From c4f9f46b3fb3b2d7b59f96fe9148f24405430c7f Mon Sep 17 00:00:00 2001
From: Elie Michel <elie.michel@exppad.com>
Date: Sun, 27 Oct 2024 09:42:19 +0100
Subject: [PATCH] Remove triage_mapped

---
 wgpu-core/src/device/life.rs     | 54 ++++++--------------------------
 wgpu-core/src/device/resource.rs |  2 --
 2 files changed, 10 insertions(+), 46 deletions(-)

diff --git a/wgpu-core/src/device/life.rs b/wgpu-core/src/device/life.rs
index bc66a4d1b9..47e33ab11f 100644
--- a/wgpu-core/src/device/life.rs
+++ b/wgpu-core/src/device/life.rs
@@ -126,35 +126,20 @@ pub enum WaitIdleError {
 /// -   Each buffer's `ResourceInfo::submission_index` records the index of the
 ///     most recent queue submission that uses that buffer.
 ///
-/// -   Calling `Global::buffer_map_async` adds the buffer to
-///     `self.mapped`, and changes `Buffer::map_state` to prevent it
-///     from being used in any new submissions.
-///
 /// -   When the device is polled, the following `LifetimeTracker` methods decide
 ///     what should happen next:
 ///
-///     1)  `triage_mapped` drains `self.mapped`, checking the submission index
-///         of each buffer against the queue submissions that have finished
-///         execution. Buffers used by submissions still in flight go in
-///         `self.active[index].mapped`, and the rest go into
-///         `self.ready_to_map`.
-///
-///     2)  `triage_submissions` moves entries in `self.active[i]` for completed
+///     1)  `triage_submissions` moves entries in `self.active[i]` for completed
 ///         submissions to `self.ready_to_map`.  At this point, both
 ///         `self.active` and `self.ready_to_map` are up to date with the given
 ///         submission index.
 ///
-///     3)  `handle_mapping` drains `self.ready_to_map` and actually maps the
+///     2)  `handle_mapping` drains `self.ready_to_map` and actually maps the
 ///         buffers, collecting a list of notification closures to call.
 ///
 /// Only calling `Global::buffer_map_async` clones a new `Arc` for the
 /// buffer. This new `Arc` is only dropped by `handle_mapping`.
 pub(crate) struct LifetimeTracker {
-    /// Buffers for which a call to [`Buffer::map_async`] has succeeded, but
-    /// which haven't been examined by `triage_mapped` yet to decide when they
-    /// can be mapped.
-    mapped: Vec<Arc<Buffer>>,
-
     /// Resources used by queue submissions still in flight. One entry per
     /// submission, with older submissions appearing before younger.
     ///
@@ -182,7 +167,6 @@ pub(crate) struct LifetimeTracker {
 impl LifetimeTracker {
     pub fn new() -> Self {
         Self {
-            mapped: Vec::new(),
             active: Vec::new(),
             ready_to_map: Vec::new(),
             work_done_closures: SmallVec::new(),
@@ -212,16 +196,20 @@ impl LifetimeTracker {
     }
 
     pub(crate) fn map(&mut self, buffer: &Arc<Buffer>) -> Option<SubmissionIndex> {
-        self.mapped.push(buffer.clone());
-
-        // Warning: this duplicates what is in triage_mapped()
+        // Determine which buffers are ready to map, and which must wait for the GPU.
         let submission = self
             .active
             .iter_mut()
             .rev()
             .find(|a| a.contains_buffer(&buffer));
 
-        submission.map(|s| s.index)
+        let maybe_submission_index = submission.as_ref().map(|s| s.index.clone());
+
+        submission
+            .map_or(&mut self.ready_to_map, |a| &mut a.mapped)
+            .push(buffer.clone());
+
+        maybe_submission_index
     }
 
     /// Returns the submission index of the most recent submission that uses the
@@ -331,28 +319,6 @@ impl LifetimeTracker {
         }
     }
 
-    /// Determine which buffers are ready to map, and which must wait for the
-    /// GPU.
-    ///
-    /// See the documentation for [`LifetimeTracker`] for details.
-    pub(crate) fn triage_mapped(&mut self) {
-        if self.mapped.is_empty() {
-            return;
-        }
-
-        for buffer in self.mapped.drain(..) {
-            let submission = self
-                .active
-                .iter_mut()
-                .rev()
-                .find(|a| a.contains_buffer(&buffer));
-
-            submission
-                .map_or(&mut self.ready_to_map, |a| &mut a.mapped)
-                .push(buffer);
-        }
-    }
-
     /// Map the buffers in `self.ready_to_map`.
     ///
     /// Return a list of mapping notifications to send.
diff --git a/wgpu-core/src/device/resource.rs b/wgpu-core/src/device/resource.rs
index 21ecf85d24..46271f7ac9 100644
--- a/wgpu-core/src/device/resource.rs
+++ b/wgpu-core/src/device/resource.rs
@@ -493,8 +493,6 @@ impl Device {
         let submission_closures =
             life_tracker.triage_submissions(submission_index, &self.command_allocator);
 
-        life_tracker.triage_mapped();
-
         let mapping_closures = life_tracker.handle_mapping(self.raw(), &snatch_guard);
 
         let queue_empty = life_tracker.queue_empty();