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.stickyms;
014    
015    import org.mmtk.plan.TraceLocal;
016    import org.mmtk.plan.Trace;
017    import org.mmtk.policy.Space;
018    import org.mmtk.utility.HeaderByte;
019    import org.mmtk.utility.deque.ObjectReferenceDeque;
020    import org.mmtk.vm.VM;
021    
022    import org.vmmagic.pragma.*;
023    import org.vmmagic.unboxed.*;
024    
025    /**
026     * This class implements the thread-local functionality for a transitive
027     * closure over a mark-sweep space.
028     */
029    @Uninterruptible
030    public final class StickyMSNurseryTraceLocal extends TraceLocal {
031    
032      /****************************************************************************
033      *
034      * Instance fields.
035      */
036    
037     /**
038      *
039      */
040     private final ObjectReferenceDeque modBuffer;
041    
042      /**
043       * Constructor
044       */
045      public StickyMSNurseryTraceLocal(Trace trace, ObjectReferenceDeque modBuffer) {
046        super(StickyMS.SCAN_NURSERY, trace);
047        this.modBuffer = modBuffer;
048      }
049    
050      /****************************************************************************
051       *
052       * Externally visible Object processing and tracing
053       */
054    
055      /**
056       * {@inheritDoc}
057       */
058      @Override
059      public boolean isLive(ObjectReference object) {
060        if (object.isNull()) return false;
061        if (Space.isInSpace(StickyMS.MARK_SWEEP, object))
062          return StickyMS.msSpace.isLive(object);
063        if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(super.isLive(object));
064        return true;
065      }
066    
067      /**
068       * {@inheritDoc}<p>
069       *
070       * In this instance, we refer objects in the mark-sweep space to the
071       * msSpace for tracing, and defer to the superclass for all others.
072       *
073       * @param object The object to be traced.
074       * @return The new reference to the same object instance.
075       */
076      @Override
077      @Inline
078      public ObjectReference traceObject(ObjectReference object) {
079        if (object.isNull()) return object;
080        if (Space.isInSpace(StickyMS.MARK_SWEEP, object))
081          return StickyMS.msSpace.traceObject(this, object);
082        else
083          return object;
084      }
085    
086      /**
087       * Process any remembered set entries.  This means enumerating the
088       * mod buffer and for each entry, marking the object as unlogged
089       * and enqueing it for scanning.
090       */
091      @Override
092      protected void processRememberedSets() {
093        logMessage(2, "processing modBuffer");
094        while (!modBuffer.isEmpty()) {
095          ObjectReference src = modBuffer.pop();
096          HeaderByte.markAsUnlogged(src);
097          processNode(src);
098        }
099      }
100    }