Re: Memory ordering issue in LWLockRelease, WakeupWaiters, WALInsertSlotRelease

On 2014-02-10 11:20:30 -0500, Tom Lane wrote:
> I wrote:
> > You didn't really explain why you think that ordering is necessary?
> 
> Actually, after grepping to check my memory of what those fields are
> being used for, I have a bigger question: WTF is xlog.c doing being
> so friendly with the innards of LWLocks?  Surely this needs to get
> refactored so that most of WakeupWaiters() and friends is in lwlock.c.
> Or has all notion of modularity gone out the window while I wasn't
> looking?

Well, it's not actually using any lwlock.c code, it's a special case
locking logic, just reusing the datastructures. That said, I am not
particularly happy about the amount of code it's duplicating from
lwlock.c. Pretty much all of WALInsertSlotReleaseOne and most of
WALInsertSlotAcquireOne() is a copied.

Greetings,

Andres Freund

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