org.mmtk.plan

Class MutatorContext

java.lang.Object

org.mmtk.plan.MutatorContext

Direct Known Subclasses:

NoGCMutator, SimpleMutator

public abstract class MutatorContext
extends Object

This class (and its sub-classes) implement per-mutator thread behavior. We assume N collector threads and M mutator threads, where N is often equal to the number of available processors, P (for P-way parallelism at GC-time), and M may simply be the number of mutator (application) threads. Both N and M are determined by the VM, not MMTk. In the case where a VM uses posix threads (pthreads) for each mutator ("1:1" threading), M will typically be equal to the number of mutator threads. When a uses "green threads" or a hybrid threading scheme (such as Jikes RVM), M will typically be equal to the level of true parallelism (ie the number of underlying kernel threads).

MMTk assumes that the VM instantiates instances of MutatorContext in thread local storage (TLS) for each thread participating in collection. Accesses to this state are therefore assumed to be low-cost during mutator time.

This class (and its children) is therefore used for unsynchronized per-mutator operations such as allocation and write barriers. The semantics and necessary state for these operations are therefore specified in the GC-specific subclasses of this class. MMTk explicitly separates thread-local (this class) and global operations (@see Plan), so that syncrhonization is localized and explicit, and thus hopefully minimized (@see Plan). Gloabl (Plan) and per-thread (this class) state are also explicitly separated. Operations in this class (and its children) are therefore strictly local to each mutator thread, and synchronized operations always happen via access to explicitly global classes such as Plan and its children. Therefore only "fast path" (unsynchronized) allocation and barrier semantics are defined in MutatorContext and its subclasses. These call out to "slow path" (synchronize(d) methods which have global state and are globally synchronized. For example, an allocation fast path may bump a pointer without any syncrhonization (the "fast path") until a limit is reached, at which point the "slow path" is called, and more memory is aquired from a global resource.

As the super-class of all per-mutator contexts, this class implements basic per-mutator behavior common to all MMTk collectors, including support for immortal and large object space allocation, as well as empty stubs for write barriers (to be overridden by sub-classes as needed).

See Also:

CollectorContext, ActivePlan, Plan

Field Summary

Fields

Modifier and Type	Field and Description
private int	id Unique mutator identifier
protected BumpPointer	immortal Per-mutator allocator into the immortal space
protected LargeObjectLocal	lgcode Per-mutator allocator into the large code space
protected Log	log Used for printing log information in a thread safe manner
protected LargeObjectLocal	los Per-mutator allocator into the large object space
protected MarkSweepLocal	nonmove Per-mutator allocator into the non moving space
protected MarkSweepLocal	smcode Per-mutator allocator into the small code space

Constructor Summary

Constructors

Constructor and Description
MutatorContext()

