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jdk.internal.foreign

public sealed Class NativeMemorySegmentImpl

extends AbstractMemorySegmentImpl
permits MappedMemorySegmentImpl
Class Inheritance
Known Direct Subclasses
jdk.internal.foreign.MappedMemorySegmentImpl
Imports
jdk.internal.misc.Unsafe, jdk.internal.vm.annotation.ForceInline, java.nio.ByteBuffer, java.util.Optional
Implementation for native memory segments. A native memory segment is essentially a wrapper around a native long address.

Field Summary

Modifier and TypeField and Description
pack-priv final long
min

Inherited from jdk.internal.foreign.AbstractMemorySegmentImpl:
lengthNIO_ACCESSreadOnlyscope

Constructor Summary

AccessConstructor and Description
pack-priv
NativeMemorySegmentImpl(long min, long length, boolean readOnly, MemorySessionImpl scope)

Method Summary

Modifier and TypeMethod and Description
public long
address()

Implements java.lang.foreign.MemorySegment.address.

Returns the address of this memory segment.

pack-priv NativeMemorySegmentImpl
dup(long offset, long size, boolean readOnly, MemorySessionImpl scope)

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.dup.

public Optional<Object>
heapBase()

Implements java.lang.foreign.MemorySegment.heapBase.

Returns the Java object stored in the on-heap region of memory backing this memory segment, if any.

public boolean
isNative()

Overrides jdk.internal.foreign.AbstractMemorySegmentImpl.isNative.

Implements java.lang.foreign.MemorySegment.isNative.

Returns true if this segment is a native segment.

pack-priv ByteBuffer
makeByteBuffer()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.makeByteBuffer.

public long
maxAlignMask()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.maxAlignMask.

public final long
maxByteAlignment()

Implements java.lang.foreign.MemorySegment.maxByteAlignment.

Returns the maximum byte alignment associated with this memory segment.

public Object
unsafeGetBase()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.unsafeGetBase.

public long
unsafeGetOffset()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.unsafeGetOffset.

Inherited from jdk.internal.foreign.AbstractMemorySegmentImpl:
allocateasByteBufferasOverlappingSliceasReadOnlyasSliceasSliceasSliceasSlicebyteSizecheckAccesscheckAccessBoundscheckEnclosingLayoutcheckReadOnlycheckSliceBoundscopycopycopycopycopyFromelementsequalsfillforcegetgetgetgetgetgetgetgetgetgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetAtIndexgetStringgetStringgetStringhashCodeisAccessibleByisAlignedForElementisAlignedForElementisLoadedisMappedisReadOnlyloadmismatchofBufferoverlapsreinterpretreinterpretreinterpretscopesessionImplsetsetsetsetsetsetsetsetsetsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetAtIndexsetStringsetStringspliteratortoArraytoArraytoArraytoArraytoArraytoArraytoArraytoStringunload

Field Detail

minback to summary
pack-priv final long min

Constructor Detail

NativeMemorySegmentImplback to summary
pack-priv NativeMemorySegmentImpl(long min, long length, boolean readOnly, MemorySessionImpl scope)
Annotations
@ForceInline

Method Detail

addressback to summary
public long address()

Implements java.lang.foreign.MemorySegment.address.

Doc from java.lang.foreign.MemorySegment.address.

Returns the address of this memory segment.

Annotations
@Override
dupback to summary
pack-priv NativeMemorySegmentImpl dup(long offset, long size, boolean readOnly, MemorySessionImpl scope)

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.dup.

Annotations
@ForceInline
@Override
heapBaseback to summary
public Optional<Object> heapBase()

Implements java.lang.foreign.MemorySegment.heapBase.

Doc from java.lang.foreign.MemorySegment.heapBase.

Returns the Java object stored in the on-heap region of memory backing this memory segment, if any. For instance, if this memory segment is a heap segment created with the ofArray(byte[]) factory method, this method will return the byte[] object which was used to obtain the segment. This method returns an empty Optional value if either this segment is a native segment, or if this segment is read-only.

Annotations
@Override
isNativeback to summary
public boolean isNative()

Overrides jdk.internal.foreign.AbstractMemorySegmentImpl.isNative.

Implements java.lang.foreign.MemorySegment.isNative.

Doc from java.lang.foreign.MemorySegment.isNative.

Returns true if this segment is a native segment.

A native segment is created e.g. using the Arena#allocate(long, long) (and related) factory, or by wrapping a direct buffer.

Annotations
@Override
makeByteBufferback to summary
pack-priv ByteBuffer makeByteBuffer()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.makeByteBuffer.

Annotations
@Override
maxAlignMaskback to summary
public long maxAlignMask()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.maxAlignMask.

Annotations
@Override
maxByteAlignmentback to summary
public final long maxByteAlignment()

Implements java.lang.foreign.MemorySegment.maxByteAlignment.

Doc from java.lang.foreign.MemorySegment.maxByteAlignment.

Returns the maximum byte alignment associated with this memory segment.

The returned alignment is always a power of two and is derived from the segment address() and, if it is a heap segment, the type of the backing heap storage.

This method can be used to ensure that a segment is sufficiently aligned with a layout:

MemoryLayout layout = ... MemorySegment segment = ... if (segment.maxByteAlignment() < layout.byteAlignment()) { // Take action (e.g. throw an Exception) } 
MemoryLayout layout = ...
MemorySegment segment = ...
if (segment.maxByteAlignment() < layout.byteAlignment()) {
    // Take action (e.g. throw an Exception)
}
unsafeGetBaseback to summary
public Object unsafeGetBase()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.unsafeGetBase.

Annotations
@Override
unsafeGetOffsetback to summary
public long unsafeGetOffset()

Implements abstract jdk.internal.foreign.AbstractMemorySegmentImpl.unsafeGetOffset.

Annotations
@Override