307557 - Only guess system timezone once per session

Status: RESOLVED FIXED

(Calendar :: General, defect)

Description

[Joey Minta]

Currently, calendarUtils.js (used by both lightning and sunbird) has a
calendarDefaultTimezone() function that guesses the system timezone, if one is
not defined.  This is a rather expensive call to make though, as it iterates
through many timezones that have to be parsed from an ics file.  A better
solution would be to only guess the timezone on startup, and then cache that
value.  This would introduce the small downside that any changes to the system
timezone would require a restart to be recognized.  However, for an 0.x program,
that seems like a legitimate limitation, especially for the performance boost.

Comment 1

[Michiel van Leeuwen (email: mvl+moz@)]

http://lxr.mozilla.org/seamonkey/source/calendar/resources/content/calendarUtils.js#205

That code already caches, so we really only guess once. The result of the
guessing isn't stored, so on the next run the guess is made again. But never
twice in the same session.

I think this bug is worksforme.

Comment 2

[Joey Minta]

OK, this is somewhat worksforme.  Using the patch from Bug 307344, I see proper
caching in calendarWindow.  However, anytime the event dialog opens, the guess
is re-run.  We should improve that, but since that's the only problem I see,
this bug is much less of a priority.

Comment 3

[Joey Minta]

Good first bug: gDefaultTimezone becomes -1 again, since global variables belong to a specific window.  Perf related, so we want this for 0.3b (or whatever it's going to be called)

Comment 4

[Matthew (lilmatt) Willis]

Reassigning all automatically assigned bugs from Mostafa to nobody@m.o

Bugspam filter: TorontoMostafaMove

Comment 5

[Joey Minta]

Attachment: use opener scope

This is a significant enough performance win that I'd like to get it for 0.3.  By calling calendarDefaultTimezone in the opener's scope, we can use that cached value, rather than re-guessing.  You should notice the performance win every time you open the event dialog.

Comment 6

[Joey Minta]

Comment on attachment 231035 [details] [diff] [review]
use opener scope

r=dmose

Comment 7

[Joey Minta]

patch checked in.