test/jdk/java/foreign/TestSegments.java - platform/libcore - Git at Google

 /*
  *  Copyright (c) 2019, 2023, 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
  * @enablePreview
  * @requires ((os.arch == "amd64" | os.arch == "x86_64") & sun.arch.data.model == "64") | os.arch == "aarch64"
  * @run testng/othervm -Xmx4G -XX:MaxDirectMemorySize=1M --enable-native-access=ALL-UNNAMED TestSegments
  */

 import java.lang.foreign.Arena;
 import java.lang.foreign.MemoryLayout;
 import java.lang.foreign.MemorySegment;
 import java.lang.foreign.SegmentScope;
 import java.lang.foreign.ValueLayout;
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;

 import java.lang.invoke.VarHandle;
 import java.nio.ByteBuffer;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.IntFunction;
 import java.util.function.Supplier;

 import static java.lang.foreign.ValueLayout.JAVA_INT;
 import static org.testng.Assert.*;

 public class TestSegments {

     @Test(dataProvider = "badSizeAndAlignments", expectedExceptions = IllegalArgumentException.class)
     public void testBadAllocateAlign(long size, long align) {
         MemorySegment.allocateNative(size, align, SegmentScope.auto());
     }

     @Test
     public void testZeroLengthNativeSegment() {
         try (Arena arena = Arena.openConfined()) {
             SegmentScope session = arena.scope();
             var segment = MemorySegment.allocateNative(0, session);
             assertEquals(segment.byteSize(), 0);
             MemoryLayout seq = MemoryLayout.sequenceLayout(0, JAVA_INT);
             segment = MemorySegment.allocateNative(seq, session);
             assertEquals(segment.byteSize(), 0);
             assertEquals(segment.address() % seq.byteAlignment(), 0);
             segment = MemorySegment.allocateNative(0, 4, session);
             assertEquals(segment.byteSize(), 0);
             assertEquals(segment.address() % 4, 0);
             MemorySegment rawAddress = MemorySegment.ofAddress(segment.address(), 0, session);
             assertEquals(rawAddress.byteSize(), 0);
             assertEquals(rawAddress.address() % 4, 0);
         }
     }

     @Test(expectedExceptions = { OutOfMemoryError.class,
                                  IllegalArgumentException.class })
     public void testAllocateTooBig() {
         MemorySegment.allocateNative(Long.MAX_VALUE, SegmentScope.auto());
     }

     @Test(expectedExceptions = OutOfMemoryError.class)
     public void testNativeAllocationTooBig() {
         MemorySegment segment = MemorySegment.allocateNative(1024L * 1024 * 8 * 2, SegmentScope.auto()); // 2M
     }

     @Test
     public void testNativeSegmentIsZeroed() {
         VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();
         try (Arena arena = Arena.openConfined()) {
             MemorySegment segment = MemorySegment.allocateNative(1000, 1, arena.scope());
             for (long i = 0 ; i < segment.byteSize() ; i++) {
                 assertEquals(0, (byte)byteHandle.get(segment, i));
             }
         }
     }

     @Test
     public void testSlices() {
         VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();
         try (Arena arena = Arena.openConfined()) {
             MemorySegment segment = MemorySegment.allocateNative(10, 1, arena.scope());
             //init
             for (byte i = 0 ; i < segment.byteSize() ; i++) {
                 byteHandle.set(segment, (long)i, i);
             }
             for (int offset = 0 ; offset < 10 ; offset++) {
                 MemorySegment slice = segment.asSlice(offset);
                 for (long i = offset ; i < 10 ; i++) {
                     assertEquals(
                             byteHandle.get(segment, i),
                             byteHandle.get(slice, i - offset)
                     );
                 }
             }
         }
     }

