Re: Stefan's bug (was: max_standby_delay considered harmful) - Mailing list pgsql-hackers

On Tue, 2010-05-18 at 16:05 +0900, Fujii Masao wrote:
> >>> >> ISTM that we can use XLogCtl->SharedRecoveryInProgress for that.
> >>> >> Is this OK?
> >>> >
> >>> > That can change state at any time. Would that work?
> >>>
> >>> Yes. XLogCtl->SharedRecoveryInProgress is set to TRUE only when
> >>> XLogCtl structure is initialized (i.e., XLOGShmemInit), and it's
> >>> set to FALSE only at the end of recovery.
> >>
> >> You should be using RecoveryInProgress()
> >
> > Isn't access to a bool variable atomic?
> 
> If it's not atomic, I'll add the following comment into CancelBackup():
> 
>     Don't bother with lock to access XLogCtl->SharedRecoveryInProgress,
>     because there should be no other processes running when this code
>     is reached.

Call it via a function. There is no need for postmaster to know the
innards of xlog.c, which could change in future. Modularity.

-- Simon Riggs           www.2ndQuadrant.com