| /* |
| * 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.marksweep; |
| |
| import org.mmtk.plan.TraceLocal; |
| import org.mmtk.plan.Trace; |
| import org.mmtk.policy.Space; |
| import org.mmtk.utility.HeaderByte; |
| import org.mmtk.utility.deque.ObjectReferenceDeque; |
| |
| import org.vmmagic.pragma.*; |
| import org.vmmagic.unboxed.*; |
| |
| /** |
| * This class implements the thread-local functionality for a transitive |
| * closure over a mark-sweep space. |
| */ |
| @Uninterruptible |
| public final class MSTraceLocal extends TraceLocal { |
| /**************************************************************************** |
| * Instance fields |
| */ |
| private final ObjectReferenceDeque modBuffer; |
| |
| /** |
| * Constructor |
| */ |
| public MSTraceLocal(Trace trace, ObjectReferenceDeque modBuffer) { |
| super(MS.SCAN_MARK, trace); |
| this.modBuffer = modBuffer; |
| } |
| |
| |
| /**************************************************************************** |
| * Externally visible Object processing and tracing |
| */ |
| |
| /** |
| * Is the specified object live? |
| * |
| * @param object The object. |
| * @return <code>true</code> if the object is live. |
| */ |
| @Override |
| public boolean isLive(ObjectReference object) { |
| if (object.isNull()) return false; |
| if (Space.isInSpace(MS.MARK_SWEEP, object)) { |
| return MS.msSpace.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. |
| * |
| * In this instance, we refer objects in the mark-sweep space to the |
| * msSpace for tracing, and defer to the superclass for all others. |
| * |
| * @param object The object to be traced. |
| * @return The new reference to the same object instance. |
| */ |
| @Inline |
| @Override |
| public ObjectReference traceObject(ObjectReference object) { |
| if (object.isNull()) return object; |
| if (Space.isInSpace(MS.MARK_SWEEP, object)) |
| return MS.msSpace.traceObject(this, object); |
| return super.traceObject(object); |
| } |
| |
| /** |
| * Process any remembered set entries. This means enumerating the |
| * mod buffer and for each entry, marking the object as unlogged |
| * (we don't enqueue for scanning since we're doing a full heap GC). |
| */ |
| protected void processRememberedSets() { |
| if (modBuffer != null) { |
| logMessage(5, "clearing modBuffer"); |
| while (!modBuffer.isEmpty()) { |
| ObjectReference src = modBuffer.pop(); |
| HeaderByte.markAsUnlogged(src); |
| } |
| } |
| } |
| } |