4.x: Streamable Operator optimizations 7/18

[akarnokd]

Methodology

With help from Claude Fable, a new state machine has been implemented for several looping-consuming operators where it is by default synchronous bias and no need for a trampoline because there is only two phase of the async coordination: drain still running vs async completion running.

Plus more sources implement IndexableSource and EnumerableSource sometimes both because some chains may not work with indexable, such as map+filter+collect. Also if an operator is Indexable, it will be also enumerable.

Operators affected

• collect
• last, lastOrError
• filter
• just
• empty

Scrabble status

https://github.com/akarnokd/akarnokd-misc/blob/master/src/jmh/java/hu/akarnokd/comparison/scrabble/ShakespearePlaysScrabbleWithRxJava4StreamableOpt.java

New measurements below the ~~~~~~~ markers.

Step	Time (ms)	Improvement	vs Baseline
Baseline	42,512	-	-
Avoid whenComplete usage in collect	37,566	-11,65%	-
IndexableSource in collect	35,815	-4,66%	-15,77%
concatIterable optimizations	31,971	-10,73%	-24,81%
map fusions	30,623	-4,22%	-27,98%
flattenAsFlowable deferred opt	27,999	-8,57%	-34,15%
MutableLong in the bench	26,159	-6,57%	-38,48%
lastOrError opt	25,164	-3,80%	-40,82%
custom Collector summers	24,885	-1,11%	-41,47%
skip optimizations	24,791	-0,38%	-41,69%
~~~~	~~~~~~~	~~~~~~~	~~~~~~~~
filter opt, filter+map fusion, lastOrError opt	23,566	-4,94%	-44,58%
slow path collect optimization	22,392	-4,98%	-47,34%
CharStreamer EnumerableSource marker	21,843	-2,45%	-48,63%

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.627 bits/char
Verdict: ✅ Mid-4 beauty detected (thoughtful human code!)

Changed files entropy:

src/jmh/java/io/reactivex/rxjava4/streamable/StreamableCollectPerf.java: 4.948
src/jmh/java/io/reactivex/rxjava4/streamable/StreamableFilterPerf.java: 4.713
src/jmh/java/io/reactivex/rxjava4/streamable/StreamableLastAsSinglePerf.java: 4.948
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableCollector.java: 4.042
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableEmpty.java: 4.805
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableFilter.java: 4.226
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableJust.java: 4.670
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableLastAsSingle.java: 4.158
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableMap.java: 4.495
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRange.java: 4.574
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRangeLong.java: 4.535
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableCollectorTest.java: 4.787
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableConcatIterableTest.java: 4.395
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableEmptyTest.java: 4.828
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableFilterTest.java: 4.636
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableJustTest.java: 4.852
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableLastAsSingleTest.java: 4.795
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableMapTest.java: 4.731
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRangeTest.java: 4.777

✅ No secrets or suspicious high-entropy strings found.

Mid-4 beauty heuristic in action — powered by our entropy chats! 😊

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.627 bits/char
Verdict: ✅ Mid-4 beauty detected (thoughtful human code!)

Changed files entropy:

src/jmh/java/io/reactivex/rxjava4/streamable/StreamableCollectPerf.java: 4.948
src/jmh/java/io/reactivex/rxjava4/streamable/StreamableFilterPerf.java: 4.713
src/jmh/java/io/reactivex/rxjava4/streamable/StreamableLastAsSinglePerf.java: 4.948
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableCollector.java: 4.042
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableEmpty.java: 4.805
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableFilter.java: 4.226
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableJust.java: 4.670
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableLastAsSingle.java: 4.158
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableMap.java: 4.495
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRange.java: 4.574
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRangeLong.java: 4.535
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableCollectorTest.java: 4.787
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableConcatIterableTest.java: 4.395
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableEmptyTest.java: 4.828
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableFilterTest.java: 4.636
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableJustTest.java: 4.852
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableLastAsSingleTest.java: 4.795
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableMapTest.java: 4.731
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableRangeTest.java: 4.777

✅ No secrets or suspicious high-entropy strings found.

Mid-4 beauty heuristic in action — powered by our entropy chats! 😊

[codecov]

Codecov Report

❌ Patch coverage is 89.03226% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.59%. Comparing base (8ed1fbc) to head (0712af6).

Files with missing lines	Patch %	Lines
...nternal/operators/streamable/StreamableFilter.java	89.02%	4 Missing and 5 partials ⚠️
...l/operators/streamable/StreamableLastAsSingle.java	81.48%	2 Missing and 3 partials ⚠️
...rnal/operators/streamable/StreamableCollector.java	88.00%	1 Missing and 2 partials ⚠️

❌ Your patch check has failed because the patch coverage (89.03%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x    #8239      +/-   ##
============================================
- Coverage     98.63%   98.59%   -0.04%     
- Complexity     7152     7154       +2     
============================================
  Files           822      822              
  Lines         50543    50625      +82     
  Branches       6862     6879      +17     
============================================
+ Hits          49852    49914      +62     
- Misses          475      481       +6     
- Partials        216      230      +14     

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