org.mmtk.plan.immix

Class ImmixTraceLocal

java.lang.Object

org.mmtk.plan.TransitiveClosure

org.mmtk.plan.TraceLocal

org.mmtk.plan.immix.ImmixTraceLocal

public final class ImmixTraceLocal
extends TraceLocal

This class implements the thread-local functionality for a 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
ImmixTraceLocal(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) Ensure that the referenced object will not move from this point through to the end of the collection.

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

ImmixTraceLocal

public ImmixTraceLocal(Trace trace,
                       ObjectReferenceDeque modBuffer)

Constructor

Parameters:

trace - The trace associated with this trace local.

modBuffer - The modified objects buffer associated with this trace local. Possibly null.

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)

Ensure that the referenced object will not move from this point through to the end of the collection. This can involve forwarding the object if necessary.

Overrides:

willNotMoveInCurrentCollection in class TraceLocal

Parameters:

object - The object that must not move during the collection.

Returns:

true If the object will not move during 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