ceph/src/common/DecayCounter.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #include "DecayCounter.h"
  16 #include "Formatter.h"
  17
  18 #include "include/encoding.h"
  19
  20 void DecayCounter::encode(ceph::buffer::list& bl) const
  21 {
  22   decay();
  23   ENCODE_START(5, 4, bl);
  24   encode(val, bl);
  25   ENCODE_FINISH(bl);
  26 }
  27
  28 void DecayCounter::decode(ceph::buffer::list::const_iterator &p)
  29 {
  30   DECODE_START_LEGACY_COMPAT_LEN(5, 4, 4, p);
  31   if (struct_v < 2) {
  32     double k = 0.0;
  33     decode(k, p);
  34   }
  35   if (struct_v < 3) {
  36     double k = 0.0;
  37     decode(k, p);
  38   }
  39   decode(val, p);
  40   if (struct_v < 5) {
  41     double delta, _;
  42     decode(delta, p);
  43     val += delta;
  44     decode(_, p); /* velocity */
  45   }
  46   last_decay = clock::now();
  47   DECODE_FINISH(p);
  48 }
  49
  50 void DecayCounter::dump(ceph::Formatter *f) const
  51 {
  52   decay();
  53   f->dump_float("value", val);
  54   f->dump_float("halflife", rate.get_halflife());
  55 }
  56
  57 void DecayCounter::generate_test_instances(std::list<DecayCounter*>& ls)
  58 {
  59   DecayCounter *counter = new DecayCounter();
  60   counter->val = 3.0;
  61   ls.push_back(counter);
  62   counter = new DecayCounter();
  63   ls.push_back(counter);
  64 }
  65
  66 void DecayCounter::decay(double delta) const
  67 {
  68   auto now = clock::now();
  69   double el = std::chrono::duration<double>(now - last_decay).count();
  70
  71   // calculate new value
  72   double newval = val * exp(el * rate.k) + delta;
  73   if (newval < .01) {
  74     newval = 0.0;
  75   }
  76
  77   val = newval;
  78   last_decay = now;
  79 }