Re: FlexLocks

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Well, it would certainly be easy enough to add those macros, and I'm
> not necessarily opposed to it, but I fear it could end up being a bit
> confusing in the long run. If we adopt this infrastructure, then I
> expect knowledge of different types of FlexLocks to gradually
> propagate through the system. Now, you're always going to use
> LWLockAcquire() and LWLockRelease() to acquire and release an LWLock,
> but a FlexLockId isn't guaranteed to be an LWLockId - any given value
> might also refer to a FlexLock of some other type. If we let everyone
> continue to refer to those things as LWLockIds, then it seems like
> only a matter of time before someone has a variable that's declared as
> LWLockId but actually doesn't refer to an LWLock at all. I think it's
> better to bite the bullet and do the renaming up front, rather than
> having to think about it every time you modify some code that uses
> LWLockId or LWLockHeldByMe and say to yourself, "oh, wait a minute, is
> this really guaranteed to be an LWLock?"

In that case, I think you've chosen an unfortunate naming convention
and should rethink it. There is not any benefit to be gained from a
global search and replace here, and as somebody who spends quite enough
time dealing with cross-branch coding differences already, I'm going to
put my foot down about introducing a useless one.

Perhaps it would be better to think of this as "they're all lightweight
locks, but some have different locking policies". Or "we're taking a
different type of lock on this particular lock" --- that would match up
rather better with the way we think about heavyweight locks.

regards, tom lane