MetaStoreManagerFactory: make purgeRealms() return purge results

[adutra]

Make the purgeRealms method return the purge results.
These changes are a prerequisite for #878 and #887.

[snazy]

why copying? it's immutable

[eric-maynard]

It's RequestScoped, so I think it can get lost.

[adutra]

It's potentially a CDI bean, and these are poor choices as map keys: the CDI specs do not say anything about how CDI proxies should handle equals() and hashCode(). Such beans can have surprising effects when put in a set or a map.

[collado-mike]

I worry that this is an extremely easy mistake to make. I dislike proxies for this and other reasons. A person has to have a lot of context in their head before they do simple things like add keys to maps.

[snazy]

@eric-maynard @adutra fair point. However, the realm-IDs here are parameters for bootstrap?

[adutra]

Unfortunately the bootstrapRealms method can be called both from a bootstrap command (in which case RealmId is not a CDI proxy) and from "regular" server code (in which case it is a proxy). (The "regular" path only happens with the in-memory metastore though.)

[eric-maynard]

This class seems like it does nothing

[adutra]

It's used by Picocli to automatically convert Strings to RealmId.

[eric-maynard]

I see, and what does that do?

[adutra]

It's removed anyways.

[eric-maynard]

ditto

[adutra]

Same but this one is used by Quarkus / MicroProfile.

[eric-maynard]

Shouldn't this use RealmId not String, so we don't need to call id()?

[adutra]

See my previous comment: CDI beans as map keys or set elements would have surprising effects here, notably containsKey() and addAll() wouldn't work as expected. We would need to copy the RealmId each time to be sure. In the end I think it's not worth it since these maps and collections are not public.

[collado-mike]

no general opposition to the PR, but it does highlight some concern regarding the use of RealmId as a plain ole java object. There's now some assumed base framework knowledge, that, AFACIT, isn't documented anywhere and will likely lead to issues in the future.

I also think we are missing a lot of basic javadocs that will help those of us who are ramping up on the frameworks being used here.

[collado-mike]

I worry that this is an extremely easy mistake to make. I dislike proxies for this and other reasons. A person has to have a lot of context in their head before they do simple things like add keys to maps.

[collado-mike]

Javadoc comments are extremely helpful for people ramping up on the frameworks being used here

[collado-mike]

Same re: javadoc comments

[adutra]

@collado-mike @eric-maynard @snazy

Since the mailing list discussion around RealmId is still ongoing, and given that you raised concerns about using RealmId as map keys or set elements:

Would it be better for you if we keep using String ids in the bootstrap/purge parts of the MetaStoreManagerFactory API?

I think I could make it work. The only change I really need to keep working on #887 is that purgeRealms should return the purge results.

[snazy]

Would it be better for you if we keep using String ids in the bootstrap/purge parts of the MetaStoreManagerFactory API?

WFM

[collado-mike]

Would it be better for you if we keep using String ids in the bootstrap/purge parts of the MetaStoreManagerFactory API?

I certainly like typed keys over String keys, but my worry is that it will be too easy to make mistakes. If it was a POJO, I'd say use the typed key, but I don't think people should have to wonder about whether a Realm passed in as a method argument was originally a CDI bean or if it's safe to use.

[adutra]

Alright, I reverted the map key changes and went back to String keys.

[adutra]

PR rebased.

With the revert from RealmId back to RealmContext, the scope of this PR faded to almost nothing. Indeed, RealmContext is even worse than RealmId as a map key or set element, because all its instances are just lambdas, and thus do not have any strong contract for equals() and hashCode(). It is therefore really a bad idea to use those in any collection.

The new scope of this PR is now focused around making the purgeRealms method return the purge results.

@snazy @collado-mike @eric-maynard can an I have another review please?

[adutra]

Rebased again.

@snazy @collado-mike @eric-maynard can an I have another review please?