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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/287155">287155</a></dd>
<dt>Author</dt> <dd>alancoon@apple.com</dd>
<dt>Date</dt> <dd>2021-12-16 13:20:10 -0800 (Thu, 16 Dec 2021)</dd>
</dl>

<h3>Log Message</h3>
<pre>Cherry-pick <a href="http://trac.webkit.org/projects/webkit/changeset/287079">r287079</a>. rdar://problem/85892959

This reverts <a href="http://trac.webkit.org/projects/webkit/changeset/287150">r287150</a>.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#branchessafari612branchSourceWebCoreChangeLog">branches/safari-612-branch/Source/WebCore/ChangeLog</a></li>
<li><a href="#branchessafari612branchSourceWebCoreSourcesCocoatxt">branches/safari-612-branch/Source/WebCore/SourcesCocoa.txt</a></li>
<li><a href="#branchessafari612branchSourceWebCoreWebCorexcodeprojprojectpbxproj">branches/safari-612-branch/Source/WebCore/WebCore.xcodeproj/project.pbxproj</a></li>
<li><a href="#branchessafari612branchSourceWebCorepagescrollingScrollingTreeh">branches/safari-612-branch/Source/WebCore/page/scrolling/ScrollingTree.h</a></li>
<li><a href="#branchessafari612branchSourceWebCorepagescrollingmacScrollingCoordinatorMach">branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.h</a></li>
<li><a href="#branchessafari612branchSourceWebCorepagescrollingmacScrollingCoordinatorMacmm">branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.mm</a></li>
<li><a href="#branchessafari612branchSourceWebCorepagescrollingmacScrollingTreeMach">branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.h</a></li>
<li><a href="#branchessafari612branchSourceWebCorepagescrollingmacScrollingTreeMacmm">branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.mm</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscaGraphicsLayerCAcpp">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscaPlatformCALayercpp">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.cpp</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscaPlatformCALayerh">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.h</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerCocoah">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.h</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerCocoamm">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm</a></li>
</ul>

<h3>Added Paths</h3>
<ul>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerContentsDelayedReleaserh">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h</a></li>
<li><a href="#branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerContentsDelayedReleasermm">branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="branchessafari612branchSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/ChangeLog (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/ChangeLog      2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/ChangeLog 2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -1,3 +1,123 @@
</span><ins>+2021-12-15  Alan Coon  <alancoon@apple.com>
+
+        Cherry-pick r287079. rdar://problem/85892959
+
+    Twitter scroll stutter: ensure that CA backing store is always deallocated on the main thread
+    https://bugs.webkit.org/show_bug.cgi?id=234328
+    <rdar://85892959>
+    
+    Reviewed by Tim Horton.
+    
+    When scrolling pages like Twitter and Facebook we observed CoreAnimation commits on the
+    scrolling thread taking longer than they should because CABackingStore objects were being
+    released in those transactions.
+    
+    Work around this issue by extending the lifetime of CABackingStore objects if we detect that
+    they might be entrained into a scrolling tree commit, by virtue of having overlapping main
+    thread and scrolling thread commits.
+    
+    The logic is contained in PlatformCALayerContentsDelayedReleaser, which puts layer contents
+    into a retaining vector when they are being cleared on the layer. They are released at the
+    end of a main thread commit; if we detected overlapping commits, then we release on a
+    dispatch to extend the lifetime slightly.
+    
+    The remaining changes are plumbing to get commit willBegin/didEnd messages to PlatformCALayerContentsDelayedReleaser
+    for main and scrolling threads.
