1 /* 2 * Copyright (c) 2002, 2006, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 package sun.jvm.hotspot.utilities; 26 27 import java.util.*; 28 import sun.jvm.hotspot.oops.*; 29 30 /** ReversePtrs hashtable. */ 31 32 public class ReversePtrs { 33 private HashMap rp; 34 ReversePtrs()35 public ReversePtrs() { 36 rp = new HashMap(); 37 } 38 put(LivenessPathElement from, Oop to)39 public void put(LivenessPathElement from, Oop to) { 40 if (to == null) return; 41 ArrayList al = (ArrayList) rp.get((Object) to); 42 if (al == null) al = new ArrayList(); 43 // Inserting at the beginning is a hack to change the reported 44 // paths from LivenessAnalysis to look more like they used to; 45 // otherwise paths through the Finalizer queue to popular objects 46 // seem to be preferred 47 al.add(0, (Object) from); 48 rp.put((Object) to, (Object) al); 49 } 50 51 /** Returns an ArrayList of the incoming references to this Oop if 52 it is alive, and null if it is dead according to the 53 ReversePtrsAnalysis. Currently not all roots are scanned so this 54 result is frequently inaccurate for JVM-internal objects, but is 55 usually correct for Java-level objects. */ get(Oop obj)56 public ArrayList/*<LivenessPathElement>*/ get(Oop obj) { 57 return (ArrayList) rp.get((Object)obj); 58 } 59 } 60