Bug 261123 – Performance improvement for the word boundary finding algorithm (findNextWordFromIndex)

• Status: NEW
• Component: HTML Editing

[Ahmad Saleem]

Hi Team,

While going through Blink's commit, I came across test case, where Safari hangs (it is performance test case, so it is kind of edge case).

Both Chrome Canary 118 and Firefox Nightly 118 are fast and complete it in 3xx milliseconds while I am unable to see timing for Safari due to hangs.

Test Case - in URL field.

Just wanted to raise so we can fix it.

Thanks!

[Karl Dubost]

This is indeed failing quite hard.

[Radar WebKit Bug Importer]

<rdar://problem/114954726>

[zalan]

Looks like we spend some time in nextWordFromIndex:forward

32.79 s   82.2%	0 s	 	                          WebCore::jsDOMSelectionPrototypeFunction_modify(JSC::JSGlobalObject*, JSC::CallFrame*)
32.79 s   82.2%	0 s	 	                           WebCore::DOMSelection::modify(WTF::String const&, WTF::String const&, WTF::String const&)
32.79 s   82.2%	0 s	 	                            WebCore::FrameSelection::modify(WebCore::FrameSelection::EAlteration, WebCore::SelectionDirection, WebCore::TextGranularity, WebCore::EUserTriggered)
32.79 s   82.2%	0 s	 	                             WebCore::FrameSelection::modifyExtendingForward(WebCore::TextGranularity)
32.79 s   82.2%	0 s	 	                              WebCore::FrameSelection::nextWordPositionForPlatform(WebCore::VisiblePosition const&)
32.79 s   82.2%	0 s	 	                               WebCore::nextWordPosition(WebCore::VisiblePosition const&)
32.79 s   82.2%	0 s	 	                                WebCore::nextBoundary(WebCore::VisiblePosition const&, unsigned int (*)(WTF::StringView, unsigned int, WebCore::BoundarySearchContextAvailability, bool&))
32.79 s   82.2%	0 s	 	                                 WebCore::forwardSearchForBoundaryWithTextIterator(WebCore::TextIterator&, WTF::Vector<char16_t, 1024ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>&, unsigned int, unsigned int (*)(WTF::StringView, unsigned int, WebCore::BoundarySearchContextAvailability, bool&))
29.34 s   73.6%	0 s	 	                                  WebCore::findNextWordFromIndex(WTF::StringView, int, bool)
27.03 s   67.8%	0 s	 	                                   -[NSAttributedString(NSAttributedStringUIFoundationAdditions) nextWordFromIndex:forward:]

(changing component to editing)