Looks good! Best regards, Vladimir Ivanov
On 22/10/2018 02:58, Claes Redestad wrote:
Hi, StringConcatFactory uses a customized internal foldArguments implementation which takes positional arguments to avoid intermediary permutation steps, see JDK-8165492[1]. My intent has been to clean this up for possible inclusion in the public API. In preparation of that, I realized that we could probably profit from a filtering combinator on top of the existing folding one. Said and done: http://cr.openjdk.java.net/~redestad/8212726/jdk.00/ https://bugs.openjdk.java.net/browse/JDK-8212726 Using this new MethodHandles.filterArgumentsWithCombiner in place of MHs.dropArguments + MHs.foldArgumentsWithCombiner gets rid of a significant number of MethodHandles with retained performance characteristics. In startup tests exercising indified String concatenation the number of generated classes drops by ~25-30%, with a measurable improvement in startup time as a result. Subjectively it also makes the code in StringConcatFactory easier to read and follow. While this surely strengthens the case to include these in the public API, I'd like to move ahead with this as an internal optimization first and propose MethodHandles.filter-/foldArgumentsWithCombiner as public API points as a follow-up: apart from improving the javadoc we need to work out specification for corner cases - especially illegal values - and harden the implementation with more tests. I'm sure there might be opinions about the naming of these methods, too... :-) Thanks! /Claes [1] https://bugs.openjdk.java.net/browse/JDK-8165492