     @Test
     public void testEqualsOffHeap() {
         try (Arena arena = Arena.openConfined()) {
             MemorySegment segment = MemorySegment.allocateNative(100, arena.scope());
             assertEquals(segment, segment.asReadOnly());
             assertEquals(segment, segment.asSlice(0, 100));
             assertNotEquals(segment, segment.asSlice(10, 90));
             assertEquals(segment, segment.asSlice(0, 90));
             assertEquals(segment, MemorySegment.ofAddress(segment.address(), 100, SegmentScope.global()));
             MemorySegment segment2 = MemorySegment.allocateNative(100, arena.scope());
             assertNotEquals(segment, segment2);
         }
     }

     @Test
     public void testEqualsOnHeap() {
         MemorySegment segment = MemorySegment.ofArray(new byte[100]);
         assertEquals(segment, segment.asReadOnly());
         assertEquals(segment, segment.asSlice(0, 100));
         assertNotEquals(segment, segment.asSlice(10, 90));
         assertEquals(segment, segment.asSlice(0, 90));
         MemorySegment segment2 = MemorySegment.ofArray(new byte[100]);
         assertNotEquals(segment, segment2);
     }

     @Test
     public void testHashCodeOffHeap() {
         try (Arena arena = Arena.openConfined()) {
             MemorySegment segment = MemorySegment.allocateNative(100, arena.scope());
             assertEquals(segment.hashCode(), segment.asReadOnly().hashCode());
             assertEquals(segment.hashCode(), segment.asSlice(0, 100).hashCode());
             assertEquals(segment.hashCode(), segment.asSlice(0, 90).hashCode());
             assertEquals(segment.hashCode(), MemorySegment.ofAddress(segment.address(), 100, SegmentScope.global()).hashCode());
         }
     }

     @Test
     public void testHashCodeOnHeap() {
         MemorySegment segment = MemorySegment.ofArray(new byte[100]);
         assertEquals(segment.hashCode(), segment.asReadOnly().hashCode());
         assertEquals(segment.hashCode(), segment.asSlice(0, 100).hashCode());
         assertEquals(segment.hashCode(), segment.asSlice(0, 90).hashCode());
     }

     @Test(expectedExceptions = IndexOutOfBoundsException.class)
     public void testSmallSegmentMax() {
         long offset = (long)Integer.MAX_VALUE + (long)Integer.MAX_VALUE + 2L + 6L; // overflows to 6 when cast to int
         MemorySegment memorySegment = MemorySegment.allocateNative(10, SegmentScope.auto());
         memorySegment.get(JAVA_INT, offset);
     }

     @Test(expectedExceptions = IndexOutOfBoundsException.class)
     public void testSmallSegmentMin() {
         long offset = ((long)Integer.MIN_VALUE * 2L) + 6L; // underflows to 6 when cast to int
         MemorySegment memorySegment = MemorySegment.allocateNative(10L, SegmentScope.auto());
         memorySegment.get(JAVA_INT, offset);
     }

     @Test
     public void testSegmentOOBMessage() {
         try {
             var segment = MemorySegment.allocateNative(10, SegmentScope.global());
             segment.getAtIndex(ValueLayout.JAVA_INT, 2);
         } catch (IndexOutOfBoundsException ex) {
             assertTrue(ex.getMessage().contains("Out of bound access"));
             assertTrue(ex.getMessage().contains("offset = 8"));
             assertTrue(ex.getMessage().contains("length = 4"));
         }
     }

     @Test(dataProvider = "segmentFactories")
     public void testAccessModesOfFactories(Supplier<MemorySegment> segmentSupplier) {
         MemorySegment segment = segmentSupplier.get();
         assertFalse(segment.isReadOnly());
     }

     @DataProvider(name = "scopes")
     public Object[][] scopes() {
         return new Object[][] {
                 { SegmentScope.auto(), false },
                 { SegmentScope.global(), false },
                 { Arena.openConfined().scope(), true },
                 { Arena.openShared().scope(), false }
         };
     }

     @Test(dataProvider = "scopes")
     public void testIsAccessibleBy(SegmentScope scope, boolean isConfined) {
         assertTrue(scope.isAccessibleBy(Thread.currentThread()));
         assertTrue(scope.isAccessibleBy(new Thread()) != isConfined);
         MemorySegment segment = MemorySegment.ofAddress(0, 0, scope);
         assertTrue(segment.scope().isAccessibleBy(Thread.currentThread()));
         assertTrue(segment.scope().isAccessibleBy(new Thread()) != isConfined);
     }

     @DataProvider(name = "segmentFactories")
     public Object[][] segmentFactories() {
         List<Supplier<MemorySegment>> l = List.of(
                 () -> MemorySegment.ofArray(new byte[] { 0x00, 0x01, 0x02, 0x03 }),
                 () -> MemorySegment.ofArray(new char[] {'a', 'b', 'c', 'd' }),
                 () -> MemorySegment.ofArray(new double[] { 1d, 2d, 3d, 4d} ),
                 () -> MemorySegment.ofArray(new float[] { 1.0f, 2.0f, 3.0f, 4.0f }),
                 () -> MemorySegment.ofArray(new int[] { 1, 2, 3, 4 }),
                 () -> MemorySegment.ofArray(new long[] { 1l, 2l, 3l, 4l } ),
                 () -> MemorySegment.ofArray(new short[] { 1, 2, 3, 4 } ),
                 () -> MemorySegment.allocateNative(4L, SegmentScope.auto()),
                 () -> MemorySegment.allocateNative(4L, 8, SegmentScope.auto()),
                 () -> MemorySegment.allocateNative(JAVA_INT, SegmentScope.auto()),
                 () -> MemorySegment.allocateNative(4L, SegmentScope.auto()),
                 () -> MemorySegment.allocateNative(4L, 8, SegmentScope.auto()),
                 () -> MemorySegment.allocateNative(JAVA_INT, SegmentScope.auto())

         );
         return l.stream().map(s -> new Object[] { s }).toArray(Object[][]::new);
     }

     @Test(dataProvider = "segmentFactories")
     public void testFill(Supplier<MemorySegment> segmentSupplier) {
         VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();

         for (byte value : new byte[] {(byte) 0xFF, (byte) 0x00, (byte) 0x45}) {
             MemorySegment segment = segmentSupplier.get();
             segment.fill(value);
             for (long l = 0; l < segment.byteSize(); l++) {
                 assertEquals((byte) byteHandle.get(segment, l), value);
             }

             // fill a slice
             var sliceSegment = segment.asSlice(1, segment.byteSize() - 2).fill((byte) ~value);
             for (long l = 0; l < sliceSegment.byteSize(); l++) {
                 assertEquals((byte) byteHandle.get(sliceSegment, l), ~value);
             }
             // assert enclosing slice
             assertEquals((byte) byteHandle.get(segment, 0L), value);
             for (long l = 1; l < segment.byteSize() - 2; l++) {
                 assertEquals((byte) byteHandle.get(segment, l), (byte) ~value);
             }
             assertEquals((byte) byteHandle.get(segment, segment.byteSize() - 1L), value);
         }
     }

     @Test(dataProvider = "segmentFactories")
     public void testNativeSegments(Supplier<MemorySegment> segmentSupplier) {
         MemorySegment segment = segmentSupplier.get();
         assertEquals(segment.isNative(), !segment.array().isPresent());
     }

     @Test(dataProvider = "segmentFactories", expectedExceptions = UnsupportedOperationException.class)
     public void testFillIllegalAccessMode(Supplier<MemorySegment> segmentSupplier) {
         MemorySegment segment = segmentSupplier.get();
         segment.asReadOnly().fill((byte) 0xFF);
     }

     @Test(dataProvider = "segmentFactories")
     public void testFillThread(Supplier<MemorySegment> segmentSupplier) throws Exception {
         MemorySegment segment = segmentSupplier.get();
         AtomicReference<RuntimeException> exception = new AtomicReference<>();
         Runnable action = () -> {
             try {
                 segment.fill((byte) 0xBA);
             } catch (RuntimeException e) {
                 exception.set(e);
             }
         };
         Thread thread = new Thread(action);
         thread.start();
         thread.join();

         if (!segment.scope().isAccessibleBy(Thread.currentThread())) {
             RuntimeException e = exception.get();
             throw e;
         } else {
             assertNull(exception.get());
         }
     }

     @Test
     public void testFillEmpty() {
         MemorySegment.ofArray(new byte[] { }).fill((byte) 0xFF);
         MemorySegment.ofArray(new byte[2]).asSlice(0, 0).fill((byte) 0xFF);
         MemorySegment.ofBuffer(ByteBuffer.allocateDirect(0)).fill((byte) 0xFF);
     }

     @Test(dataProvider = "heapFactories")
     public void testVirtualizedBaseAddress(IntFunction<MemorySegment> heapSegmentFactory, int factor) {
         MemorySegment segment = heapSegmentFactory.apply(10);
         assertEquals(segment.address(), 0); // base address should be zero (no leaking of impl details)
         MemorySegment end = segment.asSlice(segment.byteSize(), 0);
         assertEquals(end.address(), segment.byteSize()); // end address should be equal to segment byte size
     }

     @DataProvider(name = "badSizeAndAlignments")
     public Object[][] sizesAndAlignments() {
         return new Object[][] {
                 { -1, 8 },
                 { 1, 15 },
                 { 1, -15 }
         };
     }

     @DataProvider(name = "heapFactories")
     public Object[][] heapFactories() {
         return new Object[][] {
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new byte[size]), 1 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new char[size]), 2 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new short[size]), 2 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new int[size]), 4 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new float[size]), 4 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new long[size]), 8 },
                 { (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new double[size]), 8 }
         };
     }
 }
	/*
	* Copyright (c) 2019, 2023, 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
	* @enablePreview
	* @requires ((os.arch == "amd64" \| os.arch == "x86_64") & sun.arch.data.model == "64") \| os.arch == "aarch64"
	* @run testng/othervm -Xmx4G -XX:MaxDirectMemorySize=1M --enable-native-access=ALL-UNNAMED TestSegments
	*/

	import java.lang.foreign.Arena;
	import java.lang.foreign.MemoryLayout;
	import java.lang.foreign.MemorySegment;
	import java.lang.foreign.SegmentScope;
	import java.lang.foreign.ValueLayout;
	import org.testng.annotations.DataProvider;
	import org.testng.annotations.Test;

	import java.lang.invoke.VarHandle;
	import java.nio.ByteBuffer;
	import java.util.List;
	import java.util.concurrent.atomic.AtomicReference;
	import java.util.function.IntFunction;
	import java.util.function.Supplier;

	import static java.lang.foreign.ValueLayout.JAVA_INT;
	import static org.testng.Assert.*;

	public class TestSegments {

	@Test(dataProvider = "badSizeAndAlignments", expectedExceptions = IllegalArgumentException.class)
	public void testBadAllocateAlign(long size, long align) {
	MemorySegment.allocateNative(size, align, SegmentScope.auto());
	}

	@Test
	public void testZeroLengthNativeSegment() {
	try (Arena arena = Arena.openConfined()) {
	SegmentScope session = arena.scope();
	var segment = MemorySegment.allocateNative(0, session);
	assertEquals(segment.byteSize(), 0);
	MemoryLayout seq = MemoryLayout.sequenceLayout(0, JAVA_INT);
	segment = MemorySegment.allocateNative(seq, session);
	assertEquals(segment.byteSize(), 0);
	assertEquals(segment.address() % seq.byteAlignment(), 0);
	segment = MemorySegment.allocateNative(0, 4, session);
	assertEquals(segment.byteSize(), 0);
	assertEquals(segment.address() % 4, 0);
	MemorySegment rawAddress = MemorySegment.ofAddress(segment.address(), 0, session);
	assertEquals(rawAddress.byteSize(), 0);
	assertEquals(rawAddress.address() % 4, 0);
	}
	}

	@Test(expectedExceptions = { OutOfMemoryError.class,
	IllegalArgumentException.class })
	public void testAllocateTooBig() {
	MemorySegment.allocateNative(Long.MAX_VALUE, SegmentScope.auto());
	}

	@Test(expectedExceptions = OutOfMemoryError.class)
	public void testNativeAllocationTooBig() {
	MemorySegment segment = MemorySegment.allocateNative(1024L * 1024 * 8 * 2, SegmentScope.auto()); // 2M
	}

	@Test
	public void testNativeSegmentIsZeroed() {
	VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();
	try (Arena arena = Arena.openConfined()) {
	MemorySegment segment = MemorySegment.allocateNative(1000, 1, arena.scope());
	for (long i = 0 ; i < segment.byteSize() ; i++) {
	assertEquals(0, (byte)byteHandle.get(segment, i));
	}
	}
	}

	@Test
	public void testSlices() {
	VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();
	try (Arena arena = Arena.openConfined()) {
	MemorySegment segment = MemorySegment.allocateNative(10, 1, arena.scope());
	//init
	for (byte i = 0 ; i < segment.byteSize() ; i++) {
	byteHandle.set(segment, (long)i, i);
	}
	for (int offset = 0 ; offset < 10 ; offset++) {
	MemorySegment slice = segment.asSlice(offset);
	for (long i = offset ; i < 10 ; i++) {
	assertEquals(
	byteHandle.get(segment, i),
	byteHandle.get(slice, i - offset)
	);
	}
	}
	}
	}

	@Test
	public void testEqualsOffHeap() {
	try (Arena arena = Arena.openConfined()) {
	MemorySegment segment = MemorySegment.allocateNative(100, arena.scope());
	assertEquals(segment, segment.asReadOnly());
	assertEquals(segment, segment.asSlice(0, 100));
	assertNotEquals(segment, segment.asSlice(10, 90));
	assertEquals(segment, segment.asSlice(0, 90));
	assertEquals(segment, MemorySegment.ofAddress(segment.address(), 100, SegmentScope.global()));
	MemorySegment segment2 = MemorySegment.allocateNative(100, arena.scope());
	assertNotEquals(segment, segment2);
	}
	}

	@Test
	public void testEqualsOnHeap() {
	MemorySegment segment = MemorySegment.ofArray(new byte[100]);
	assertEquals(segment, segment.asReadOnly());
	assertEquals(segment, segment.asSlice(0, 100));
	assertNotEquals(segment, segment.asSlice(10, 90));
	assertEquals(segment, segment.asSlice(0, 90));
	MemorySegment segment2 = MemorySegment.ofArray(new byte[100]);
	assertNotEquals(segment, segment2);
	}

	@Test
	public void testHashCodeOffHeap() {
	try (Arena arena = Arena.openConfined()) {
	MemorySegment segment = MemorySegment.allocateNative(100, arena.scope());
	assertEquals(segment.hashCode(), segment.asReadOnly().hashCode());
	assertEquals(segment.hashCode(), segment.asSlice(0, 100).hashCode());
	assertEquals(segment.hashCode(), segment.asSlice(0, 90).hashCode());
	assertEquals(segment.hashCode(), MemorySegment.ofAddress(segment.address(), 100, SegmentScope.global()).hashCode());
	}
	}

	@Test
	public void testHashCodeOnHeap() {
	MemorySegment segment = MemorySegment.ofArray(new byte[100]);
	assertEquals(segment.hashCode(), segment.asReadOnly().hashCode());
	assertEquals(segment.hashCode(), segment.asSlice(0, 100).hashCode());
	assertEquals(segment.hashCode(), segment.asSlice(0, 90).hashCode());
	}

