[infinispan-issues] [JBoss JIRA] (ISPN-11249) Unexpected functionality added by Java8 default interface methods

[Will Burns (Jira)]

    [ https://issues.redhat.com/browse/ISPN-11249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13976480#comment-13976480 ] 

Will Burns commented on ISPN-11249:
-----------------------------------

For now I will just add in UnsupportedOperationException, however compute is more than doable with an override of the following:

```
   @Override
   public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction, long lifespan, TimeUnit lifespanUnit, long maxIdleTime, TimeUnit maxIdleTimeUnit) {
      V newValue;
      while (true) {
         MetadataValue<V> metadataValue = getWithMetadata(key);
         V oldValue;
         long version;
         if (metadataValue != null) {
            oldValue = metadataValue.getValue();
            version = metadataValue.getVersion();
         } else {
            oldValue = null;
            version = -1;
         }
         newValue = remappingFunction.apply(key, oldValue);

         boolean done;
         if (newValue != null) {
            if (oldValue != null) {
               done = replaceWithVersion(key, newValue, version, lifespan, lifespanUnit, maxIdleTime, maxIdleTimeUnit);
            } else {
               done = putIfAbsent(key, newValue, lifespan, lifespanUnit, maxIdleTime, maxIdleTimeUnit) != null;
            }
         } else  {
            done = removeWithVersion(key, version);
         }
         if (done) {
            break;
         }
      }
      return newValue;
   }
```

> Unexpected functionality added by Java8 default interface methods
> -----------------------------------------------------------------
>
>                 Key: ISPN-11249
>                 URL: https://issues.redhat.com/browse/ISPN-11249
>             Project: Infinispan
>          Issue Type: Bug
>            Reporter: Wolf-Dieter Fink
>            Priority: Critical
>
> With Java8 there are interfaces which implement default methods.
> Those defaults are available if not overridden, but the function behind might not be correct because the method was not meant to be implemented.
> There are issues with the transaction and locking because of the remote invocation, so the conditional operation will not work consistent.
> Such methods need to be checked and throw a UnsupportedOperation.
> This appears for the compute(...) methods
> compute(key, BiFunct) -> default to java.util.concurrent.ConcurrentMap interface
> compute() methods with expiration will throw an UnsupportedOperationException as expected.



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