Method Summary

Modifier and Type	Method and Description
boolean	addressBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of Addresse's are about to be copied from object src to object dst (as in an array copy).
Address	addressRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read an Address.
boolean	addressTryCompareAndSwap(ObjectReference src, Address slot, Address old, Address value, Word metaDataA, Word metaDataB, int mode) Attempt to atomically exchange the value in the given slot with the passed replacement value.
void	addressWrite(ObjectReference src, Address slot, Address value, Word metaDataA, Word metaDataB, int mode) Write an Address.
Address	alloc(int bytes, int align, int offset, int allocator, int site) Allocate memory for an object.
void	assertRemsetsFlushed() Assert that the remsets have been flushed.
boolean	booleanBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of booleans are about to be copied from object src to object dst (as in an array copy).
boolean	booleanRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a boolean.
void	booleanWrite(ObjectReference src, Address slot, boolean value, Word metaDataA, Word metaDataB, int mode) Write a boolean.
boolean	byteBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of bytes are about to be copied from object src to object dst (as in an array copy).
byte	byteRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a byte.
void	byteWrite(ObjectReference src, Address slot, byte value, Word metaDataA, Word metaDataB, int mode) Write a byte.
boolean	charBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of chars are about to be copied from object src to object dst (as in an array copy).
char	charRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a char.
void	charWrite(ObjectReference src, Address slot, char value, Word metaDataA, Word metaDataB, int mode) Write a char.
int	checkAllocator(int bytes, int align, int allocator) Run-time check of the allocator to use for a given allocation At the moment this method assumes that allocators will use the simple (worst) method of aligning to determine if the object is a large object to ensure that no objects are larger than other allocators can handle.
abstract void	collectionPhase(short phaseId, boolean primary) Perform a per-mutator collection phase.
void	deinitMutator() The mutator is about to be cleaned up, make sure all local data is returned.
boolean	doubleBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of doubles are about to be copied from object src to object dst (as in an array copy).
double	doubleRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a double.
void	doubleWrite(ObjectReference src, Address slot, double value, Word metaDataA, Word metaDataB, int mode) Write a double.
boolean	extentBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of Extents are about to be copied from object src to object dst (as in an array copy).
Extent	extentRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read an Extent.
void	extentWrite(ObjectReference src, Address slot, Extent value, Word metaDataA, Word metaDataB, int mode) Write an Extent.
boolean	floatBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of floats are about to be copied from object src to object dst (as in an array copy).
float	floatRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a float.
void	floatWrite(ObjectReference src, Address slot, float value, Word metaDataA, Word metaDataB, int mode) Write a float.
void	flush() Flush mutator context, in response to a requestMutatorFlush.
void	flushRememberedSets() Flush per-mutator remembered sets into the global remset pool.
Allocator	getAllocatorFromSpace(Space space) Return the allocator instance associated with a space space, for this plan instance.
int	getId()
Log	getLog()
void	initMutator(int id) Notify that the mutator context is registered and ready to execute.
boolean	intBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of ints are about to be copied from object src to object dst (as in an array copy).
int	intRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a int.
boolean	intTryCompareAndSwap(ObjectReference src, Address slot, int old, int value, Word metaDataA, Word metaDataB, int mode) Attempt to atomically exchange the value in the given slot with the passed replacement value.
void	intWrite(ObjectReference src, Address slot, int value, Word metaDataA, Word metaDataB, int mode) Write a int.
ObjectReference	javaLangReferenceReadBarrier(ObjectReference referent) Read a reference type.
boolean	longBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of longs are about to be copied from object src to object dst (as in an array copy).
long	longRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a long.
boolean	longTryCompareAndSwap(ObjectReference src, Address slot, long old, long value, Word metaDataA, Word metaDataB, int mode) Attempt to atomically exchange the value in the given slot with the passed replacement value.
void	longWrite(ObjectReference src, Address slot, long value, Word metaDataA, Word metaDataB, int mode) Write a long.
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).
ObjectReference	objectReferenceNonHeapRead(Address slot, Word metaDataA, Word metaDataB) Read an object reference.
void	objectReferenceNonHeapWrite(Address slot, ObjectReference tgt, Word metaDataA, Word metaDataB) A new reference is about to be created in a location that is not a regular heap object.
ObjectReference	objectReferenceRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read an object reference.
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 value, Word metaDataA, Word metaDataB, int mode) Write an object reference.
boolean	offsetBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of Offsets are about to be copied from object src to object dst (as in an array copy).
Offset	offsetRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read an Offset.
void	offsetWrite(ObjectReference src, Address slot, Offset value, Word metaDataA, Word metaDataB, int mode) Write an Offset.
void	postAlloc(ObjectReference ref, ObjectReference typeRef, int bytes, int allocator) Perform post-allocation actions.
boolean	shortBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of shorts are about to be copied from object src to object dst (as in an array copy).
short	shortRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a short.
void	shortWrite(ObjectReference src, Address slot, short value, Word metaDataA, Word metaDataB, int mode) Write a short.
boolean	wordBulkCopy(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) A number of Words are about to be copied from object src to object dst (as in an array copy).
Word	wordRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) Read a Word.
boolean	wordTryCompareAndSwap(ObjectReference src, Address slot, Word old, Word value, Word metaDataA, Word metaDataB, int mode) Attempt to atomically exchange the value in the given slot with the passed replacement value.
void	wordWrite(ObjectReference src, Address slot, Word value, Word metaDataA, Word metaDataB, int mode) Write a Word.