+    
+    * SourcesCocoa.txt:
+    * WebCore.xcodeproj/project.pbxproj:
+    * page/scrolling/ScrollingTree.h:
+    * page/scrolling/ThreadedScrollingTree.h:
+    * page/scrolling/mac/ScrollingCoordinatorMac.h:
+    * page/scrolling/mac/ScrollingCoordinatorMac.mm:
+    (WebCore::ScrollingCoordinatorMac::willStartPlatformRenderingUpdate):
+    (WebCore::ScrollingCoordinatorMac::didCompletePlatformRenderingUpdate):
+    * page/scrolling/mac/ScrollingTreeMac.h:
+    * page/scrolling/mac/ScrollingTreeMac.mm:
+    (ScrollingTreeMac::applyLayerPositionsInternal):
+    (ScrollingTreeMac::registerForPlatformRenderingUpdateCallback):
+    * platform/graphics/ca/GraphicsLayerCA.cpp:
+    (WebCore::GraphicsLayerCA::updateContentsVisibility):
+    (WebCore::GraphicsLayerCA::updateDrawsContent):
+    * platform/graphics/ca/PlatformCALayer.cpp:
+    (WebCore::PlatformCALayer::clearContents):
+    * platform/graphics/ca/PlatformCALayer.h:
+    * platform/graphics/ca/cocoa/PlatformCALayerCocoa.h:
+    * platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm:
+    (WebCore::PlatformCALayerCocoa::setBackingStoreAttached):
+    (WebCore::PlatformCALayerCocoa::clearContents):
+    * platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h: Added.
+    (WebCore::PlatformCALayerContentsDelayedReleaser::WTF_GUARDED_BY_LOCK):
+    * platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm: Added.
+    (WebCore::PlatformCALayerContentsDelayedReleaser::singleton):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::takeLayerContents):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::mainThreadCommitWillStart):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::mainThreadCommitDidEnd):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitWillStart):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitDidEnd):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::updateSawOverlappingCommit):
+    (WebCore::PlatformCALayerContentsDelayedReleaser::clearRetainedContents):
+    
+    git-svn-id: https://svn.webkit.org/repository/webkit/trunk@287079 268f45cc-cd09-0410-ab3c-d52691b4dbfc
+
+    2021-12-15  Simon Fraser  <simon.fraser@apple.com>
+
+            Twitter scroll stutter: ensure that CA backing store is always deallocated on the main thread
+            https://bugs.webkit.org/show_bug.cgi?id=234328
+            <rdar://85892959>
+
+            Reviewed by Tim Horton.
+
+            When scrolling pages like Twitter and Facebook we observed CoreAnimation commits on the
+            scrolling thread taking longer than they should because CABackingStore objects were being
+            released in those transactions.
+
+            Work around this issue by extending the lifetime of CABackingStore objects if we detect that
+            they might be entrained into a scrolling tree commit, by virtue of having overlapping main
+            thread and scrolling thread commits.
+
+            The logic is contained in PlatformCALayerContentsDelayedReleaser, which puts layer contents
+            into a retaining vector when they are being cleared on the layer. They are released at the
+            end of a main thread commit; if we detected overlapping commits, then we release on a
+            dispatch to extend the lifetime slightly.
+
+            The remaining changes are plumbing to get commit willBegin/didEnd messages to PlatformCALayerContentsDelayedReleaser
+            for main and scrolling threads.
+
+            * SourcesCocoa.txt:
+            * WebCore.xcodeproj/project.pbxproj:
+            * page/scrolling/ScrollingTree.h:
+            * page/scrolling/ThreadedScrollingTree.h:
+            * page/scrolling/mac/ScrollingCoordinatorMac.h:
+            * page/scrolling/mac/ScrollingCoordinatorMac.mm:
+            (WebCore::ScrollingCoordinatorMac::willStartPlatformRenderingUpdate):
+            (WebCore::ScrollingCoordinatorMac::didCompletePlatformRenderingUpdate):
+            * page/scrolling/mac/ScrollingTreeMac.h:
+            * page/scrolling/mac/ScrollingTreeMac.mm:
+            (ScrollingTreeMac::applyLayerPositionsInternal):
+            (ScrollingTreeMac::registerForPlatformRenderingUpdateCallback):
+            * platform/graphics/ca/GraphicsLayerCA.cpp:
+            (WebCore::GraphicsLayerCA::updateContentsVisibility):
+            (WebCore::GraphicsLayerCA::updateDrawsContent):
+            * platform/graphics/ca/PlatformCALayer.cpp:
+            (WebCore::PlatformCALayer::clearContents):
+            * platform/graphics/ca/PlatformCALayer.h:
+            * platform/graphics/ca/cocoa/PlatformCALayerCocoa.h:
+            * platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm:
+            (WebCore::PlatformCALayerCocoa::setBackingStoreAttached):
+            (WebCore::PlatformCALayerCocoa::clearContents):
+            * platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h: Added.
