[mythtv] [Fwd: Re: [mythtv-commits] Re: Ticket #341: Music database update does not reread metadata]

Daniel Kristjansson danielk at cuymedia.net
Fri Oct 28 09:40:40 EDT 2005


On Fri, 2005-10-28 at 03:50 +0000, MythTV wrote:
> #341: Music database update does not reread metadata
> ------------------------------------+---------------------------------------
>  Reporter:  eskil <myth at eskil.org>  |        Owner:  ijr   
>      Type:  patch                   |       Status:  closed
>  Priority:  minor                   |    Milestone:  0.19  
> Component:  mythmusic               |      Version:  head  
>  Severity:  low                     |   Resolution:  fixed 
> ------------------------------------+---------------------------------------
> Comment (by ijr):
> 
>  Daniel, err, stuff's not right in your comments/code.  'deleteLater' is
>  only useful for deleting a QObject from the non-Qt thread,
Yep, I'm sorry if I said something different. I actually started
writing up a proper an explanation of this last night.

>  or when there may be pending events delivered.
It is still safe to use plain old delete in the Qt event thread in the
presence of posted events, only a QApp::sendEvent() from outside the
event thread are unsafe. AFAIC, AutoExpire is the only class that uses
this unsafe event dispatch.

>  It doesn't really do anything at all for signals/slots, so the 
> 'deleteLater's that you've added here aren't doing anything useful at all.
My fear was that MythBusyDialog might be deleted from a thread other
than a Qt thread because it is a busy dialog.

BTW deleteLater() does prevent the class from being deleted while you
are receiving a signal from the Qt event thread (a timer event say).

But you do need to disconnect() all the signals you are getting from
other threads, and disconnect() is no more thread safe than signal
emission itself. I wish trolltech had made the signal/slot mechanism
thread-safe by default, and then added the option of doing your own
more fine grained locking.

-- Daniel




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