4 +1,3 @@
-use piet::RenderContext;
 use piet_gpu_hal::{Error, ImageLayout, Instance, Session, SubmittedCmdBuf};
 
 use piet_gpu::{test_scenes, PietGpuRenderContext, Renderer};
@@ -152,6 +151,13 @@ fn main() -> Result<(), Error> {
 
                     current_frame += 1;
                 }
+                Event::LoopDestroyed => {
+                    if let Some(submitted) = submitted.take() {
+                        // Wait for command list submission, otherwise dropping of renderer may
+                        // cause validation errors (and possibly crashes).
+                        submitted.wait().unwrap();
+                    }
+                }
                 _ => (),
             }
         })