Class DTFJJavaReference

java.lang.Object

com.ibm.j9ddr.vm29.view.dtfj.java.DTFJJavaReference

All Implemented Interfaces:

JavaReference

public class DTFJJavaReference
extends Object
implements JavaReference

JavaReference is intended to represent either a standard reference within a java heap, for example a reference from one object to another, or a root. A root is a reference that is held outside of the heap, in the Java stack or within the JVM itself.

Field Summary

Fields declared in interface JavaReference

HEAP_ROOT_CLASSLOADER, HEAP_ROOT_FINALIZABLE_OBJ, HEAP_ROOT_JNI_GLOBAL, HEAP_ROOT_JNI_LOCAL, HEAP_ROOT_MONITOR, HEAP_ROOT_OTHER, HEAP_ROOT_STACK_LOCAL, HEAP_ROOT_STRINGTABLE, HEAP_ROOT_SYSTEM_CLASS, HEAP_ROOT_THREAD, HEAP_ROOT_UNFINALIZED_OBJ, HEAP_ROOT_UNKNOWN, REACHABILITY_PHANTOM, REACHABILITY_SOFT, REACHABILITY_STRONG, REACHABILITY_UNKNOWN, REACHABILITY_WEAK, REFERENCE_ARRAY_ELEMENT, REFERENCE_ASSOCIATED_CLASS, REFERENCE_CLASS, REFERENCE_CLASS_LOADER, REFERENCE_CLASS_OBJECT, REFERENCE_CONSTANT_POOL, REFERENCE_FIELD, REFERENCE_INTERFACE, REFERENCE_LOADED_CLASS, REFERENCE_PROTECTION_DOMAIN, REFERENCE_SIGNERS, REFERENCE_STATIC_FIELD, REFERENCE_SUPERCLASS, REFERENCE_UNKNOWN, REFERENCE_UNUSED_14

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

Constructor Summary

Constructors

Constructor	Description
DTFJJavaReference(Object source, Object target, String description, int referencetype, int roottype, int reachability)	Constructor

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?

Methods declared in class Object

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

Constructor Details

DTFJJavaReference

public DTFJJavaReference(Object source,
 Object target,
 String description,
 int referencetype,
 int roottype,
 int reachability)

Constructor

Parameters:

source - Object The source of this reference/root, for example the JVM or an object on the heap

target - Object The target object of this reference/root.

description - String

referencetype - int Mutually exclusive with respect to roottype.

roottype - int Mutually exclusive with respect to referencetype.

reachability - int The strength of the reference (this helps the GC in selection of objects for collection).

javaVM - JavaRuntime

Method Details

getDescription

public String getDescription()

Description copied from interface: JavaReference

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

Specified by:

getDescription in interface JavaReference

Returns:

a String describing the reference type

getReachability

public int getReachability()
                    throws CorruptDataException

Description copied from interface: JavaReference

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

Specified by:

getReachability in interface JavaReference

Returns:

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

Throws:

CorruptDataException

getReferenceType

public int getReferenceType()
                     throws CorruptDataException

Description copied from interface: JavaReference

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

Specified by:

getReferenceType in interface JavaReference

Returns:

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

Throws:

CorruptDataException

getRootType

public int getRootType()
                throws CorruptDataException

Description copied from interface: JavaReference

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

Specified by:

getRootType in interface JavaReference

Returns:

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

Throws:

CorruptDataException

getSource

public Object getSource()
                 throws DataUnavailable,
CorruptDataException

Description copied from interface: JavaReference

Get the source of this reference if available.

Specified by:

getSource in interface JavaReference

Returns:

a JavaClass, JavaObject, JavaStackFrame or null if unknown

Throws:

DataUnavailable

CorruptDataException

getTarget

public Object getTarget()
                 throws DataUnavailable,
CorruptDataException

Description copied from interface: JavaReference

Get the object referred to by this reference.

Specified by:

getTarget in interface JavaReference

Returns:

a JavaObject or a JavaClass

Throws:

DataUnavailable

CorruptDataException

isClassReference

public boolean isClassReference()
                         throws DataUnavailable,
CorruptDataException

Description copied from interface: JavaReference

Does this reference point to a class?

Specified by:

isClassReference in interface JavaReference

Returns:

true if the target of this root is a class

Throws:

DataUnavailable

CorruptDataException

isObjectReference

public boolean isObjectReference()
                          throws DataUnavailable,
CorruptDataException

Description copied from interface: JavaReference

Does this reference point to an object in the heap?

Specified by:

isObjectReference in interface JavaReference

Returns:

true if the target of this root is an object

Throws:

DataUnavailable

CorruptDataException