> Just a very tiny clean-up. > > There are some places in JDK code base where we call > `Enum.class.getEnumConstants()` to get all the values of the referenced > `enum`. This is excessive, less-readable and slower than just calling > `Enum.values()` as in `getEnumConstants()` we have volatile access: > > public T[] getEnumConstants() { > T[] values = getEnumConstantsShared(); > return (values != null) ? values.clone() : null; > } > > private transient volatile T[] enumConstants; > > T[] getEnumConstantsShared() { > T[] constants = enumConstants; > if (constants == null) { /* ... */ } > return constants; > } > > Calling values() method is slightly faster: > > @BenchmarkMode(Mode.AverageTime) > @OutputTimeUnit(TimeUnit.NANOSECONDS) > @Fork(jvmArgsAppend = {"-Xms2g", "-Xmx2g"}) > public class EnumBenchmark { > > @Benchmark > public Enum[] values() { > return Enum.values(); > } > > @Benchmark > public Enum[] getEnumConstants() { > return Enum.class.getEnumConstants(); > } > > private enum Enum { > A, > B > } > } > > > Benchmark Mode Cnt > Score Error Units > EnumBenchmark.getEnumConstants avgt 15 > 6,265 ± 0,051 ns/op > EnumBenchmark.getEnumConstants:·gc.alloc.rate avgt 15 > 2434,075 ± 19,568 MB/sec > EnumBenchmark.getEnumConstants:·gc.alloc.rate.norm avgt 15 > 24,002 ± 0,001 B/op > EnumBenchmark.getEnumConstants:·gc.churn.G1_Eden_Space avgt 15 > 2433,709 ± 70,216 MB/sec > EnumBenchmark.getEnumConstants:·gc.churn.G1_Eden_Space.norm avgt 15 > 23,998 ± 0,659 B/op > EnumBenchmark.getEnumConstants:·gc.churn.G1_Survivor_Space avgt 15 > 0,009 ± 0,003 MB/sec > EnumBenchmark.getEnumConstants:·gc.churn.G1_Survivor_Space.norm avgt 15 > ≈ 10⁻⁴ B/op > EnumBenchmark.getEnumConstants:·gc.count avgt 15 > 210,000 counts > EnumBenchmark.getEnumConstants:·gc.time avgt 15 > 119,000 ms > > EnumBenchmark.values avgt 15 > 4,164 ± 0,134 ns/op > EnumBenchmark.values:·gc.alloc.rate avgt 15 > 3665,341 ± 120,721 MB/sec > EnumBenchmark.values:·gc.alloc.rate.norm avgt 15 > 24,002 ± 0,001 B/op > EnumBenchmark.values:·gc.churn.G1_Eden_Space avgt 15 > 3660,512 ± 137,250 MB/sec > EnumBenchmark.values:·gc.churn.G1_Eden_Space.norm avgt 15 > 23,972 ± 0,529 B/op > EnumBenchmark.values:·gc.churn.G1_Survivor_Space avgt 15 > 0,017 ± 0,003 MB/sec > EnumBenchmark.values:·gc.churn.G1_Survivor_Space.norm avgt 15 > ≈ 10⁻⁴ B/op > EnumBenchmark.values:·gc.count avgt 15 > 262,000 counts > EnumBenchmark.values:·gc.time avgt 15 > 155,000 ms
Сергей Цыпанов has updated the pull request incrementally with one additional commit since the last revision: 8273140: Fix copyright year ------------- Changes: - all: https://git.openjdk.java.net/jdk/pull/5303/files - new: https://git.openjdk.java.net/jdk/pull/5303/files/90319b2f..1cfb0af3 Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5303&range=01 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5303&range=00-01 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.java.net/jdk/pull/5303.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/5303/head:pull/5303 PR: https://git.openjdk.java.net/jdk/pull/5303