| /* |
| * This file is part of the Jikes RVM project (http://jikesrvm.org). |
| * |
| * This file is licensed to You under the Eclipse Public License (EPL); |
| * You may not use this file except in compliance with the License. You |
| * may obtain a copy of the License at |
| * |
| * http://www.opensource.org/licenses/eclipse-1.0.php |
| * |
| * See the COPYRIGHT.txt file distributed with this work for information |
| * regarding copyright ownership. |
| */ |
| package org.mmtk.plan.generational.immix; |
| |
| import static org.mmtk.policy.immix.ImmixConstants.MARK_LINE_AT_SCAN_TIME; |
| |
| import org.mmtk.plan.generational.GenCollector; |
| import org.mmtk.plan.generational.GenMatureTraceLocal; |
| import org.mmtk.plan.Trace; |
| import org.mmtk.policy.Space; |
| import org.mmtk.utility.Log; |
| import org.mmtk.utility.options.Options; |
| import org.mmtk.vm.VM; |
| |
| import org.vmmagic.unboxed.*; |
| import org.vmmagic.pragma.*; |
| |
| /** |
| * This class implments the core functionality for a transitive |
| * closure over the heap graph, specifically in a defragmenting pass over |
| * a generational immix collector. |
| */ |
| @Uninterruptible |
| public final class GenImmixMatureDefragTraceLocal extends GenMatureTraceLocal{ |
| |
| /** |
| * Constructor |
| */ |
| public GenImmixMatureDefragTraceLocal(Trace global, GenCollector plan) { |
| super(GenImmix.SCAN_DEFRAG, global, plan); |
| } |
| |
| /** |
| * Is the specified object live? |
| * |
| * @param object The object. |
| * @return True if the object is live. |
| */ |
| public boolean isLive(ObjectReference object) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(GenImmix.immixSpace.inImmixDefragCollection()); |
| if (object.isNull()) return false; |
| if (Space.isInSpace(GenImmix.IMMIX, object)) { |
| return GenImmix.immixSpace.isLive(object); |
| } |
| return super.isLive(object); |
| } |
| |
| /** |
| * This method is the core method during the trace of the object graph. |
| * The role of this method is to: |
| * |
| * 1. Ensure the traced object is not collected. |
| * 2. If this is the first visit to the object enqueue it to be scanned. |
| * 3. Return the forwarded reference to the object. |
| * |
| * @param object The object to be traced. |
| * @return The new reference to the same object instance. |
| */ |
| @Inline |
| public ObjectReference traceObject(ObjectReference object) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(GenImmix.immixSpace.inImmixDefragCollection()); |
| if (object.isNull()) return object; |
| if (Space.isInSpace(GenImmix.IMMIX, object)) |
| return GenImmix.immixSpace.traceObject(this, object, GenImmix.ALLOC_MATURE_MAJORGC); |
| return super.traceObject(object); |
| } |
| |
| @Inline |
| @Override |
| public ObjectReference precopyObject(ObjectReference object) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(GenImmix.immixSpace.inImmixDefragCollection()); |
| ObjectReference rtn = traceObject(object); |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(willNotMoveInCurrentCollection(rtn)); |
| return rtn; |
| } |
| |
| /** |
| * Return true if this object is guaranteed not to move during this |
| * collection (i.e. this object is defintely not an unforwarded |
| * object). |
| * |
| * @param object |
| * @return True if this object is guaranteed not to move during this |
| * collection. |
| */ |
| @Override |
| public boolean willNotMoveInCurrentCollection(ObjectReference object) { |
| if (Space.isInSpace(GenImmix.IMMIX, object)) { |
| return GenImmix.immixSpace.willNotMoveThisGC(object); |
| } |
| return super.willNotMoveInCurrentCollection(object); |
| } |
| |
| /** |
| * Collectors that move objects <b>must</b> override this method. |
| * It performs the deferred scanning of objects which are forwarded |
| * during bootstrap of each copying collection. Because of the |
| * complexities of the collection bootstrap (such objects are |
| * generally themselves gc-critical), the forwarding and scanning of |
| * the objects must be dislocated. It is an error for a non-moving |
| * collector to call this method. |
| * |
| * @param object The forwarded object to be scanned |
| */ |
| @Inline |
| @Override |
| protected void scanObject(ObjectReference object) { |
| if (VM.VERIFY_ASSERTIONS && Options.verbose.getValue() >= 9) { |
| Log.write("SO["); Log.write(object); Log.writeln("]"); |
| } |
| super.scanObject(object); |
| if (MARK_LINE_AT_SCAN_TIME && Space.isInSpace(GenImmix.IMMIX, object)) |
| GenImmix.immixSpace.markLines(object); |
| } |
| } |