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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/174960">174960</a></dd>
<dt>Author</dt> <dd>carlosgc@webkit.org</dd>
<dt>Date</dt> <dd>2014-10-21 07:46:59 -0700 (Tue, 21 Oct 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/174345">r174345</a> - AX: Performance: Certain Web site causes Safari to hang completely while entering form data
https://bugs.webkit.org/show_bug.cgi?id=137420
Reviewed by Mario Sanchez Prada.
If a website has multiple nested tables that are not "accessibility" tables, the performance of accessibility slows to a crawl because:
1) We are re-computing accessibilityIsIgnored many times.
As a solution, we can enable the isIgnoredCache when updating children.
2) When asking if an object isTableCell, we'd go up the parent chain, asking each of those parents the same question, which exploded into calling this many times.
As a solution, I've changed our determination of isTableCell to instead check if the parent is an accessibiltyTable which should be much faster.
No new functionality. Existing tests cover changes.
* accessibility/AccessibilityObject.cpp:
(WebCore::AccessibilityObject::updateChildrenIfNecessary):
(WebCore::AccessibilityObject::accessibilityIsIgnored):
* accessibility/AccessibilityTableCell.cpp:
(WebCore::AccessibilityTableCell::parentTable):
(WebCore::AccessibilityTableCell::isTableCell):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#releasesWebKitGTKwebkit26SourceWebCoreChangeLog">releases/WebKitGTK/webkit-2.6/Source/WebCore/ChangeLog</a></li>
<li><a href="#releasesWebKitGTKwebkit26SourceWebCoreaccessibilityAccessibilityObjectcpp">releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityObject.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit26SourceWebCoreaccessibilityAccessibilityTableCellcpp">releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityTableCell.cpp</a></li>
</ul>
</div>
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<h3>Diff</h3>
<a id="releasesWebKitGTKwebkit26SourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.6/Source/WebCore/ChangeLog (174959 => 174960)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.6/Source/WebCore/ChangeLog 2014-10-21 14:27:49 UTC (rev 174959)
+++ releases/WebKitGTK/webkit-2.6/Source/WebCore/ChangeLog 2014-10-21 14:46:59 UTC (rev 174960)
</span><span class="lines">@@ -1,3 +1,25 @@
</span><ins>+2014-10-06 Chris Fleizach <cfleizach@apple.com>
+
+ AX: Performance: Certain Web site causes Safari to hang completely while entering form data
+ https://bugs.webkit.org/show_bug.cgi?id=137420
+
+ Reviewed by Mario Sanchez Prada.
+
+ If a website has multiple nested tables that are not "accessibility" tables, the performance of accessibility slows to a crawl because:
+ 1) We are re-computing accessibilityIsIgnored many times.
+ As a solution, we can enable the isIgnoredCache when updating children.
+ 2) When asking if an object isTableCell, we'd go up the parent chain, asking each of those parents the same question, which exploded into calling this many times.
+ As a solution, I've changed our determination of isTableCell to instead check if the parent is an accessibiltyTable which should be much faster.
+
+ No new functionality. Existing tests cover changes.
+
+ * accessibility/AccessibilityObject.cpp:
+ (WebCore::AccessibilityObject::updateChildrenIfNecessary):
+ (WebCore::AccessibilityObject::accessibilityIsIgnored):
+ * accessibility/AccessibilityTableCell.cpp:
+ (WebCore::AccessibilityTableCell::parentTable):
+ (WebCore::AccessibilityTableCell::isTableCell):
+
</ins><span class="cx"> 2014-10-19 Carlos Garcia Campos <cgarcia@igalia.com>
</span><span class="cx">
</span><span class="cx"> [GTK] Move GtkDragAndDropHelper from Platform to WebKit2
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit26SourceWebCoreaccessibilityAccessibilityObjectcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityObject.cpp (174959 => 174960)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityObject.cpp 2014-10-21 14:27:49 UTC (rev 174959)
+++ releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityObject.cpp 2014-10-21 14:46:59 UTC (rev 174960)
</span><span class="lines">@@ -1583,8 +1583,11 @@
</span><span class="cx">
</span><span class="cx"> void AccessibilityObject::updateChildrenIfNecessary()
</span><span class="cx"> {
</span><del>- if (!hasChildren())
- addChildren();
</del><ins>+ if (!hasChildren()) {
+ // Enable the cache in case we end up adding a lot of children, we don't want to recompute axIsIgnored each time.
+ AXAttributeCacheEnabler enableCache(axObjectCache());
+ addChildren();
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void AccessibilityObject::clearChildren()
</span><span class="lines">@@ -2500,7 +2503,8 @@
</span><span class="cx"> bool AccessibilityObject::accessibilityIsIgnored() const
</span><span class="cx"> {
</span><span class="cx"> AXComputedObjectAttributeCache* attributeCache = nullptr;
</span><del>- if (AXObjectCache* cache = axObjectCache())
</del><ins>+ AXObjectCache* cache = axObjectCache();
+ if (cache)
</ins><span class="cx"> attributeCache = cache->computedObjectAttributeCache();
</span><span class="cx">
</span><span class="cx"> if (attributeCache) {
</span><span class="lines">@@ -2517,7 +2521,8 @@
</span><span class="cx">
</span><span class="cx"> bool result = computeAccessibilityIsIgnored();
</span><span class="cx">
</span><del>- if (attributeCache)
</del><ins>+ // In case computing axIsIgnored disables attribute caching, we should refetch the object to see if it exists.
+ if (cache && (attributeCache = cache->computedObjectAttributeCache()))
</ins><span class="cx"> attributeCache->setIgnored(axObjectID(), result ? IgnoreObject : IncludeObject);
</span><span class="cx">
</span><span class="cx"> return result;
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit26SourceWebCoreaccessibilityAccessibilityTableCellcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityTableCell.cpp (174959 => 174960)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityTableCell.cpp 2014-10-21 14:27:49 UTC (rev 174959)
+++ releases/WebKitGTK/webkit-2.6/Source/WebCore/accessibility/AccessibilityTableCell.cpp 2014-10-21 14:46:59 UTC (rev 174960)
</span><span class="lines">@@ -86,17 +86,20 @@
</span><span class="cx"> // by javascript, and creating a table element may try to access the render tree while in a bad state.
</span><span class="cx"> // By using only get() implies that the AXTable must be created before AXTableCells. This should
</span><span class="cx"> // always be the case when AT clients access a table.
</span><del>- // https://bugs.webkit.org/show_bug.cgi?id=42652
- return toAccessibilityTable(axObjectCache()->get(toRenderTableCell(m_renderer)->table()));
</del><ins>+ // https://bugs.webkit.org/show_bug.cgi?id=42652
+ AccessibilityObject* parentTable = axObjectCache()->get(toRenderTableCell(m_renderer)->table());
+ if (!parentTable || !parentTable->isTable())
+ return nullptr;
+ return toAccessibilityTable(parentTable);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> bool AccessibilityTableCell::isTableCell() const
</span><span class="cx"> {
</span><del>- AccessibilityObject* parent = parentObjectUnignored();
- if (!parent || !parent->isTableRow())
- return false;
-
- return true;
</del><ins>+ // If the parent table is an accessibility table, then we are a table cell.
+ // This used to check if the unignoredParent was a row, but that exploded performance if
+ // this was in nested tables. This check should be just as good.
+ AccessibilityObject* parentTable = this->parentTable();
+ return parentTable && parentTable->isAccessibilityTable();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> AccessibilityRole AccessibilityTableCell::determineAccessibilityRole()
</span></span></pre>
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