jdk8-mips64-public/hotspot: src/share/vm/utilities/numberSeq.hpp@c96030fff130 (annotated)

src/share/vm/utilities/numberSeq.hpp@c96030fff130 (annotated)

src/share/vm/utilities/numberSeq.hpp

Thu, 20 Nov 2008 16:56:09 -0800

author: ysr
date: Thu, 20 Nov 2008 16:56:09 -0800
changeset 888: c96030fff130
parent 777: 37f87013dfd8
child 1521: 89f1b9ae8991
permissions: -rw-r--r--

6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

 /*
  * Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 /**
  **  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 {
 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"
 };
 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);
   NumberSeq(NumberSeq* total, int n_parts, NumberSeq** parts);
   virtual void add(double val);
   virtual double maximum() const { return _maximum; }
   virtual double last() const { return _last; }
 };
 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);
   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
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/numberSeq.hpp@c96030fff130 (annotated)

src/share/vm/utilities/numberSeq.hpp