| /* |
| * 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.refcount.generational; |
| |
| import org.mmtk.plan.TraceLocal; |
| import org.mmtk.plan.Trace; |
| import org.mmtk.plan.refcount.RCHeader; |
| import org.mmtk.policy.Space; |
| import org.mmtk.utility.deque.ObjectReferenceDeque; |
| import org.mmtk.vm.VM; |
| |
| import org.vmmagic.pragma.*; |
| import org.vmmagic.unboxed.*; |
| |
| /** |
| * This class implements the thread-local core functionality for a transitive |
| * closure over the heap graph. |
| */ |
| @Uninterruptible |
| public final class GenRCFindRootSetTraceLocal extends TraceLocal { |
| |
| private final ObjectReferenceDeque rootBuffer; |
| |
| /** |
| * Constructor |
| */ |
| public GenRCFindRootSetTraceLocal(Trace trace, ObjectReferenceDeque rootBuffer) { |
| super(trace); |
| this.rootBuffer = rootBuffer; |
| } |
| |
| /**************************************************************************** |
| * |
| * Externally visible Object processing and tracing |
| */ |
| |
| /** |
| * Is the specified object reachable? |
| * |
| * @param object The object. |
| * @return <code>true</code> if the object is reachable. |
| */ |
| public boolean isLive(ObjectReference object) { |
| return GenRC.isRCObject(object) && RCHeader.isLiveRC(object) || |
| (!Space.isInSpace(GenRC.NURSERY, object) && super.isLive(object)); |
| } |
| |
| /** |
| * When we trace a non-root object we do nothing. |
| * |
| * @param object The object to be traced. |
| * @return The new reference to the same object instance. |
| */ |
| @Inline |
| public ObjectReference traceObject(ObjectReference object) { |
| return traceObject(object, false); |
| } |
| |
| /** |
| * When we trace a root object we remember it. |
| * |
| * @param object The object to be traced. |
| * @return The new reference to the same object instance. |
| */ |
| @Inline |
| public ObjectReference traceObject(ObjectReference object, boolean root) { |
| if (object.isNull()) return object; |
| |
| if (Space.isInSpace(GenRC.NURSERY, object)) { |
| object = GenRC.nurserySpace.traceObject(this, object, GenRC.ALLOC_RC); |
| } else if (!GenRC.isRCObject(object)) { |
| return object; |
| } |
| |
| if (root) { |
| rootBuffer.push(object); |
| } else { |
| RCHeader.incRC(object); |
| } |
| |
| return object; |
| } |
| |
| /** |
| * Ensure that the referenced object will not move from this point through |
| * to the end of the collection. This can involve forwarding the object |
| * if necessary. |
| * |
| * <i>Non-copying collectors do nothing, copying collectors must |
| * override this method in each of their trace classes.</i> |
| * |
| * @param object The object that must not move during the collection. |
| * @return True If the object will not move during collection |
| */ |
| public boolean willNotMoveInCurrentCollection(ObjectReference object) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(!object.isNull()); |
| return !(Space.isInSpace(GenRC.NURSERY, object)); |
| } |
| |
| /** |
| * Ensure that this object will not move for the rest of the GC. |
| * |
| * @param object The object that must not move |
| * @return The new object, guaranteed stable for the rest of the GC. |
| */ |
| public ObjectReference precopyObject(ObjectReference object) { |
| if (Space.isInSpace(GenRC.NURSERY, object)) { |
| return GenRC.nurserySpace.traceObject(this, object, GenRC.ALLOC_RC); |
| } |
| return object; |
| } |
| |
| } |