On Thu, 22 Jun 2023 11:07:09 GMT, 温绍锦 <d...@openjdk.org> wrote:
>> By optimizing the implementation of java.lang.Long#fastUUID, the performance
>> of the java.util.UUID#toString method can be significantly improved.
>>
>> The following are the test results of JMH:
>>
>> Benchmark Mode Cnt Score Error Units
>> UUIDUtilsBenchmark.new thrpt 5 92676.550 ± 292.213 ops/ms
>> UUIDUtilsBenchmark.original thrpt 5 37040.165 ± 1023.532 ops/ms
>
> 温绍锦 has updated the pull request incrementally with one additional commit
> since the last revision:
>
> use ByteArray.setInt & setLong
src/java.base/share/classes/java/lang/Long.java line 527:
> 525: buf[70 + off] = (byte) i15;
> 526:
> 527: return new String(buf, UTF16);
Maybe restore the `else` block?
Suggestion:
} else {
byte[] buf = new byte[72];
int off = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN ? 1 : 0;
buf[0 + off] = (byte) (i0 >> 8);
buf[2 + off] = (byte) i0;
buf[4 + off] = (byte) (i1 >> 8);
buf[6 + off] = (byte) i1;
buf[8 + off] = (byte) (i2 >> 8);
buf[10 + off] = (byte) i2;
buf[12 + off] = (byte) (i3 >> 8);
buf[14 + off] = (byte) i3;
buf[16 + off] = '-';
buf[18 + off] = (byte) (i4 >> 8);
buf[20 + off] = (byte) i4;
buf[22 + off] = (byte) (i5 >> 8);
buf[24 + off] = (byte) i5;
buf[26 + off] = '-';
buf[28 + off] = (byte) (i6 >> 8);
buf[30 + off] = (byte) i6;
buf[32 + off] = (byte) (i7 >> 8);
buf[34 + off] = (byte) i7;
buf[36 + off] = '-';
buf[38 + off] = (byte) (i8 >> 8);
buf[40 + off] = (byte) i8;
buf[42 + off] = (byte) (i9 >> 8);
buf[44 + off] = (byte) i9;
buf[46 + off] = '-';
buf[48 + off] = (byte) (i10 >> 8);
buf[50 + off] = (byte) i10;
buf[52 + off] = (byte) (i11 >> 8);
buf[54 + off] = (byte) i11;
buf[56 + off] = (byte) (i12 >> 8);
buf[58 + off] = (byte) i12;
buf[60 + off] = (byte) (i13 >> 8);
buf[62 + off] = (byte) i13;
buf[64 + off] = (byte) (i14 >> 8);
buf[66 + off] = (byte) i14;
buf[68 + off] = (byte) (i15 >> 8);
buf[70 + off] = (byte) i15;
return new String(buf, UTF16);
}
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14578#discussion_r1238446588