+            (WebCore::PlatformCALayerContentsDelayedReleaser::WTF_GUARDED_BY_LOCK):
+            * platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm: Added.
+            (WebCore::PlatformCALayerContentsDelayedReleaser::singleton):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::takeLayerContents):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::mainThreadCommitWillStart):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::mainThreadCommitDidEnd):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitWillStart):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitDidEnd):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::updateSawOverlappingCommit):
+            (WebCore::PlatformCALayerContentsDelayedReleaser::clearRetainedContents):
+
</ins><span class="cx"> 2021-12-16  Alan Coon  <alancoon@apple.com>
</span><span class="cx"> 
</span><span class="cx">         Apply patch. rdar://problem/86505382
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreSourcesCocoatxt"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/SourcesCocoa.txt (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/SourcesCocoa.txt       2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/SourcesCocoa.txt  2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -331,6 +331,7 @@
</span><span class="cx"> platform/graphics/ca/cocoa/PlatformCAAnimationCocoa.mm
</span><span class="cx"> platform/graphics/ca/cocoa/PlatformCAFiltersCocoa.mm
</span><span class="cx"> platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm
</span><ins>+platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm
</ins><span class="cx"> platform/graphics/ca/cocoa/WebSystemBackdropLayer.mm
</span><span class="cx"> platform/graphics/ca/cocoa/WebTiledBackingLayer.mm
</span><span class="cx"> platform/graphics/ca/cocoa/WebVideoContainerLayer.mm
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreWebCorexcodeprojprojectpbxproj"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/WebCore.xcodeproj/project.pbxproj (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/WebCore.xcodeproj/project.pbxproj      2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/WebCore.xcodeproj/project.pbxproj 2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -6291,6 +6291,8 @@
</span><span class="cx">          0FA0A0E523AEAA35000EEB94 /* dialog.css */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.css; path = dialog.css; sourceTree = "<group>"; };
</span><span class="cx">          0FA24D77162DF91900A3F4C0 /* GraphicsLayerUpdater.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = GraphicsLayerUpdater.cpp; sourceTree = "<group>"; };
</span><span class="cx">          0FA24D78162DF91900A3F4C0 /* GraphicsLayerUpdater.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GraphicsLayerUpdater.h; sourceTree = "<group>"; };
</span><ins>+               0FA2B233276817540020C7C1 /* PlatformCALayerContentsDelayedReleaser.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = PlatformCALayerContentsDelayedReleaser.h; sourceTree = "<group>"; };
+               0FA2B235276817550020C7C1 /* PlatformCALayerContentsDelayedReleaser.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = PlatformCALayerContentsDelayedReleaser.mm; sourceTree = "<group>"; };
</ins><span class="cx">           0FB0689425243B90001E8E75 /* DisplayTextBox.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = DisplayTextBox.cpp; sourceTree = "<group>"; };
</span><span class="cx">          0FB0689625243B90001E8E75 /* DisplayTextBox.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = DisplayTextBox.h; sourceTree = "<group>"; };
</span><span class="cx">          0FB6252C18DE1B1500A07C05 /* GeometryUtilities.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = GeometryUtilities.cpp; sourceTree = "<group>"; };
</span><span class="lines">@@ -20068,6 +20070,8 @@
</span><span class="cx">                          0F13163F16ED0CDE0035CC04 /* PlatformCAFiltersCocoa.mm */,
</span><span class="cx">                          2D70BA1218074DDF0001908A /* PlatformCALayerCocoa.h */,
</span><span class="cx">                          4958782012A57DDF007238AC /* PlatformCALayerCocoa.mm */,
</span><ins>+                               0FA2B233276817540020C7C1 /* PlatformCALayerContentsDelayedReleaser.h */,
+                               0FA2B235276817550020C7C1 /* PlatformCALayerContentsDelayedReleaser.mm */,
</ins><span class="cx">                           31DEA4541B39F4D900F77178 /* WebSystemBackdropLayer.h */,
</span><span class="cx">                          31DEA4531B39F4D900F77178 /* WebSystemBackdropLayer.mm */,
</span><span class="cx">                          0F580FA11496939100FB5BD8 /* WebTiledBackingLayer.h */,
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCorepagescrollingScrollingTreeh"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/page/scrolling/ScrollingTree.h (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/page/scrolling/ScrollingTree.h 2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/page/scrolling/ScrollingTree.h    2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -259,7 +259,7 @@
</span><span class="cx">     void setGestureState(std::optional<WheelScrollGestureState>);
</span><span class="cx">     std::optional<WheelScrollGestureState> gestureState();
</span><span class="cx"> 
</span><del>-    void applyLayerPositionsInternal() WTF_REQUIRES_LOCK(m_treeLock);
</del><ins>+    WEBCORE_EXPORT virtual void applyLayerPositionsInternal() WTF_REQUIRES_LOCK(m_treeLock);
</ins><span class="cx">     void removeAllNodes() WTF_REQUIRES_LOCK(m_treeLock);
</span><span class="cx"> 
</span><span class="cx">     Lock m_treeLock; // Protects the scrolling tree.
