Merge #984

984: Fix locking of device lifetime tracker on resource drop r=kvark a=kvark

**Connections**
Fixes the player hang in #983

**Description**
It turns out the current type-level protection from locking device's lifetime tracker is not working properly. TODO is left.

**Testing**
Tested on the trace from #983

Co-authored-by: Dzmitry Malyshau <dmalyshau@mozilla.com>

wgpu-core/src/device/mod.rs

@@ -336,6 +336,7 @@ impl<B: GfxBackend> Device<B> {
 
     pub(crate) fn lock_life<'this, 'token: 'this>(
         &'this self,
+        //TODO: fix this - the token has to be borrowed for the lock
         token: &mut Token<'token, Self>,
     ) -> MutexGuard<'this, life::LifetimeTracker<B>> {
         Self::lock_life_internal(&self.life_tracker, token)
@@ -1282,19 +1283,20 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
 
         let (device_guard, mut token) = hub.devices.read(&mut token);
         let device = &device_guard[device_id];
-        let mut life_lock = device_guard[device_id].lock_life(&mut token);
-
-        if device.pending_writes.dst_buffers.contains(&buffer_id) {
-            life_lock.future_suspected_buffers.push(Stored {
-                value: id::Valid(buffer_id),
-                ref_count,
-            });
-        } else {
-            drop(ref_count);
-            life_lock
-                .suspected_resources
-                .buffers
-                .push(id::Valid(buffer_id));
+        {
+            let mut life_lock = device.lock_life(&mut token);
+            if device.pending_writes.dst_buffers.contains(&buffer_id) {
+                life_lock.future_suspected_buffers.push(Stored {
+                    value: id::Valid(buffer_id),
+                    ref_count,
+                });
+            } else {
+                drop(ref_count);
+                life_lock
+                    .suspected_resources
+                    .buffers
+                    .push(id::Valid(buffer_id));
+            }
         }
 
         if wait {
@@ -1429,19 +1431,20 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
 
         let (device_guard, mut token) = hub.devices.read(&mut token);
         let device = &device_guard[device_id];
-        let mut life_lock = device_guard[device_id].lock_life(&mut token);
-
-        if device.pending_writes.dst_textures.contains(&texture_id) {
-            life_lock.future_suspected_textures.push(Stored {
-                value: id::Valid(texture_id),
-                ref_count,
-            });
-        } else {
-            drop(ref_count);
-            life_lock
-                .suspected_resources
-                .textures
-                .push(id::Valid(texture_id));
+        {
+            let mut life_lock = device.lock_life(&mut token);
+            if device.pending_writes.dst_textures.contains(&texture_id) {
+                life_lock.future_suspected_textures.push(Stored {
+                    value: id::Valid(texture_id),
+                    ref_count,
+                });
+            } else {
+                drop(ref_count);
+                life_lock
+                    .suspected_resources
+                    .textures
+                    .push(id::Valid(texture_id));
+            }
         }
 
         if wait {

wgpu-core/src/device/trace.rs

@@ -3,9 +3,9 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use crate::id;
+use std::ops::Range;
 #[cfg(feature = "trace")]
-use std::io::Write as _;
-use std::{borrow::Cow, ops::Range};
+use std::{borrow::Cow, io::Write as _};
 
 //TODO: consider a readable Id that doesn't include the backend