org.mmtk.plan.copyms

Class CopyMS

java.lang.Object

org.mmtk.plan.Plan

org.mmtk.plan.Simple

org.mmtk.plan.StopTheWorld

org.mmtk.plan.copyms.CopyMS

public class CopyMS
extends StopTheWorld

This class implements the global state of a full-heap collector with a copying nursery and mark-sweep mature space. Unlike a full generational collector, there is no write barrier, no remembered set, and every collection is full-heap.

All plans make a clear distinction between global and thread-local activities, and divides global and local state into separate class hierarchies. Global activities must be synchronized, whereas no synchronization is required for thread-local activities. There is a single instance of Plan (or the appropriate sub-class), and a 1:1 mapping of PlanLocal to "kernel threads" (aka CPUs). Thus instance methods of PlanLocal allow fast, unsychronized access to functions such as allocation and collection.

The global instance defines and manages static resources (such as memory and virtual memory resources). This mapping of threads to instances is crucial to understanding the correctness and performance properties of MMTk plans.

Field Summary

Fields

Modifier and Type	Field and Description
static int	ALLOC_MS
static int	ALLOC_NURSERY
static int	MARK_SWEEP
static MarkSweepSpace	msSpace
static int	NURSERY
static CopySpace	nurserySpace
static int	SCAN_COPYMS
Trace	trace

Fields inherited from class org.mmtk.plan.StopTheWorld

postSanityPhase, preSanityPhase

Fields inherited from class org.mmtk.plan.Simple

CLOSURE, collection, collectionAttempt, COMPLETE, completeClosurePhase, FINALIZABLE, finishPhase, FORWARD, FORWARD_FINALIZABLE, FORWARD_REFS, forwardPhase, INITIATE, initPhase, PHANTOM_REFS, POST_SANITY_PLACEHOLDER, PRE_SANITY_PLACEHOLDER, PREPARE, PREPARE_STACKS, prepareStacks, refTypeClosurePhase, RELEASE, rootClosurePhase, ROOTS, SANITY_BUILD_TABLE, SANITY_CHECK_TABLE, SANITY_COPY_ROOTS, SANITY_PREPARE, SANITY_RELEASE, SANITY_ROOTS, SANITY_SET_POSTGC, SANITY_SET_PREGC, sanityBuildPhase, sanityCheckPhase, SET_COLLECTION_KIND, SOFT_REFS, STACK_ROOTS, WEAK_REFS, WEAK_TRACK_REFS

Fields inherited from class org.mmtk.plan.Plan

ALLOC_CODE, ALLOC_COLD_CODE, ALLOC_DEFAULT, ALLOC_GCSPY, ALLOC_HOT_CODE, ALLOC_IMMORTAL, ALLOC_LARGE_CODE, ALLOC_LOS, ALLOC_NON_MOVING, ALLOC_NON_REFERENCE, ALLOC_PRIMITIVE_LOS, ALLOC_STACK, allocationSiteCount, ALLOCATORS, concurrentWorkers, controlCollectorContext, DEFAULT_MAX_NURSERY, DEFAULT_MIN_NURSERY, DEFAULT_SITE, defaultCollectorContext, emergencyCollection, GATHER_WRITE_BARRIER_STATS, GC_PREPARE, GC_PROPER, IMMORTAL, immortalSpace, insideHarness, internalTriggeredCollection, LARGE_CODE, largeCodeSpace, lastInternalTriggeredCollection, LOS, loSpace, MAX_NON_LOS_COPY_BYTES, MAX_NON_LOS_DEFAULT_ALLOC_BYTES, MAX_NON_LOS_NONMOVING_ALLOC_BYTES, META, metaDataSpace, NEEDS_LOG_BIT_IN_HEADER, NON_MOVING, NON_PARTICIPANT, nonMovingSpace, NOT_IN_GC, parallelWorkers, pretenureThreshold, SANITY, sanityChecker, sanitySpace, SCAN_BOOT_IMAGE, SMALL_CODE, smallCodeSpace, stacksPrepared, totalTime, USE_CODE_SPACE, userTriggeredCollection, VM_SPACE, vmSpace

Constructor Summary

Constructors

Constructor and Description
CopyMS() Constructor.

