tor-browser

commit 7749fdd33aedaf9d72956cc6fa6e892f1edbf418
parent e89552cb83b38b77e82a84f5c2c932291c2f7ff0
Author: Markus Stange <mstange.moz@gmail.com>
Date:   Tue,  7 Oct 2025 14:12:05 +0000

Bug 1992872 - Reuse snapshotters between reftest readbacks. r=bradwerth

Before: https://share.firefox.dev/46HvB2g (2582 samples)
After: https://share.firefox.dev/3IxEZMD  (754 samples, 3.4x faster)

I captured these profiles with the following command:

```
samply record python3 ./mach reftest layout/reftests/reftest-sanity/reftest.list --setpref layers.gpu-process.enabled=true
```

Differential Revision: https://phabricator.services.mozilla.com/D267681

Diffstat:
M
gfx/layers/NativeLayerRootRemoteMacParent.h
 | 
1
+
M
gfx/layers/NativeLayerRootRemoteMacParent.mm
 | 
12
+++++++-----

2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/gfx/layers/NativeLayerRootRemoteMacParent.h b/gfx/layers/NativeLayerRootRemoteMacParent.h
@@ -47,6 +47,7 @@ class NativeLayerRootRemoteMacParent final : public NativeLayerRemoteParent {
                             bool aIsHDR, IntSize aSize);
 
   RefPtr<NativeLayerRootCA> mRealNativeLayerRoot;
+  UniquePtr<NativeLayerRootSnapshotter> mSnapshotter;
   nsTHashMap<uint64_t, RefPtr<NativeLayer>> mKnownLayers;
 };
 
diff --git a/gfx/layers/NativeLayerRootRemoteMacParent.mm b/gfx/layers/NativeLayerRootRemoteMacParent.mm
@@ -102,13 +102,15 @@ mozilla::ipc::IPCResult NativeLayerRootRemoteMacParent::RecvRequestReadback(
     return IPC_FAIL(this, "Can't allocate shmem.");
   }
 
-  auto snapshotter = mRealNativeLayerRoot->CreateSnapshotter();
-  if (!snapshotter) {
-    return IPC_FAIL(this, "Can't create parent-side snapshotter.");
+  if (!mSnapshotter) {
+    mSnapshotter = mRealNativeLayerRoot->CreateSnapshotter();
+    if (!mSnapshotter) {
+      return IPC_FAIL(this, "Can't create parent-side snapshotter.");
+    }
   }
 
-  if (!snapshotter->ReadbackPixels(aSize, readbackFormat,
-                                   buffer.Range<uint8_t>())) {
+  if (!mSnapshotter->ReadbackPixels(aSize, readbackFormat,
+                                    buffer.Range<uint8_t>())) {
     return IPC_FAIL(this, "Failed readback.");
   }