1 /*

     2  * Copyright (c) 2003, 2012, 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.debugger.*;

    29 import sun.jvm.hotspot.oops.Oop;

    30 import sun.jvm.hotspot.oops.ObjectHeap;

    31 import sun.jvm.hotspot.types.*;

    32 import sun.jvm.hotspot.runtime.*;

    33 

    34 public class BasicHashtableEntry extends VMObject {

    35   static {

    36     VM.registerVMInitializedObserver(new Observer() {

    37         public void update(Observable o, Object data) {

    38           initialize(VM.getVM().getTypeDataBase());

    39         }

    40       });

    41   }

    42 

    43   private static synchronized void initialize(TypeDataBase db) {

    44     Type type = db.lookupType("BasicHashtableEntry<mtInternal>");

    45     hashField      = type.getCIntegerField("_hash");

    46     nextField      = type.getAddressField("_next");

    47   }

    48 

    49   // Fields

    50   private static CIntegerField hashField;

    51   private static AddressField  nextField;

    52 

    53   // Accessors

    54   public long hash() {

    55     return hashField.getValue(addr) & 0xFFFFFFFFL;

    56   }

    57 

    58   private long nextAddressValue() {

    59     Debugger dbg = VM.getVM().getDebugger();

    60     Address nextValue = nextField.getValue(addr);

    61     return (nextValue != null) ? dbg.getAddressValue(nextValue) : 0L;

    62   }

    63 

    64   public boolean isShared() {

    65     return (nextAddressValue() & 1L) != 0;

    66   }

    67 

    68   public BasicHashtableEntry next() {

    69     Address nextValue = nextField.getValue(addr);

    70     Address next = (nextValue != null)? nextValue.andWithMask(-2L) : null;

    71     // using this.getClass so that return type will be as expected in

    72     // subclass context. But, because we can't use covariant return type

    73     // caller has to use this next and cast the result to correct type.

    74     return (BasicHashtableEntry) VMObjectFactory.newObject(this.getClass(), next);

    75   }

    76 

    77   public BasicHashtableEntry(Address addr) {

    78     super(addr);

    79   }

    80 }