--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/Symbol.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2000, 2016, 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.oops;
+
+import java.io.*;
+import java.util.*;
+import sun.jvm.hotspot.debugger.*;
+import sun.jvm.hotspot.runtime.*;
+import sun.jvm.hotspot.types.*;
+import sun.jvm.hotspot.utilities.*;
+
+// A Symbol is a canonicalized string.
+// All Symbols reside in global symbolTable.
+
+public class Symbol extends VMObject {
+  static {
+    VM.registerVMInitializedObserver(new Observer() {
+        public void update(Observable o, Object data) {
+          initialize(VM.getVM().getTypeDataBase());
+        }
+      });
+  }
+
+  private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
+    Type type  = db.lookupType("Symbol");
+    length     = type.getCIntegerField("_length");
+    baseOffset = type.getField("_body").getOffset();
+    idHash = type.getCIntegerField("_identity_hash");
+  }
+
+  // Format:
+  //   [header]
+  //   [klass ]
+  //   [length] byte size of uft8 string
+  //   ..body..
+
+  public static Symbol create(Address addr) {
+    if (addr == null) {
+      return null;
+    }
+    return new Symbol(addr);
+  }
+
+  Symbol(Address addr) {
+    super(addr);
+  }
+
+  public boolean isSymbol()            { return true; }
+
+  private static long baseOffset; // tells where the array part starts
+
+  // Fields
+  private static CIntegerField length;
+
+  // Accessors for declared fields
+  public long   getLength() { return          length.getValue(this.addr); }
+
+  public byte getByteAt(long index) {
+    return addr.getJByteAt(baseOffset + index);
+  }
+  // _identity_hash is a short
+  private static CIntegerField idHash;
+
+  public int identityHash() {
+    long addr_value = getAddress().asLongValue();
+    int  addr_bits = (int)(addr_value >> (VM.getVM().getLogMinObjAlignmentInBytes() + 3));
+    int  length = (int)getLength();
+    int  byte0 = getByteAt(0);
+    int  byte1 = getByteAt(1);
+    int  id_hash = (int)(0xffff & idHash.getValue(this.addr));
+    return id_hash |
+           ((addr_bits ^ (length << 8) ^ ((byte0 << 8) | byte1)) << 16);
+  }
+
+  public boolean equals(byte[] modUTF8Chars) {
+    int l = (int) getLength();
+    if (l != modUTF8Chars.length) return false;
+    while (l-- > 0) {
+      if (modUTF8Chars[l] != getByteAt(l)) return false;
+    }
+    if (Assert.ASSERTS_ENABLED) {
+      Assert.that(l == -1, "we should be at the beginning");
+    }
+    return true;
+  }
+
+  public byte[] asByteArray() {
+    int length = (int) getLength();
+    byte [] result = new byte [length];
+    for (int index = 0; index < length; index++) {
+      result[index] = getByteAt(index);
+    }
+    return result;
+  }
+
+  public String asString() {
+    // Decode the byte array and return the string.
+    try {
+      return readModifiedUTF8(asByteArray());
+    } catch(Exception e) {
+      System.err.println(addr);
+      e.printStackTrace();
+      return null;
+    }
+  }
+
+  public boolean startsWith(String str) {
+    return asString().startsWith(str);
+  }
+
+  public void printValueOn(PrintStream tty) {
+    tty.print("#" + asString());
+  }
+
+  /** Note: this comparison is used for vtable sorting only; it
+      doesn't matter what order it defines, as long as it is a total,
+      time-invariant order Since Symbol* are in C_HEAP, their
+      relative order in memory never changes, so use address
+      comparison for speed. */
+  public long fastCompare(Symbol other) {
+    return addr.minus(other.addr);
+  }
+
+  private static String readModifiedUTF8(byte[] buf) throws IOException {
+    final int len = buf.length;
+    byte[] tmp = new byte[len + 2];
+    // write modified UTF-8 length as short in big endian
+    tmp[0] = (byte) ((len >>> 8) & 0xFF);
+    tmp[1] = (byte) ((len >>> 0) & 0xFF);
+    // copy the data
+    System.arraycopy(buf, 0, tmp, 2, len);
+    DataInputStream dis = new DataInputStream(new ByteArrayInputStream(tmp));
+    return dis.readUTF();
+  }
+}