001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.mmtk.plan.copyms;
014    
015    import org.mmtk.plan.TraceLocal;
016    import org.mmtk.plan.Trace;
017    import org.mmtk.policy.Space;
018    
019    import org.vmmagic.pragma.*;
020    import org.vmmagic.unboxed.*;
021    
022    /**
023     * This class implements the thread-local functionality for a
024     * transitive closure over a coping/mark-sweep hybrid collector.
025     */
026    @Uninterruptible
027    public final class CopyMSTraceLocal extends TraceLocal {
028    
029      /**
030       * Constructor
031       */
032      public CopyMSTraceLocal(Trace trace) {
033        super(CopyMS.SCAN_COPYMS, trace);
034      }
035    
036      /****************************************************************************
037       *
038       * Externally visible Object processing and tracing
039       */
040    
041      /**
042       * Is the specified object reachable?
043       */
044      @Override
045      public boolean isLive(ObjectReference object) {
046        if (object.isNull()) return false;
047        if (Space.isInSpace(CopyMS.NURSERY, object)) {
048          return CopyMS.nurserySpace.isLive(object);
049        }
050        if (Space.isInSpace(CopyMS.MARK_SWEEP, object)) {
051          return CopyMS.msSpace.isLive(object);
052        }
053        return super.isLive(object);
054      }
055    
056      /**
057       * {@inheritDoc}<p>
058       *
059       * In this instance, we refer objects in the mark-sweep space to the
060       * msSpace for tracing, and defer to the superclass for all others.
061       */
062      @Inline
063      @Override
064      public ObjectReference traceObject(ObjectReference object) {
065        if (object.isNull()) return object;
066        if (Space.isInSpace(CopyMS.NURSERY, object))
067          return CopyMS.nurserySpace.traceObject(this, object, CopyMS.ALLOC_MS);
068        if (Space.isInSpace(CopyMS.MARK_SWEEP, object))
069          return CopyMS.msSpace.traceObject(this, object);
070        return super.traceObject(object);
071      }
072    
073      /**
074       * Will this object move from this point on, during the current collection ?
075       *
076       * @param object The object to query.
077       */
078      @Override
079      public boolean willNotMoveInCurrentCollection(ObjectReference object) {
080        return !Space.isInSpace(CopyMS.NURSERY, object);
081      }
082    }