On Sat, 1 Jul 2023 02:33:11 GMT, 温绍锦 <d...@openjdk.org> wrote: > > Is using `Unsafe` directly consistently faster than using ByteArray? It > > should have similar performance as ByteArray's VarHandle is simply a > > wrapper around Unsafe's put/get methods. > > Using Unsafe on aliyun_ecs_c8i.xlarge and MacBookPro M1 Pro is faster than > ByteArray, and I haven't figured out why
Then it's probably VarHandle's overhead. No worries; your change to use Unsafe is totally fine. Meanwhile, can you enable GitHub actions on your fork, so it can detect compile and test errors? Like this: <img width="1259" alt="image" src="https://github.com/openjdk/jdk/assets/7806504/fa843978-757c-4ba0-a23f-055f25ddda7e";> >> src/java.base/share/classes/java/util/HexDigits.java line 108: >> >>> 106: * Combine two hex shorts into one int based on big endian >>> 107: */ >>> 108: static int packDigits(int b0, int b1) { >> >> I recommend such a refactor: >> >> /** >> * Return a big-endian packed integer for the 4 ASCII bytes for an input >> unsigned short value. >> */ >> static int packDigits16(int b) { >> return (DIGITS[(b >> 8) & 0xff] << 16) | DIGITS[b & 0xff]; >> } >> >> And all your usages can be `HexDigits.packDigits16(((int) msb) >> 16)` and >> `HexDigits.packDigits16((int) msb)` without the `>> 24` and `>> 8` > > but it's return an int value The current code snippet still returns a int value... I think I can probably make a patch and demonstrate. >> src/java.base/share/classes/java/util/HexDigits.java line 115: >> >>> 113: * Combine four hex shorts into one long based on big endian >>> 114: */ >>> 115: static long packDigits(int b0, int b1, int b2, int b3) { >> >> Same comment here: >> >> >> /** >> * Return a big-endian packed long for the 8 ASCII bytes for an input >> unsigned int value. >> */ >> static long packDigits32(int b) { >> return (((long) DIGITS[(b >> 24) & 0xff]) << 48) >> | (((long) DIGITS[(b >> 16) & 0xff]) << 32) >> | (DIGITS[(b >> 8) & 0xff] << 16) >> | DIGITS[b & 0xff]; >> } >> >> And use sites become: >> >> // old >> HexDigits.packDigits((int) (msb >> 56), (int) (msb >> 48), (int) (msb >> >> 40), (int) (msb >> 32)) >> // new >> HexDigits.packDigits32((int) (msb >> 32)) >> >> and `HexDigits.packDigits32((int) (lsb >> 16))` > > but it's return a long value My fault, fixed the return type in my code snippet. ------------- PR Comment: https://git.openjdk.org/jdk/pull/14745#issuecomment-1615379558 PR Review Comment: https://git.openjdk.org/jdk/pull/14745#discussion_r1248397625 PR Review Comment: https://git.openjdk.org/jdk/pull/14745#discussion_r1248397481
