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
GuessVerificationProgress(const CCheckpointData & data,CBlockIndex * pindex,bool fSigchecks)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 
GetLastCheckpoint(const CCheckpointData & data)58     CBlockIndex* GetLastCheckpoint(const CCheckpointData& data)
59     {
60         const MapCheckpoints& checkpoints = data.mapCheckpoints;
61 
62         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
63         {
64             const uint256& hash = i.second;
65             BlockMap::const_iterator t = mapBlockIndex.find(hash);
66             if (t != mapBlockIndex.end())
67                 return t->second;
68         }
69         return NULL;
70     }
71 
72 } // namespace Checkpoints
73