--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/agent/src/share/classes/sun/jvm/hotspot/utilities/ReversePtrs.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2002-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+package sun.jvm.hotspot.utilities;
+
+import java.util.*;
+import sun.jvm.hotspot.oops.*;
+
+/** ReversePtrs hashtable. */
+
+public class ReversePtrs  {
+  private HashMap rp;
+
+  public ReversePtrs() {
+    rp = new HashMap();
+  }
+
+  public void put(LivenessPathElement from, Oop to) {
+    if (to == null) return;
+    ArrayList al = (ArrayList) rp.get((Object) to);
+    if (al == null) al = new ArrayList();
+    // Inserting at the beginning is a hack to change the reported
+    // paths from LivenessAnalysis to look more like they used to;
+    // otherwise paths through the Finalizer queue to popular objects
+    // seem to be preferred
+    al.add(0, (Object) from);
+    rp.put((Object) to, (Object) al);
+  }
+
+  /** Returns an ArrayList of the incoming references to this Oop if
+      it is alive, and null if it is dead according to the
+      ReversePtrsAnalysis. Currently not all roots are scanned so this
+      result is frequently inaccurate for JVM-internal objects, but is
+      usually correct for Java-level objects. */
+  public ArrayList/*<LivenessPathElement>*/ get(Oop obj) {
+    return (ArrayList) rp.get((Object)obj);
+  }
+}