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.policy;
014
015import org.mmtk.utility.alloc.BumpPointer;
016import org.vmmagic.pragma.Uninterruptible;
017import org.vmmagic.unboxed.Extent;
018
019/**
020 * This class implements unsynchronized (local) elements of a
021 * sliding mark-compact collector. Allocation is via the bump pointer
022 * (@see BumpPointer).
023 *
024 * @see BumpPointer
025 * @see MarkCompactSpace
026 */
027@Uninterruptible
028public final class MarkCompactLocal extends BumpPointer {
029
030  /**
031   * Constructor
032   *
033   * @param space The space to bump point into.
034   */
035  public MarkCompactLocal(MarkCompactSpace space) {
036    super(space, true);
037  }
038
039  private MarkCompactSpace mcSpace() {
040    return (MarkCompactSpace)space;
041  }
042
043  /**
044   * Prepare for collection: update the metadata for the current region, and flush
045   * this bump-pointer's allocations to the global page list.
046   */
047  public void prepare() {
048    if (!initialRegion.isZero()) {
049      setDataEnd(region,cursor);
050      mcSpace().append(initialRegion);
051    }
052    reset();
053  }
054
055  /**
056   * Flush this thread-local component in preparation for the mutator thread
057   * to die.
058   */
059  public void flush() {
060    prepare();
061  }
062
063  @Override
064  protected Extent maximumRegionSize() {
065    return Extent.fromIntZeroExtend(4 << LOG_BLOCK_SIZE);
066  }
067
068}