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1   /*
2    * Copyright (c) 2001, 2013, 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.memory;
26  
27  import java.io.*;
28  import java.util.*;
29  import sun.jvm.hotspot.debugger.*;
30  import sun.jvm.hotspot.oops.*;
31  import sun.jvm.hotspot.types.*;
32  import sun.jvm.hotspot.runtime.*;
33  import sun.jvm.hotspot.utilities.*;
34  
35  public class SymbolTable extends sun.jvm.hotspot.utilities.Hashtable {
36    static {
37      VM.registerVMInitializedObserver(new Observer() {
38          public void update(Observable o, Object data) {
39            initialize(VM.getVM().getTypeDataBase());
40          }
41        });
42    }
43  
44    private static synchronized void initialize(TypeDataBase db) {
45      Type type = db.lookupType("SymbolTable");
46      theTableField  = type.getAddressField("_the_table");
47    }
48  
49    // Fields
50    private static AddressField theTableField;
51  
52    // Accessors
53    public static SymbolTable getTheTable() {
54      Address tmp = theTableField.getValue();
55      return (SymbolTable) VMObjectFactory.newObject(SymbolTable.class, tmp);
56    }
57  
58    public SymbolTable(Address addr) {
59      super(addr);
60    }
61  
62    /** Clone of VM's "temporary" probe routine, as the SA currently
63        does not support mutation so lookup() would have no effect
64        anyway. Returns null if the given string is not in the symbol
65        table. */
66    public Symbol probe(String name) {
67      try {
68        return probe(toModifiedUTF8Bytes(name));
69      } catch (IOException e) {
70        return null;
71      }
72    }
73  
74    /** Clone of VM's "temporary" probe routine, as the SA currently
75        does not support mutation so lookup() would have no effect
76        anyway. Returns null if the given string is not in the symbol
77        table. */
78    public Symbol probe(byte[] name) {
79      long hashValue = hashSymbol(name);
80      for (HashtableEntry e = (HashtableEntry) bucket(hashToIndex(hashValue)); e != null; e = (HashtableEntry) e.next()) {
81        if (e.hash() == hashValue) {
82           Symbol sym = Symbol.create(e.literalValue());
83           if (sym.equals(name)) {
84             return sym;
85           }
86        }
87      }
88      return null;
89    }
90  
91    public interface SymbolVisitor {
92      public void visit(Symbol sym);
93    }
94  
95    public void symbolsDo(SymbolVisitor visitor) {
96      int numBuckets = tableSize();
97      for (int i = 0; i < numBuckets; i++) {
98        for (HashtableEntry e = (HashtableEntry) bucket(i); e != null;
99             e = (HashtableEntry) e.next()) {
100         visitor.visit(Symbol.create(e.literalValue()));
101       }
102     }
103   }
104 
105   private static byte[] toModifiedUTF8Bytes(String name) throws IOException {
106     ByteArrayOutputStream baos = new ByteArrayOutputStream();
107     DataOutputStream dos = new DataOutputStream(baos);
108     dos.writeUTF(name);
109     dos.flush();
110     byte[] buf = baos.toByteArray();
111     byte[] res = new byte[buf.length - 2];
112     // skip the length part
113     System.arraycopy(buf, 2, res, 0, res.length);
114     return res;
115   }
116 }