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.semispace.gcspy;
014    
015    import org.mmtk.plan.Trace;
016    import org.mmtk.plan.semispace.SSTraceLocal;
017    import org.mmtk.policy.Space;
018    
019    import org.vmmagic.pragma.*;
020    import org.vmmagic.unboxed.*;
021    
022    /**
023     * This class implements the core functionality for a transitive
024     * closure over the heap graph.
025     */
026    @Uninterruptible
027    public final class SSGCspyTraceLocal extends SSTraceLocal {
028      /**
029       * Constructor
030       */
031      public SSGCspyTraceLocal(Trace trace) {
032        super(trace);
033      }
034    
035      /****************************************************************************
036       *
037       * Externally visible Object processing and tracing
038       */
039    
040      /**
041       * {@inheritDoc}
042       */
043      @Override
044      @Inline
045      public ObjectReference traceObject(ObjectReference object) {
046        if (object.isNull()) return object;
047        if (Space.isInSpace(SSGCspy.GCSPY, object))
048          return SSGCspy.gcspySpace.traceObject(this, object);
049        return super.traceObject(object);
050      }
051    
052      /**
053       * Will this object move from this point on, during the current trace ?
054       *
055       * @param object The object to query.
056       * @return True if the object will not move.
057       */
058      @Override
059      public boolean willNotMoveInCurrentCollection(ObjectReference object) {
060        if (Space.isInSpace(SSGCspy.GCSPY, object))
061          return true;
062        return super.willNotMoveInCurrentCollection(object);
063      }
064    }