Re: [Engine-devel] Guid & NGuid

From: "Alon Bar-Lev" <alonbl(a)redhat.com&gt; To: "Michael Kublin" <mkublin(a)redhat.com&gt; Cc: engine-devel(a)ovirt.org Sent: Tuesday, February 5, 2013 9:29:20 AM Subject: Re: [Engine-devel] Guid & NGuid ----- Original Message ----- > From: "Michael Kublin" <mkublin(a)redhat.com&gt; > To: "Alon Bar-Lev" <alonbl(a)redhat.com&gt; > Cc: engine-devel(a)ovirt.org > Sent: Tuesday, February 5, 2013 9:28:26 AM > Subject: Re: [Engine-devel] Guid & NGuid > > > > ----- Original Message ----- > > From: "Alon Bar-Lev" <alonbl(a)redhat.com&gt; > > To: "Michael Kublin" <mkublin(a)redhat.com&gt; > > Cc: engine-devel(a)ovirt.org > > Sent: Monday, February 4, 2013 4:17:39 PM > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > ----- Original Message ----- > > > From: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > To: engine-devel(a)ovirt.org > > > Sent: Monday, February 4, 2013 2:15:40 PM > > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > > > > > ----- Original Message ----- > > > > From: "Mike Kolesnik" <mkolesni(a)redhat.com&gt; > > > > To: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > > Cc: engine-devel(a)ovirt.org > > > > Sent: Monday, February 4, 2013 11:48:45 AM > > > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > ----- Original Message ----- > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > From: "Laszlo Hornyak" <lhornyak(a)redhat.com&gt; > > > > > > To: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > > > > Cc: engine-devel(a)ovirt.org > > > > > > Sent: Monday, February 4, 2013 9:56:28 AM > > > > > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > > From: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > > > > > To: engine-devel(a)ovirt.org > > > > > > > Sent: Monday, February 4, 2013 8:47:29 AM > > > > > > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > > > > > > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > > > From: "Roy Golan" <rgolan(a)redhat.com&gt; > > > > > > > > To: engine-devel(a)ovirt.org > > > > > > > > Sent: Monday, February 4, 2013 9:18:21 AM > > > > > > > > Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > > > > > > > > > On 02/03/2013 03:19 PM, Alon Bar-Lev wrote: > > > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > > > >> From: "Omer Frenkel" <ofrenkel(a)redhat.com&gt; > > > > > > > > >> To: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > > > > > > >> Cc: "engine-devel" <engine-devel(a)ovirt.org&gt; > > > > > > > > >> Sent: Sunday, February 3, 2013 3:12:19 PM > > > > > > > > >> Subject: Re: [Engine-devel] Guid & NGuid > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> ----- Original Message ----- > > > > > > > > >>> From: "Michael Kublin" <mkublin(a)redhat.com&gt; > > > > > > > > >>> To: "engine-devel" <engine-devel(a)ovirt.org&gt; > > > > > > > > >>> Sent: Sunday, February 3, 2013 3:10:14 PM > > > > > > > > >>> Subject: [Engine-devel] Guid & NGuid > > > > > > > > >>> > > > > > > > > >>> Hi, > > > > > > > > >>> > > > > > > > > >>> In ovirt-engine code we have Guid and NGuid > > > > > > > > >>> objects. > > > > > > > > >>> Guid is extends NGuid and also NGuid class has > > > > > > > > >>> method > > > > > > > > >>> getValue() > > > > > > > > >>> which should return Guid. > > > > > > > > >>> As for me these two classes are look like the > > > > > > > > >>> same > > > > > > > > >>> and > > > > > > > > >>> I > > > > > > > > >>> don't > > > > > > > > >>> see > > > > > > > > >>> to > > > > > > > > >>> much differences between them. > > > > > > > > >>> My proposal is to remove NGuid and move it > > > > > > > > >>> functionality > > > > > > > > >>> to > > > > > > > > >>> Guid > > > > > > > > >>> (Because of Guid is much more common) > > > > > > > > >>> > > > > > > > > >> i agree, but we need to take another step forward > > > > > > > > >> and > > > > > > > > >> allow > > > > > > > > >> Guid > > > > > > > > >> to > > > > > > > > >> be null (as it should) > > > > > > > > >> and not assume its EMPTY or have a value (i'm > > > > > > > > >> pretty > > > > > > > > >> sure > > > > > > > > >> we > > > > > > > > >> have > > > > > > > > >> this assumption in many places) > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > And for the new people out here... why not kill > > > > > > > > > both > > > > > > > > > and > > > > > > > > > use > > > > > > > > > plain > > > > > > > > > standard java UUID[1]? > > > > > > > > +1 for using java.util.UUID > > > > > > > > > > > > > > > > NGuid functionality that should be extracted during > > > > > > > > the > > > > > > > > refactor > > > > > > > > is > > > > > > > > - > > > > > > > > 1. refactor DB and Java so empty or null return > > > > > > > > values > > > > > > > > are > > > > > > > > null > > > > > > > > and > > > > > > > > not > > > > > > > > EMPTY_GUID > > > > > > > > 2. the special constructor of NGuid for UUID return > > > > > > > > by > > > > > > > > Microsoft > > > > > > > > AD > > > > > > > > should be extracted to a factory/utility > > > > > > > > > I think we should kill compat, I don't see any > > > > > > > > > value > > > > > > > > > in > > > > > > > > > fixing > > > > > > > > > anything about it while leaving it intact. > > > > > > > > > > > > > > > > > > Regards, > > > > > > > > > Alon Bar-Lev. > > > > > > > > > > > > > > > > > > [1] > > > > > > > > > http://docs.oracle.com/javase/6/docs/api/java/util/UUID.html > > > > > > > Actually there is exists one reason not to use directly > > > > > > > UUID > > > > > > > at > > > > > > > server side. > > > > > > > The main operations on Guid today it is to convert > > > > > > > object > > > > > > > to > > > > > > > Guid > > > > > > > or > > > > > > > Guid to string. > > > > > > > Guid it is immutable object, number of Guids is limited > > > > > > > and > > > > > > > almost > > > > > > > never changed, > > > > > > > These sound like classical case for object that can be > > > > > > > cached. > > > > > > > Benefit - reduced number of string manipulations, > > > > > > > reduced > > > > > > > number > > > > > > > of > > > > > > > created instances, less work > > > > > > > for garbage collection > > > > > > > > > > > > UUID has the same properties, it is immutable. So you > > > > > > could > > > > > > do > > > > > > the > > > > > > same with UUID, but I am not sure you could effectively > > > > > > cache > > > > > > these > > > > > > objects and prove that you are saving either CPU, heap, > > > > > > or > > > > > > GC > > > > > > time. > > > > > These is a very common pattern: > > > > > 1) implementation of valueOf() for most classes like > > > > > Integer, > > > > > Double, > > > > > etc... has some kind of cache. > > > > > 2) JVM has cache for strings that can be used and that > > > > > cache > > > > > can > > > > > be > > > > > tweaked by some JVM opts. > > > > > 3) Most of our operations is perform query on DB, send > > > > > request > > > > > to > > > > > host or parse response from host and Guid > > > > > is very common object that is immutable. > > > > > I am agree that these will not solve all our performance > > > > > problems > > > > > but > > > > > can provide some benefit, especially when it is very easy > > > > > to implement. > > > > > > > > We could still achieve that using a UUIDCreator class and > > > > call > > > > it > > > > instead of Guid.fromString("").. > > > > > > > > Whether this is cached or not is another question which can > > > > be > > > > solved > > > > later and checked to see if the cache improves performance or > > > > not. > > > These is already implementation, if it will be > > > Guid.fromString("") > > > or > > > UUIDCreator. > > > The issue is if we want to use cache, it should be implemented > > > together > > > with deleting/replacing of Guid/NGuid , because of it much more > > > easilly > > > > I think the value of using standard java classes is higher than > > the > > tuning of the engine at this regard. Dropping the compat thing is > > important activity. > Immutable object it is a common java design pattern > > After doing this conversion, use profiler to determine where > > major > Already was done, and already tested a cache solution (Simple POC > solution took to implement less > than hour) > > bottle necks are and fix these, I am not sure the above > > optimization > > will be first in list. > Any optimization can not be first in the list, the best > optimization > is architecture change > > If we invest resources in optimization better > > to invest in these that we suffer most. > Most of the issues are well known. Please try to be less cryptic... Is this one of them?

> > > > > Regards, > > Alon > > > _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel