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org.mmtk.plan.semispace.gctrace
Class GCTraceMutator

java.lang.Object
  extended by org.mmtk.plan.MutatorContext
      extended by org.mmtk.plan.SimpleMutator
          extended by org.mmtk.plan.StopTheWorldMutator
              extended by org.mmtk.plan.semispace.SSMutator
                  extended by org.mmtk.plan.semispace.gctrace.GCTraceMutator
All Implemented Interfaces:
Constants
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
 
Fields inherited from interface org.mmtk.utility.Constants
ALIGNMENT_VALUE, ARRAY_ELEMENT, BITS_IN_ADDRESS, BITS_IN_BYTE, BITS_IN_CHAR, BITS_IN_INT, BITS_IN_PAGE, BITS_IN_SHORT, BITS_IN_WORD, BYTES_IN_ADDRESS, BYTES_IN_BYTE, BYTES_IN_CHAR, BYTES_IN_INT, BYTES_IN_KBYTE, BYTES_IN_MBYTE, BYTES_IN_PAGE, BYTES_IN_SHORT, BYTES_IN_WORD, CARD_MASK, CARD_META_PAGES_PER_REGION, INSTANCE_FIELD, LOG_BITS_IN_ADDRESS, LOG_BITS_IN_BYTE, LOG_BITS_IN_CHAR, LOG_BITS_IN_INT, LOG_BITS_IN_PAGE, LOG_BITS_IN_SHORT, LOG_BITS_IN_WORD, LOG_BYTES_IN_ADDRESS, LOG_BYTES_IN_ADDRESS_SPACE, LOG_BYTES_IN_BYTE, LOG_BYTES_IN_CHAR, LOG_BYTES_IN_INT, LOG_BYTES_IN_KBYTE, LOG_BYTES_IN_MBYTE, LOG_BYTES_IN_PAGE, LOG_BYTES_IN_SHORT, LOG_BYTES_IN_WORD, LOG_CARD_BYTES, LOG_CARD_GRAIN, LOG_CARD_META_BYTES, LOG_CARD_META_PAGES, LOG_CARD_META_SIZE, LOG_CARD_UNITS, LOG_MIN_ALIGNMENT, MAX_ALIGNMENT, MAX_BYTES_PADDING, MAX_INT, MIN_ALIGNMENT, MIN_INT, SUPPORT_CARD_SCANNING
 
Constructor Summary
GCTraceMutator()
           
 
Method Summary
 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?
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