Methods inherited from class java.lang.Object

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

Field Detail

id

private int id

Unique mutator identifier

log

protected final Log log

Used for printing log information in a thread safe manner

immortal

protected final BumpPointer immortal

Per-mutator allocator into the immortal space

los

protected final LargeObjectLocal los

Per-mutator allocator into the large object space

smcode

protected final MarkSweepLocal smcode

Per-mutator allocator into the small code space

lgcode

protected final LargeObjectLocal lgcode

Per-mutator allocator into the large code space

nonmove

protected final MarkSweepLocal nonmove

Per-mutator allocator into the non moving space

Constructor Detail

MutatorContext

public MutatorContext()

Method Detail

initMutator

public void initMutator(int id)

Notify that the mutator context is registered and ready to execute. From this point it will be included in iterations over mutators.

Parameters:

id - The id of this mutator context.

deinitMutator

public void deinitMutator()

The mutator is about to be cleaned up, make sure all local data is returned.

collectionPhase

public abstract void collectionPhase(short phaseId,
                                     boolean primary)

Perform a per-mutator collection phase.

Parameters:

phaseId - The unique phase identifier

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

checkAllocator

public int checkAllocator(int bytes,
                          int align,
                          int allocator)

Run-time check of the allocator to use for a given allocation

At the moment this method assumes that allocators will use the simple (worst) method of aligning to determine if the object is a large object to ensure that no objects are larger than other allocators can handle.

Parameters:

bytes - The number of bytes to be allocated

align - The requested alignment.

allocator - The allocator statically assigned to this allocation

Returns:

The allocator dynamically assigned to this allocation

alloc

public Address alloc(int bytes,
                     int align,
                     int offset,
                     int allocator,
                     int site)

Allocate memory for an object.

Parameters:

bytes - The number of bytes required for the object.

align - Required alignment for the object.

offset - Offset associated with the alignment.

allocator - The allocator associated with this request.

site - Allocation site

Returns:

The low address of the allocated chunk.

postAlloc

public void postAlloc(ObjectReference ref,
                      ObjectReference typeRef,
                      int bytes,
                      int allocator)

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

Parameters:

ref - 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

getAllocatorFromSpace

public Allocator getAllocatorFromSpace(Space space)

Return the allocator instance associated with a space space, for this plan instance.

Parameters:

space - The space for which the allocator instance is desired.

Returns:

The allocator instance associated with this plan instance which is allocating into space, or null if no appropriate allocator can be established.

javaLangReferenceReadBarrier

public ObjectReference javaLangReferenceReadBarrier(ObjectReference referent)

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

Parameters:

referent - The referent being read.

Returns:

The new referent.

booleanWrite

public void booleanWrite(ObjectReference src,
                         Address slot,
                         boolean value,
                         Word metaDataA,
                         Word metaDataB,
                         int mode)

Write a boolean. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new boolean

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

booleanRead

public boolean booleanRead(ObjectReference src,
                           Address slot,
                           Word metaDataA,
                           Word metaDataB,
                           int mode)

Read a boolean. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The boolean that was read.

booleanBulkCopy

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

A number of booleans 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

byteWrite

public void byteWrite(ObjectReference src,
                      Address slot,
                      byte value,
                      Word metaDataA,
                      Word metaDataB,
                      int mode)

Write a byte. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new byte

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

byteRead

public byte byteRead(ObjectReference src,
                     Address slot,
                     Word metaDataA,
                     Word metaDataB,
                     int mode)

Read a byte. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The byte that was read.

byteBulkCopy

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

A number of bytes 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

charWrite

public void charWrite(ObjectReference src,
                      Address slot,
                      char value,
                      Word metaDataA,
                      Word metaDataB,
                      int mode)

Write a char. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new char

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

charRead

public char charRead(ObjectReference src,
                     Address slot,
                     Word metaDataA,
                     Word metaDataB,
                     int mode)

