org.mmtk.plan.immix

Class ImmixDefragTraceLocal

java.lang.Object

org.mmtk.plan.TransitiveClosure

org.mmtk.plan.TraceLocal

org.mmtk.plan.immix.ImmixDefragTraceLocal

public final class ImmixDefragTraceLocal
extends TraceLocal

This class implements the thread-local functionality for a defragmenting transitive closure over an immix space.

Field Summary

Fields

Modifier and Type	Field and Description
private ObjectReferenceDeque	modBuffer Instance fields

Fields inherited from class org.mmtk.plan.TraceLocal

rootLocations, values

Fields inherited from class org.mmtk.plan.TransitiveClosure

specializedScan

Constructor Summary

Constructors

Constructor and Description
ImmixDefragTraceLocal(Trace trace, ObjectReferenceDeque modBuffer) Constructor

Method Summary

Modifier and Type	Method and Description
boolean	isLive(ObjectReference object) Is the specified object live?
protected void	processRememberedSets() Process any remembered set entries.
protected void	scanObject(ObjectReference object) Collectors that move objects must override this method.
ObjectReference	traceObject(ObjectReference object) This method is the core method during the trace of the object graph.
boolean	willNotMoveInCurrentCollection(ObjectReference object) Return true if this object is guaranteed not to move during this collection (i.e. this object is defintely not an unforwarded object).

Methods inherited from class org.mmtk.plan.TraceLocal

completeTrace, flush, getForwardedFinalizable, getForwardedReference, getForwardedReferenceType, getForwardedReferent, incrementalTrace, isReachable, isReferentLive, logMessage, overwriteReferenceDuringTrace, prepare, processEdge, processInteriorEdge, processNode, processRootEdge, processRoots, readyToFinalize, release, reportDelayedRootEdge, retainForFinalize, retainReferent, traceObject

Methods inherited from class org.mmtk.plan.TransitiveClosure

getSpecializedScanClass, registerSpecializedScan

Methods inherited from class java.lang.Object

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

Field Detail

modBuffer

private final ObjectReferenceDeque modBuffer

Instance fields

Constructor Detail

ImmixDefragTraceLocal

public ImmixDefragTraceLocal(Trace trace,
                             ObjectReferenceDeque modBuffer)

Constructor

Parameters:

trace - the associated global trace

modBuffer - TODO

Method Detail

isLive

public boolean isLive(ObjectReference object)

Is the specified object live?

Overrides:

isLive in class TraceLocal

Parameters:

object - The object.

Returns:

true if the object is live.

traceObject

public ObjectReference traceObject(ObjectReference object)

This method is the core method during the trace of the object graph. The role of this method is to:

1. Ensure the traced object is not collected.
2. If this is the first visit to the object enqueue it to be scanned.
3. Return the forwarded reference to the object.

In this instance, we refer objects in the mark-sweep space to the immixSpace for tracing, and defer to the superclass for all others.

Overrides:

traceObject in class TraceLocal

Parameters:

object - The object to be traced.

Returns:

The new reference to the same object instance.

willNotMoveInCurrentCollection

public boolean willNotMoveInCurrentCollection(ObjectReference object)

Return true if this object is guaranteed not to move during this collection (i.e. this object is defintely not an unforwarded object).

Overrides:

willNotMoveInCurrentCollection in class TraceLocal

Parameters:

object - the object whose status is of interest

Returns:

true if this object is guaranteed not to move during this collection.

scanObject

protected void scanObject(ObjectReference object)

Description copied from class: TraceLocal

Collectors that move objects must override this method. It performs the deferred scanning of objects which are forwarded during bootstrap of each copying collection. Because of the complexities of the collection bootstrap (such objects are generally themselves gc-critical), the forwarding and scanning of the objects must be dislocated. It is an error for a non-moving collector to call this method.

Overrides:

scanObject in class TraceLocal

Parameters:

object - The forwarded object to be scanned

processRememberedSets

protected void processRememberedSets()

Process any remembered set entries. This means enumerating the mod buffer and for each entry, marking the object as unlogged (we don't enqueue for scanning since we're doing a full heap GC).

Overrides:

processRememberedSets in class TraceLocal