diff -r 000000000000 -r f90c822e73f8 src/share/vm/utilities/numberSeq.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/utilities/numberSeq.cpp	Wed Apr 27 01:25:04 2016 +0800
@@ -0,0 +1,262 @@
+/*
+ * Copyright (c) 2001, 2014, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "memory/allocation.inline.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/numberSeq.hpp"
+
+AbsSeq::AbsSeq(double alpha) :
+  _num(0), _sum(0.0), _sum_of_squares(0.0),
+  _davg(0.0), _dvariance(0.0), _alpha(alpha) {
+}
+
+void AbsSeq::add(double val) {
+  if (_num == 0) {
+    // if the sequence is empty, the davg is the same as the value
+    _davg = val;
+    // and the variance is 0
+    _dvariance = 0.0;
+  } else {
+    // otherwise, calculate both
+    _davg = (1.0 - _alpha) * val + _alpha * _davg;
+    double diff = val - _davg;
+    _dvariance = (1.0 - _alpha) * diff * diff + _alpha * _dvariance;
+  }
+}
+
+double AbsSeq::avg() const {
+  if (_num == 0)
+    return 0.0;
+  else
+    return _sum / total();
+}
+
+double AbsSeq::variance() const {
+  if (_num <= 1)
+    return 0.0;
+
+  double x_bar = avg();
+  double result = _sum_of_squares / total() - x_bar * x_bar;
+  if (result < 0.0) {
+    // due to loss-of-precision errors, the variance might be negative
+    // by a small bit
+
+    //    guarantee(-0.1 < result && result < 0.0,
+    //        "if variance is negative, it should be very small");
+    result = 0.0;
+  }
+  return result;
+}
+
+double AbsSeq::sd() const {
+  double var = variance();
+  guarantee( var >= 0.0, "variance should not be negative" );
+  return sqrt(var);
+}
+
+double AbsSeq::davg() const {
+  return _davg;
+}
+
+double AbsSeq::dvariance() const {
+  if (_num <= 1)
+    return 0.0;
+
+  double result = _dvariance;
+  if (result < 0.0) {
+    // due to loss-of-precision errors, the variance might be negative
+    // by a small bit
+
+    guarantee(-0.1 < result && result < 0.0,
+               "if variance is negative, it should be very small");
+    result = 0.0;
+  }
+  return result;
+}
+
+double AbsSeq::dsd() const {
+  double var = dvariance();
+  guarantee( var >= 0.0, "variance should not be negative" );
+  return sqrt(var);
+}
+
+NumberSeq::NumberSeq(double alpha) :
+  AbsSeq(alpha), _maximum(0.0), _last(0.0) {
+}
+
+bool NumberSeq::check_nums(NumberSeq *total, int n, NumberSeq **parts) {
+  for (int i = 0; i < n; ++i) {
+    if (parts[i] != NULL && total->num() != parts[i]->num())
+      return false;
+  }
+  return true;
+}
+
+void NumberSeq::add(double val) {
+  AbsSeq::add(val);
+
+  _last = val;
+  if (_num == 0) {
+    _maximum = val;
+  } else {
+    if (val > _maximum)
+      _maximum = val;
+  }
+  _sum += val;
+  _sum_of_squares += val * val;
+  ++_num;
+}
+
+
+TruncatedSeq::TruncatedSeq(int length, double alpha):
+  AbsSeq(alpha), _length(length), _next(0) {
+  _sequence = NEW_C_HEAP_ARRAY(double, _length, mtInternal);
+  for (int i = 0; i < _length; ++i)
+    _sequence[i] = 0.0;
+}
+
+TruncatedSeq::~TruncatedSeq() {
+  FREE_C_HEAP_ARRAY(double, _sequence, mtGC);
+}
+
+void TruncatedSeq::add(double val) {
+  AbsSeq::add(val);
+
+  // get the oldest value in the sequence...
+  double old_val = _sequence[_next];
+  // ...remove it from the sum and sum of squares
+  _sum -= old_val;
+  _sum_of_squares -= old_val * old_val;
+
+  // ...and update them with the new value
+  _sum += val;
+  _sum_of_squares += val * val;
+
+  // now replace the old value with the new one
+  _sequence[_next] = val;
+  _next = (_next + 1) % _length;
+
+  // only increase it if the buffer is not full
+  if (_num < _length)
+    ++_num;
+
+  guarantee( variance() > -1.0, "variance should be >= 0" );
+}
+
+// can't easily keep track of this incrementally...
+double TruncatedSeq::maximum() const {
+  if (_num == 0)
+    return 0.0;
+  double ret = _sequence[0];
+  for (int i = 1; i < _num; ++i) {
+    double val = _sequence[i];
+    if (val > ret)
+      ret = val;
+  }
+  return ret;
+}
+
+double TruncatedSeq::last() const {
+  if (_num == 0)
+    return 0.0;
+  unsigned last_index = (_next + _length - 1) % _length;
+  return _sequence[last_index];
+}
+
+double TruncatedSeq::oldest() const {
+  if (_num == 0)
+    return 0.0;
+  else if (_num < _length)
+    // index 0 always oldest value until the array is full
+    return _sequence[0];
+  else {
+    // since the array is full, _next is over the oldest value
+    return _sequence[_next];
+  }
+}
+
+double TruncatedSeq::predict_next() const {
+  if (_num == 0)
+    return 0.0;
+
+  double num           = (double) _num;
+  double x_squared_sum = 0.0;
+  double x_sum         = 0.0;
+  double y_sum         = 0.0;
+  double xy_sum        = 0.0;
+  double x_avg         = 0.0;
+  double y_avg         = 0.0;
+
+  int first = (_next + _length - _num) % _length;
+  for (int i = 0; i < _num; ++i) {
+    double x = (double) i;
+    double y =  _sequence[(first + i) % _length];
+
+    x_squared_sum += x * x;
+    x_sum         += x;
+    y_sum         += y;
+    xy_sum        += x * y;
+  }
+  x_avg = x_sum / num;
+  y_avg = y_sum / num;
+
+  double Sxx = x_squared_sum - x_sum * x_sum / num;
+  double Sxy = xy_sum - x_sum * y_sum / num;
+  double b1 = Sxy / Sxx;
+  double b0 = y_avg - b1 * x_avg;
+
+  return b0 + b1 * num;
+}
+
+
+// Printing/Debugging Support
+
+void AbsSeq::dump() { dump_on(gclog_or_tty); }
+
+void AbsSeq::dump_on(outputStream* s) {
+  s->print_cr("\t _num = %d, _sum = %7.3f, _sum_of_squares = %7.3f",
+                  _num,      _sum,         _sum_of_squares);
+  s->print_cr("\t _davg = %7.3f, _dvariance = %7.3f, _alpha = %7.3f",
+                  _davg,         _dvariance,         _alpha);
+}
+
+void NumberSeq::dump_on(outputStream* s) {
+  AbsSeq::dump_on(s);
+  s->print_cr("\t\t _last = %7.3f, _maximum = %7.3f", _last, _maximum);
+}
+
+void TruncatedSeq::dump_on(outputStream* s) {
+  AbsSeq::dump_on(s);
+  s->print_cr("\t\t _length = %d, _next = %d", _length, _next);
+  for (int i = 0; i < _length; i++) {
+    if (i%5 == 0) {
+      s->cr();
+      s->print("\t");
+    }
+    s->print("\t[%d]=%7.3f", i, _sequence[i]);
+  }
+  s->cr();
+}