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 */
013package org.mmtk.plan.semispace.gctrace;
014
015import org.mmtk.plan.*;
016import org.mmtk.plan.semispace.*;
017import org.mmtk.vm.VM;
018
019import org.vmmagic.pragma.*;
020
021
022/**
023 * This class implements <i>per-collector thread</i> behavior and state for the
024 * <i>GCTrace</i> plan, which implements a GC tracing algorithm.<p>
025 *
026 * Specifically, this class defines <i>SS</i> collection behavior
027 * (through <code>inducedTrace</code> and the <code>collectionPhase</code>
028 * method), and collection-time allocation (copying of objects).<p>
029 *
030 * See {@link GCTrace} for an overview of the GC trace algorithm.
031 *
032 * @see SSCollector
033 * @see GCTrace
034 * @see GCTraceMutator
035 * @see org.mmtk.plan.StopTheWorldCollector
036 * @see org.mmtk.plan.CollectorContext
037 */
038@Uninterruptible public class GCTraceCollector extends SSCollector {
039  /****************************************************************************
040   * Instance fields
041   */
042  protected final GCTraceTraceLocal inducedTrace;
043
044  /****************************************************************************
045   *
046   * Initialization
047   */
048
049  /**
050   * Constructor
051   */
052  public GCTraceCollector() {
053    inducedTrace = new GCTraceTraceLocal(global().ssTrace);
054  }
055
056  /****************************************************************************
057   *
058   * Collection
059   */
060
061  /**
062   * {@inheritDoc}
063   */
064  @Override
065  public void collectionPhase(short phaseId, boolean primary) {
066    if (phaseId == GCTrace.CLOSURE) {
067      inducedTrace.completeTrace();
068      return;
069    }
070
071    if (phaseId == GCTrace.RELEASE) {
072      inducedTrace.release();
073      if (!GCTrace.traceInducedGC) {
074        super.collectionPhase(phaseId, primary);
075      }
076      return;
077    }
078
079    /* fall through case */
080    if (!GCTrace.traceInducedGC ||
081        ((phaseId != StopTheWorld.SOFT_REFS) &&
082         (phaseId != StopTheWorld.WEAK_REFS) &&
083         (phaseId != StopTheWorld.PHANTOM_REFS) &&
084         (phaseId != StopTheWorld.FINALIZABLE) &&
085         (phaseId != SS.PREPARE))) {
086      // Delegate up.
087      super.collectionPhase(phaseId, primary);
088    }
089  }
090
091  /****************************************************************************
092   *
093   * Miscellaneous
094   */
095
096  /** @return The active global plan as a <code>GCTrace</code> instance. */
097  @Inline
098  private static GCTrace global() {
099    return (GCTrace) VM.activePlan.global();
100  }
101
102  @Override
103  public TraceLocal getCurrentTrace() {
104    return inducedTrace;
105  }
106}