[Engine-devel] Guid improvements

[Liran Zelkha]

Awesome!!!


On Mon, Jul 1, 2013 at 10:29 AM, Allon Mureinik <amureini at redhat.com> wrote:

>
>
> ----- Original Message -----
> > From: "Liran Zelkha" <liran.zelkha at gmail.com>
> > To: "Yair Zaslavsky" <yzaslavs at redhat.com>
> > Cc: "Allon Mureinik" <amureini at redhat.com>, "engine-devel" <
> engine-devel at ovirt.org>
> > Sent: Sunday, June 30, 2013 11:37:26 AM
> > Subject: Re: [Engine-devel] Guid improvements
> >
> > Great news.
> > Allon - please note that GUID is being recreated from String by both DB
> calls
> > and by data received from VDSM. It is VERY useful to cache Guid
> > String-->Guid, and not just Empty GUID.
> I generally agree about the high cost of sting<->uuid operations, but I'm
> not sure caching is the way to go, at least not everywhere.
>
> At least for the database, there is a much easier solution - stop using
> strings to represent uuids.
> Here's an example of how it can be done:
> http://gerrit.ovirt.org/#/c/16281/
>
>
> >
> > However, as the Guid class runs in GWT as well, you can't use Infinispan
> and
> > you're limited in the HashMap implementations you can use. Personally, I
> > don't think it's a memory leak, as GUID number in the system are finite
> and
> > not too large. What do you think? Want to add it to your patch?
> >
> > On Jun 30, 2013, at 11:13 AM, Yair Zaslavsky wrote:
> >
> > > Well done, should have been done ages ago :)
> > > Now, for the painful rebase of async_task_mgr changes :)
> > >
> > >
> > > ----- Original Message -----
> > >> From: "Allon Mureinik" <amureini at redhat.com>
> > >> To: "engine-devel" <engine-devel at ovirt.org>, "Barak Azulay"
> > >> <bazulay at redhat.com>
> > >> Cc: "Yair Zaslavsky" <yzaslavs at redhat.com>, "Michael Pasternak"
> > >> <mpastern at redhat.com>, "Tal Nisan"
> > >> <tnisan at redhat.com>, "Ayal Baron" <abaron at redhat.com>
> > >> Sent: Sunday, June 30, 2013 11:11:30 AM
> > >> Subject: Guid improvements
> > >>
> > >> Hi all,
> > >>
> > >> I just merged a couple of improvements to the [N]Guid class [1] to
> improve
> > >> it's performance both CPU-wise and memory-wise, based on a set of
> > >> benchmarks
> > >> presented by Liran.
> > >>
> > >> What this patchset achieves:
> > >> 1. Clean up the code, so it's easier to understand and use
> > >> 2. Eliminate the inflation in the memory foot print caused by the
> > >> getValue()
> > >> method
> > >> 3. Eliminate all the heavy calls to UUID.fromString when creating a
> > >> new/empty
> > >> Guid instance as a default value
> > >> 4. Note that the cleanups proposed in (1) will have minor performance
> > >> benefits (e.g., eliminating useless conditional statements), but I
> doubt
> > >> this would be anything to write home about.
> > >>
> > >> From a developer's perspective, here's what changed:
> > >> 1. No more NGuid, just Guid. Both static methods to create a Guid from
> > >> String
> > >> still exist, and are named createGuidFromString and
> > >> createGuidFromStringDefaultEmpty.
> > >> 2. [N]Guid.getValue() was removed, it's no longer needed after (1) was
> > >> implemented
> > >> 3. The Guid() constructor was made private, as it forced a redundant
> call
> > >> to
> > >> UUID.fromString(String). If you need an empty Guid instance, just use
> > >> Guid.Empty
> > >> 4. The Guid.EMPTY_GUID_VALUE string constant was removed, as it was
> used
> > >> for
> > >> redundant calls to UUID.fromString. If you really, REALLY, need it,
> just
> > >> call Guid.Empty.getValue() for a UUID or Guid.Empty.toString() for a
> > >> String.
> > >> 5. All sorts of ways to transform Strings to Guids were removed. If
> you
> > >> have
> > >> a literal you trust, just use new Guid(String). If you suspect it may
> be
> > >> null, use Guid.createGuidFromString[DefaultEmpty]
> > >> 6. NewGuid is now called newGuid. We're in Java, not C# :-)
> > >>
> > >>
> > >> Many thanks to everyone who reviewed this patchset.
> > >> You guys rock!
> > >>
> > >>
> > >> Regards,
> > >> Allon
> > >>
> > >>
> > >> [1]
> > >>
> http://gerrit.ovirt.org/#/q/project:ovirt-engine+branch:master+topic:guid-cleanup,n,z
> > >>
> > > _______________________________________________
> > > Engine-devel mailing list
> > > Engine-devel at ovirt.org
> > > http://lists.ovirt.org/mailman/listinfo/engine-devel
> >
> >
>
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