Changeset 210226 in webkit

Timestamp:

Jan 2, 2017, 1:16:09 PM (8 years ago)

Author:

akling@apple.com

Message:

Drop the render tree for documents in the page cache.
<​https://webkit.org/b/121798>

Reviewed by Antti Koivisto.

To save memory and reduce complexity, have documents tear down their render tree
when entering the page cache. I've wanted to do this for a long time and it seems
like we can actually do it now.

This patch will enable a number of clean-ups since it's no longer valid for renderers
to exist while the document is in page cache.

• dom/Document.cpp:

(WebCore::Document::destroyRenderTree): Remove assertion that we're not in the page cache
since we will now be tearing down render trees right as they enter the page cache.

• dom/PageCache.cpp:

(WebCore::destroyRenderTree):
(WebCore::PageCache::addIfCacheable): Tear down the render tree right before setting
the in-cache flag. The render tree is destroyed in bottom-up order to ensure that the
main frame renderers die last.

• history/CachedFrame.cpp:

(WebCore::CachedFrameBase::restore):

• page/FrameView.h:
• page/FrameView.cpp:

(WebCore::FrameView::didRestoreFromPageCache): Update the scollable area set after restoring
a frame from the page cache. This dirties the scrolling tree, which was covered by tests.

• page/animation/AnimationBase.cpp:

(WebCore::AnimationBase::setNeedsStyleRecalc):

• page/animation/AnimationController.cpp:

(WebCore::AnimationController::cancelAnimations): Make these no-ops if called
while the render tree is being torn down. This fixes some assertion failures
on layout tests and avoids pointless style invalidation.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• dom/Document.cpp (modified) (1 diff)
• history/CachedFrame.cpp (modified) (1 diff)
• history/PageCache.cpp (modified) (2 diffs)
• page/FrameView.cpp (modified) (1 diff)
• page/FrameView.h (modified) (1 diff)
• page/animation/AnimationBase.cpp (modified) (1 diff)
• page/animation/AnimationController.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2017-01-02  Andreas Kling  <akling@apple.com>
+
+        Drop the render tree for documents in the page cache.
+        <https://webkit.org/b/121798>
+
+        Reviewed by Antti Koivisto.
+
+        To save memory and reduce complexity, have documents tear down their render tree
+        when entering the page cache. I've wanted to do this for a long time and it seems
+        like we can actually do it now.
+
+        This patch will enable a number of clean-ups since it's no longer valid for renderers
+        to exist while the document is in page cache.
+
+        * dom/Document.cpp:
+        (WebCore::Document::destroyRenderTree): Remove assertion that we're not in the page cache
+        since we will now be tearing down render trees right as they enter the page cache.
+
+        * dom/PageCache.cpp:
+        (WebCore::destroyRenderTree):
+        (WebCore::PageCache::addIfCacheable): Tear down the render tree right before setting
+        the in-cache flag. The render tree is destroyed in bottom-up order to ensure that the
+        main frame renderers die last.
+
+        * history/CachedFrame.cpp:
+        (WebCore::CachedFrameBase::restore):
+        * page/FrameView.h:
+        * page/FrameView.cpp:
+        (WebCore::FrameView::didRestoreFromPageCache): Update the scollable area set after restoring
+        a frame from the page cache. This dirties the scrolling tree, which was covered by tests.
+
+        * page/animation/AnimationBase.cpp:
+        (WebCore::AnimationBase::setNeedsStyleRecalc):
+        * page/animation/AnimationController.cpp:
+        (WebCore::AnimationController::cancelAnimations): Make these no-ops if called
+        while the render tree is being torn down. This fixes some assertion failures
+        on layout tests and avoids pointless style invalidation.
+
 2017-01-02  Andreas Kling  <akling@apple.com>
 

trunk/Source/WebCore/dom/Document.cpp

@@ -2203 +2203 @@
 {
     ASSERT(hasLivingRenderTree());
-    ASSERT(m_pageCacheState != InPageCache);
 
     SetForScope<bool> change(m_renderTreeBeingDestroyed, true);

trunk/Source/WebCore/history/CachedFrame.cpp

@@ -131 +131 @@
 #endif
 
+    frame.view()->didRestoreFromPageCache();
 }
 

trunk/Source/WebCore/history/PageCache.cpp

@@ -365 +365 @@
 }
 
+// When entering page cache, tear down the render tree before setting the in-cache flag.
+// This maintains the invariant that render trees are never present in the page cache.
+// Note that destruction happens bottom-up so that the main frame's tree dies last.
+static void destroyRenderTree(MainFrame& mainFrame)
+{
+    for (Frame* frame = mainFrame.tree().traversePreviousWithWrap(true); frame; frame = frame->tree().traversePreviousWithWrap(false)) {
+        if (!frame->document())
+            continue;
+        auto& document = *frame->document();
+        if (document.hasLivingRenderTree())
+            document.destroyRenderTree();
+    }
+}
+
 static void firePageHideEventRecursively(Frame& frame)
 {
@@ -408 +422 @@
     }
 
+    destroyRenderTree(page->mainFrame());
+
     setPageCacheState(*page, Document::InPageCache);
 

trunk/Source/WebCore/page/FrameView.cpp

@@ -637 +637 @@
 }
 
+void FrameView::didRestoreFromPageCache()
+{
+    // When restoring from page cache, the main frame stays in place while subframes get swapped in.
+    // We update the scrollable area set to ensure that scrolling data structures get invalidated.
+    updateScrollableAreaSet();
+}
+
 void FrameView::setContentsSize(const IntSize& size)
 {

trunk/Source/WebCore/page/FrameView.h

@@ -588 +588 @@
     bool shouldPlaceBlockDirectionScrollbarOnLeft() const final;
 
+    void didRestoreFromPageCache();
+
 protected:
     bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect) override;

trunk/Source/WebCore/page/animation/AnimationBase.cpp

@@ -90 +90 @@
 void AnimationBase::setNeedsStyleRecalc(Element* element)
 {
-    ASSERT(!element || element->document().pageCacheState() == Document::NotInPageCache);
-    if (element)
-        element->invalidateStyleAndLayerComposition();
+    if (!element || element->document().renderTreeBeingDestroyed())
+        return;
+
+    ASSERT(element->document().pageCacheState() == Document::NotInPageCache);
+    element->invalidateStyleAndLayerComposition();
 }
 

trunk/Source/WebCore/page/animation/AnimationController.cpp

@@ -589 +589 @@
 
     Element* element = renderer.element();
-    ASSERT(!element || element->document().pageCacheState() == Document::NotInPageCache);
-    if (element)
-        element->invalidateStyleAndLayerComposition();
+    if (!element || element->document().renderTreeBeingDestroyed())
+        return;
+    ASSERT(element->document().pageCacheState() == Document::NotInPageCache);
+    element->invalidateStyleAndLayerComposition();
 }