RFR: 8292937: Improve performance of some read operations of RandomAccessFile [v2]

[Сергей Цыпанов]

> Currently some operations of RandomAccessFile are implemented with multiple read() invocations:
> 
> public final int readInt() throws IOException {
>     int ch1 = this.read();
>     int ch2 = this.read();
>     int ch3 = this.read();
>     int ch4 = this.read();
>     if ((ch1 | ch2 | ch3 | ch4) < 0)
>       throw new EOFException();
>     return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
> }
> 
> This can be improved by using bulk reads:
> 
> public final int readInt() throws IOException {
>   readFully(readBuffer, 0, 4);
>   return Bits.getInt(readBuffer, 0);
> }
> 
> Benchmarking:
> 
> baselile
> Benchmark                                (kiloBytes)  Mode  Cnt     Score      Error  Units
> RandomAccessFileReadBenchmark.readInt              1  avgt   10  1060,526 ±   62,036  us/op
> RandomAccessFileReadBenchmark.readInt              5  avgt   10  5745,671 ± 1374,277  us/op
> RandomAccessFileReadBenchmark.readLong             1  avgt   10  1399,494 ±  378,072  us/op
> RandomAccessFileReadBenchmark.readLong             5  avgt   10  4864,425 ±  329,282  us/op
> RandomAccessFileReadBenchmark.readShort            1  avgt   10  1111,163 ±   70,883  us/op
> RandomAccessFileReadBenchmark.readShort            5  avgt   10  4933,058 ±  339,273  us/op
> 
> patch
> Benchmark                                (kiloBytes)  Mode  Cnt     Score    Error  Units
> RandomAccessFileReadBenchmark.readInt              1  avgt   10   311,404 ± 17,337  us/op
> RandomAccessFileReadBenchmark.readInt              5  avgt   10  1210,381 ± 22,742  us/op
> RandomAccessFileReadBenchmark.readLong             1  avgt   10   201,726 ±  8,885  us/op
> RandomAccessFileReadBenchmark.readLong             5  avgt   10   667,117 ±  6,779  us/op
> RandomAccessFileReadBenchmark.readShort            1  avgt   10   560,259 ± 16,783  us/op
> RandomAccessFileReadBenchmark.readShort            5  avgt   10  2251,975 ± 54,533  us/op

Сергей Цыпанов has updated the pull request incrementally with one additional commit since the last revision:

  8292937: Move logic into VM side

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10031/files
  - new: https://git.openjdk.org/jdk/pull/10031/files/b147a061..faae4fc5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10031&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10031&range=00-01

  Stats: 64 lines in 4 files changed: 47 ins; 5 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/10031.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10031/head:pull/10031

PR: https://git.openjdk.org/jdk/pull/10031