src/timedata.h

   1 // Copyright (c) 2014 The Bitcoin Core developers
   2 // Distributed under the MIT software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #ifndef BITCOIN_TIMEDATA_H
   6 #define BITCOIN_TIMEDATA_H
   7
   8 #include <algorithm>
   9 #include <assert.h>
  10 #include <stdint.h>
  11 #include <vector>
  12
  13 static const int64_t DEFAULT_MAX_TIME_ADJUSTMENT = 70 * 60;
  14
  15 class CNetAddr;
  16
  17 /**
  18  * Median filter over a stream of values.
  19  * Returns the median of the last N numbers
  20  */
  21 template <typename T>
  22 class CMedianFilter
  23 {
  24 private:
  25     std::vector<T> vValues;
  26     std::vector<T> vSorted;
  27     unsigned int nSize;
  28
  29 public:
  30     CMedianFilter(unsigned int size, T initial_value) : nSize(size)
  31     {
  32         vValues.reserve(size);
  33         vValues.push_back(initial_value);
  34         vSorted = vValues;
  35     }
  36
  37     void input(T value)
  38     {
  39         if (vValues.size() == nSize) {
  40             vValues.erase(vValues.begin());
  41         }
  42         vValues.push_back(value);
  43
  44         vSorted.resize(vValues.size());
  45         std::copy(vValues.begin(), vValues.end(), vSorted.begin());
  46         std::sort(vSorted.begin(), vSorted.end());
  47     }
  48
  49     T median() const
  50     {
  51         int size = vSorted.size();
  52         assert(size > 0);
  53         if (size & 1) // Odd number of elements
  54         {
  55             return vSorted[size / 2];
  56         } else // Even number of elements
  57         {
  58             return (vSorted[size / 2 - 1] + vSorted[size / 2]) / 2;
  59         }
  60     }
  61
  62     int size() const
  63     {
  64         return vValues.size();
  65     }
  66
  67     std::vector<T> sorted() const
  68     {
  69         return vSorted;
  70     }
  71 };
  72
  73 /** Functions to keep track of adjusted P2P time */
  74 int64_t GetTimeOffset();
  75 int64_t GetAdjustedTime();
  76 void AddTimeData(const CNetAddr& ip, int64_t nTime);
  77
  78 #endif // BITCOIN_TIMEDATA_H