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCorepagescrollingmacScrollingCoordinatorMach"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.h (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.h   2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.h      2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -50,6 +50,7 @@
</span><span class="cx">     void willStartRenderingUpdate() final;
</span><span class="cx">     void didCompleteRenderingUpdate() final;
</span><span class="cx"> 
</span><ins>+    void willStartPlatformRenderingUpdate() final;
</ins><span class="cx">     void didCompletePlatformRenderingUpdate() final;
</span><span class="cx"> 
</span><span class="cx">     void updateTiledScrollingIndicator();
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCorepagescrollingmacScrollingCoordinatorMacmm"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.mm (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.mm  2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingCoordinatorMac.mm     2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -33,6 +33,7 @@
</span><span class="cx"> #import "FrameView.h"
</span><span class="cx"> #import "Logging.h"
</span><span class="cx"> #import "Page.h"
</span><ins>+#import "PlatformCALayerContentsDelayedReleaser.h"
</ins><span class="cx"> #import "PlatformWheelEvent.h"
</span><span class="cx"> #import "Region.h"
</span><span class="cx"> #import "ScrollingStateTree.h"
</span><span class="lines">@@ -135,9 +136,15 @@
</span><span class="cx">     downcast<ThreadedScrollingTree>(scrollingTree())->didCompleteRenderingUpdate();
</span><span class="cx"> }
</span><span class="cx"> 
</span><ins>+void ScrollingCoordinatorMac::willStartPlatformRenderingUpdate()
+{
+    PlatformCALayerContentsDelayedReleaser::singleton().mainThreadCommitWillStart();
+}
+
</ins><span class="cx"> void ScrollingCoordinatorMac::didCompletePlatformRenderingUpdate()
</span><span class="cx"> {
</span><span class="cx">     downcast<ThreadedScrollingTree>(scrollingTree())->didCompletePlatformRenderingUpdate();
</span><ins>+    PlatformCALayerContentsDelayedReleaser::singleton().mainThreadCommitDidEnd();
</ins><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> void ScrollingCoordinatorMac::updateTiledScrollingIndicator()
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCorepagescrollingmacScrollingTreeMach"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.h (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.h  2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.h     2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -55,6 +55,9 @@
</span><span class="cx">     void deferWheelEventTestCompletionForReason(WheelEventTestMonitor::ScrollableAreaIdentifier, WheelEventTestMonitor::DeferReason) final;
</span><span class="cx">     void removeWheelEventTestCompletionDeferralForReason(WheelEventTestMonitor::ScrollableAreaIdentifier, WheelEventTestMonitor::DeferReason) final;
</span><span class="cx"> 
</span><ins>+    void registerForPlatformRenderingUpdateCallback();
+    void applyLayerPositionsInternal() final WTF_REQUIRES_LOCK(m_treeLock);
+
</ins><span class="cx">     void lockLayersForHitTesting() final WTF_ACQUIRES_LOCK(m_layerHitTestMutex);
</span><span class="cx">     void unlockLayersForHitTesting() final WTF_RELEASES_LOCK(m_layerHitTestMutex);
</span><span class="cx"> 
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCorepagescrollingmacScrollingTreeMacmm"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.mm (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.mm 2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/page/scrolling/mac/ScrollingTreeMac.mm    2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -28,6 +28,7 @@
</span><span class="cx"> 
</span><span class="cx"> #import "Logging.h"
</span><span class="cx"> #import "PlatformCALayer.h"
</span><ins>+#import "PlatformCALayerContentsDelayedReleaser.h"
</ins><span class="cx"> #import "ScrollingTreeFixedNode.h"
</span><span class="cx"> #import "ScrollingTreeFrameHostingNode.h"