Read a char. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The char that was read.

charBulkCopy

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

A number of chars 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

shortWrite

public void shortWrite(ObjectReference src,
                       Address slot,
                       short value,
                       Word metaDataA,
                       Word metaDataB,
                       int mode)

Write a short. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new short

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

shortRead

public short shortRead(ObjectReference src,
                       Address slot,
                       Word metaDataA,
                       Word metaDataB,
                       int mode)

Read a short. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The short that was read.

shortBulkCopy

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

A number of shorts 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

intWrite

public void intWrite(ObjectReference src,
                     Address slot,
                     int value,
                     Word metaDataA,
                     Word metaDataB,
                     int mode)

Write a int. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new int

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

intRead

public int intRead(ObjectReference src,
                   Address slot,
                   Word metaDataA,
                   Word metaDataB,
                   int mode)

Read a int. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The int that was read.

intBulkCopy

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

A number of ints 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

intTryCompareAndSwap

public boolean intTryCompareAndSwap(ObjectReference src,
                                    Address slot,
                                    int old,
                                    int value,
                                    Word metaDataA,
                                    Word metaDataB,
                                    int mode)

Attempt to atomically exchange the value in the given slot with the passed replacement value. By default do nothing, override if appropriate.

Parameters:

src - The object into which the value will be stored

slot - The address into which the value will be stored.

old - The old int to be swapped out

value - The new int

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.

longWrite

public void longWrite(ObjectReference src,
                      Address slot,
                      long value,
                      Word metaDataA,
                      Word metaDataB,
                      int mode)

Write a long. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new long

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

longRead

public long longRead(ObjectReference src,
                     Address slot,
                     Word metaDataA,
                     Word metaDataB,
                     int mode)

Read a long. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The long that was read.

longBulkCopy

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

A number of longs 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

longTryCompareAndSwap

public boolean longTryCompareAndSwap(ObjectReference src,
                                     Address slot,
                                     long old,
                                     long value,
                                     Word metaDataA,
                                     Word metaDataB,
                                     int mode)

Attempt to atomically exchange the value in the given slot with the passed replacement value. By default do nothing, override if appropriate.

Parameters:

src - The object into which the value will be stored

slot - The address into which the value will be stored.

old - The old long to be swapped out

value - The new long

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.

floatWrite

public void floatWrite(ObjectReference src,
                       Address slot,
                       float value,
                       Word metaDataA,
                       Word metaDataB,
                       int mode)

Write a float. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new float

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

floatRead

public float floatRead(ObjectReference src,
                       Address slot,
                       Word metaDataA,
                       Word metaDataB,
                       int mode)

Read a float. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The float that was read.

floatBulkCopy

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

A number of floats 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

doubleWrite

public void doubleWrite(ObjectReference src,
                        Address slot,
                        double value,
                        Word metaDataA,
                        Word metaDataB,
                        int mode)

Write a double. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new double

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

doubleRead

public double doubleRead(ObjectReference src,
                         Address slot,
                         Word metaDataA,
                         Word metaDataB,
                         int mode)

Read a double. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The double that was read.

doubleBulkCopy

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

A number of doubles 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

wordWrite

public void wordWrite(ObjectReference src,
                      Address slot,
                      Word value,
                      Word metaDataA,
                      Word metaDataB,
                      int mode)

Write a Word. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new Word

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

wordRead

public Word wordRead(ObjectReference src,
                     Address slot,
                     Word metaDataA,
                     Word metaDataB,
                     int mode)

Read a Word. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The Word that was read.

wordBulkCopy

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

A number of Words 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

wordTryCompareAndSwap

public boolean wordTryCompareAndSwap(ObjectReference src,
                                     Address slot,
                                     Word old,
                                     Word value,
                                     Word metaDataA,
                                     Word metaDataB,
                                     int mode)

Attempt to atomically exchange the value in the given slot with the passed replacement value. By default do nothing, override if appropriate.

