[Engine-devel] Guid improvements

[Tal Nisan]

On 06/30/2013 11:13 AM, Yair Zaslavsky wrote:
> Well done, should have been done ages ago :)
> Now, for the painful rebase of async_task_mgr changes :)
And for the total removal of Guid wrapper usage of java.util.UUID 
directly instead ;)

>
> ----- 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
>>