| /* |
| * 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; |
| |
| import org.mmtk.vm.VM; |
| import org.vmmagic.pragma.*; |
| import org.vmmagic.unboxed.*; |
| |
| /** |
| * This abstract class is the fundamental mechanism for performing a |
| * transitive closure over an object graph.<p> |
| * |
| * Some mechanisms only operate on nodes or edges, but due to limitations |
| * of inheritance we have combined these two here. |
| * |
| * @see org.mmtk.plan.TraceLocal |
| */ |
| @Uninterruptible |
| public abstract class TransitiveClosure { |
| |
| /** Database of specialized scan classes. */ |
| private static final Class<?>[] specializedScans = new Class[VM.activePlan.constraints().numSpecializedScans()]; |
| |
| /** |
| * A transitive closure has been created that is designed to work with a specialized scan method. We must |
| * register it here so the specializer can return the class when queried. |
| * |
| * @param id The method id to register. |
| * @param specializedScanClass The class to register. |
| */ |
| @Interruptible |
| public static synchronized void registerSpecializedScan(int id, Class<?> specializedScanClass) { |
| specializedScans[id] = specializedScanClass; |
| } |
| |
| /** |
| * Get the specialized scan with the given id. |
| */ |
| public static Class<?> getSpecializedScanClass(int id) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(specializedScans[id] != null); |
| return specializedScans[id]; |
| } |
| |
| /** The specialized scan identifier */ |
| protected final int specializedScan; |
| |
| /** |
| * Constructor |
| */ |
| protected TransitiveClosure() { |
| this(-1); |
| } |
| |
| /** |
| * Constructor |
| * |
| * @param specializedScan The specialized scan for this trace. |
| */ |
| protected TransitiveClosure(int specializedScan) { |
| this.specializedScan = specializedScan; |
| if (specializedScan >= 0) { |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(getClass() == getSpecializedScanClass(specializedScan)); |
| } |
| } |
| |
| /** |
| * Trace an edge during GC. |
| * |
| * @param source The source of the reference. |
| * @param slot The location containing the object reference. |
| */ |
| public void processEdge(ObjectReference source, Address slot) { |
| VM.assertions.fail("processEdge not implemented."); |
| } |
| |
| /** |
| * Trace a node during GC. |
| * |
| * @param object The object to be processed. |
| */ |
| public void processNode(ObjectReference object) { |
| VM.assertions.fail("processNode not implemented."); |
| } |
| } |