Fix panic in Webrender during shutdown (#32897)

* Fix panic in webrender during shutdown

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

* Pass webgl_threads_sender to WebGLThreads::exit

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

* follow the naming convention and use sender instead of webgl_threads_sender

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

* Avoid deadlock when webgl_threads is None

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

* Use tuple matching for webgl_threads and webgl_threads_receiver

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

* Remove unused _webgl_threads_sender

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

---------

Signed-off-by: Bentaimia Haddadi <haddadi.taym@gmail.com>

components/canvas/webgl_thread.rs

@@ -368,7 +368,10 @@ impl WebGLThread {
             WebGLMsg::SwapBuffers(swap_ids, sender, sent_time) => {
                 self.handle_swap_buffers(swap_ids, sender, sent_time);
             },
-            WebGLMsg::Exit => {
+            WebGLMsg::Exit(sender) => {
+                if let Err(e) = sender.send(()) {
+                    warn!("Failed to send response to WebGLMsg::Exit ({e})");
+                }
                 return true;
             },
         }

components/constellation/constellation.rs

@@ -2644,6 +2644,7 @@ where
             ipc::channel().expect("Failed to create IPC channel!");
         let (storage_ipc_sender, storage_ipc_receiver) =
             ipc::channel().expect("Failed to create IPC channel!");
+        let mut webgl_threads_receiver = None;
 
         debug!("Exiting core resource threads.");
         if let Err(e) = self
@@ -2710,9 +2711,12 @@ where
         }
 
         if let Some(webgl_threads) = self.webgl_threads.as_ref() {
+            let (sender, receiver) = ipc::channel().expect("Failed to create IPC channel!");
+            webgl_threads_receiver = Some(receiver);
             debug!("Exiting WebGL thread.");
-            if let Err(e) = webgl_threads.exit() {
-                warn!("Exit WebGL Thread failed ({})", e);
+
+            if let Err(e) = webgl_threads.exit(sender) {
+                warn!("Exit WebGL Thread failed ({e})");
             }
         }
 
@@ -2733,6 +2737,14 @@ where
         if let Err(e) = storage_ipc_receiver.recv() {
             warn!("Exit storage thread failed ({:?})", e);
         }
+        if self.webgl_threads.is_some() {
+            if let Err(e) = webgl_threads_receiver
+                .expect("webgl_threads_receiver to be Some")
+                .recv()
+            {
+                warn!("Exit WebGL thread failed ({:?})", e);
+            }
+        }
 
         debug!("Asking compositor to complete shutdown.");
         self.compositor_proxy.send(CompositorMsg::ShutdownComplete);

components/shared/canvas/webgl.rs

@@ -14,7 +14,7 @@ pub use base::generic_channel::GenericSender as WebGLSender;
 /// Result type for send()/recv() calls in in WebGLCommands.
 pub use base::generic_channel::SendResult as WebGLSendResult;
 use euclid::default::{Rect, Size2D};
-use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender, IpcSharedMemory};
+use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender, IpcSender, IpcSharedMemory};
 use malloc_size_of_derive::MallocSizeOf;
 use pixels::PixelFormat;
 use serde::{Deserialize, Serialize};
@@ -73,9 +73,9 @@ impl WebGLThreads {
     }
 
     /// Sends a exit message to close the WebGLThreads and release all WebGLContexts.
-    pub fn exit(&self) -> Result<(), &'static str> {
+    pub fn exit(&self, sender: IpcSender<()>) -> Result<(), &'static str> {
         self.0
-            .send(WebGLMsg::Exit)
+            .send(WebGLMsg::Exit(sender))
             .map_err(|_| "Failed to send Exit message")
     }
 }
@@ -106,7 +106,7 @@ pub enum WebGLMsg {
     /// request is fulfilled
     SwapBuffers(Vec<WebGLContextId>, WebGLSender<u64>, u64),
     /// Frees all resources and closes the thread.
-    Exit,
+    Exit(IpcSender<()>),
 }
 
 #[derive(Clone, Copy, Debug, Deserialize, MallocSizeOf, PartialEq, Serialize)]