| /* |
| * Copyright (c) 2001, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| package sun.jvm.hotspot.memory; |
| |
| import java.io.*; |
| import java.util.*; |
| import sun.jvm.hotspot.debugger.*; |
| import sun.jvm.hotspot.oops.*; |
| import sun.jvm.hotspot.types.*; |
| import sun.jvm.hotspot.runtime.*; |
| import sun.jvm.hotspot.utilities.*; |
| |
| public class SymbolTable extends sun.jvm.hotspot.utilities.Hashtable { |
| static { |
| VM.registerVMInitializedObserver(new Observer() { |
| public void update(Observable o, Object data) { |
| initialize(VM.getVM().getTypeDataBase()); |
| } |
| }); |
| } |
| |
| private static synchronized void initialize(TypeDataBase db) { |
| Type type = db.lookupType("SymbolTable"); |
| theTableField = type.getAddressField("_the_table"); |
| sharedTableField = type.getAddressField("_shared_table"); |
| type = db.lookupType("RehashableSymbolHashtable"); |
| seedField = type.getCIntegerField("_seed"); |
| } |
| |
| // Fields |
| private static AddressField theTableField; |
| private static AddressField sharedTableField; |
| private static CIntegerField seedField; |
| |
| private CompactHashTable sharedTable; |
| |
| // Accessors |
| public static SymbolTable getTheTable() { |
| Address tmp = theTableField.getValue(); |
| SymbolTable table = (SymbolTable) VMObjectFactory.newObject(SymbolTable.class, tmp); |
| Address shared = sharedTableField.getStaticFieldAddress(); |
| table.sharedTable = (CompactHashTable)VMObjectFactory.newObject(CompactHashTable.class, shared); |
| return table; |
| } |
| |
| public static long getSeed() { |
| return (long) seedField.getValue(); |
| } |
| |
| public static boolean useAlternateHashcode() { |
| if (getSeed() != 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| public SymbolTable(Address addr) { |
| super(addr); |
| } |
| |
| /** Clone of VM's "temporary" probe routine, as the SA currently |
| does not support mutation so lookup() would have no effect |
| anyway. Returns null if the given string is not in the symbol |
| table. */ |
| public Symbol probe(String name) { |
| try { |
| return probe(toModifiedUTF8Bytes(name)); |
| } catch (IOException e) { |
| return null; |
| } |
| } |
| |
| /** Clone of VM's "temporary" probe routine, as the SA currently |
| does not support mutation so lookup() would have no effect |
| anyway. Searches the regular symbol table and the shared symbol |
| table. Null is returned if the given name is not found in both |
| tables. */ |
| public Symbol probe(byte[] name) { |
| long hashValue = hashSymbol(name); |
| |
| // shared table does not use alternate hashing algorithm, |
| // it always uses the same original hash code. |
| Symbol s = sharedTable.probe(name, hashValue); |
| if (s != null) { |
| return s; |
| } |
| |
| if (useAlternateHashcode()) { |
| hashValue = AltHashing.murmur3_32(getSeed(), name); |
| } |
| |
| for (HashtableEntry e = (HashtableEntry) bucket(hashToIndex(hashValue)); e != null; e = (HashtableEntry) e.next()) { |
| if (e.hash() == hashValue) { |
| Symbol sym = Symbol.create(e.literalValue()); |
| if (sym.equals(name)) { |
| return sym; |
| } |
| } |
| } |
| |
| return null; |
| } |
| |
| public interface SymbolVisitor { |
| public void visit(Symbol sym); |
| } |
| |
| public void symbolsDo(SymbolVisitor visitor) { |
| int numBuckets = tableSize(); |
| for (int i = 0; i < numBuckets; i++) { |
| for (HashtableEntry e = (HashtableEntry) bucket(i); e != null; |
| e = (HashtableEntry) e.next()) { |
| visitor.visit(Symbol.create(e.literalValue())); |
| } |
| } |
| } |
| |
| private static byte[] toModifiedUTF8Bytes(String name) throws IOException { |
| ByteArrayOutputStream baos = new ByteArrayOutputStream(); |
| DataOutputStream dos = new DataOutputStream(baos); |
| dos.writeUTF(name); |
| dos.flush(); |
| byte[] buf = baos.toByteArray(); |
| byte[] res = new byte[buf.length - 2]; |
| // skip the length part |
| System.arraycopy(buf, 2, res, 0, res.length); |
| return res; |
| } |
| } |