	@Test(expectedExceptions = IndexOutOfBoundsException.class)
	public void testSmallSegmentMax() {
	long offset = (long)Integer.MAX_VALUE + (long)Integer.MAX_VALUE + 2L + 6L; // overflows to 6 when cast to int
	MemorySegment memorySegment = MemorySegment.allocateNative(10, SegmentScope.auto());
	memorySegment.get(JAVA_INT, offset);
	}

	@Test(expectedExceptions = IndexOutOfBoundsException.class)
	public void testSmallSegmentMin() {
	long offset = ((long)Integer.MIN_VALUE * 2L) + 6L; // underflows to 6 when cast to int
	MemorySegment memorySegment = MemorySegment.allocateNative(10L, SegmentScope.auto());
	memorySegment.get(JAVA_INT, offset);
	}

	@Test
	public void testSegmentOOBMessage() {
	try {
	var segment = MemorySegment.allocateNative(10, SegmentScope.global());
	segment.getAtIndex(ValueLayout.JAVA_INT, 2);
	} catch (IndexOutOfBoundsException ex) {
	assertTrue(ex.getMessage().contains("Out of bound access"));
	assertTrue(ex.getMessage().contains("offset = 8"));
	assertTrue(ex.getMessage().contains("length = 4"));
	}
	}

	@Test(dataProvider = "segmentFactories")
	public void testAccessModesOfFactories(Supplier<MemorySegment> segmentSupplier) {
	MemorySegment segment = segmentSupplier.get();
	assertFalse(segment.isReadOnly());
	}

	@DataProvider(name = "scopes")
	public Object[][] scopes() {
	return new Object[][] {
	{ SegmentScope.auto(), false },
	{ SegmentScope.global(), false },
	{ Arena.openConfined().scope(), true },
	{ Arena.openShared().scope(), false }
	};
	}

	@Test(dataProvider = "scopes")
	public void testIsAccessibleBy(SegmentScope scope, boolean isConfined) {
	assertTrue(scope.isAccessibleBy(Thread.currentThread()));
	assertTrue(scope.isAccessibleBy(new Thread()) != isConfined);
	MemorySegment segment = MemorySegment.ofAddress(0, 0, scope);
	assertTrue(segment.scope().isAccessibleBy(Thread.currentThread()));
	assertTrue(segment.scope().isAccessibleBy(new Thread()) != isConfined);
	}

	@DataProvider(name = "segmentFactories")
	public Object[][] segmentFactories() {
	List<Supplier<MemorySegment>> l = List.of(
	() -> MemorySegment.ofArray(new byte[] { 0x00, 0x01, 0x02, 0x03 }),
	() -> MemorySegment.ofArray(new char[] {'a', 'b', 'c', 'd' }),
	() -> MemorySegment.ofArray(new double[] { 1d, 2d, 3d, 4d} ),
	() -> MemorySegment.ofArray(new float[] { 1.0f, 2.0f, 3.0f, 4.0f }),
	() -> MemorySegment.ofArray(new int[] { 1, 2, 3, 4 }),
	() -> MemorySegment.ofArray(new long[] { 1l, 2l, 3l, 4l } ),
	() -> MemorySegment.ofArray(new short[] { 1, 2, 3, 4 } ),
	() -> MemorySegment.allocateNative(4L, SegmentScope.auto()),
	() -> MemorySegment.allocateNative(4L, 8, SegmentScope.auto()),
	() -> MemorySegment.allocateNative(JAVA_INT, SegmentScope.auto()),
	() -> MemorySegment.allocateNative(4L, SegmentScope.auto()),
	() -> MemorySegment.allocateNative(4L, 8, SegmentScope.auto()),
	() -> MemorySegment.allocateNative(JAVA_INT, SegmentScope.auto())

