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 class CNetAddr;
  14
  15 /**
  16  * Median filter over a stream of values.
  17  * Returns the median of the last N numbers
  18  */
  19 template <typename T>
  20 class CMedianFilter
  21 {
  22 private:
  23     std::vector<T> vValues;
  24     std::vector<T> vSorted;
  25     unsigned int nSize;
  26
  27 public:
  28     CMedianFilter(unsigned int size, T initial_value) : nSize(size)
  29     {
  30         vValues.reserve(size);
  31         vValues.push_back(initial_value);
  32         vSorted = vValues;
  33     }
  34
  35     void input(T value)
  36     {
  37         if (vValues.size() == nSize) {
  38             vValues.erase(vValues.begin());
  39         }
  40         vValues.push_back(value);
  41
  42         vSorted.resize(vValues.size());
  43         std::copy(vValues.begin(), vValues.end(), vSorted.begin());
  44         std::sort(vSorted.begin(), vSorted.end());
  45     }
  46
  47     T median() const
  48     {
  49         int size = vSorted.size();
  50         assert(size > 0);
  51         if (size & 1) // Odd number of elements
  52         {
  53             return vSorted[size / 2];
  54         } else // Even number of elements
  55         {
  56             return (vSorted[size / 2 - 1] + vSorted[size / 2]) / 2;
  57         }
  58     }
  59
  60     int size() const
  61     {
  62         return vValues.size();
  63     }
  64
  65     std::vector<T> sorted() const
  66     {
  67         return vSorted;
  68     }
  69 };
  70
  71 /** Functions to keep track of adjusted P2P time */
  72 int64_t GetTimeOffset();
  73 int64_t GetAdjustedTime();
  74 void AddTimeData(const CNetAddr& ip, int64_t nTime);
  75
  76 #endif // BITCOIN_TIMEDATA_H