</span><span class="cx"> #import "ScrollingTreeFrameScrollingNodeMac.h"
</span><span class="lines">@@ -38,6 +39,7 @@
</span><span class="cx"> #import "WebCoreCALayerExtras.h"
</span><span class="cx"> #import "WebLayer.h"
</span><span class="cx"> #import "WheelEventTestMonitor.h"
</span><ins>+#import <pal/spi/cocoa/QuartzCoreSPI.h>
</ins><span class="cx"> #import <wtf/text/TextStream.h>
</span><span class="cx"> 
</span><span class="cx"> #if ENABLE(ASYNC_SCROLLING) && ENABLE(SCROLLING_THREAD)
</span><span class="lines">@@ -240,6 +242,25 @@
</span><span class="cx">     m_layerHitTestMutex.unlock();
</span><span class="cx"> }
</span><span class="cx"> 
</span><ins>+void ScrollingTreeMac::applyLayerPositionsInternal()
+{
+    if (ScrollingThread::isCurrentThread())
+        registerForPlatformRenderingUpdateCallback();
+
+    ThreadedScrollingTree::applyLayerPositionsInternal();
+}
+
+void ScrollingTreeMac::registerForPlatformRenderingUpdateCallback()
+{
+    [CATransaction addCommitHandler:[] {
+        PlatformCALayerContentsDelayedReleaser::singleton().scrollingThreadCommitWillStart();
+    } forPhase:kCATransactionPhasePreLayout];
+
+    [CATransaction addCommitHandler:[] {
+        PlatformCALayerContentsDelayedReleaser::singleton().scrollingThreadCommitDidEnd();
+    } forPhase:kCATransactionPhasePostCommit];
+}
+
</ins><span class="cx"> void ScrollingTreeMac::setWheelEventTestMonitor(RefPtr<WheelEventTestMonitor>&& monitor)
</span><span class="cx"> {
</span><span class="cx">     m_wheelEventTestMonitor = WTFMove(monitor);
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscaGraphicsLayerCAcpp"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp       2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp  2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -2278,7 +2278,7 @@
</span><span class="cx">         if (m_backdropLayer)
</span><span class="cx">             m_backdropLayer->setHidden(false);
</span><span class="cx">     } else {
</span><del>-        m_layer->setContents(nullptr);
</del><ins>+        m_layer->clearContents();
</ins><span class="cx"> 
</span><span class="cx">         if (m_layerClones) {
</span><span class="cx">             for (auto& layer : m_layerClones->primaryLayerClones.values())
</span><span class="lines">@@ -2593,7 +2593,7 @@
</span><span class="cx">         m_layer->setNeedsDisplay();
</span><span class="cx">         m_hasEverPainted = false;
</span><span class="cx">     } else {
</span><del>-        m_layer->setContents(nullptr);
</del><ins>+        m_layer->clearContents();
</ins><span class="cx">         if (m_layerClones) {
</span><span class="cx">             for (auto& layer : m_layerClones->primaryLayerClones.values())
</span><span class="cx">                 layer->setContents(nullptr);
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscaPlatformCALayercpp"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.cpp (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.cpp       2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.cpp  2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -199,6 +199,11 @@
</span><span class="cx">     return *sharedPool;
</span><span class="cx"> }
</span><span class="cx"> 
</span><ins>+void PlatformCALayer::clearContents()
+{
+    setContents(nullptr);
+}
+
</ins><span class="cx"> void PlatformCALayer::dumpAdditionalProperties(TextStream&, OptionSet<PlatformLayerTreeAsTextFlags>)
</span><span class="cx"> {
</span><span class="cx"> }
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscaPlatformCALayerh"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.h (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.h 2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/PlatformCALayer.h    2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -189,6 +189,7 @@
</span><span class="cx">     virtual bool hasContents() const = 0;
</span><span class="cx">     virtual CFTypeRef contents() const = 0;
</span><span class="cx">     virtual void setContents(CFTypeRef) = 0;
</span><ins>+    virtual void clearContents();
</ins><span class="cx"> 
</span><span class="cx">     virtual void setContentsRect(const FloatRect&) = 0;
