/*
* 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.concurrent.marksweep;
import org.mmtk.plan.*;
import org.mmtk.plan.concurrent.ConcurrentMutator;
import org.mmtk.policy.MarkSweepLocal;
import org.mmtk.policy.Space;
import org.mmtk.utility.alloc.Allocator;
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>CMS</i> plan, which implements a full-heap
* concurrent mark-sweep collector.<p>
*
* FIXME The SegregatedFreeList class (and its descendants 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 CMS
* @see CMSCollector
* @see StopTheWorldMutator
* @see MutatorContext
*/
@Uninterruptible
public abstract class CMSMutator extends ConcurrentMutator {
/****************************************************************************
* Instance fields
*/
private MarkSweepLocal ms;
private TraceWriteBuffer remset;
/****************************************************************************
*
* Initialization
*/
/**
* Constructor
*/
public CMSMutator() {
ms = new MarkSweepLocal(CMS.msSpace);
remset = new TraceWriteBuffer(global().msTrace);
}
/****************************************************************************
*
* 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.
* @return The low address of the allocated memory.
*/
@Inline
public Address alloc(int bytes, int align, int offset, int allocator, int site) {
if (allocator == CMS.ALLOC_DEFAULT) {
return ms.alloc(bytes, align, offset);
}
return super.alloc(bytes, align, offset, allocator, site);
}
/**
* 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) {
if (allocator == CMS.ALLOC_DEFAULT)
CMS.msSpace.initializeHeader(ref, false);
else
super.postAlloc(ref, typeRef, bytes, allocator);
}
/**
* 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 == ms) return CMS.msSpace;
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 == CMS.msSpace) return ms;
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 == CMS.PREPARE) {
super.collectionPhase(phaseId, primary);
ms.prepare();
return;
}
if (phaseId == CMS.RELEASE) {
ms.release();
super.collectionPhase(phaseId, primary);
return;
}
super.collectionPhase(phaseId, primary);
}
/**
* Flush per-mutator remembered sets into the global remset pool.
*/
public void flushRememberedSets() {
remset.flush();
}
/****************************************************************************
*
* Write and read barriers.
*/
/**
* Process a reference that may require being enqueued as part of a concurrent
* collection.
*
* @param ref The reference to check.
*/
protected void checkAndEnqueueReference(ObjectReference ref) {
if (barrierActive) {
if (!ref.isNull()) {
if (Space.isInSpace(CMS.MARK_SWEEP, ref)) CMS.msSpace.traceObject(remset, ref);
else if (Space.isInSpace(CMS.IMMORTAL, ref)) CMS.immortalSpace.traceObject(remset, ref);
else if (Space.isInSpace(CMS.PLOS, ref)) CMS.ploSpace.traceObject(remset, ref);
else if (Space.isInSpace(CMS.LOS, ref)) CMS.loSpace.traceObject(remset, ref);
}
}
if (VM.VERIFY_ASSERTIONS) {
if (!ref.isNull() && !Plan.gcInProgress()) {
if (Space.isInSpace(CMS.MARK_SWEEP, ref)) VM.assertions._assert(CMS.msSpace.isLive(ref));
else if (Space.isInSpace(CMS.PLOS, ref)) VM.assertions._assert(CMS.ploSpace.isLive(ref));
else if (Space.isInSpace(CMS.LOS, ref)) VM.assertions._assert(CMS.loSpace.isLive(ref));
}
}
}
/****************************************************************************
*
* Miscellaneous
*/
/** @return The active global plan as a <code>Gen</code> instance. */
@Inline
private static CMS global() {
return (CMS) VM.activePlan.global();
}
}