RFR [9] 8151384: Examine sun.misc.ASCIICaseInsensitiveComparator
Chris Hegarty
chris.hegarty at oracle.com
Mon Mar 7 21:55:52 UTC 2016
Aleksey,
Very helpful, as always.
I pushed the methods down into String[Latin1|UTF16], and followed existing
style. This is much cleaner.
Thanks for catching the silly mistakes in the benchmarks.
Updated links:
http://cr.openjdk.java.net/~chegar/8151384/webrev.01/
http://cr.openjdk.java.net/~chegar/8151384/bench.01/
-Chris.
On 7 Mar 2016, at 16:51, Aleksey Shipilev <aleksey.shipilev at oracle.com> wrote:
> Hi,
>
> On 03/07/2016 07:29 PM, Chris Hegarty wrote:
>> What is in the webrev is specialized versions of compare when
>> the coder of the strings match. Alternatively, this could be pushed
>> down to String[Latin1|UTF16].
>>
>> Webrev & bug:
>> http://cr.openjdk.java.net/~chegar/8151384/webrev.00/
>> https://bugs.openjdk.java.net/browse/JDK-8151384
>
> Overall, good cleanup idea. I think the actual helpers deserve to be
> pushed to String[Latin1|UTF16], as String is already overloaded with
> lots of code. See how e.g. String.regionMatches(boolean ignoreCase, int
> toffset, String other, int ooffset, int len) does it.
>
> Nits:
>
> *) Change: compareLatin1ToUTF16(v2, v1) * -1;
> To: -compareLatin1ToUTF16(v2, v1);
>
> *) Do we really need to cast up/down to "char" in compareLatin1*?
>
>
>> Benchmarks and results ( based, somewhat, on Aleksey's [1] ):
>> http://cr.openjdk.java.net/~chegar/8151384/bench/
>
> Comments on benchmarks (that might have impact on validity):
>
> *) "# JMH 1.6 (released 388 days ago, please consider updating!)"
>
> *) CaseInsensitiveCompare.cmp1_cmp1 is suspiciously unaffected by size.
> That's because benchmark goes through the identity comparison:
>
> @Benchmark
> @CompilerControl(CompilerControl.Mode.DONT_INLINE)
> public int cmp1_cmp1() {
> return CASE_INSENSITIVE_ORDER.compare(cmp1_1, cmp1_1);
> }
>
> ...should really be:
>
> @Benchmark
> @CompilerControl(CompilerControl.Mode.DONT_INLINE)
> public int cmp1_cmp1() {
> return CASE_INSENSITIVE_ORDER.compare(cmp1_1, cmp1_2);
> }
>
> *) Probable dead-code elimination here:
>
> @Benchmark
> @CompilerControl(CompilerControl.Mode.DONT_INLINE)
> public void StringCaseInsensitiveComparator() {
> List<String> strings = AVAILABLE_CHARSETS;
> for (String s1 : strings) {
> for (String s2 : strings) {
> String.CASE_INSENSITIVE_ORDER.compare(s1, s2);
> }
> }
> }
>
> ...should be:
>
> @Benchmark
> @CompilerControl(CompilerControl.Mode.DONT_INLINE)
> public void StringCaseInsensitiveComparator(Blackhole bh) {
> List<String> strings = AVAILABLE_CHARSETS;
> for (String s1 : strings) {
> for (String s2 : strings) {
> bh.consume(String.CASE_INSENSITIVE_ORDER.compare(s1, s2));
> }
> }
> }
>
>
> Thanks,
> -Aleksey
>
More information about the core-libs-dev
mailing list