com.oracle.svm.core.handles

Class ObjectHandlesImpl

java.lang.Object

com.oracle.svm.core.handles.ObjectHandlesImpl

All Implemented Interfaces:

org.graalvm.nativeimage.ObjectHandles

public final class ObjectHandlesImpl
extends Object
implements org.graalvm.nativeimage.ObjectHandles

This class implements word-sized integer handles that refer to Java objects. Creating, dereferencing and destroying handles is thread-safe and the handles themselves are valid across threads. This class also supports weak handles, with which the referenced object may be garbage-collected, after which ObjectHandlesImpl.get(ObjectHandle) returns null. Still, weak handles must also be explicitly destroyed to reclaim their handle value.

The implementation uses a variable number of object arrays, in which each array element represents a handle. The array element's index determines the handle's integer value, and the element's stored value is the referenced object. Creating a handle entails finding a null array element and using compare-and-set to write the referenced object into it, avoiding a heavy-weight lock. If there are no null elements in the existing arrays, an additional array is created. This array has twice the capacity of the previous array, which plays a significant role in how indexing is implemented.

Constructor Summary

Constructors

Constructor and Description
ObjectHandlesImpl()
ObjectHandlesImpl(org.graalvm.word.SignedWord rangeMin, org.graalvm.word.SignedWord rangeMax, org.graalvm.word.SignedWord nullHandle)

Method Summary

Modifier and Type	Method and Description
long	computeCurrentCapacity()
long	computeCurrentCount()
org.graalvm.nativeimage.ObjectHandle	create(Object obj)
org.graalvm.nativeimage.ObjectHandle	createWeak(Object obj)
void	destroy(org.graalvm.nativeimage.ObjectHandle handle)
void	destroyWeak(org.graalvm.nativeimage.ObjectHandle handle)
<T> T	get(org.graalvm.nativeimage.ObjectHandle handle)
boolean	isInRange(org.graalvm.nativeimage.ObjectHandle handle)
boolean	isWeak(org.graalvm.nativeimage.ObjectHandle handle)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.graalvm.nativeimage.ObjectHandles

create, getGlobal

Constructor Detail

ObjectHandlesImpl

public ObjectHandlesImpl()

ObjectHandlesImpl

public ObjectHandlesImpl(org.graalvm.word.SignedWord rangeMin,
                         org.graalvm.word.SignedWord rangeMax,
                         org.graalvm.word.SignedWord nullHandle)

Method Detail

isInRange

public boolean isInRange(org.graalvm.nativeimage.ObjectHandle handle)

create

public org.graalvm.nativeimage.ObjectHandle create(Object obj)

Specified by:

create in interface org.graalvm.nativeimage.ObjectHandles

createWeak

public org.graalvm.nativeimage.ObjectHandle createWeak(Object obj)

get

public <T> T get(org.graalvm.nativeimage.ObjectHandle handle)

Specified by:

get in interface org.graalvm.nativeimage.ObjectHandles

isWeak

public boolean isWeak(org.graalvm.nativeimage.ObjectHandle handle)

destroy

public void destroy(org.graalvm.nativeimage.ObjectHandle handle)

Specified by:

destroy in interface org.graalvm.nativeimage.ObjectHandles

destroyWeak

public void destroyWeak(org.graalvm.nativeimage.ObjectHandle handle)

computeCurrentCount

public long computeCurrentCount()

computeCurrentCapacity

public long computeCurrentCapacity()