Re: [Libguestfs] [nbdkit PATCH 3/6] connections: Add read/write lock over client I/O
On 11/17/2017 12:28 PM, Eric Blake wrote:
> There's nothing wrong with this patch, but it might be easier
to use
> an attribute((cleanup)) handler to deal with the unlocking. See these
> links for how we do it in libguestfs:
Oh cool! Yes, that looks nicer. Although the diffstat for doing so is
larger, because it requires adding to new sub-function {} scopes and
reindenting (we have two different locks in play here).
Interestingly, it doesn't compile if you lack attribute((cleanup)).
Libguestfs has:
common/utils/cleanups.h:/* XXX no safe equivalent to
CLEANUP_GL_RECURSIVE_LOCK_UNLOCK */
and will fail to compile if the compiler lacks the attribute - arguably,
since no one has reported that compilation failure, it seems no one
cares about libguestfs that is not also in possession of modern gcc or
clang. And we already have a configure-time check whether
attribute((cleanup)) is detected. Is it okay to tighten that check to
now require a modern compiler for nbdkit, just to get nicer code?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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