Module openj9.dtfj

Package com.ibm.j9ddr.vm29.j9.gc

Class GCHeapMap

java.lang.Object

com.ibm.j9ddr.vm29.j9.gc.GCHeapMap

Direct Known Subclasses:

GCMarkMap

public abstract class GCHeapMap
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	GCHeapMap.MarkedObject

Field Summary

Fields

Modifier and Type	Field	Description
protected VoidPointer	_heapBase
protected com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer	_heapMap
protected UDATA	_heapMapBitMask
protected UDATAPointer	_heapMapBits
protected UDATA	_heapMapBitShift
protected UDATA	_heapMapIndexShift
protected VoidPointer	_heapTop
protected UDATA	_maxOffset
static final long	BITS_IN_BYTES
static final long	J9BITS_BITS_IN_SLOT
static final UDATA	J9MODRON_HEAP_BYTES_PER_HEAPMAP_BIT
static final UDATA	J9MODRON_HEAP_BYTES_PER_HEAPMAP_BYTE
static final UDATA	J9MODRON_HEAP_BYTES_PER_HEAPMAP_SLOT
static final UDATA	J9MODRON_HEAP_SLOTS_PER_HEAPMAP_SLOT

Constructor Summary

Constructors

Constructor	Description
GCHeapMap(com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer heapMap)

Method Summary

Modifier and Type	Method	Description
static GCHeapMap	from()
static GCHeapMap	fromHeapMap(com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer heapMap)
VoidPointer	getHeapBase()
com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer	getHeapMap()
UDATAPointer	getHeapMapBits()
VoidPointer	getHeapTop()
int	getObjectGrain()
int	getPageSize(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)
UDATA[]	getSlotIndexAndMask(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)	Return the index into the heap map bits array and the bitmask to use.
boolean	isBitSet(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer address)	Check if a bit is set in the GCHeapMap
protected boolean	isBitSetNoCheck(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)	Check if a bit is set without checking the pointer.
boolean	isMarked(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer address)	Check if a bit is set in the GCHeapMap.
GCHeapMap.MarkedObject	queryObject(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)	Query the mark map to see if the specified object is found.
GCHeapMap.MarkedObject[]	queryRange(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer base, com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer top)	Query the mark map to see what objects are marked within the specified range.

Methods declared in class java.lang.Object

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

Field Details

J9BITS_BITS_IN_SLOT

public static final long J9BITS_BITS_IN_SLOT

BITS_IN_BYTES

public static final long BITS_IN_BYTES

See Also:

• Constant Field Values

J9MODRON_HEAP_SLOTS_PER_HEAPMAP_SLOT

public static final UDATA J9MODRON_HEAP_SLOTS_PER_HEAPMAP_SLOT

J9MODRON_HEAP_BYTES_PER_HEAPMAP_BIT

public static final UDATA J9MODRON_HEAP_BYTES_PER_HEAPMAP_BIT

J9MODRON_HEAP_BYTES_PER_HEAPMAP_BYTE

public static final UDATA J9MODRON_HEAP_BYTES_PER_HEAPMAP_BYTE

J9MODRON_HEAP_BYTES_PER_HEAPMAP_SLOT

public static final UDATA J9MODRON_HEAP_BYTES_PER_HEAPMAP_SLOT

_heapMap

protected com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer _heapMap

_heapBase

protected VoidPointer _heapBase

_heapTop

protected VoidPointer _heapTop

_heapMapBits

protected UDATAPointer _heapMapBits

_maxOffset

protected UDATA _maxOffset

_heapMapIndexShift

protected UDATA _heapMapIndexShift

_heapMapBitMask

protected UDATA _heapMapBitMask

_heapMapBitShift

protected UDATA _heapMapBitShift

Constructor Details

GCHeapMap

public GCHeapMap(com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer heapMap)
          throws CorruptDataException

Throws:

CorruptDataException

Method Details

from

public static GCHeapMap from()
                      throws CorruptDataException

Throws:

CorruptDataException

fromHeapMap

public static GCHeapMap fromHeapMap(com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer heapMap)
                             throws CorruptDataException

Throws:

CorruptDataException

getHeapMap

public com.ibm.j9ddr.vm29.pointer.generated.MM_HeapMapPointer getHeapMap()

getHeapBase

public VoidPointer getHeapBase()

getHeapMapBits

public UDATAPointer getHeapMapBits()

getHeapTop

public VoidPointer getHeapTop()

getObjectGrain

public int getObjectGrain()

getPageSize

public int getPageSize(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)

getSlotIndexAndMask

public UDATA[] getSlotIndexAndMask(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)

Return the index into the heap map bits array and the bitmask to use.

Parameters:

object -

Returns:

an array containing the slot index and bit mask

isBitSet

public boolean isBitSet(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer address)
                 throws CorruptDataException

Check if a bit is set in the GCHeapMap

Parameters:

address - Must be a pointer into the heap. The pointer must point to committed heap memory.

Returns:

True if the bit is set. False otherwise.

Throws:

CorruptDataException

isMarked

public boolean isMarked(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer address)
                 throws CorruptDataException

Check if a bit is set in the GCHeapMap. Differs from isBitSet(J9Object) in that it will return true if the address is not in the heap.

Parameters:

address - An address. If the address is not in the Heap, will return True.

Returns:

True if the bit is set. True if the address of the object is not in the heap. False otherwise.

Throws:

CorruptDataException

isBitSetNoCheck

protected boolean isBitSetNoCheck(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)
                           throws CorruptDataException

Check if a bit is set without checking the pointer. Will throw an exception if the pointer is forces HeapMap to read from uncommitted memory.

Parameters:

object -

Throws:

CorruptDataException

queryObject

public GCHeapMap.MarkedObject queryObject(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer object)
                                   throws CorruptDataException

Query the mark map to see if the specified object is found. If so return a MarkedObject describing it, otherwise null.

Parameters:

object - The object to query

Returns:

A MarkedObject, or null

Throws:

CorruptDataException

queryRange

public GCHeapMap.MarkedObject[] queryRange(com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer base,
 com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer top)
                                    throws CorruptDataException

Query the mark map to see what objects are marked within the specified range. Return an array of MarkedObject records describing each entry found.

Parameters:

base - Bottom of the range to query (inclusive)

top - Top of the range to query (exclusive)

Returns:

A MarkedObject[] containing the results

Throws:

CorruptDataException