This is a multi-part message in MIME format. --------------020009000007090902020606 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 03/27/2013 05:48 PM, Mike Kolesnik wrote:
----- Original Message -----
On 03/20/2013 08:20 PM, Yair Zaslavsky wrote:
From: "Shireesh Anjal" <sanjal@redhat.com> To: "Mike Kolesnik" <mkolesni@redhat.com> Cc: engine-devel@ovirt.org Sent: Wednesday, March 20, 2013 4:47:08 PM Subject: Re: [Engine-devel] FeatureSupported and compatibility versions
On 03/18/2013 12:59 PM, Mike Kolesnik wrote:
----- Original Message ----- > Hi all, > > The current mechanism in oVirt to check whether a feature is > supported > in a particular compatibility version is to use the > FeatureSupported > class. e.g. > > FeatureSupported.networkLinking(getVm().getVdsGroupCompatibilityVersion()) > > > Checks whether the "network linking" feature is supported for > the > the > VM's cluster compatibility version. This internally checks > whether > the > value of the corresponding config (NetworkLinkingSupported) for > the > given compatibility version is true/false. > > I'm not sure if this is a good idea, since a feature is > typically > supported "from" a particular version. E.g. Gluster support was > introduced in 3.1, and it continues to be available in all > subsequent > versions. So I see no point in adding configuration for every > version > indicating whether the feature is supported in that version or > not. I > suggest to use either of the following options: You can "merge" the configs into a single config when older versions go out of the supported versions for the system.
i.e. in 4.0 you can have upgrade script that merges all GlusterFeatureSupported to one entry instead of several. Why are we even storing this information in config? Is this something
On 03/18/2013 01:11 PM, Shireesh Anjal wrote: that can be "configured" at customer site? As previously explained (but off list :) ) , Config gives you the ability to have a cachable "map" of entry (i.e - "feature name")
----- Original Message ----- per version and value. I guess it was convinient for the developers to use that. I also mentioned that customers/oVirt users should config the entries of vdc_options using engine-config tool only. Not all entries are exposed via engine-config.properties (and no, not just "is feature supported" entries are hidden).
> 1) Instead of using a boolean config for each version, use a > single > string config that indicates the "supported from" version e.g. > GlusterSupportedFrom = 3.1. There could be rare cases where a > feature, > for some reason, is removed in some release. In such cases, we > could > use > one additional config for the "supported to" version. > > 2) Continue with the boolean approach, but do not have entries > for > every > version; rather make use of the "default value" for majority of > cases, > and add the explicit version mapping for the minority e.g. > GlusterSupported = true by default, and false in case of 3.0 > (only > one > config required for 3.0) I'm not sure why we would want to complicate this simple mechanism?
Is there much to gain? I think option 1 suggested above is simpler - to implement as well as to understand.
Let me give you an example of why I don't like current mechanism. I introduce a version check for a feature that was introduced in 3.1. I'm being asked now to add three entries in config
3.0 - false 3.1 - true 3.2 - true
It will also mean that when 3.3 goes out, someone has to make sure that another entry is added for 3.3-true. I think it is not logical as well as scalable if you have more versions. And it sounds far more complex (to maintain) than just having
<Feature>SupportedFrom = 3.1
So I would like to know if there are any objections to my proposal. I intend to use this for at least the gluster related features. I've sent a patch (http://gerrit.ovirt.org/12970) with following changes:
1) Introduced CompatibilityUtils that provides utility methods for checking if a given feature is supported in the config. One method to check based on boolean values (as is being done today for virt features), and nother to check based on a range (from, to) which I would like to use for gluster features. 2) Renamed FeatureSupported to VirtFeatureSupported, and made it use the first utility method from CompatibilityUtils 3) Introduced GlusterFeatureSupported for gluster features, which uses the second utility method from CompatibilityUtils
Key advantage here is that - we don't have to touch any virt specifc source for adding compatibility checks for gluster features - virt features continue to use the existing boolean config check
Any comments / suggestions / reviews will be highly appreciated :) I think splitting to two classes is OK, but the underlying mechanism IMO should be as Omer suggested: Use the default value from the java config file, and if in the DB there is a version specific value then use it for that version only.
Review comments here are on the contrary: http://gerrit.ovirt.org/#/c/12970/5/backend/manager/dbscripts/upgrade/pre_up...
I don't think "From, To, etc" is a good design, it's not a standard way and is very restrictive.
Can you please explain in what way is it restrictive? Also, what is the "etc" you are referring to?
