--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/agent/src/share/classes/sun/jvm/hotspot/utilities/CompactHashTable.java	Fri Jan 30 20:31:05 2015 -0500
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2015, 2015, 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.utilities;
+
+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 CompactHashTable 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("SymbolCompactHashTable");
+    baseAddressField = type.getAddressField("_base_address");
+    bucketCountField = type.getCIntegerField("_bucket_count");
+    tableEndOffsetField = type.getCIntegerField("_table_end_offset");
+    bucketsField = type.getAddressField("_buckets");
+    uintSize = db.lookupType("juint").getSize();
+  }
+
+  // Fields
+  private static CIntegerField bucketCountField;
+  private static CIntegerField tableEndOffsetField;
+  private static AddressField  baseAddressField;
+  private static AddressField  bucketsField;
+  private static long uintSize;
+
+  private static int BUCKET_OFFSET_MASK = 0x3FFFFFFF;
+  private static int BUCKET_TYPE_SHIFT = 30;
+  private static int COMPACT_BUCKET_TYPE = 1;
+
+  public CompactHashTable(Address addr) {
+    super(addr);
+  }
+
+  private int bucketCount() {
+    return (int)bucketCountField.getValue(addr);
+  }
+
+  private int tableEndOffset() {
+    return (int)tableEndOffsetField.getValue(addr);
+  }
+
+  private boolean isCompactBucket(int bucket_info) {
+    return (bucket_info >> BUCKET_TYPE_SHIFT) == COMPACT_BUCKET_TYPE;
+  }
+
+  private int bucketOffset(int bucket_info) {
+    return bucket_info & BUCKET_OFFSET_MASK;
+  }
+
+  public Symbol probe(byte[] name, long hash) {
+    long    symOffset;
+    Symbol  sym;
+    Address baseAddress = baseAddressField.getValue(addr);
+    Address bucket = bucketsField.getValue(addr);
+    Address bucketEnd = bucket;
+    long index = hash % bucketCount();
+    int bucketInfo = (int)bucket.getCIntegerAt(index * uintSize, uintSize, true);
+    int bucketOffset = bucketOffset(bucketInfo);
+    int nextBucketInfo = (int)bucket.getCIntegerAt((index+1) * uintSize, uintSize, true);
+    int nextBucketOffset = bucketOffset(nextBucketInfo);
+
+    bucket = bucket.addOffsetTo(bucketOffset * uintSize);
+
+    if (isCompactBucket(bucketInfo)) {
+      symOffset = bucket.getCIntegerAt(0, uintSize, true);
+      sym = Symbol.create(baseAddress.addOffsetTo(symOffset));
+      if (sym.equals(name)) {
+        return sym;
+      }
+    } else {
+      bucketEnd = bucket.addOffsetTo(nextBucketOffset * uintSize);
+      while (bucket.lessThan(bucketEnd)) {
+        long symHash = bucket.getCIntegerAt(0, uintSize, true);
+        if (symHash == hash) {
+          symOffset = bucket.getCIntegerAt(uintSize, uintSize, true);
+          Address symAddr = baseAddress.addOffsetTo(symOffset);
+          sym = Symbol.create(symAddr);
+          if (sym.equals(name)) {
+            return sym;
+          }
+        }
+        bucket = bucket.addOffsetTo(2 * uintSize);
+      }
+    }
+    return null;
+  }
+}