212223 - Charset alias performance issues

Status: RESOLVED WORKSFORME

(MailNews Core :: Internationalization, defect)

Description

[Boris Zbarsky [:bzbarsky]]

I'm looking at a jprof profile here...

There are 112 hits under nsStandardURL::SetSpec
Of these, 40 are under GetCharsetAlias; the breakdown is:

 84317   0       40 nsCharsetConverterManager::GetCharsetAlias
                 24 nsCOMPtr_base::assign_from_helper
                 10 _ZN15nsCharsetAlias212GetPreferredERK10nsACStringRS0_
                  1 _ZN13nsCOMPtr_baseD2Ev
                  1 _ZN12nsAutoStringC1Ev
                  1 _ZN9nsCStringD2Ev
                  1 _ZN10nsACString21do_AssignFromReadableERKS_
                  1 _Z7CompareRK10nsACStringS1_RK19nsCStringComparator
                  1 _ZNK9nsCString6LengthEv

There are a few issues here:

1)  We may want to cache the charset alias service
2)  GetPreferred should be much faster. Here is a breakdown of the time spent
    under GetPreferred:

 84234   2       11 _ZN15nsCharsetAlias212GetPreferredERK10nsACStringRS0_
                  4 _ZN10nsACString21do_AssignFromReadableERKS_
                  3 _ZN13nsCAutoStringC1ERK10nsACString
                  1 _Z7CompareRK10nsACStringS1_RK19nsCStringComparator
                  1 _ZNK26nsDefaultCStringComparatorclEPKcS1_j

Note that most of the time is spent copying about strings.  If this used a
hashtable with ascii keys and ascii values, most of this time could probably be
eliminated.

Comment 1

[Henri Sivonen (:hsivonen) (temporarily away from Bugzilla)]

This code is no longer in Core.

Comment 2

[Wayne Mery (:wsmwk)]

Could this still be an issue?

Comment 3

[Magnus Melin [:mkmelin]]

Let's close.