src/checkpoints.cpp

   1 // Copyright (c) 2009-2015 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 #include "checkpoints.h"
   6
   7 #include "chain.h"
   8 #include "chainparams.h"
   9 #include "main.h"
  10 #include "uint256.h"
  11
  12 #include <stdint.h>
  13
  14 #include <boost/foreach.hpp>
  15
  16 namespace Checkpoints {
  17
  18     /**
  19      * How many times slower we expect checking transactions after the last
  20      * checkpoint to be (from checking signatures, which is skipped up to the
  21      * last checkpoint). This number is a compromise, as it can't be accurate
  22      * for every system. When reindexing from a fast disk with a slow CPU, it
  23      * can be up to 20, while when downloading from a slow network with a
  24      * fast multicore CPU, it won't be much higher than 1.
  25      */
  26     static const double SIGCHECK_VERIFICATION_FACTOR = 5.0;
  27
  28     //! Guess how far we are in the verification process at the given block index
  29     double GuessVerificationProgress(const CCheckpointData& data, CBlockIndex *pindex, bool fSigchecks) {
  30         if (pindex==NULL)
  31             return 0.0;
  32
  33         int64_t nNow = time(NULL);
  34
  35         double fSigcheckVerificationFactor = fSigchecks ? SIGCHECK_VERIFICATION_FACTOR : 1.0;
  36         double fWorkBefore = 0.0; // Amount of work done before pindex
  37         double fWorkAfter = 0.0;  // Amount of work left after pindex (estimated)
  38         // Work is defined as: 1.0 per transaction before the last checkpoint, and
  39         // fSigcheckVerificationFactor per transaction after.
  40
  41         if (pindex->nChainTx <= data.nTransactionsLastCheckpoint) {
  42             double nCheapBefore = pindex->nChainTx;
  43             double nCheapAfter = data.nTransactionsLastCheckpoint - pindex->nChainTx;
  44             double nExpensiveAfter = (nNow - data.nTimeLastCheckpoint)/86400.0*data.fTransactionsPerDay;
  45             fWorkBefore = nCheapBefore;
  46             fWorkAfter = nCheapAfter + nExpensiveAfter*fSigcheckVerificationFactor;
  47         } else {
  48             double nCheapBefore = data.nTransactionsLastCheckpoint;
  49             double nExpensiveBefore = pindex->nChainTx - data.nTransactionsLastCheckpoint;
  50             double nExpensiveAfter = (nNow - pindex->GetBlockTime())/86400.0*data.fTransactionsPerDay;
  51             fWorkBefore = nCheapBefore + nExpensiveBefore*fSigcheckVerificationFactor;
  52             fWorkAfter = nExpensiveAfter*fSigcheckVerificationFactor;
  53         }
  54
  55         return fWorkBefore / (fWorkBefore + fWorkAfter);
  56     }
  57
  58     int GetTotalBlocksEstimate(const CCheckpointData& data)
  59     {
  60         const MapCheckpoints& checkpoints = data.mapCheckpoints;
  61
  62         if (checkpoints.empty())
  63             return 0;
  64
  65         return checkpoints.rbegin()->first;
  66     }
  67
  68     CBlockIndex* GetLastCheckpoint(const CCheckpointData& data)
  69     {
  70         const MapCheckpoints& checkpoints = data.mapCheckpoints;
  71
  72         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
  73         {
  74             const uint256& hash = i.second;
  75             BlockMap::const_iterator t = mapBlockIndex.find(hash);
  76             if (t != mapBlockIndex.end())
  77                 return t->second;
  78         }
  79         return NULL;
  80     }
  81
  82 } // namespace Checkpoints