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8294432: Add provisions to calculate hash values from MemorySegments

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Reviewed-by: mcimadamore
This commit is contained in:
Per Minborg 2024-11-27 13:26:36 +00:00
parent 4a22c1fefc
commit a1473ec302
3 changed files with 338 additions and 0 deletions
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90
src/java.base/share/classes/jdk/internal/foreign/SegmentBulkOperations.java
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@ -28,7 +28,9 @@ package jdk.internal.foreign;
import jdk.internal.misc.ScopedMemoryAccess;
import jdk.internal.util.Architecture;
import jdk.internal.util.ArraysSupport;
import jdk.internal.util.ByteArrayLittleEndian;
import jdk.internal.vm.annotation.ForceInline;
import jdk.internal.vm.annotation.Stable;
import java.lang.foreign.MemorySegment;
@ -156,6 +158,94 @@ public final class SegmentBulkOperations {
}
}
private static final @Stable int[] POWERS_OF_31 = new int[]{
0x0000001f, 0x000003c1, 0x0000745f, 0x000e1781,
0x01b4d89f, 0x34e63b41, 0x67e12cdf, 0x94446f01};
/**
* {@return a 32-bit hash value calculated from the content in the provided
* {@code segment} between the provided offsets}
* <p>
* The method is implemented as a 32-bit polynomial hash function equivalent to:
* {@snippet lang=java :
* final long length = toOffset - fromOffset;
* segment.checkBounds(fromOffset, length);
* int result = 1;
* for (long i = fromOffset; i < toOffset; i++) {
* result = 31 * result + segment.get(JAVA_BYTE, i);
* }
* return result;
* }
* but is potentially more performant.
*
* @param segment from which a content hash should be computed
* @param fromOffset starting offset (inclusive) in the segment
* @param toOffset ending offset (non-inclusive) in the segment
* @throws WrongThreadException if this method is called from a thread {@code T},
* such that {@code srcSegment.isAccessibleBy(T) == false}
* @throws IllegalStateException if the {@linkplain MemorySegment#scope() scope}
* associated with {@code segment} is not
* {@linkplain MemorySegment.Scope#isAlive() alive}
* @throws IndexOutOfBoundsException if either {@code fromOffset} or {@code toOffset}
* are {@code > segment.byteSize}
* @throws IndexOutOfBoundsException if either {@code fromOffset} or {@code toOffset}
* are {@code < 0}
* @throws IndexOutOfBoundsException if {@code toOffset - fromOffset} is {@code < 0}
*/
@ForceInline
public static int contentHash(AbstractMemorySegmentImpl segment, long fromOffset, long toOffset) {
final long length = toOffset - fromOffset;
segment.checkBounds(fromOffset, length);
if (length == 0) {
// The state has to be checked explicitly for zero-length segments
segment.scope.checkValidState();
return 1;
}
int result = 1;
final long longBytes = length & ((1L << 62) - 8);
final long limit = fromOffset + longBytes;
for (; fromOffset < limit; fromOffset += 8) {
long val = SCOPED_MEMORY_ACCESS.getLongUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + fromOffset, !Architecture.isLittleEndian());
result = result * POWERS_OF_31[7]
+ ((byte) (val >>> 56)) * POWERS_OF_31[6]
+ ((byte) (val >>> 48)) * POWERS_OF_31[5]
+ ((byte) (val >>> 40)) * POWERS_OF_31[4]
+ ((byte) (val >>> 32)) * POWERS_OF_31[3]
+ ((byte) (val >>> 24)) * POWERS_OF_31[2]
+ ((byte) (val >>> 16)) * POWERS_OF_31[1]
+ ((byte) (val >>> 8)) * POWERS_OF_31[0]
+ ((byte) val);
}
int remaining = (int) (length - longBytes);
// 0...0X00
if (remaining >= 4) {
int val = SCOPED_MEMORY_ACCESS.getIntUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + fromOffset, !Architecture.isLittleEndian());
result = result * POWERS_OF_31[3]
+ ((byte) (val >>> 24)) * POWERS_OF_31[2]
+ ((byte) (val >>> 16)) * POWERS_OF_31[1]
+ ((byte) (val >>> 8)) * POWERS_OF_31[0]
+ ((byte) val);
fromOffset += 4;
remaining -= 4;
}
// 0...00X0
if (remaining >= 2) {
short val = SCOPED_MEMORY_ACCESS.getShortUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + fromOffset, !Architecture.isLittleEndian());
result = result * POWERS_OF_31[1]
+ ((byte) (val >>> 8)) * POWERS_OF_31[0]
+ ((byte) val);
fromOffset += 2;
remaining -= 2;
}
// 0...000X
if (remaining == 1) {
byte val = SCOPED_MEMORY_ACCESS.getByte(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + fromOffset);
result = result * POWERS_OF_31[0]
+ val;
}
return result;
}
@ForceInline
public static long mismatch(AbstractMemorySegmentImpl src, long srcFromOffset, long srcToOffset,
AbstractMemorySegmentImpl dst, long dstFromOffset, long dstToOffset) {

