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.generational.marksweep;
014
015 import org.mmtk.plan.generational.Gen;
016 import org.mmtk.plan.Trace;
017 import org.mmtk.plan.TransitiveClosure;
018 import org.mmtk.policy.MarkSweepSpace;
019 import org.mmtk.policy.Space;
020 import org.mmtk.utility.heap.VMRequest;
021
022 import org.vmmagic.pragma.*;
023 import org.vmmagic.unboxed.*;
024
025 /**
026 * This class implements the functionality of a two-generation copying
027 * collector where <b>the higher generation is a mark-sweep space</b>
028 * (free list allocation, mark-sweep collection). Nursery collections
029 * occur when either the heap is full or the nursery is full. The
030 * nursery size is determined by an optional command line argument.
031 * If undefined, the nursery size is "infinite", so nursery
032 * collections only occur when the heap is full (this is known as a
033 * flexible-sized nursery collector). Thus both fixed and flexible
034 * nursery sizes are supported. Full heap collections occur when the
035 * nursery size has dropped to a statically defined threshold,
036 * <code>NURSERY_THRESHOLD</code><p>
037 *
038 * See the Jones & Lins GC book, chapter 7 for a detailed discussion
039 * of generational collection and section 7.3 for an overview of the
040 * flexible nursery behavior ("The Standard ML of New Jersey
041 * collector"), or go to Appel's paper "Simple generational garbage
042 * collection and fast allocation." SP&E 19(2):171--183, 1989.<p>
043 *
044 *
045 * For general comments about the global/local distinction among classes refer
046 * to Plan.java and PlanLocal.java.
047 */
048 @Uninterruptible
049 public class GenMS extends Gen {
050
051 /*****************************************************************************
052 *
053 * Class fields
054 */
055
056 /** The mature space, which for GenMS uses a mark sweep collection policy. */
057 public static final MarkSweepSpace msSpace = new MarkSweepSpace("ms", VMRequest.create());
058
059 public static final int MS = msSpace.getDescriptor();
060
061 /****************************************************************************
062 *
063 * Instance fields
064 */
065
066 /** The trace class for a full-heap collection */
067 public final Trace matureTrace = new Trace(metaDataSpace);
068
069 /*****************************************************************************
070 *
071 * Collection
072 */
073
074 /**
075 * {@inheritDoc}
076 */
077 @Inline
078 @Override
079 public final void collectionPhase(short phaseId) {
080 if (traceFullHeap()) {
081 if (phaseId == PREPARE) {
082 super.collectionPhase(phaseId);
083 matureTrace.prepare();
084 msSpace.prepare(true);
085 return;
086 }
087
088 if (phaseId == CLOSURE) {
089 matureTrace.prepare();
090 return;
091 }
092 if (phaseId == RELEASE) {
093 matureTrace.release();
094 msSpace.release();
095 super.collectionPhase(phaseId);
096 return;
097 }
098 }
099 super.collectionPhase(phaseId);
100 }
101
102 /*****************************************************************************
103 *
104 * Accounting
105 */
106
107 /**
108 * Return the number of pages reserved for use given the pending
109 * allocation.
110 */
111 @Inline
112 @Override
113 public int getPagesUsed() {
114 return msSpace.reservedPages() + super.getPagesUsed();
115 }
116
117 @Override
118 public int getMaturePhysicalPagesAvail() {
119 return (int) (msSpace.availablePhysicalPages()/MarkSweepSpace.WORST_CASE_FRAGMENTATION);
120 }
121
122 /*****************************************************************************
123 *
124 * Miscellaneous
125 */
126
127 /**
128 * {@inheritDoc}
129 */
130 @Override
131 @Inline
132 protected final Space activeMatureSpace() {
133 return msSpace;
134 }
135
136 @Override
137 public boolean willNeverMove(ObjectReference object) {
138 if (Space.isInSpace(MS, object))
139 return true;
140 return super.willNeverMove(object);
141 }
142
143 @Override
144 @Interruptible
145 protected void registerSpecializedMethods() {
146 TransitiveClosure.registerSpecializedScan(SCAN_MATURE, GenMSMatureTraceLocal.class);
147 super.registerSpecializedMethods();
148 }
149 }