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.policy;
014    
015    import org.mmtk.plan.TransitiveClosure;
016    import org.mmtk.utility.heap.FreeListPageResource;
017    import org.mmtk.utility.heap.VMRequest;
018    import org.mmtk.utility.Constants;
019    
020    import org.mmtk.vm.VM;
021    
022    import org.vmmagic.pragma.*;
023    import org.vmmagic.unboxed.*;
024    
025    /**
026     * Each instance of this class corresponds to one raw page space.
027     *
028     * This class provides access to raw memory for managing internal meta
029     * data.
030     */
031    @Uninterruptible public final class RawPageSpace extends Space
032      implements Constants {
033    
034      /**
035       * The caller specifies the region of virtual memory to be used for
036       * this space.  If this region conflicts with an existing space,
037       * then the constructor will fail.
038       *
039       * @param name The name of this space (used when printing error messages etc)
040       * @param pageBudget The number of pages this space may consume
041       * before consulting the plan
042       * @param vmRequest An object describing the virtual memory requested.
043       */
044      public RawPageSpace(String name, int pageBudget, VMRequest vmRequest) {
045        super(name, false, false, vmRequest);
046        if (vmRequest.isDiscontiguous()) {
047          pr = new FreeListPageResource(pageBudget, this, 0);
048        } else {
049          pr = new FreeListPageResource(pageBudget, this, start, extent);
050        }
051      }
052    
053      public void prepare() { }
054      public void release() { }
055    
056      /**
057       * Release a group of pages that were allocated together.
058       *
059       * @param first The first page in the group of pages that were
060       * allocated together.
061       */
062      @Inline
063      public void release(Address first) {
064        ((FreeListPageResource) pr).releasePages(first);
065      }
066    
067      /**
068       * Trace an object.
069       *
070       * This makes no sense for a raw page space and should never be
071       * called.
072       *
073       * @param object The object to be traced.
074       * @return <code>zero</code>: calling this is an error.
075       */
076      @Inline
077      public ObjectReference traceObject(TransitiveClosure trace, ObjectReference object) {
078        if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(false);
079        return ObjectReference.nullReference();
080      }
081    
082      public boolean isLive(ObjectReference object) {
083        return true;
084      }
085    }