diff -r 000000000000 -r f90c822e73f8 src/share/vm/utilities/numberSeq.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/utilities/numberSeq.hpp	Wed Apr 27 01:25:04 2016 +0800
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2001, 2012, 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.
+ *
+ */
+
+#ifndef SHARE_VM_UTILITIES_NUMBERSEQ_HPP
+#define SHARE_VM_UTILITIES_NUMBERSEQ_HPP
+
+#include "memory/allocation.hpp"
+
+/**
+ **  This file contains a few classes that represent number sequence,
+ **  x1, x2, x3, ..., xN, and can calculate their avg, max, and sd.
+ **
+ **  Here's a quick description of the classes:
+ **
+ **    AbsSeq: abstract superclass
+ **    NumberSeq: the sequence is assumed to be very long and the
+ **      maximum, avg, sd, davg, and dsd are calculated over all its elements
+ **    TruncatedSeq: this class keeps track of the last L elements
+ **      of the sequence and calculates avg, max, and sd only over them
+ **/
+
+#define DEFAULT_ALPHA_VALUE 0.7
+
+class AbsSeq: public CHeapObj<mtInternal> {
+private:
+  void init(double alpha);
+
+protected:
+  int    _num; // the number of elements in the sequence
+  double _sum; // the sum of the elements in the sequence
+  double _sum_of_squares; // the sum of squares of the elements in the sequence
+
+  double _davg; // decaying average
+  double _dvariance; // decaying variance
+  double _alpha; // factor for the decaying average / variance
+
+  // This is what we divide with to get the average. In a standard
+  // number sequence, this should just be the number of elements in it.
+  virtual double total() const { return (double) _num; };
+
+public:
+  AbsSeq(double alpha = DEFAULT_ALPHA_VALUE);
+
+  virtual void add(double val); // adds a new element to the sequence
+  void add(unsigned val) { add((double) val); }
+  virtual double maximum() const = 0; // maximum element in the sequence
+  virtual double last() const = 0; // last element added in the sequence
+
+  // the number of elements in the sequence
+  int num() const { return _num; }
+  // the sum of the elements in the sequence
+  double sum() const { return _sum; }
+
+  double avg() const; // the average of the sequence
+  double variance() const; // the variance of the sequence
+  double sd() const; // the standard deviation of the sequence
+
+  double davg() const; // decaying average
+  double dvariance() const; // decaying variance
+  double dsd() const; // decaying "standard deviation"
+
+  // Debugging/Printing
+  virtual void dump();
+  virtual void dump_on(outputStream* s);
+};
+
+class NumberSeq: public AbsSeq {
+private:
+  bool check_nums(NumberSeq* total, int n, NumberSeq** parts);
+
+protected:
+  double _last;
+  double _maximum; // keep track of maximum value
+
+public:
+  NumberSeq(double alpha = DEFAULT_ALPHA_VALUE);
+
+  virtual void add(double val);
+  virtual double maximum() const { return _maximum; }
+  virtual double last() const { return _last; }
+
+  // Debugging/Printing
+  virtual void dump_on(outputStream* s);
+};
+
+class TruncatedSeq: public AbsSeq {
+private:
+  enum PrivateConstants {
+    DefaultSeqLength = 10
+  };
+  void init();
+protected:
+  double *_sequence; // buffers the last L elements in the sequence
+  int     _length; // this is L
+  int     _next;   // oldest slot in the array, i.e. next to be overwritten
+
+public:
+  // accepts a value for L
+  TruncatedSeq(int length = DefaultSeqLength,
+               double alpha = DEFAULT_ALPHA_VALUE);
+  ~TruncatedSeq();
+  virtual void add(double val);
+  virtual double maximum() const;
+  virtual double last() const; // the last value added to the sequence
+
+  double oldest() const; // the oldest valid value in the sequence
+  double predict_next() const; // prediction based on linear regression
+
+  // Debugging/Printing
+  virtual void dump_on(outputStream* s);
+};
+
+#endif // SHARE_VM_UTILITIES_NUMBERSEQ_HPP