Bug 24463

Summary: Do not detach/copy QString twice in WebCore::qstring
Product: WebKit Reporter: Adam Treat <manyoso>
Component: WebKit QtAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal CC: hausmann, staikos
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Other   
OS: All   
Attachments:
Description Flags
Don't detach so often staikos: review+

Adam Treat
Reported 2009-03-09 09:17:18 PDT
Currently, WebCore::qstring is detaching and copying twice for every single TextRun that is processed and drawn. This is a very expensive operation and profiling suggests this method is one of the top ten most expensive operations in all of QtWebKit. The patch attached minimizes the QString copying/detaching to only those cases where it is necessary. Even with this change this method is still a very expensive operation since almost all TextRuns contain a character that needs special handling by the QTextEngine. A forthcoming patch will address this too, but it requires an addition to Qt's API.
Attachments
Don't detach so often (3.92 KB, patch)
2009-03-09 09:21 PDT, Adam Treat 		staikos: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Adam Treat
Comment 1 2009-03-09 09:21:43 PDT
Created attachment 28414 [details] Don't detach so often
Adam Treat
Comment 2 2009-03-09 09:39:34 PDT
Landed with r41527.
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