> Thoughts? > > Regards, > Shireesh
--------------020009000007090902020606 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit <html> <head> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <div class="moz-cite-prefix">On 03/27/2013 05:48 PM, Mike Kolesnik wrote:<br> </div> <blockquote cite="mid:36623975.7044697.1364386718971.JavaMail.root@redhat.com" type="cite"> <pre wrap="">----- Original Message ----- </pre> <blockquote type="cite"> <pre wrap="">On 03/20/2013 08:20 PM, Yair Zaslavsky wrote: </pre> <blockquote type="cite"> <pre wrap=""> ----- Original Message ----- </pre> <blockquote type="cite"> <pre wrap="">From: "Shireesh Anjal" <a class="moz-txt-link-rfc2396E" href="mailto:sanjal@redhat.com"><sanjal@redhat.com></a> To: "Mike Kolesnik" <a class="moz-txt-link-rfc2396E" href="mailto:mkolesni@redhat.com"><mkolesni@redhat.com></a> Cc: <a class="moz-txt-link-abbreviated" href="mailto:engine-devel@ovirt.org">engine-devel@ovirt.org</a> Sent: Wednesday, March 20, 2013 4:47:08 PM Subject: Re: [Engine-devel] FeatureSupported and compatibility versions On 03/18/2013 01:11 PM, Shireesh Anjal wrote: </pre> <blockquote type="cite"> <pre wrap="">On 03/18/2013 12:59 PM, Mike Kolesnik wrote: </pre> <blockquote type="cite"> <pre wrap="">----- Original Message ----- </pre> <blockquote type="cite"> <pre wrap="">Hi all, The current mechanism in oVirt to check whether a feature is supported in a particular compatibility version is to use the FeatureSupported class. e.g. FeatureSupported.networkLinking(getVm().getVdsGroupCompatibilityVersion()) Checks whether the "network linking" feature is supported for the the VM's cluster compatibility version. This internally checks whether the value of the corresponding config (NetworkLinkingSupported) for the given compatibility version is true/false. I'm not sure if this is a good idea, since a feature is typically supported "from" a particular version. E.g. Gluster support was introduced in 3.1, and it continues to be available in all subsequent versions. So I see no point in adding configuration for every version indicating whether the feature is supported in that version or not. I suggest to use either of the following options: </pre> </blockquote> <pre wrap="">You can "merge" the configs into a single config when older versions go out of the supported versions for the system. i.e. in 4.0 you can have upgrade script that merges all GlusterFeatureSupported to one entry instead of several. </pre> </blockquote> </blockquote> <pre wrap="">Why are we even storing this information in config? Is this something that can be "configured" at customer site? </pre> </blockquote> <pre wrap="">As previously explained (but off list :) ) , Config gives you the ability to have a cachable "map" of entry (i.e - "feature name") per version and value. I guess it was convinient for the developers to use that. I also mentioned that customers/oVirt users should config the entries of vdc_options using engine-config tool only. Not all entries are exposed via engine-config.properties (and no, not just "is feature supported" entries are hidden). </pre> <blockquote type="cite"> <blockquote type="cite"> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">1) Instead of using a boolean config for each version, use a single string config that indicates the "supported from" version e.g. GlusterSupportedFrom = 3.1. There could be rare cases where a feature, for some reason, is removed in some release. In such cases, we could use one additional config for the "supported to" version. 2) Continue with the boolean approach, but do not have entries for every version; rather make use of the "default value" for majority of cases, and add the explicit version mapping for the minority e.g. GlusterSupported = true by default, and false in case of 3.0 (only one config required for 3.0) </pre> </blockquote> <pre wrap="">I'm not sure why we would want to complicate this simple mechanism? Is there much to gain? </pre> </blockquote> <pre wrap="">I think option 1 suggested above is simpler - to implement as well as to understand. Let me give you an example of why I don't like current mechanism. I introduce a version check for a feature that was introduced in 3.1. I'm being asked now to add three entries in config 3.0 - false 3.1 - true 3.2 - true It will also mean that when 3.3 goes out, someone has to make sure that another entry is added for 3.3-true. I think it is not logical as well as scalable if you have more versions. And it sounds far more complex (to maintain) than just having <Feature>SupportedFrom = 3.1 So I would like to know if there are any objections to my proposal. I intend to use this for at least the gluster related features. </pre> </blockquote> </blockquote> </blockquote> <pre wrap=""> I've sent a patch (<a class="moz-txt-link-freetext" href="http://gerrit.ovirt.org/12970">http://gerrit.ovirt.org/12970</a>) with following changes: 1) Introduced CompatibilityUtils that provides utility methods for checking if a given feature is supported in the config. One method to check based on boolean values (as is being done today for virt features), and nother to check based on a range (from, to) which I would like to use for gluster features. 2) Renamed FeatureSupported to VirtFeatureSupported, and made it use the first utility method from CompatibilityUtils 3) Introduced GlusterFeatureSupported for gluster features, which uses the second utility method from CompatibilityUtils Key advantage here is that - we don't have to touch any virt specifc source for adding compatibility checks for gluster features - virt features continue to use the existing boolean config check Any comments / suggestions / reviews will be highly appreciated :) </pre> </blockquote> <pre wrap=""> I think splitting to two classes is OK, but the underlying mechanism IMO should be as Omer suggested: Use the default value from the java config file, and if in the DB there is a version specific value then use it for that version only.</pre> </blockquote> <br> Review comments here are on the contrary:<br> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <a href="http://gerrit.ovirt.org/#/c/12970/5/backend/manager/dbscripts/upgrade/pre_upgrade/0000_config.sql">http://gerrit.ovirt.org/#/c/12970/5/backend/manager/dbscripts/upgrade/pre_upgrade/0000_config.sql</a><br> <br> <blockquote cite="mid:36623975.7044697.1364386718971.JavaMail.root@redhat.com" type="cite"> <pre wrap=""> I don't think "From, To, etc" is a good design, it's not a standard way and is very restrictive.</pre> </blockquote> <br> Can you please explain in what way is it restrictive?<br> <br> Also, what is the "etc" you are referring to?<br> <br> <blockquote cite="mid:36623975.7044697.1364386718971.JavaMail.root@redhat.com" type="cite"> <pre wrap=""> </pre> <blockquote type="cite"> <pre wrap=""> </pre> <blockquote type="cite"> <blockquote type="cite"> <blockquote type="cite"> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">Thoughts? Regards, Shireesh </pre> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> </blockquote> <br> </body> </html> --------------020009000007090902020606--