Reduce usages of String::createUninitialized

• Component: Web Template Framework
• Status: RESOLVED FIXED

[Annie Sullivan]

WTF::String is supposed to be immutable, but createUninitialized() allows callers to hang on to a non-const reference to the underlying data buffer. Some of these usages could be replaced by StringBuilder.

[Annie Sullivan]

Created attachment 104219 [details]
Patch

[Annie Sullivan]

If anyone has suggestions for performance benchmark tests to run before submitting, please comment.

[James Robinson]

PerformanceTests/Parser has a good test for the html parser.  I'm not sure if that test hits these codepaths or not.

[Annie Sullivan]

(In reply to comment #3)
> PerformanceTests/Parser has a good test for the html parser.  I'm not sure if that test hits these codepaths or not.

Numbers from html-parser.html look similar before/after applying my patch.

Before patch:
avg 1605.3
median 1604
stdev 9.935290634903437
min 1594
max 1629

After patch:
avg 1595.1
median 1592
stdev 6.579513659838393
min 1589
max 1609

[Adam Barth]

Comment on attachment 104219 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=104219&action=review

> Source/WebCore/html/parser/HTMLSourceTracker.cpp:59
> +    int length = token.endIndex() - token.startIndex();

int => size_t probably

[Adam Barth]

There shouldn't be any perf impact.  ReserveCapacity effectively does the same thing by pre-allocating the buffer.

[WebKit Review Bot]

Comment on attachment 104219 [details]
Patch

Clearing flags on attachment: 104219

Committed r93281: <http://trac.webkit.org/changeset/93281>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.