org.mmtk.plan.generational.immix

Class GenImmixMatureDefragTraceLocal

java.lang.Object

org.mmtk.plan.TransitiveClosure

org.mmtk.plan.TraceLocal

org.mmtk.plan.generational.GenMatureTraceLocal

org.mmtk.plan.generational.immix.GenImmixMatureDefragTraceLocal

public final class GenImmixMatureDefragTraceLocal
extends GenMatureTraceLocal

This class implements the core functionality for a transitive closure over the heap graph, specifically in a defragmenting pass over a generational immix collector.

Field Summary

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
GenImmixMatureDefragTraceLocal(Trace global, GenCollector plan)

Method Summary

Modifier and Type	Method and Description
boolean	isLive(ObjectReference object) Is the specified object live?
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 definitely not an unforwarded object).

Methods inherited from class org.mmtk.plan.generational.GenMatureTraceLocal

processRememberedSets

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

Constructor Detail

GenImmixMatureDefragTraceLocal

public GenImmixMatureDefragTraceLocal(Trace global,
                                      GenCollector plan)

Parameters:

global - the global trace class to use

plan - the state of the generational collector

Method Detail

isLive

public boolean isLive(ObjectReference object)

Description copied from class: GenMatureTraceLocal

Is the specified object live?

Overrides:

isLive in class GenMatureTraceLocal

Parameters:

object - The object.

Returns:

true if the object is live.

traceObject

public ObjectReference traceObject(ObjectReference object)

Description copied from class: TraceLocal

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.

Overrides:

traceObject in class GenMatureTraceLocal

Parameters:

object - The object to be traced.

Returns:

The new reference to the same object instance.

willNotMoveInCurrentCollection

public boolean willNotMoveInCurrentCollection(ObjectReference object)

Description copied from class: GenMatureTraceLocal

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

Overrides:

willNotMoveInCurrentCollection in class GenMatureTraceLocal

Parameters:

object - the object that might move

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