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@mcimadamore
mcimadamore committed Oct 29, 2024
1 parent afb62f7 commit bbc94bc
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Showing 4 changed files with 129 additions and 44 deletions.
50 changes: 18 additions & 32 deletions src/java.base/share/classes/java/lang/foreign/SegmentAllocator.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -140,12 +140,12 @@ default MemorySegment allocateFrom(String str, Charset charset) {
int length;
if (StringSupport.bytesCompatible(str, charset)) {
length = str.length();
segment = allocateNoInit((long) length + termCharSize);
segment = asUninitialized().allocate((long) length + termCharSize);
StringSupport.copyToSegmentRaw(str, segment, 0);
} else {
byte[] bytes = str.getBytes(charset);
length = bytes.length;
segment = allocateNoInit((long) bytes.length + termCharSize);
segment = asUninitialized().allocate((long) bytes.length + termCharSize);
MemorySegment.copy(bytes, 0, segment, ValueLayout.JAVA_BYTE, 0, bytes.length);
}
for (int i = 0 ; i < termCharSize ; i++) {
Expand Down Expand Up @@ -174,7 +174,7 @@ default MemorySegment allocateFrom(String str, Charset charset) {
*/
default MemorySegment allocateFrom(ValueLayout.OfByte layout, byte value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -199,7 +199,7 @@ default MemorySegment allocateFrom(ValueLayout.OfByte layout, byte value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfChar layout, char value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -224,7 +224,7 @@ default MemorySegment allocateFrom(ValueLayout.OfChar layout, char value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfShort layout, short value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -249,7 +249,7 @@ default MemorySegment allocateFrom(ValueLayout.OfShort layout, short value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfInt layout, int value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -274,7 +274,7 @@ default MemorySegment allocateFrom(ValueLayout.OfInt layout, int value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfFloat layout, float value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -299,7 +299,7 @@ default MemorySegment allocateFrom(ValueLayout.OfFloat layout, float value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfLong layout, long value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand All @@ -324,7 +324,7 @@ default MemorySegment allocateFrom(ValueLayout.OfLong layout, long value) {
*/
default MemorySegment allocateFrom(ValueLayout.OfDouble layout, double value) {
Objects.requireNonNull(layout);
MemorySegment seg = allocateNoInit(layout);
MemorySegment seg = asUninitialized().allocate(layout);
seg.set(layout, 0, value);
return seg;
}
Expand Down Expand Up @@ -357,7 +357,7 @@ default MemorySegment allocateFrom(ValueLayout.OfDouble layout, double value) {
default MemorySegment allocateFrom(AddressLayout layout, MemorySegment value) {
Objects.requireNonNull(value);
Objects.requireNonNull(layout);
MemorySegment segment = allocateNoInit(layout);
MemorySegment segment = asUninitialized().allocate(layout);
segment.set(layout, 0, value);
return segment;
}
Expand Down Expand Up @@ -405,7 +405,7 @@ default MemorySegment allocateFrom(ValueLayout elementLayout,
Objects.requireNonNull(source);
Objects.requireNonNull(sourceElementLayout);
Objects.requireNonNull(elementLayout);
MemorySegment dest = allocateNoInit(elementLayout, elementCount);
MemorySegment dest = asUninitialized().allocate(elementLayout, elementCount);
MemorySegment.copy(source, sourceElementLayout, sourceOffset, dest, elementLayout, 0, elementCount);
return dest;
}
Expand Down Expand Up @@ -659,6 +659,13 @@ default MemorySegment allocate(long byteSize) {
*/
MemorySegment allocate(long byteSize, long byteAlignment);

/**
* {@return a view of this allocator which does not initialize freshly allocated memory}
* Not all allocators support this. When not supported, an allocator is allowed
* to return itself.
*/
default SegmentAllocator asUninitialized() { return this; }

/**
* Returns a segment allocator that responds to allocation requests by returning
* consecutive slices obtained from the provided segment. Each new allocation
Expand Down Expand Up @@ -718,25 +725,4 @@ private static void assertWritable(MemorySegment segment) {
throw new IllegalArgumentException("read-only segment");
}
}

@ForceInline
private MemorySegment allocateNoInit(long byteSize) {
return this instanceof ArenaImpl arenaImpl ?
arenaImpl.allocateNoInit(byteSize, 1) :
allocate(byteSize);
}