</span><span class="cx"> 
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerCocoah"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.h (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.h      2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.h 2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -120,6 +120,7 @@
</span><span class="cx">     bool hasContents() const override;
</span><span class="cx">     CFTypeRef contents() const override;
</span><span class="cx">     void setContents(CFTypeRef) override;
</span><ins>+    void clearContents() override;
</ins><span class="cx"> 
</span><span class="cx">     void setContentsRect(const FloatRect&) override;
</span><span class="cx"> 
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerCocoamm"></a>
<div class="modfile"><h4>Modified: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm (287154 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm     2021-12-16 21:05:43 UTC (rev 287154)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm        2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -35,6 +35,7 @@
</span><span class="cx"> #import "Model.h"
</span><span class="cx"> #import "PlatformCAAnimationCocoa.h"
</span><span class="cx"> #import "PlatformCAFilters.h"
</span><ins>+#import "PlatformCALayerContentsDelayedReleaser.h"
</ins><span class="cx"> #import "ScrollbarThemeMac.h"
</span><span class="cx"> #import "TileController.h"
</span><span class="cx"> #import "TiledBacking.h"
</span><span class="lines">@@ -684,7 +685,7 @@
</span><span class="cx">     if (attached)
</span><span class="cx">         setNeedsDisplay();
</span><span class="cx">     else
</span><del>-        setContents(nullptr);
</del><ins>+        clearContents();
</ins><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> bool PlatformCALayerCocoa::backingStoreAttached() const
</span><span class="lines">@@ -790,6 +791,15 @@
</span><span class="cx">     return (__bridge CFTypeRef)[m_layer contents];
</span><span class="cx"> }
</span><span class="cx"> 
</span><ins>+void PlatformCALayerCocoa::clearContents()
+{
+#if PLATFORM(MAC)
+    PlatformCALayerContentsDelayedReleaser::singleton().takeLayerContents(*this);
+#else
+    setContents(nullptr);
+#endif
+}
+
</ins><span class="cx"> void PlatformCALayerCocoa::setContents(CFTypeRef value)
</span><span class="cx"> {
</span><span class="cx">     BEGIN_BLOCK_OBJC_EXCEPTIONS
</span></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerContentsDelayedReleaserh"></a>
<div class="addfile"><h4>Added: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h (0 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h                            (rev 0)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.h       2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -0,0 +1,70 @@
</span><ins>+/*
+ * Copyright (C) 2021 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#if PLATFORM(MAC)
+
+#include <wtf/Lock.h>
+#include <wtf/ThreadSafeRefCounted.h>
+
+namespace WebCore {
+
+class PlatformCALayer;
+
+// This class exists to work around rdar://85892959, where CABackingStore objects would get released on the ScrollingThread
+// during scrolling commits, which can take long enough to cause scrolling frame drops.
+class PlatformCALayerContentsDelayedReleaser : ThreadSafeRefCounted<PlatformCALayerContentsDelayedReleaser> {
+    WTF_MAKE_NONCOPYABLE(PlatformCALayerContentsDelayedReleaser);
+public:
+    static PlatformCALayerContentsDelayedReleaser& singleton();
+
+    void takeLayerContents(PlatformCALayer&);
+    
+    void mainThreadCommitWillStart();
+    void mainThreadCommitDidEnd();
+
+    void scrollingThreadCommitWillStart();
+    void scrollingThreadCommitDidEnd();
+
+private:
+    friend LazyNeverDestroyed<PlatformCALayerContentsDelayedReleaser>;
+    
+    PlatformCALayerContentsDelayedReleaser();
+
+    void updateSawOverlappingCommit() WTF_REQUIRES_LOCK(m_lock);
+    void clearRetainedContents();
+
+    Vector<RetainPtr<CFTypeRef>> m_retainedContents;
+
+    Lock m_lock;