147
test/jdk/java/foreign/TestSegmentBulkOperationsContentHash.java Normal file
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@ -0,0 +1,147 @@
/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @summary Test SegmentBulkOperations::contentHash
* @modules java.base/jdk.internal.foreign
* @run junit TestSegmentBulkOperationsContentHash
*/
import jdk.internal.foreign.AbstractMemorySegmentImpl;
import jdk.internal.foreign.SegmentBulkOperations;
import org.junit.jupiter.api.Disabled;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.util.Arrays;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import static org.junit.jupiter.api.Assertions.*;
final class TestSegmentBulkOperationsContentHash {
@ParameterizedTest
@MethodSource("sizes")
@Disabled
void testHashValues(int len) {
try (var arena = Arena.ofConfined()) {
for (int i = Byte.MIN_VALUE; i <= Byte.MAX_VALUE ; i++) {
var segment = arena.allocate(len);
segment.fill((byte) i);
int hash = hash(segment);
int expected = Arrays.hashCode(segment.toArray(ValueLayout.JAVA_BYTE));
assertEquals(expected, hash, Arrays.toString(segment.toArray(ValueLayout.JAVA_BYTE)));
}
}
}
@ParameterizedTest
@MethodSource("sizes")
void testOffsets(int len) {
if (len < 2) {
return;
}
try (var arena = Arena.ofConfined()) {
for (int i = Byte.MIN_VALUE; i <= Byte.MAX_VALUE ; i++) {
var segment = arena.allocate(len);
segment.fill((byte) i);
int hash = hash(segment, 1, segment.byteSize() - 1);
MemorySegment slice = segment.asSlice(1, segment.byteSize() - 2);
byte[] arr = slice.toArray(ValueLayout.JAVA_BYTE);
System.out.println(Arrays.toString(arr));
int expected = Arrays.hashCode(arr);
assertEquals(expected, hash, Arrays.toString(segment.toArray(ValueLayout.JAVA_BYTE)));
}
}
}
@ParameterizedTest
@MethodSource("sizes")
void testOutOfBounds(int len) {
try (var arena = Arena.ofConfined()) {
var segment = arena.allocate(len);
assertThrows(IndexOutOfBoundsException.class,
() -> hash(segment, 0, segment.byteSize() + 1));
assertThrows(IndexOutOfBoundsException.class,
() -> hash(segment, 0, -1));
assertThrows(IndexOutOfBoundsException.class,
() -> hash(segment, -1, 0));
if (len > 2) {
assertThrows(IndexOutOfBoundsException.class,
() -> hash(segment, 2, 1));
}
}
}
@ParameterizedTest
@MethodSource("sizes")
void testConfinement(int len) {
try (var arena = Arena.ofConfined()) {
var segment = arena.allocate(len);
AtomicReference<RuntimeException> ex = new AtomicReference<>();
CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
try {
hash(segment);
} catch (RuntimeException e) {
ex.set(e);
}
});
future.join();
assertInstanceOf(WrongThreadException.class, ex.get());
}
}
@ParameterizedTest
@MethodSource("sizes")
void testScope(int len) {
var arena = Arena.ofConfined();
var segment = arena.allocate(len);
arena.close();
assertThrows(IllegalStateException.class, () -> hash(segment));
}
private static int hash(MemorySegment segment) {
return hash(segment, 0, segment.byteSize());
}
private static int hash(MemorySegment segment, long fromOffset, long toOffset) {
return SegmentBulkOperations.contentHash((AbstractMemorySegmentImpl) segment, fromOffset, toOffset);
}
private static final int MAX_SIZE = 1 << 10;
private static Stream<Arguments> sizes() {
return IntStream.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 23, 32, 63, 128, 256, 511, MAX_SIZE)
.boxed()
.map(Arguments::of);
}
}

101
test/micro/org/openjdk/bench/java/lang/foreign/SegmentBulkHash.java Normal file
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@ -0,0 +1,101 @@
/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
package org.openjdk.bench.java.lang.foreign;
import jdk.internal.foreign.AbstractMemorySegmentImpl;
import jdk.internal.foreign.SegmentBulkOperations;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import static java.lang.foreign.ValueLayout.JAVA_BYTE;
@BenchmarkMode(Mode.AverageTime)
@Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Fork(value = 3, jvmArgs = {"--add-exports=java.base/jdk.internal.foreign=ALL-UNNAMED"})
public class SegmentBulkHash {
@Param({"8", "64"})
public int ELEM_SIZE;
byte[] array;
AbstractMemorySegmentImpl heapSegment;
AbstractMemorySegmentImpl nativeSegment;
@Setup
public void setup() {
// Always use the same alignment regardless of size
nativeSegment = (AbstractMemorySegmentImpl) Arena.ofAuto().allocate(ELEM_SIZE, 16);
var rnd = new Random(42);
for (int i = 0; i < ELEM_SIZE; i++) {
nativeSegment.set(JAVA_BYTE, i, (byte) rnd.nextInt(Byte.MIN_VALUE, Byte.MAX_VALUE));
}
array = nativeSegment.toArray(JAVA_BYTE);
heapSegment = (AbstractMemorySegmentImpl) MemorySegment.ofArray(array);
}
@Benchmark
public int array() {
return Arrays.hashCode(array);
}
@Benchmark
public int heapSegment() {
return SegmentBulkOperations.contentHash(heapSegment, 0, ELEM_SIZE);
}
@Benchmark
public int nativeSegment() {
return SegmentBulkOperations.contentHash(nativeSegment, 0, ELEM_SIZE);
}
@Benchmark
public int nativeSegmentJava() {
int result = 1;
for (long i = 0; i < ELEM_SIZE; i++) {
result = 31 * result + nativeSegment.get(JAVA_BYTE, i);
}
return result;
}
}