/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Common Public License (CPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/cpl1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.mmtk.plan.refcount;
import org.mmtk.plan.Plan;
import org.mmtk.plan.StopTheWorldMutator;
import org.mmtk.plan.refcount.cd.CDMutator;
import org.mmtk.plan.refcount.cd.NullCDMutator;
import org.mmtk.plan.refcount.cd.TrialDeletionMutator;
import org.mmtk.policy.ExplicitFreeListLocal;
import org.mmtk.policy.ExplicitFreeListSpace;
import org.mmtk.policy.ExplicitLargeObjectLocal;
import org.mmtk.policy.Space;
import org.mmtk.utility.alloc.Allocator;
import org.mmtk.utility.deque.ObjectReferenceDeque;
import org.mmtk.vm.VM;
import org.vmmagic.pragma.*;
import org.vmmagic.unboxed.*;
/**
* This class implements <i>per-mutator thread</i> behavior
* and state for the <i>RCBase</i> plan, which implements the
* base functionality for reference counted collectors.
*
* @see RCBase for an overview of the reference counting algorithm.<p>
*
* FIXME The SegregatedFreeList class (and its decendents such as
* MarkSweepLocal) does not properly separate mutator and collector
* behaviors, so the ms field below should really not exist in
* this class as there is no collection-time allocation in this
* collector.
*
* @see RCBase
* @see RCBaseCollector
* @see org.mmtk.plan.StopTheWorldMutator
* @see org.mmtk.plan.MutatorContext
*/
@Uninterruptible public class RCBaseMutator extends StopTheWorldMutator {
/****************************************************************************
* Instance fields
*/
public ExplicitFreeListLocal rc;
public ExplicitLargeObjectLocal los;
private ExplicitFreeListLocal smcode = Plan.USE_CODE_SPACE ? new ExplicitFreeListLocal(RCBase.smallCodeSpace) : null;
private ExplicitLargeObjectLocal lgcode = Plan.USE_CODE_SPACE ? new ExplicitLargeObjectLocal(Plan.largeCodeSpace) : null;
public ObjectReferenceDeque modBuffer;
public DecBuffer decBuffer;
private NullCDMutator nullCD;
private TrialDeletionMutator trialDeletionCD;
/****************************************************************************
*
* Initialization
*/
/**
* Constructor
*/
public RCBaseMutator() {
rc = new ExplicitFreeListLocal(RCBase.rcSpace);
los = new ExplicitLargeObjectLocal(RCBase.loSpace);
decBuffer = new DecBuffer(global().decPool);
modBuffer = new ObjectReferenceDeque("mod buf", global().modPool);
switch (RCBase.CYCLE_DETECTOR) {
case RCBase.NO_CYCLE_DETECTOR:
nullCD = new NullCDMutator();
break;
case RCBase.TRIAL_DELETION:
trialDeletionCD = new TrialDeletionMutator();
break;
}
}
/****************************************************************************
*
* Mutator-time allocation
*/
/**
* Allocate memory for an object. This class handles the default allocator
* from the mark sweep space, and delegates everything else to the
* superclass.
*
* @param bytes The number of bytes required for the object.
* @param align Required alignment for the object.
* @param offset Offset associated with the alignment.
* @param allocator The allocator associated with this request.
* @param site Allocation site
* @return The low address of the allocated memory.
*/
@Inline
public Address alloc(int bytes, int align, int offset, int allocator, int site) {
switch(allocator) {
case RCBase.ALLOC_RC:
return rc.alloc(bytes, align, offset);
case RCBase.ALLOC_LOS:
case RCBase.ALLOC_PRIMITIVE_LOS:
return los.alloc(bytes, align, offset);
case RCBase.ALLOC_IMMORTAL:
return immortal.alloc(bytes, align, offset);
case Plan.ALLOC_CODE:
return smcode.alloc(bytes, align, offset);
case Plan.ALLOC_LARGE_CODE:
return lgcode.alloc(bytes, align, offset);
default:
VM.assertions.fail("RC not aware of allocator");
return Address.zero();
}
}
/**
* Perform post-allocation actions. Initialize the object header for
* objects in the mark-sweep space, and delegate to the superclass for
* other objects.
