[GitHub] [incubator-druid] leventov commented on a change in pull request #8323: Make sure ReferenceCountingSegment.decrement() is invoked correctly when useCache=true

[GitBox <gi...@apache.org>]

leventov commented on a change in pull request #8323: Make sure ReferenceCountingSegment.decrement() is invoked correctly when useCache=true
URL: https://github.com/apache/incubator-druid/pull/8323#discussion_r315329128
 
 

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 File path: server/src/main/java/org/apache/druid/segment/realtime/appenderator/SinkQuerySegmentWalker.java
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 @@ -231,7 +231,7 @@ public SegmentDescriptor apply(final PartitionChunk<Sink> chunk)
                                                       // 1) Only use caching if data is immutable
                                                       // 2) Hydrants are not the same between replicas, make sure cache is local
                                                       if (hydrantDefinitelySwapped && cache.isLocal()) {
-                                                        QueryRunner<T> cachingRunner = new CachingQueryRunner<>(
+                                                        QueryRunner<T> cachingRunner = new CloseableCachingQueryRunner<>(
 
 Review comment:
   I think you could achieve the same effect using the following code:
   ```java
   QueryRunner<T> runner;
   // 1) Only use caching if data is immutable
   // 2) Hydrants are not the same between replicas, make sure cache is local
   if (hydrantDefinitelySwapped && cache.isLocal()) {
     runner = CachingQueryRunner<>(...);
   } else {
     runner = factory.createRunner(segment.lhs);
   }
   runner = QueryRunnerHelper.makeClosingQueryRunner(runner, segment.rhs);
   return new Pair<>(segment.lhs.getDataInterval(), runner);
   ```
   
   Thus new class `CloseableCachingQueryRunner` is not needed.
   
   Please also:
    - Rename `segment` to something like `segmentAndCloseable`
    - Reduce the level of nesting by extracting variables, such as `FunctionalIterable.create(specs).transform(...)` as `perSegmentRunners` variable.

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