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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/169729">169729</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2014-06-09 16:29:57 -0700 (Mon, 09 Jun 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>Document::updateStyleIfNeededForNode can get very expensive
https://bugs.webkit.org/show_bug.cgi?id=133599
Patch by Benjamin Poulain <bpoulain@apple.com> on 2014-06-09
Reviewed by Andreas Kling.
When pages are querying their style, we first run through
Document::updateStyleIfNeededForNode() to find if that particular node needs style recalc.
The problem was that updateStyleIfNeededForNode() could get really expensive. For each node,
it needs to check the whole parent chain to find if any needs style recalc.
When web pages get a bunch of nodes and querying their style, we ended up going over a lot
of nodes just to find there is nothing to do.
This patch adds two tweaks to reduce the problem:
First, before querying nodeOrItsAncestorNeedsStyleRecalc() we check if the Document is dirty at all.
The other part is making nodeOrItsAncestorNeedsStyleRecalc() faster by removing useless elements check.
* dom/Document.cpp:
(WebCore::nodeOrItsAncestorNeedsStyleRecalc):
(WebCore::Document::updateStyleIfNeededForNode):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoredomDocumentcpp">trunk/Source/WebCore/dom/Document.cpp</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (169728 => 169729)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2014-06-09 23:20:11 UTC (rev 169728)
+++ trunk/Source/WebCore/ChangeLog 2014-06-09 23:29:57 UTC (rev 169729)
</span><span class="lines">@@ -1,3 +1,26 @@
</span><ins>+2014-06-09 Benjamin Poulain <bpoulain@apple.com>
+
+ Document::updateStyleIfNeededForNode can get very expensive
+ https://bugs.webkit.org/show_bug.cgi?id=133599
+
+ Reviewed by Andreas Kling.
+
+ When pages are querying their style, we first run through
+ Document::updateStyleIfNeededForNode() to find if that particular node needs style recalc.
+
+ The problem was that updateStyleIfNeededForNode() could get really expensive. For each node,
+ it needs to check the whole parent chain to find if any needs style recalc.
+ When web pages get a bunch of nodes and querying their style, we ended up going over a lot
+ of nodes just to find there is nothing to do.
+
+ This patch adds two tweaks to reduce the problem:
+ First, before querying nodeOrItsAncestorNeedsStyleRecalc() we check if the Document is dirty at all.
+ The other part is making nodeOrItsAncestorNeedsStyleRecalc() faster by removing useless elements check.
+
+ * dom/Document.cpp:
+ (WebCore::nodeOrItsAncestorNeedsStyleRecalc):
+ (WebCore::Document::updateStyleIfNeededForNode):
+
</ins><span class="cx"> 2014-06-09 Enrica Casucci <enrica@apple.com>
</span><span class="cx">
</span><span class="cx"> iOS WebKit: Crash in charactersAroundPosition.
</span></span></pre></div>
<a id="trunkSourceWebCoredomDocumentcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/dom/Document.cpp (169728 => 169729)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/dom/Document.cpp 2014-06-09 23:20:11 UTC (rev 169728)
+++ trunk/Source/WebCore/dom/Document.cpp 2014-06-09 23:29:57 UTC (rev 169729)
</span><span class="lines">@@ -6111,7 +6111,7 @@
</span><span class="cx">
</span><span class="cx"> static inline bool nodeOrItsAncestorNeedsStyleRecalc(const Node& node)
</span><span class="cx"> {
</span><del>- for (const Node* n = &node; n; n = n->parentOrShadowHostElement()) {
</del><ins>+ for (const Node* n = &node; n; n = n->parentOrShadowHostNode()) {
</ins><span class="cx"> if (n->needsStyleRecalc())
</span><span class="cx"> return true;
</span><span class="cx"> }
</span><span class="lines">@@ -6120,7 +6120,7 @@
</span><span class="cx">
</span><span class="cx"> bool Document::updateStyleIfNeededForNode(const Node& node)
</span><span class="cx"> {
</span><del>- if (!hasPendingForcedStyleRecalc() && !nodeOrItsAncestorNeedsStyleRecalc(node))
</del><ins>+ if (!hasPendingForcedStyleRecalc() && !(childNeedsStyleRecalc() && nodeOrItsAncestorNeedsStyleRecalc(node)))
</ins><span class="cx"> return false;
</span><span class="cx"> updateStyleIfNeeded();
</span><span class="cx"> return true;
</span></span></pre>
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