+    unsigned m_inMainThreadCommitEntryCount WTF_GUARDED_BY_LOCK(m_lock) { 0 };
+    unsigned m_scrollingThreadCommitEntryCount WTF_GUARDED_BY_LOCK(m_lock) { 0 };
+    bool m_hadOverlappingCommit WTF_GUARDED_BY_LOCK(m_lock) { false };
+};
+
+} // namespace WebCore
+
+#endif // PLATFORM(MAC)
</ins></span></pre></div>
<a id="branchessafari612branchSourceWebCoreplatformgraphicscacocoaPlatformCALayerContentsDelayedReleasermm"></a>
<div class="addfile"><h4>Added: branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm (0 => 287155)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm                           (rev 0)
+++ branches/safari-612-branch/Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm      2021-12-16 21:20:10 UTC (rev 287155)
</span><span class="lines">@@ -0,0 +1,130 @@
</span><ins>+/*
+ * Copyright (C) 2021 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#import "config.h"
+#import "PlatformCALayerContentsDelayedReleaser.h"
+
+#if PLATFORM(MAC)
+
+#import "PlatformCALayer.h"
+#import <wtf/RunLoop.h>
+
+namespace WebCore {
+
+PlatformCALayerContentsDelayedReleaser& PlatformCALayerContentsDelayedReleaser::singleton()
+{
+    static LazyNeverDestroyed<PlatformCALayerContentsDelayedReleaser> delayedReleaser;
+    static std::once_flag onceFlag;
+    std::call_once(onceFlag, [] {
+        delayedReleaser.construct();
+    });
+
+    return delayedReleaser;
+}
+
+PlatformCALayerContentsDelayedReleaser::PlatformCALayerContentsDelayedReleaser() = default;
+
+void PlatformCALayerContentsDelayedReleaser::takeLayerContents(PlatformCALayer& layer)
+{
+    ASSERT(isMainThread());
+
+    auto retainedContents = RetainPtr { layer.contents() };
+    if (retainedContents)
+        m_retainedContents.append(WTFMove(retainedContents));
+    layer.setContents(nullptr);
+}
+
+void PlatformCALayerContentsDelayedReleaser::mainThreadCommitWillStart()
+{
+    Locker locker { m_lock };
+    ++m_inMainThreadCommitEntryCount;
+    updateSawOverlappingCommit();
+}
+
+void PlatformCALayerContentsDelayedReleaser::mainThreadCommitDidEnd()
+{
+    bool bothCommitsDone;
+    bool hadOverlappingCommit;
+    {
+        Locker locker { m_lock };
+        ASSERT(m_inMainThreadCommitEntryCount);
+        --m_inMainThreadCommitEntryCount;
+        bothCommitsDone = !m_scrollingThreadCommitEntryCount && !m_inMainThreadCommitEntryCount;
+        hadOverlappingCommit = m_hadOverlappingCommit;
+    }
+
+    if (bothCommitsDone) {
+        if (hadOverlappingCommit && m_retainedContents.size()) {
+            RunLoop::main().dispatch([] {
+                PlatformCALayerContentsDelayedReleaser::singleton().clearRetainedContents();
+            });
+            return;
+        }
+
+        clearRetainedContents();
+    }
+}
+
+void PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitWillStart()
+{
+    ASSERT(!isMainThread());
+    Locker locker { m_lock };
+    ++m_scrollingThreadCommitEntryCount;
+    updateSawOverlappingCommit();
+}
+
+void PlatformCALayerContentsDelayedReleaser::scrollingThreadCommitDidEnd()
+{
+    ASSERT(!isMainThread());
+    Locker locker { m_lock };
+
+    ASSERT(m_scrollingThreadCommitEntryCount);
+    --m_scrollingThreadCommitEntryCount;
+    if (!m_scrollingThreadCommitEntryCount && !m_inMainThreadCommitEntryCount) {
+        if (m_hadOverlappingCommit) {
+            // m_retainedContents might be empty (it's not protected by the lock so we can't check it here),
+            // so this might be a pointless dispatch, but m_hadOverlappingCommit is rare.
+            RunLoop::main().dispatch([] {
+                PlatformCALayerContentsDelayedReleaser::singleton().clearRetainedContents();
+            });
+        }
+    }
+}
+
+void PlatformCALayerContentsDelayedReleaser::updateSawOverlappingCommit()
+{
+    m_hadOverlappingCommit |= (m_inMainThreadCommitEntryCount && m_scrollingThreadCommitEntryCount);
+}
+
+void PlatformCALayerContentsDelayedReleaser::clearRetainedContents()
+{
+    ASSERT(isMainThread());
+    m_retainedContents.clear();
+}
+
+} // namespace WebCore
+
+#endif
+
</ins></span></pre>
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