Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: b0d52573ef1d019347c8f3ef4d5fc95866106572
https://github.com/WebKit/WebKit/commit/b0d52573ef1d019347c8f3ef4d5fc95866106572
Author: Ahmad Saleem <[email protected]>
Date: 2026-07-13 (Mon, 13 Jul 2026)
Changed paths:
M Source/WebCore/Modules/fetch/FetchHeaders.cpp
Log Message:
-----------
FetchHeaders::appendToHeaderMap does a redundant header-map lookup on every
append
https://bugs.webkit.org/show_bug.cgi?id=318701
rdar://181516418
Reviewed by Chris Dumez.
When appending a header, appendToHeaderMap() called
HTTPHeaderMap::contains(name)
and then HTTPHeaderMap::get(name) to build the combined value. Both calls
perform
the same resolution work -- findHTTPHeaderName() followed by a common-header
probe
or a linear scan of the uncommon headers -- so every appended header paid for
two
identical lookups.
HTTPHeaderMap::get() already returns a null String when the header is absent,
and
a present header always stores a non-null value, so a single get() plus an
isNull() check is equivalent to the contains()/get() pair. Collapse the two
lookups into one.
The optimization relies on the invariant that a header present in the map never
stores a null value. To guard against that invariant silently breaking, assert
it in debug builds before relying on the isNull() check.
No change in behavior; covered by existing fetch tests.
* Source/WebCore/Modules/fetch/FetchHeaders.cpp:
(WebCore::appendToHeaderMap):
Canonical link: https://commits.webkit.org/317044@main
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