Method Summary

Modifier and Type	Method and Description
void	collectionPhase(short phaseId) Perform a (global) collection phase.
boolean	collectionRequired(boolean spaceFull, Space space) This method controls the triggering of a GC.
void	fullyBooted()
int	getCollectionReserve() Return the number of pages reserved for collection.
int	getPagesAvail() Return the number of pages available for allocation.
int	getPagesUsed() Return the number of pages reserved for use given the pending allocation.
protected void	registerSpecializedMethods() Registers specialized methods.
int	sanityExpectedRC(ObjectReference object, int sanityRootRC) Return the expected reference count.

Methods inherited from class org.mmtk.plan.StopTheWorld

processOptions

Methods inherited from class org.mmtk.plan.Simple

replacePhase, replacePlaceholderPhase, switchNurseryZeroingApproach

Methods inherited from class org.mmtk.plan.Plan

availableMemory, bootTimeWriteBarrier, concurrentCollectionRequired, determineThreadCount, enableAllocation, enableCollection, forceFullHeapCollection, freeMemory, gcInProgress, gcInProgressProper, getAllocationSite, getPagesReserved, getSpecializedScanClass, getTotalPages, handleUserCollectionRequest, harnessBegin, harnessEnd, insertPhaseAfter, isCurrentGCNursery, isEmergencyCollection, isInitialized, isInternalTriggeredCollection, isUserTriggeredCollection, lastCollectionFullHeap, lastCollectionWasExhaustive, loadObjectReference, logPoll, notifyExit, poll, preCollectorSpawn, printDetailedTiming, printPostStats, printPreStats, printUsedPages, reservedMemory, resetCollectionTrigger, sanityLinearScan, setBuildTimeGCByte, setGCStatus, spawnCollectorThreads, stacksPrepared, startGCspyServer, storeObjectReference, stressTestGCRequired, totalMemory, triggerInternalCollectionRequest, usedMemory, willNeverMove

Methods inherited from class java.lang.Object

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

Field Detail

nurserySpace

public static final CopySpace nurserySpace

msSpace

public static final MarkSweepSpace msSpace

NURSERY

public static final int NURSERY

MARK_SWEEP

public static final int MARK_SWEEP

ALLOC_NURSERY

public static final int ALLOC_NURSERY

See Also:

Constant Field Values

ALLOC_MS

public static final int ALLOC_MS

See Also:

Constant Field Values

SCAN_COPYMS

public static final int SCAN_COPYMS

See Also:

Constant Field Values

trace

public final Trace trace

Constructor Detail

CopyMS

public CopyMS()

Constructor.

Method Detail

collectionPhase

public final void collectionPhase(short phaseId)

Perform a (global) collection phase.

Overrides:

collectionPhase in class Simple

Parameters:

phaseId - The unique id of the phase to perform.

collectionRequired

public final boolean collectionRequired(boolean spaceFull,
                                        Space space)

Description copied from class: Plan

This method controls the triggering of a GC. It is called periodically during allocation. Returns true to trigger a collection.

Overrides:

collectionRequired in class Plan

Parameters:

spaceFull - Space request failed, must recover pages within 'space'.

space - TODO

Returns:

true if a collection is requested by the plan.

getPagesUsed

public int getPagesUsed()

Return the number of pages reserved for use given the pending allocation.

Overrides:

getPagesUsed in class Plan

Returns:

The number of pages reserved given the pending allocation, excluding space reserved for copying.

getCollectionReserve

public int getCollectionReserve()

Return the number of pages reserved for collection. For mark sweep this is a fixed fraction of total pages.

Overrides:

getCollectionReserve in class Plan

Returns:

The number of pages reserved given the pending allocation, including space reserved for collection.

getPagesAvail

public final int getPagesAvail()

Description copied from class: Plan

Return the number of pages available for allocation.

Overrides:

getPagesAvail in class Plan

Returns:

The number of pages available for allocation, assuming all future allocation is to the nursery.

sanityExpectedRC

public int sanityExpectedRC(ObjectReference object,
                            int sanityRootRC)

Description copied from class: Plan

Return the expected reference count. For non-reference counting collectors this becomes a true/false relationship.

Overrides:

sanityExpectedRC in class Plan

Parameters:

object - The object to check.

sanityRootRC - The number of root references to the object.

Returns:

The expected (root excluded) reference count.

registerSpecializedMethods

protected void registerSpecializedMethods()

Description copied from class: Plan

Registers specialized methods.

Overrides:

registerSpecializedMethods in class Plan

fullyBooted

public void fullyBooted()

Overrides:

fullyBooted in class Plan