Hi Sherman, nice performance trick :-) Do you remember the discussion about : https://bugs.openjdk.java.net/browse/JDK-6939278 ;-) (this bug was originally filed by me!) -Ulf Am 16.01.2014 19:08, schrieb Xueming Shen:
Hi,
The proposed changeset is to improve the performance (both speed and memory usage) of String.toLowerCase/toUpperCase, by
(1) to separate the "most likely" use scenario (non supplementary character, no special case mapping handling) into simple/quick iteration loop code path (2) to use the package private constructor String(char[], boolean) to avoid unnecessary target char[] copy in fast-path case. (3) some tiny code cleanup.
Since it's supposed to be a simple/quick round of code cleanup, I did not go too far to optimize the supplementary/special mapping code.
The webrev is
http://cr.openjdk.java.net/~sherman/8032012/
My small non-scientific speed measurement test suggests we can get 25% to 40% speed boost.
http://cr.openjdk.java.net/~sherman/str_toCase/TestToCase.java
Thanks! -Sherman