org.mmtk.plan.stickyimmix

Class StickyImmixMutator

java.lang.Object

org.mmtk.plan.MutatorContext

org.mmtk.plan.SimpleMutator

org.mmtk.plan.StopTheWorldMutator

org.mmtk.plan.immix.ImmixMutator

org.mmtk.plan.stickyimmix.StickyImmixMutator

public class StickyImmixMutator
extends ImmixMutator

This class implements per-mutator thread behavior and state for the StickyImmix plan, which implements a generational mark-sweep collector.

Specifically, this class defines MS mutator-time allocation and per-mutator thread collection semantics (flushing and restoring per-mutator allocator state).

*

See Also:

StickyImmix, StickyImmixCollector, MutatorContext, Phase

Field Summary

Fields

Modifier and Type	Field and Description
private ObjectReferenceDeque	modBuffer

Fields inherited from class org.mmtk.plan.immix.ImmixMutator

immix

Fields inherited from class org.mmtk.plan.MutatorContext

immortal, lgcode, log, los, nonmove, smcode

Constructor Summary

Constructors

Constructor and Description
StickyImmixMutator() Constructor

Method Summary

Modifier and Type	Method and Description
void	assertRemsetFlushed()
void	collectionPhase(short phaseId, boolean primary) Perform a per-mutator collection phase.
void	flushRememberedSets() Flush per-mutator remembered sets into the global remset pool.
private static StickyImmix	global()
private void	logSource(ObjectReference src) Add an object to the modified objects buffer and mark the object has having been logged.
boolean	objectReferenceBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of references are about to be copied from object src to object dst (as in an array copy).
boolean	objectReferenceTryCompareAndSwap(ObjectReference src, Address slot, ObjectReference old, ObjectReference tgt, Word metaDataA, Word metaDataB, int mode) Attempt to atomically exchange the value in the given slot with the passed replacement value.
void	objectReferenceWrite(ObjectReference src, Address slot, ObjectReference tgt, Word metaDataA, Word metaDataB, int mode) Write an object reference.

Methods inherited from class org.mmtk.plan.immix.ImmixMutator

alloc, getAllocatorFromSpace, postAlloc

Methods inherited from class org.mmtk.plan.MutatorContext

addressBulkCopy, addressRead, addressTryCompareAndSwap, addressWrite, assertRemsetsFlushed, booleanBulkCopy, booleanRead, booleanWrite, byteBulkCopy, byteRead, byteWrite, charBulkCopy, charRead, charWrite, checkAllocator, deinitMutator, doubleBulkCopy, doubleRead, doubleWrite, extentBulkCopy, extentRead, extentWrite, floatBulkCopy, floatRead, floatWrite, flush, getId, getLog, initMutator, intBulkCopy, intRead, intTryCompareAndSwap, intWrite, javaLangReferenceReadBarrier, longBulkCopy, longRead, longTryCompareAndSwap, longWrite, objectReferenceNonHeapRead, objectReferenceNonHeapWrite, objectReferenceRead, offsetBulkCopy, offsetRead, offsetWrite, shortBulkCopy, shortRead, shortWrite, wordBulkCopy, wordRead, wordTryCompareAndSwap, wordWrite

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

Constructor Detail

StickyImmixMutator

public StickyImmixMutator()

Constructor

Method Detail

objectReferenceWrite

public final void objectReferenceWrite(ObjectReference src,
                                       Address slot,
                                       ObjectReference tgt,
                                       Word metaDataA,
                                       Word metaDataB,
                                       int mode)

Write an object reference. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

In this case, we remember the address of the source of the pointer if the new reference points into the nursery from non-nursery space.

Overrides:

objectReferenceWrite in class MutatorContext

Parameters:

src - The object into which the new reference will be stored

slot - The address into which the new reference will be stored.

tgt - The value of the new reference

metaDataA - A value that assists the host VM in creating a store

metaDataB - A value that assists the host VM in creating a store

mode - The context in which the store occurred

objectReferenceBulkCopy

public final boolean objectReferenceBulkCopy(ObjectReference src,
                                             Offset srcOffset,
                                             ObjectReference dst,
                                             Offset dstOffset,
                                             int bytes)

A number of references are about to be copied from object src to object dst (as in an array copy). Thus, dst is the mutated object. Take appropriate write barrier actions.

In this case, we remember the mutated source address range and will scan that address range at GC time.

Overrides:

objectReferenceBulkCopy in class MutatorContext

Parameters:

src - The source of the values to copied

srcOffset - The offset of the first source address, in bytes, relative to src (in principle, this could be negative).

dst - The mutated object, i.e. the destination of the copy.

dstOffset - The offset of the first destination address, in bytes relative to tgt (in principle, this could be negative).

bytes - The size of the region being copied, in bytes.

Returns:

True if the update was performed by the barrier, false if left to the caller (always false in this case).

objectReferenceTryCompareAndSwap

public boolean objectReferenceTryCompareAndSwap(ObjectReference src,
                                                Address slot,
                                                ObjectReference old,
                                                ObjectReference tgt,
                                                Word metaDataA,
                                                Word metaDataB,
                                                int mode)

Description copied from class: MutatorContext

Attempt to atomically exchange the value in the given slot with the passed replacement value. If a new reference is created, we must then take appropriate write barrier actions.

By default do nothing, override if appropriate.

Overrides:

objectReferenceTryCompareAndSwap in class MutatorContext

Parameters:

src - The object into which the new reference will be stored

slot - The address into which the new reference will be stored.

old - The old reference to be swapped out

tgt - The target of the new reference

metaDataA - A value that assists the host VM in creating a store

metaDataB - A value that assists the host VM in creating a store

mode - The context in which the store occurred

Returns:

True if the swap was successful.

logSource

private void logSource(ObjectReference src)

Add an object to the modified objects buffer and mark the object has having been logged. Since duplicate entries do not raise any correctness issues, we do not worry about synchronization and allow threads to race to log the object, potentially including it twice (unlike reference counting where duplicates would lead to incorrect reference counts).

Parameters:

src - The object to be logged

flushRememberedSets

public final void flushRememberedSets()

Description copied from class: MutatorContext

Flush per-mutator remembered sets into the global remset pool.

Overrides:

flushRememberedSets in class MutatorContext

assertRemsetFlushed

public final void assertRemsetFlushed()

collectionPhase

public final void collectionPhase(short phaseId,
                                  boolean primary)

Perform a per-mutator collection phase. This is executed by one collector thread on behalf of a mutator thread.

Overrides:

collectionPhase in class ImmixMutator

Parameters:

phaseId - The unique phase identifier

primary - Should this thread be used to execute any single-threaded local operations?

global

private static StickyImmix global()

Returns:

The active global plan as an MSGen instance.