RFR: 8321620: Optimize JImage decompressors

[Glavo]

I generated runtime images using `jlink --compress 2 --add-modules java.se,jdk.unsupported,jdk.management` and then ran the following JMH benchmark:


@Warmup(iterations = 10, time = 2)
@Measurement(iterations = 5, time = 3)
@Fork(value = 1, jvmArgsAppend = {"-XX:+UseG1GC", "-Xms8g", "-Xmx8g", "--add-exports=java.base/jdk.internal.jimage=ALL-UNNAMED"})
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
public class Decompress {

    private static final ImageReader READER = ImageReaderFactory.getImageReader();
    private static final ImageLocation LOC = READER.findLocation("java.base", "java/lang/String.class");

    @Benchmark
    public ByteBuffer test() {
        return READER.getResourceBuffer(LOC);
    }

}



This is the result:


Zip

Benchmark                           Mode  Cnt       Score       Error   Units        Score       Error   Units
Decompress.test                     avgt    5  194237.534 ±  1026.180   ns/op   152855.728 ± 16058.780   ns/op   (-21.30%)
Decompress.test:gc.alloc.rate       avgt    5    1197.700 ±     6.306  MB/sec      464.278 ±    47.465  MB/sec
Decompress.test:gc.alloc.rate.norm  avgt    5  243953.338 ±     5.810    B/op    74376.291 ±     2.175    B/op   (-69.51%)
Decompress.test:gc.count            avgt    5       2.000              counts        1.000              counts
Decompress.test:gc.time             avgt    5       4.000                  ms        3.000                  ms


The results show that memory allocation is reduced by 70% while decompression speed is significantly improved.

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

Commit messages:
 - Update ZipDecompressor

Changes: https://git.openjdk.org/jdk/pull/17405/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17405&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321620
  Stats: 21 lines in 1 file changed: 10 ins; 5 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/17405.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17405/head:pull/17405

PR: https://git.openjdk.org/jdk/pull/17405