archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-28 15:24:43 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8265029: Preserve SIZED characteristics on slice operations (skip, limit)

Browse source 
Reviewed-by: psandoz
This commit is contained in:
Tagir F. Valeev 2021-05-28 01:56:38 +00:00
parent 95b1fa7a88
commit 0c9daa7ed5
12 changed files with 704 additions and 89 deletions
Download patch file Download diff file Expand all files Collapse all files

29
src/java.base/share/classes/java/util/stream/AbstractPipeline.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -466,7 +466,32 @@ abstract class AbstractPipeline<E_IN, E_OUT, S extends BaseStream<E_OUT, S>>
@Override
final <P_IN> long exactOutputSizeIfKnown(Spliterator<P_IN> spliterator) {
return StreamOpFlag.SIZED.isKnown(getStreamAndOpFlags()) ? spliterator.getExactSizeIfKnown() : -1;
int flags = getStreamAndOpFlags();
long size = StreamOpFlag.SIZED.isKnown(flags) ? spliterator.getExactSizeIfKnown() : -1;
// Currently, we have no stateless SIZE_ADJUSTING intermediate operations,
// so we can simply ignore SIZE_ADJUSTING in parallel streams, since adjustments
// are already accounted in the input spliterator.
//
// If we ever have a stateless SIZE_ADJUSTING intermediate operation,
// we would need step back until depth == 0, then call exactOutputSize() for
// the subsequent stages.
if (size != -1 && StreamOpFlag.SIZE_ADJUSTING.isKnown(flags) && !isParallel()) {
// Skip the source stage as it's never SIZE_ADJUSTING
for (AbstractPipeline<?, ?, ?> stage = sourceStage.nextStage; stage != null; stage = stage.nextStage) {
size = stage.exactOutputSize(size);
}
}
return size;
}
/**
* Returns the exact output size of the pipeline given the exact size reported by the previous stage.
*
* @param previousSize the exact size reported by the previous stage
* @return the output size of this stage
*/
long exactOutputSize(long previousSize) {
return previousSize;
}
@Override