	);
	return l.stream().map(s -> new Object[] { s }).toArray(Object[][]::new);
	}

	@Test(dataProvider = "segmentFactories")
	public void testFill(Supplier<MemorySegment> segmentSupplier) {
	VarHandle byteHandle = ValueLayout.JAVA_BYTE.arrayElementVarHandle();

	for (byte value : new byte[] {(byte) 0xFF, (byte) 0x00, (byte) 0x45}) {
	MemorySegment segment = segmentSupplier.get();
	segment.fill(value);
	for (long l = 0; l < segment.byteSize(); l++) {
	assertEquals((byte) byteHandle.get(segment, l), value);
	}

	// fill a slice
	var sliceSegment = segment.asSlice(1, segment.byteSize() - 2).fill((byte) ~value);
	for (long l = 0; l < sliceSegment.byteSize(); l++) {
	assertEquals((byte) byteHandle.get(sliceSegment, l), ~value);
	}
	// assert enclosing slice
	assertEquals((byte) byteHandle.get(segment, 0L), value);
	for (long l = 1; l < segment.byteSize() - 2; l++) {
	assertEquals((byte) byteHandle.get(segment, l), (byte) ~value);
	}
	assertEquals((byte) byteHandle.get(segment, segment.byteSize() - 1L), value);
	}
	}

	@Test(dataProvider = "segmentFactories")
	public void testNativeSegments(Supplier<MemorySegment> segmentSupplier) {
	MemorySegment segment = segmentSupplier.get();
	assertEquals(segment.isNative(), !segment.array().isPresent());
	}

	@Test(dataProvider = "segmentFactories", expectedExceptions = UnsupportedOperationException.class)
	public void testFillIllegalAccessMode(Supplier<MemorySegment> segmentSupplier) {
	MemorySegment segment = segmentSupplier.get();
	segment.asReadOnly().fill((byte) 0xFF);
	}

	@Test(dataProvider = "segmentFactories")
	public void testFillThread(Supplier<MemorySegment> segmentSupplier) throws Exception {
	MemorySegment segment = segmentSupplier.get();
	AtomicReference<RuntimeException> exception = new AtomicReference<>();
	Runnable action = () -> {
	try {
	segment.fill((byte) 0xBA);
	} catch (RuntimeException e) {
	exception.set(e);
	}
	};
	Thread thread = new Thread(action);
	thread.start();
	thread.join();

	if (!segment.scope().isAccessibleBy(Thread.currentThread())) {
	RuntimeException e = exception.get();
	throw e;
	} else {
	assertNull(exception.get());
	}
	}

	@Test
	public void testFillEmpty() {
	MemorySegment.ofArray(new byte[] { }).fill((byte) 0xFF);
	MemorySegment.ofArray(new byte[2]).asSlice(0, 0).fill((byte) 0xFF);
	MemorySegment.ofBuffer(ByteBuffer.allocateDirect(0)).fill((byte) 0xFF);
	}

	@Test(dataProvider = "heapFactories")
	public void testVirtualizedBaseAddress(IntFunction<MemorySegment> heapSegmentFactory, int factor) {
	MemorySegment segment = heapSegmentFactory.apply(10);
	assertEquals(segment.address(), 0); // base address should be zero (no leaking of impl details)
	MemorySegment end = segment.asSlice(segment.byteSize(), 0);
	assertEquals(end.address(), segment.byteSize()); // end address should be equal to segment byte size
	}

	@DataProvider(name = "badSizeAndAlignments")
	public Object[][] sizesAndAlignments() {
	return new Object[][] {
	{ -1, 8 },
	{ 1, 15 },
	{ 1, -15 }
	};
	}

	@DataProvider(name = "heapFactories")
	public Object[][] heapFactories() {
	return new Object[][] {
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new byte[size]), 1 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new char[size]), 2 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new short[size]), 2 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new int[size]), 4 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new float[size]), 4 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new long[size]), 8 },
	{ (IntFunction<MemorySegment>) size -> MemorySegment.ofArray(new double[size]), 8 }
	};
	}
	}