org.mmtk.plan.semispace.gctrace

Class GCTraceMutator

java.lang.Object

org.mmtk.plan.MutatorContext

org.mmtk.plan.SimpleMutator

org.mmtk.plan.StopTheWorldMutator

org.mmtk.plan.semispace.SSMutator

org.mmtk.plan.semispace.gctrace.GCTraceMutator

public class GCTraceMutator
extends SSMutator

This class implements per-mutator thread behavior and state for the GCTrace plan, which implements a GC tracing algorithm.

Specifically, this class defines SS mutator-time allocation, write barriers, and per-mutator collection semantics.

See GCTrace for an overview of the GC trace algorithm.

See Also:

SSMutator, GCTrace, GCTraceCollector, StopTheWorldMutator, MutatorContext

Field Summary

Fields inherited from class org.mmtk.plan.semispace.SSMutator

ss

Fields inherited from class org.mmtk.plan.MutatorContext

immortal, lgcode, log, los, nonmove, smcode

Constructor Summary

Constructors

Constructor and Description
GCTraceMutator()

Method Summary

Modifier and Type	Method and Description
void	collectionPhase(short phaseId, boolean primary) Perform a per-mutator collection phase.
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.
void	postAlloc(ObjectReference object, ObjectReference typeRef, int bytes, int allocator) Perform post-allocation actions.

Methods inherited from class org.mmtk.plan.semispace.SSMutator

alloc, getAllocatorFromSpace, initMutator, show

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, flushRememberedSets, getId, getLog, 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

Constructor Detail

GCTraceMutator

public GCTraceMutator()

Method Detail

postAlloc

public final void postAlloc(ObjectReference object,
                            ObjectReference typeRef,
                            int bytes,
                            int allocator)

Perform post-allocation actions. For many allocators none are required.

Overrides:

postAlloc in class SSMutator

Parameters:

object - The newly allocated object

typeRef - the type reference for the instance being created

bytes - The size of the space to be allocated (in bytes)

allocator - The allocator number to be used for this allocation

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

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).

collectionPhase

public 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 SSMutator

Parameters:

phaseId - The unique phase identifier

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