Module openj9.dtfj

Package com.ibm.dtfj.java

Interface JavaReference

All Known Implementing Classes:

DTFJJavaReference, JavaReference

public interface JavaReference

Represents a Java reference.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	HEAP_ROOT_CLASSLOADER	Classloader heap root
static final int	HEAP_ROOT_FINALIZABLE_OBJ	Finalizable object heap root
static final int	HEAP_ROOT_JNI_GLOBAL	JNI global reference heap root
static final int	HEAP_ROOT_JNI_LOCAL	JNI local reference heap root
static final int	HEAP_ROOT_MONITOR	Monitor heap root
static final int	HEAP_ROOT_OTHER	Other heap root type
static final int	HEAP_ROOT_STACK_LOCAL	Stack local heap root
static final int	HEAP_ROOT_STRINGTABLE	Stringtable heap root
static final int	HEAP_ROOT_SYSTEM_CLASS	System class heap root
static final int	HEAP_ROOT_THREAD	Thread heap root
static final int	HEAP_ROOT_UNFINALIZED_OBJ	Unfinalized object heap root
static final int	HEAP_ROOT_UNKNOWN	Unknown heap root type
static final int	REACHABILITY_PHANTOM	Reachability of target object via this reference is Phantom
static final int	REACHABILITY_SOFT	Reachability of target object via this reference is Soft
static final int	REACHABILITY_STRONG	Reachability of target object via this reference is Strong
static final int	REACHABILITY_UNKNOWN	Reachability of target object via this reference is unknown
static final int	REACHABILITY_WEAK	Reachability of target object via this reference is Weak
static final int	REFERENCE_ARRAY_ELEMENT	Reference from an array to one of its elements
static final int	REFERENCE_ASSOCIATED_CLASS	Reference from a JavaObject representing a Class to the associated JavaClass
static final int	REFERENCE_CLASS	Reference from an object to its class
static final int	REFERENCE_CLASS_LOADER	Reference from a class to its class loader
static final int	REFERENCE_CLASS_OBJECT	Reference from a class to its java.lang.Class instance
static final int	REFERENCE_CONSTANT_POOL	Reference from a class to a resolved entry in the constant pool
static final int	REFERENCE_FIELD	Reference from an object to the value of one of its instance fields
static final int	REFERENCE_INTERFACE	Reference from a class to one of its interfaces
static final int	REFERENCE_LOADED_CLASS	Reference from a classloader object to its loaded classes
static final int	REFERENCE_PROTECTION_DOMAIN	Reference from a class to its protection domain
static final int	REFERENCE_SIGNERS	Reference from a class to its signers array
static final int	REFERENCE_STATIC_FIELD	Reference from a class to the value of one of its static fields
static final int	REFERENCE_SUPERCLASS	Reference from a class to its superclass
static final int	REFERENCE_UNKNOWN	Unknown reference type
static final int	REFERENCE_UNUSED_14

Method Summary

Modifier and Type	Method	Description
String	getDescription()	Get a string describing the reference type.
int	getReachability()	Get the reachability of the target object via this specific reference.
int	getReferenceType()	Get the reference type, as defined in the JVMTI specification.
int	getRootType()	Get the root type, as defined in the JVMTI specification.
Object	getSource()	Get the source of this reference if available.
Object	getTarget()	Get the object referred to by this reference.
boolean	isClassReference()	Does this reference point to a class?
boolean	isObjectReference()	Does this reference point to an object in the heap?

Field Details

HEAP_ROOT_UNKNOWN

static final int HEAP_ROOT_UNKNOWN

Unknown heap root type

See Also:

• Constant Field Values

HEAP_ROOT_JNI_GLOBAL

static final int HEAP_ROOT_JNI_GLOBAL

JNI global reference heap root

See Also:

• Constant Field Values

HEAP_ROOT_SYSTEM_CLASS

static final int HEAP_ROOT_SYSTEM_CLASS

System class heap root

See Also:

• Constant Field Values

HEAP_ROOT_MONITOR

static final int HEAP_ROOT_MONITOR

Monitor heap root

See Also:

• Constant Field Values

HEAP_ROOT_STACK_LOCAL

static final int HEAP_ROOT_STACK_LOCAL

Stack local heap root

See Also:

• Constant Field Values

HEAP_ROOT_JNI_LOCAL

static final int HEAP_ROOT_JNI_LOCAL

JNI local reference heap root

See Also:

• Constant Field Values

HEAP_ROOT_THREAD

static final int HEAP_ROOT_THREAD

Thread heap root

See Also:

• Constant Field Values

HEAP_ROOT_OTHER

static final int HEAP_ROOT_OTHER

Other heap root type

See Also:

• Constant Field Values

HEAP_ROOT_FINALIZABLE_OBJ

static final int HEAP_ROOT_FINALIZABLE_OBJ

Finalizable object heap root

See Also:

• Constant Field Values

HEAP_ROOT_UNFINALIZED_OBJ

static final int HEAP_ROOT_UNFINALIZED_OBJ

Unfinalized object heap root

See Also:

• Constant Field Values

HEAP_ROOT_CLASSLOADER

static final int HEAP_ROOT_CLASSLOADER

Classloader heap root

See Also:

