Title: [156902] trunk/Source/WebCore
- Revision
- 156902
- Author
- [email protected]
- Date
- 2013-10-04 11:41:09 -0700 (Fri, 04 Oct 2013)
Log Message
Optimize strings copies in srcset parser
https://bugs.webkit.org/show_bug.cgi?id=121899
Patch by Romain Perier <[email protected]> on 2013-10-04
Reviewed by Alexey Proskuryakov.
No new tests, covered by existing ones.
* html/parser/HTMLParserIdioms.cpp:
(WebCore::parseImagesWithScaleFromSrcsetAttribute): Don't copy
image.imageURL at each loop iteration, save indexes instead.
(WebCore::bestFitSourceForImageAttributes): Make a String for
the URL only when the corresponding candidate is chosen
by the selection algorithm. It reduces the number of copies
significantly and improves performance
(around 30% with the "Release" profile and 60% with the "Debug" one).
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (156901 => 156902)
--- trunk/Source/WebCore/ChangeLog 2013-10-04 18:40:03 UTC (rev 156901)
+++ trunk/Source/WebCore/ChangeLog 2013-10-04 18:41:09 UTC (rev 156902)
@@ -1,3 +1,21 @@
+2013-10-04 Romain Perier <[email protected]>
+
+ Optimize strings copies in srcset parser
+ https://bugs.webkit.org/show_bug.cgi?id=121899
+
+ Reviewed by Alexey Proskuryakov.
+
+ No new tests, covered by existing ones.
+
+ * html/parser/HTMLParserIdioms.cpp:
+ (WebCore::parseImagesWithScaleFromSrcsetAttribute): Don't copy
+ image.imageURL at each loop iteration, save indexes instead.
+ (WebCore::bestFitSourceForImageAttributes): Make a String for
+ the URL only when the corresponding candidate is chosen
+ by the selection algorithm. It reduces the number of copies
+ significantly and improves performance
+ (around 30% with the "Release" profile and 60% with the "Debug" one).
+
2013-10-04 Alexey Proskuryakov <[email protected]>
Add svn:ignore to *.pyc files in inspector/Scripts directory, so that they don't
Modified: trunk/Source/WebCore/html/parser/HTMLParserIdioms.cpp (156901 => 156902)
--- trunk/Source/WebCore/html/parser/HTMLParserIdioms.cpp 2013-10-04 18:40:03 UTC (rev 156901)
+++ trunk/Source/WebCore/html/parser/HTMLParserIdioms.cpp 2013-10-04 18:41:09 UTC (rev 156902)
@@ -300,11 +300,20 @@
#endif
struct ImageWithScale {
- String imageURL;
+ unsigned imageURLStart;
+ unsigned imageURLLength;
float scaleFactor;
- bool operator==(const ImageWithScale& image) const
+
+ ImageWithScale()
+ : imageURLStart(0)
+ , imageURLLength(0)
+ , scaleFactor(1)
+ {
+ }
+
+ bool hasImageURL() const
{
- return scaleFactor == image.scaleFactor && imageURL == image.imageURL;
+ return imageURLLength;
}
};
typedef Vector<ImageWithScale> ImageCandidates;
@@ -390,7 +399,8 @@
}
}
ImageWithScale image;
- image.imageURL = String(srcsetAttribute.characters() + imageURLStart, imageURLEnd - imageURLStart);
+ image.imageURLStart = imageURLStart;
+ image.imageURLLength = imageURLEnd - imageURLStart;
image.scaleFactor = imageScaleFactor;
imageCandidates.append(image);
@@ -406,11 +416,8 @@
parseImagesWithScaleFromSrcsetAttribute(srcsetAttribute, imageCandidates);
if (!srcAttribute.isEmpty()) {
- ImageWithScale image;
- image.imageURL = srcAttribute;
- image.scaleFactor = 1.0;
-
- imageCandidates.append(image);
+ ImageWithScale srcPlaceholderImage;
+ imageCandidates.append(srcPlaceholderImage);
}
if (imageCandidates.isEmpty())
@@ -420,9 +427,10 @@
for (size_t i = 0; i < imageCandidates.size() - 1; ++i) {
if (imageCandidates[i].scaleFactor >= deviceScaleFactor)
- return String(imageCandidates[i].imageURL);
+ return imageCandidates[i].hasImageURL() ? srcsetAttribute.substringSharingImpl(imageCandidates[i].imageURLStart, imageCandidates[i].imageURLLength) : srcAttribute;
}
- return String(imageCandidates.last().imageURL);
+ const ImageWithScale& lastCandidate = imageCandidates.last();
+ return lastCandidate.hasImageURL() ? srcsetAttribute.substringSharingImpl(lastCandidate.imageURLStart, lastCandidate.imageURLLength) : srcAttribute;
}
}
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