OAK-11458 : added utils class for replacing Guava's Iterables

[rishabhdaim]

No description provided.

[github-actions]

Commit-Check ✔️

[reschke]

What do we do when a class needs both our IterarbleUtils and those from commons-collections?

(I'd say implement the methods and delegate)

[rishabhdaim]

This is why I created the IterableUtils inside oak-commons module so we can implement the method with the same name and delegate it to Apache commons-collections4.

[reschke]

Maybe I'm mssing something. Aren't we already using commons-collection4's IterableUtils in other places?

[rishabhdaim]

Yes, we are using commons-collection4's IterableUtils in other places. But for this Iterables.concat use case, we hit a roadblock and had to implement our replacement for Iterables<Iterables> [1].

To avoid using different IterableUtils in each class (and polluting it with a complete class name), I have added other methods (to replace Iterables.concat) in oak-commons IterableUtils.

Now, to avoid using both IterableUtils in the same class for other methods, When we hit this case, we will implement the method in oak-common's IterableUtils and replace it.

So, gradually we would be replacing the commons-collection4's IterableUtils with our delegating methods.

[1] https://guava.dev/releases/20.0/api/docs/com/google/common/collect/Iterables.html#concat-java.lang.Iterable-

[reschke]

Please see https://sonarcloud.io/project/issues?id=org.apache.jackrabbit%3Ajackrabbit-oak&pullRequest=2055&issueStatuses=OPEN,CONFIRMED&sinceLeakPeriod=true

Missed valid complaints from Solarcloud.

[rishabhdaim]

@mbaedke the sonar complaints regarding Remove this array creation and simply pass the elements. are due to fact that I am creating an array beforehand passing the variables to an method that accepts varargs.

public static <E> Iterable<E> chainedIterable(final Iterable<? extends E> a,
                                                  final Iterable<? extends E> b) {
        return chainedIterable(new Iterable[] {a, b});
    }

is calling

@SafeVarargs
    public static <E> Iterable<E> chainedIterable(final Iterable<? extends E>... iterables) {
        Objects.requireNonNull(iterables);
        return org.apache.commons.collections4.IterableUtils.chainedIterable(iterables);
    }

from same class i.e. IterableUtils in oak-commons.

In case I don't create an array, I would be calling the caller method thus creating an infinite loop.

public static <E> Iterable<E> chainedIterable(final Iterable<? extends E> a,
                                                  final Iterable<? extends E> b) {
        return chainedIterable(a, b);
    }

this is the same pattern used inside commons-collections4.

One possible way to avoid is to call commons-collections4 api's from each method rather than delegating the call to commons-collections4 to a single method.

public static <E> Iterable<E> chainedIterable(final Iterable<? extends E> a,
                                                  final Iterable<? extends E> b) {
        return org.apache.commons.collections4.IterableUtils.chainedIterable(a, b);
    }

[rishabhdaim]

@mbaedke @reschke changes addressed in 16134e5

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[thomasmueller]

Is this actually used anywhere in the code?