*
* @param ref The newly allocated object
* @param typeRef the type reference for the instance being created
* @param bytes The size of the space to be allocated (in bytes)
* @param allocator The allocator number to be used for this allocation
*/
@Inline
public void postAlloc(ObjectReference ref, ObjectReference typeRef,
int bytes, int allocator) {
switch(allocator) {
case RCBase.ALLOC_RC:
case Plan.ALLOC_CODE:
ExplicitFreeListSpace.unsyncSetLiveBit(ref);
case RCBase.ALLOC_LOS:
case Plan.ALLOC_LARGE_CODE:
case RCBase.ALLOC_IMMORTAL:
if (RCBase.WITH_COALESCING_RC) modBuffer.push(ref);
case RCBase.ALLOC_PRIMITIVE_LOS:
RCHeader.initializeHeader(ref, typeRef, true);
decBuffer.push(ref);
break;
default:
VM.assertions.fail("RC not aware of allocator");
break;
}
}
/**
* Return the space into which an allocator is allocating. This
* particular method will match against those spaces defined at this
* level of the class hierarchy. Subclasses must deal with spaces
* they define and refer to superclasses appropriately.
*
* @param a An allocator
* @return The space into which <code>a</code> is allocating, or
* <code>null</code> if there is no space associated with
* <code>a</code>.
*/
public Space getSpaceFromAllocator(Allocator a) {
if (a == rc) return RCBase.rcSpace;
if (a == los) return RCBase.loSpace;
if (a == smcode) return RCBase.smallCodeSpace;
if (a == lgcode) return RCBase.largeCodeSpace;
return super.getSpaceFromAllocator(a);
}
/**
* Return the allocator instance associated with a space
* <code>space</code>, for this plan instance.
*
* @param space The space for which the allocator instance is desired.
* @return The allocator instance associated with this plan instance
* which is allocating into <code>space</code>, or <code>null</code>
* if no appropriate allocator can be established.
*/
public Allocator getAllocatorFromSpace(Space space) {
if (space == RCBase.rcSpace) return rc;
if (space == RCBase.loSpace) return los;
if (space == RCBase.smallCodeSpace) return smcode;
if (space == RCBase.largeCodeSpace) return lgcode;
return super.getAllocatorFromSpace(space);
}
/****************************************************************************
*
* Collection
*/
/**
* Perform a per-mutator collection phase.
*
* @param phaseId The collection phase to perform
* @param primary Perform any single-threaded activities using this thread.
*/
@Inline
public void collectionPhase(short phaseId, boolean primary) {
if (phaseId == RCBase.PREPARE) {
rc.prepare();
los.prepare();
smcode.prepare();
lgcode.prepare();
decBuffer.flushLocal();
modBuffer.flushLocal();
return;
}
if (phaseId == RCBase.RELEASE) {
los.release();
rc.release();
smcode.release();
lgcode.release();
return;
}
if (!cycleDetector().collectionPhase(phaseId)) {
super.collectionPhase(phaseId, primary);
}
}
/****************************************************************************
*
* RC methods
*/
/**
* Add an object to the dec buffer for this mutator.
*
* @param object The object to add
*/
public final void addToDecBuffer(ObjectReference object) {
decBuffer.push(object);
}
/****************************************************************************
*
* Miscellaneous
*/
/** @return The active global plan as an <code>RC</code> instance. */
@Inline
private static RCBase global() {
return (RCBase) VM.activePlan.global();
}
/** @return The active cycle detector instance */
@Inline
public final CDMutator cycleDetector() {
switch (RCBase.CYCLE_DETECTOR) {
case RCBase.NO_CYCLE_DETECTOR:
return nullCD;
case RCBase.TRIAL_DELETION:
return trialDeletionCD;
}
VM.assertions.fail("No cycle detector instance found.");
return null;
}
}