org.mmtk.plan.concurrent

Class ConcurrentMutator

java.lang.Object

org.mmtk.plan.MutatorContext

org.mmtk.plan.SimpleMutator

org.mmtk.plan.concurrent.ConcurrentMutator

Direct Known Subclasses:

CMSMutator

public abstract class ConcurrentMutator
extends SimpleMutator

This class implements per-mutator thread behavior and state for a simple whole-heap concurrent collector.

See Also:

Concurrent, ConcurrentCollector, StopTheWorldMutator, MutatorContext

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	barrierActive
static boolean	newMutatorBarrierActive

Fields inherited from class org.mmtk.plan.MutatorContext

immortal, lgcode, log, los, nonmove, smcode

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ConcurrentMutator()

Method Summary

Modifier and Type	Method and Description
protected abstract void	checkAndEnqueueReference(ObjectReference ref) Process a reference that may require being enqueued as part of a concurrent collection.
void	collectionPhase(short phaseId, boolean primary) Perform a per-mutator collection phase.
ObjectReference	javaLangReferenceReadBarrier(ObjectReference ref) Read a reference type.
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.MutatorContext

addressBulkCopy, addressRead, addressTryCompareAndSwap, addressWrite, alloc, assertRemsetsFlushed, booleanBulkCopy, booleanRead, booleanWrite, byteBulkCopy, byteRead, byteWrite, charBulkCopy, charRead, charWrite, checkAllocator, deinitMutator, doubleBulkCopy, doubleRead, doubleWrite, extentBulkCopy, extentRead, extentWrite, floatBulkCopy, floatRead, floatWrite, flush, flushRememberedSets, getAllocatorFromSpace, getId, getLog, initMutator, intBulkCopy, intRead, intTryCompareAndSwap, intWrite, longBulkCopy, longRead, longTryCompareAndSwap, longWrite, objectReferenceNonHeapRead, objectReferenceNonHeapWrite, objectReferenceRead, offsetBulkCopy, offsetRead, offsetWrite, postAlloc, 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

newMutatorBarrierActive

public static boolean newMutatorBarrierActive

barrierActive

protected volatile boolean barrierActive

Constructor Detail

ConcurrentMutator

protected ConcurrentMutator()

Method Detail

collectionPhase

public void collectionPhase(short phaseId,
                            boolean primary)

Perform a per-mutator collection phase.

Overrides:

collectionPhase in class SimpleMutator

Parameters:

phaseId - The unique phase identifier

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

objectReferenceWrite

public 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 employ a Yuasa style snapshot barrier.

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

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.

objectReferenceBulkCopy

public 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.

Overrides:

objectReferenceBulkCopy in class MutatorContext

Parameters:

src - The source of the values to be 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).

javaLangReferenceReadBarrier

public ObjectReference javaLangReferenceReadBarrier(ObjectReference ref)

Description copied from class: MutatorContext

Read a reference type. In a concurrent collector this may involve adding the referent to the marking queue.

Overrides:

javaLangReferenceReadBarrier in class MutatorContext

Parameters:

ref - The referent being read.

Returns:

The new referent.

checkAndEnqueueReference

protected abstract void checkAndEnqueueReference(ObjectReference ref)

Process a reference that may require being enqueued as part of a concurrent collection.

Parameters:

ref - The reference to check.