clintropolis commented on code in PR #18005: URL: https://github.com/apache/druid/pull/18005#discussion_r2105674198
########## processing/src/main/java/org/apache/druid/segment/SegmentMapFunction.java: ########## @@ -0,0 +1,58 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.druid.segment; + +import java.util.Optional; +import java.util.function.Function; + +/** + * Functional interface that captures the process of acquiring a {@link Segment} from a + * {@link ReferenceCountedObjectProvider<Segment>} and performing any transformations done on top of this leaf {@link Segment} + * before it is available to query processing engines. + * <p> + * The {@link Segment} returned by this method, if present, must always be closed to return the reference to the base + * {@link ReferenceCountedObjectProvider<Segment>} that it came from. + */ +@FunctionalInterface +public interface SegmentMapFunction extends Function<ReferenceCountedObjectProvider<Segment>, Optional<Segment>> +{ + /** + * {@link SegmentMapFunction} that acuires a {@link Segment} from the {@link ReferenceCountedObjectProvider<Segment>} + */ + SegmentMapFunction IDENTITY = ReferenceCountedObjectProvider::acquireReference; + + /** + * Returns a {@link SegmentMapFunction} that calls {@link ReferenceCountedObjectProvider#acquireReference()} and then + * applies the function to the resulting {@link Segment}, if present + */ + static SegmentMapFunction map(Function<Segment, Segment> mapFn) + { + return segmentReference -> segmentReference.acquireReference().map(mapFn); + } + + /** + * Returns a {@link SegmentMapFunction} which first applies the supplied {@link SegmentMapFunction} and then applies + * the function to the resulting {@link Segment}, if present + */ + static SegmentMapFunction wrap(SegmentMapFunction segmentMapFn, Function<Segment, Segment> mapFn) Review Comment: made this change, though I can't call it `andThen` because that is already defined by `Function` with a slightly different signature, so I called this `thenMap` (open to other name ideas too). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org