• Constant Field Values

HEAP_ROOT_STRINGTABLE

static final int HEAP_ROOT_STRINGTABLE

Stringtable heap root

See Also:

• Constant Field Values

REFERENCE_UNKNOWN

static final int REFERENCE_UNKNOWN

Unknown reference type

See Also:

• Constant Field Values

REFERENCE_CLASS

static final int REFERENCE_CLASS

Reference from an object to its class

See Also:

• Constant Field Values

REFERENCE_FIELD

static final int REFERENCE_FIELD

Reference from an object to the value of one of its instance fields

See Also:

• Constant Field Values

REFERENCE_ARRAY_ELEMENT

static final int REFERENCE_ARRAY_ELEMENT

Reference from an array to one of its elements

See Also:

• Constant Field Values

REFERENCE_CLASS_LOADER

static final int REFERENCE_CLASS_LOADER

Reference from a class to its class loader

See Also:

• Constant Field Values

REFERENCE_SIGNERS

static final int REFERENCE_SIGNERS

Reference from a class to its signers array

See Also:

• Constant Field Values

REFERENCE_PROTECTION_DOMAIN

static final int REFERENCE_PROTECTION_DOMAIN

Reference from a class to its protection domain

See Also:

• Constant Field Values

REFERENCE_INTERFACE

static final int REFERENCE_INTERFACE

Reference from a class to one of its interfaces

See Also:

• Constant Field Values

REFERENCE_STATIC_FIELD

static final int REFERENCE_STATIC_FIELD

Reference from a class to the value of one of its static fields

See Also:

• Constant Field Values

REFERENCE_CONSTANT_POOL

static final int REFERENCE_CONSTANT_POOL

Reference from a class to a resolved entry in the constant pool

See Also:

• Constant Field Values

REFERENCE_SUPERCLASS

static final int REFERENCE_SUPERCLASS

Reference from a class to its superclass

See Also:

• Constant Field Values

REFERENCE_LOADED_CLASS

static final int REFERENCE_LOADED_CLASS

Reference from a classloader object to its loaded classes

See Also:

• Constant Field Values

REFERENCE_CLASS_OBJECT

static final int REFERENCE_CLASS_OBJECT

Reference from a class to its java.lang.Class instance

See Also:

• Constant Field Values

REFERENCE_ASSOCIATED_CLASS

static final int REFERENCE_ASSOCIATED_CLASS

Reference from a JavaObject representing a Class to the associated JavaClass

See Also:

• Constant Field Values

REFERENCE_UNUSED_14

static final int REFERENCE_UNUSED_14

See Also:

• Constant Field Values

REACHABILITY_UNKNOWN

static final int REACHABILITY_UNKNOWN

Reachability of target object via this reference is unknown

See Also:

• Constant Field Values

REACHABILITY_STRONG

static final int REACHABILITY_STRONG

Reachability of target object via this reference is Strong

See Also:

• Constant Field Values

REACHABILITY_SOFT

static final int REACHABILITY_SOFT

Reachability of target object via this reference is Soft

See Also:

• Constant Field Values

REACHABILITY_WEAK

static final int REACHABILITY_WEAK

Reachability of target object via this reference is Weak

See Also:

• Constant Field Values

REACHABILITY_PHANTOM

static final int REACHABILITY_PHANTOM

Reachability of target object via this reference is Phantom

See Also:

• Constant Field Values

Method Details

getRootType

int getRootType()
         throws CorruptDataException

Get the root type, as defined in the JVMTI specification.

Returns:

an integer representing the root type, see the HEAP_ROOT_ static fields.

Throws:

CorruptDataException

getReferenceType

int getReferenceType()
              throws CorruptDataException

Get the reference type, as defined in the JVMTI specification.

Returns:

an integer representing the reference type, see the REFERENCE_ static fields.

Throws:

CorruptDataException

getReachability

int getReachability()
             throws CorruptDataException

Get the reachability of the target object via this specific reference.

Returns:

an integer representing the reachability, see the REACHABILITY_ static fields.

Throws:

CorruptDataException

getDescription

String getDescription()

Get a string describing the reference type. Implementers should not depend on the contents or identity of this string. e.g. JNI Weak global reference, Instance field 'MyClass.value', Constant pool string constant

Returns:

a String describing the reference type

isObjectReference

boolean isObjectReference()
                   throws DataUnavailable,
CorruptDataException

Does this reference point to an object in the heap?

Returns:

true if the target of this root is an object

Throws:

DataUnavailable

CorruptDataException

isClassReference

boolean isClassReference()
                  throws DataUnavailable,
CorruptDataException

Does this reference point to a class?

Returns:

true if the target of this root is a class

Throws:

DataUnavailable

CorruptDataException

getTarget

Object getTarget()
          throws DataUnavailable,
CorruptDataException

Get the object referred to by this reference.

Returns:

a JavaObject or a JavaClass

Throws:

DataUnavailable

CorruptDataException

getSource

Object getSource()
          throws DataUnavailable,
CorruptDataException

Get the source of this reference if available.

Returns:

a JavaClass, JavaObject, JavaStackFrame or null if unknown

Throws:

DataUnavailable

CorruptDataException