@ForceInline
private MemorySegment allocateNoInit(MemoryLayout layout) {
return this instanceof ArenaImpl arenaImpl ?
arenaImpl.allocateNoInit(layout.byteSize(), layout.byteAlignment()) :
allocate(layout);
}

@ForceInline
private MemorySegment allocateNoInit(MemoryLayout layout, long size) {
return this instanceof ArenaImpl arenaImpl ?
arenaImpl.allocateNoInit(layout.byteSize() * size, layout.byteAlignment()) :
allocate(layout, size);
}
}
104 changes: 93 additions & 11 deletions src/java.base/share/classes/jdk/internal/foreign/ArenaImpl.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,19 +25,16 @@

package jdk.internal.foreign;

import java.lang.foreign.Arena;
import java.lang.foreign.MemoryLayout;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.*;
import java.lang.foreign.MemorySegment.Scope;
import java.nio.charset.Charset;
import java.util.Objects;

public final class ArenaImpl implements Arena {

private final MemorySessionImpl session;
private final boolean shouldReserveMemory;
ArenaImpl(MemorySessionImpl session) {
this.session = session;
shouldReserveMemory = session instanceof ImplicitSession;
}

@Override
Expand All @@ -50,14 +47,99 @@ public void close() {
session.close();
}

public MemorySegment allocateNoInit(long byteSize, long byteAlignment) {
Utils.checkAllocationSizeAndAlign(byteSize, byteAlignment);
return SegmentFactories.allocateSegment(byteSize, byteAlignment, session, shouldReserveMemory);
@Override
public MemorySegment allocate(long byteSize, long byteAlignment) {
return session.allocate(byteSize, byteAlignment)
.fill((byte)0);
}

@Override
public MemorySegment allocate(long byteSize, long byteAlignment) {
MemorySegment segment = allocateNoInit(byteSize, byteAlignment);
return segment.fill((byte)0);
public MemorySegment allocateFrom(String str) {
return session.allocateFrom(str);
}

@Override
public MemorySegment allocateFrom(String str, Charset charset) {
return session.allocateFrom(str, charset);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfByte layout, byte value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfChar layout, char value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfShort layout, short value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfInt layout, int value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfFloat layout, float value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfLong layout, long value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfDouble layout, double value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(AddressLayout layout, MemorySegment value) {
return session.allocateFrom(layout, value);
}

@Override
public MemorySegment allocateFrom(ValueLayout elementLayout, MemorySegment source, ValueLayout sourceElementLayout, long sourceOffset, long elementCount) {
return session.allocateFrom(elementLayout, source, sourceElementLayout, sourceOffset, elementCount);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfByte elementLayout, byte... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfShort elementLayout, short... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfChar elementLayout, char... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfInt elementLayout, int... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfFloat elementLayout, float... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfLong elementLayout, long... elements) {
return session.allocateFrom(elementLayout, elements);
}

@Override
public MemorySegment allocateFrom(ValueLayout.OfDouble elementLayout, double... elements) {
return session.allocateFrom(elementLayout, elements);
}
}
5 changes: 5 additions & 0 deletions src/java.base/share/classes/jdk/internal/foreign/ImplicitSession.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,4 +64,9 @@ public boolean isCloseable() {
public void justClose() {
throw nonCloseable();
}

@Override
public boolean shouldReserve() {
return true;
}
}
14 changes: 13 additions & 1 deletion src/java.base/share/classes/jdk/internal/foreign/MemorySessionImpl.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
import java.lang.foreign.MemorySegment;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment.Scope;
import java.lang.foreign.SegmentAllocator;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.lang.ref.Cleaner;
Expand All @@ -53,7 +54,7 @@
* access is possible when a session is being closed (see {@link jdk.internal.misc.ScopedMemoryAccess}).
*/
public abstract sealed class MemorySessionImpl
implements Scope
implements Scope, SegmentAllocator
permits ConfinedSession, GlobalSession, SharedSession {
static final int OPEN = 0;
static final int CLOSED = -1;
Expand Down Expand Up @@ -218,6 +219,17 @@ public boolean isCloseable() {
return true;
}

@Override
public MemorySegment allocate(long byteSize, long byteAlignment) {
Utils.checkAllocationSizeAndAlign(byteSize, byteAlignment);
boolean shouldReserve = shouldReserve();
return SegmentFactories.allocateSegment(byteSize, byteAlignment, this, shouldReserve);
}

public boolean shouldReserve() {
return false;
}

/**
* Closes this session, executing any cleanup action (where provided).
* @throws IllegalStateException if this session is already closed or if this is
Expand Down

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