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 Word to be swapped out

value - The new Word

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.

addressWrite

public void addressWrite(ObjectReference src,
                         Address slot,
                         Address value,
                         Word metaDataA,
                         Word metaDataB,
                         int mode)

Write an Address. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

src - The object into which the Word will be stored

slot - The address into which the Word will be stored.

value - The value of the new Address

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

addressRead

public Address addressRead(ObjectReference src,
                           Address slot,
                           Word metaDataA,
                           Word metaDataB,
                           int mode)

Read an Address. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The Address that was read.

addressBulkCopy

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

A number of Addresse's 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

addressTryCompareAndSwap

public boolean addressTryCompareAndSwap(ObjectReference src,
                                        Address slot,
                                        Address old,
                                        Address value,
                                        Word metaDataA,
                                        Word metaDataB,
                                        int mode)

Attempt to atomically exchange the value in the given slot with the passed replacement value. By default do nothing, override if appropriate.

Parameters:

src - The object into which the Address will be stored

slot - The address into which the Address will be stored.

old - The old Address to be swapped out

value - The new Address

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.

extentWrite

public void extentWrite(ObjectReference src,
                        Address slot,
                        Extent value,
                        Word metaDataA,
                        Word metaDataB,
                        int mode)

Write an Extent. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new Extent

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

extentRead

public Extent extentRead(ObjectReference src,
                         Address slot,
                         Word metaDataA,
                         Word metaDataB,
                         int mode)

Read an Extent. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The Extent that was read.

extentBulkCopy

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

A number of Extents 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

offsetWrite

public void offsetWrite(ObjectReference src,
                        Address slot,
                        Offset value,
                        Word metaDataA,
                        Word metaDataB,
                        int mode)

Write an Offset. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - The value of the new Offset

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

offsetRead

public Offset offsetRead(ObjectReference src,
                         Address slot,
                         Word metaDataA,
                         Word metaDataB,
                         int mode)

Read an Offset. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The Offset that was read.

offsetBulkCopy

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

A number of Offsets 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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

objectReferenceWrite

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

Write an object reference. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

value - 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

objectReferenceRead

public ObjectReference objectReferenceRead(ObjectReference src,
                                           Address slot,
                                           Word metaDataA,
                                           Word metaDataB,
                                           int mode)

Read an object reference. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

src - The object reference holding the field being read.

slot - The address of the slot being read.

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

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

mode - The context in which the load occurred

Returns:

The reference that was read.

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.

Parameters:

src - The source array

srcOffset - The starting source offset

dst - The destination array

dstOffset - The starting destination offset

bytes - The number of bytes to be copied

Returns:

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

objectReferenceNonHeapWrite

public void objectReferenceNonHeapWrite(Address slot,
                                        ObjectReference tgt,
                                        Word metaDataA,
                                        Word metaDataB)

A new reference is about to be created in a location that is not a regular heap object. Take appropriate write barrier actions.

By default do nothing, override if appropriate.

Parameters:

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

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

objectReferenceNonHeapRead

public ObjectReference objectReferenceNonHeapRead(Address slot,
                                                  Word metaDataA,
                                                  Word metaDataB)

Read an object reference. Take appropriate read barrier action, and return the value that was read.

This is a substituting barrier. The call to this barrier takes the place of a load.

Parameters:

slot - The address of the slot being read.

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

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

Returns:

The reference that was read.

objectReferenceTryCompareAndSwap

public 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. If a new reference is created, we must then take appropriate write barrier actions.

By default do nothing, override if appropriate.

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.

flush

public void flush()

Flush mutator context, in response to a requestMutatorFlush. Also called by the default implementation of deinitMutator.

flushRememberedSets

public void flushRememberedSets()

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

assertRemsetsFlushed

public void assertRemsetsFlushed()

Assert that the remsets have been flushed. This is critical to correctness. We need to maintain the invariant that remset entries do not accrue during GC. If the host JVM generates barrier entries it is its own responsibility to ensure that they are flushed before returning to MMTk.

getLog

public final Log getLog()

Returns:

the Log instance for this mutator context.

getId

public int getId()

Returns:

the unique identifier for this mutator context.