Implement style invalidation tree walk for targeted style recalc upon class change.

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 1510 matching lines @@
 {
     if (!root) {
         exceptionState.throwDOMException(NotSupportedError, "The provided node is invalid.");
         return 0;
     }
     return TreeWalker::create(root, whatToShow, filter);
 }
 
 bool Document::shouldCallRecalcStyleForDocument()
 {
-    return needsStyleRecalc() || childNeedsStyleRecalc() || childNeedsDistributionRecalc() || !m_useElementsNeedingUpdate.isEmpty();
+    return needsStyleRecalc() || childNeedsStyleRecalc() || childNeedsDistributionRecalc() || !m_useElementsNeedingUpdate.isEmpty() || childNeedsStyleInvalidation();
 }
 
 void Document::scheduleStyleRecalc()
 {
     if (!isActive())
         return;
 
     if (m_styleRecalcTimer.isActive() || !shouldScheduleLayout())
         return;
 
@@ skipping 21 matching lines @@
 }
 
 void Document::updateDistributionIfNeeded()
 {
     if (!childNeedsDistributionRecalc())
         return;
     TRACE_EVENT0("webkit", "Document::recalcDistribution");
     recalcDistribution();
 }
 
+void Document::updateStyleInvalidationIfNeeded()
+{
+    if (!childNeedsStyleInvalidation())
+        return;
+    TRACE_EVENT0("webkit", "Document::computeNeedsStyleRecalcState");
+    if (!styleResolver()) {
+        clearChildNeedsStyleInvalidation();

[ojan, 2014/01/29 00:50:07]

I think we still need to do the style invalidation walk even if there's no
styleResolver, no?

[chrishtr, 2014/01/29 01:56:42]

The style invalidation data structure lives in the styleResolver() object right
now, so either that is incorrect (even with the style resolver reset timer
removed), or the code is ok. Is it ok so long as the style resolver is never
cleared?

[ojan, 2014/01/29 02:00:25]

I see. Yeah, it seems like we have to block turning this flag on on getting rid
of the reset timer. Otherwise, you'll get in a situation where you don't do the
style invalidation in some cases and miss doing some recalcs you need to do,
right?

[chrishtr, 2014/01/29 02:02:32]

Yes. My plan is to try to land the change that removes the timer, but not block
this CL on that, since the code in this CL is behind a flag. If I can't get the
other change to land, I'll move the data for this CL elsewhere in a followup.

+        return;
+    }
+
+    // FIXME: the style resolver can be deleted at present. Either resolve
+    // crbug.com/335964 or move the invalidation data elsewhere.

[ojan, 2014/01/29 00:50:07]

You can use use ensureStyleResolver(). I don't see any problem with recreateding
the styleResolver here if it doesn't exist. You're going to need it right after
this to do the rest of the styleRecalc anyways.

[chrishtr, 2014/01/29 01:56:42]

See above.

+    styleResolver()->ensureRuleFeatureSet().computeStyleInvalidation(*this);
+}
+
 void Document::updateDistributionForNodeIfNeeded(Node* node)
 {
     if (node->inDocument()) {
         updateDistributionIfNeeded();
         return;
     }
     Node* root = node;
     while (Node* host = root->shadowHost())
         root = host;
     while (Node* ancestor = root->parentOrShadowHostNode())
@@ skipping 68 matching lines @@
                 body->setNeedsStyleRecalc();
         }
     }
 
     if (RenderStyle* style = documentElement()->renderStyle()) {
         if (style->direction() != rootDirection || style->writingMode() != rootWritingMode)
             documentElement()->setNeedsStyleRecalc();
     }
 }
 
+// FIXME: need a better name than recalcStyle. It's performing style invalidation, style recalc, and distribution.
 void Document::recalcStyle(StyleRecalcChange change)
 {
     // we should not enter style recalc while painting
     RELEASE_ASSERT(!view() || !view()->isPainting());
 
     // FIXME: We should never enter here without a FrameView or with an inactive document.
     if (!isActive() || !view())
         return;
 
     if (m_inStyleRecalc)
         return;
 
     TRACE_EVENT0("webkit", "Document::recalcStyle");
     TRACE_EVENT_SCOPED_SAMPLING_STATE("Blink", "RecalcStyle");
 
     InspectorInstrumentationCookie cookie = InspectorInstrumentation::willRecalculateStyle(this);
 
     updateDistributionIfNeeded();
     updateUseShadowTrees();
+    updateStyleInvalidationIfNeeded();
 
     if (m_evaluateMediaQueriesOnStyleRecalc) {
         m_evaluateMediaQueriesOnStyleRecalc = false;
         evaluateMediaQueryList();
     }
 
     // FIXME: We should update style on our ancestor chain before proceeding
     // however doing so currently causes several tests to crash, as Frame::setDocument calls Document::attach
     // before setting the DOMWindow on the Frame, or the SecurityOrigin on the document. The attach, in turn
     // resolves style (here) and then when we resolve style on the parent chain, we may end up
@@ skipping 82 matching lines @@
 void Document::updateStyleForNodeIfNeeded(Node* node)
 {
     if (!shouldCallRecalcStyleForDocument())
         return;
 
     // At this point, we know that we need to recalc some style on the document in order to fully update styles.
     // However, style on 'node' only needs to be recalculated if a global recomputation is needed, or a node on
     // the path from 'node' to the root needs style recalc.
 
     // Global needed.
-    bool needsRecalc = needsStyleRecalc() || childNeedsDistributionRecalc() || !m_useElementsNeedingUpdate.isEmpty();
+    bool needsRecalc = needsStyleRecalc() || childNeedsDistributionRecalc() || !m_useElementsNeedingUpdate.isEmpty() || childNeedsStyleInvalidation();
 
     // On the path.
     for (Node* ancestor = node; ancestor && !needsRecalc; ancestor = ancestor->parentOrShadowHostNode())
         needsRecalc = ancestor->needsStyleRecalc();
     if (needsRecalc)
         updateStyleIfNeeded();
 }
 
 void Document::updateLayout()
 {
@@ skipping 3526 matching lines @@
     if (!page->focusController().isActive() || !page->focusController().isFocused())
         return false;
     if (Frame* focusedFrame = page->focusController().focusedFrame()) {
         if (focusedFrame->tree().isDescendantOf(frame()))
             return true;
     }
     return false;
 }
 
 } // namespace WebCore