checkpoints.cpp

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// Copyright (c) 2009-2012 The Bitcoin developers
// Copyright (c) 2013 Feathercoin Developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <boost/assign/list_of.hpp> // for 'map_list_of()'
#include <boost/foreach.hpp>

#include "checkpoints.h"

#include "main.h"
#include "uint256.h"

namespace Checkpoints
{
    typedef std::map<int, uint256> MapCheckpoints;

    // How many times we expect transactions after the last checkpoint to
    // be slower. This number is a compromise, as it can't be accurate for
    // every system. When reindexing from a fast disk with a slow CPU, it
    // can be up to 20, while when downloading from a slow network with a
    // fast multicore CPU, it won't be much higher than 1.
    static const double fSigcheckVerificationFactor = 5.0;

    struct CCheckpointData {
        const MapCheckpoints *mapCheckpoints;
        int64 nTimeLastCheckpoint;
        int64 nTransactionsLastCheckpoint;
        double fTransactionsPerDay;
    };

    // What makes a good checkpoint block?
    // + Is surrounded by blocks with reasonable timestamps
    //   (no blocks before with a timestamp after, none after with
    //    timestamp before)
    // + Contains no strange transactions
    static MapCheckpoints mapCheckpoints =
            boost::assign::map_list_of
            (     1, uint256("0xfdbe99b90c90bae7505796461471d89ae8388ab953997aa06a355bbda8d915cb"))
            (     22267, uint256("0x23dc7d871fc2a9b994112e978019f6370bab0b8979f557afe77a7ab620224b70"))
            (     22847, uint256("0x1450b80c150fee1e657ee8309819276342c021fab5e6a20ccf5407f5e2218d0f"))
            (     23453, uint256("0x7c25d3f9671e1d9400c9a1be2ff68e68db561ab85ae6b7020062d8d26da81e4c"))
            (     28230, uint256("0xd3feb71f92c63c682f994d7c615adc425226c669a83d46012b32fc8d518b08bb"))
            (     31846, uint256("0xba7d5c0e6d46f6448253290ce037e13975c13ca9c375ae854b6b2f85044fc0f9"))
            (     33918, uint256("0x023cf4acfd8bf0114090a7ce048e79ac28152de78bb41f1277742904494e6c49"))
                        (     34000, uint256("0x082f5d9023af3f068733ab68cf81b741f58e3c75ae28d2a9bd07f30b74c38356"))
                        (     41300, uint256("0x8c4e02f6c0d20e856fd7e952a147fee30ce145ca6932a284f354924362d2b408"))
            ;
    static const CCheckpointData data = {
        &mapCheckpoints,
        1372166807, // * UNIX timestamp of last checkpoint block
        257285,    // * total number of transactions between genesis and last checkpoint
                    //   (the tx=... number in the SetBestChain debug.log lines)
        3450.0     // * estimated number of transactions per day after checkpoint
    };

    const CCheckpointData &Checkpoints() {
        return data;
    }

    bool CheckBlock(int nHeight, const uint256& hash)
    {
        if (fTestNet) return true; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            return true;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
        if (i == checkpoints.end()) return true;
        return hash == i->second;
    }

    // Guess how far we are in the verification process at the given block index
    double GuessVerificationProgress(CBlockIndex *pindex) {
        if (pindex==NULL)
            return 0.0;

        int64 nNow = time(NULL);

        double fWorkBefore = 0.0; // Amount of work done before pindex
        double fWorkAfter = 0.0;  // Amount of work left after pindex (estimated)
        // Work is defined as: 1.0 per transaction before the last checkoint, and
        // fSigcheckVerificationFactor per transaction after.

        const CCheckpointData &data = Checkpoints();

        if (pindex->nChainTx <= data.nTransactionsLastCheckpoint) {
            double nCheapBefore = pindex->nChainTx;
            double nCheapAfter = data.nTransactionsLastCheckpoint - pindex->nChainTx;
            double nExpensiveAfter = (nNow - data.nTimeLastCheckpoint)/86400.0*data.fTransactionsPerDay;
            fWorkBefore = nCheapBefore;
            fWorkAfter = nCheapAfter + nExpensiveAfter*fSigcheckVerificationFactor;
        } else {
            double nCheapBefore = data.nTransactionsLastCheckpoint;
            double nExpensiveBefore = pindex->nChainTx - data.nTransactionsLastCheckpoint;
            double nExpensiveAfter = (nNow - pindex->nTime)/86400.0*data.fTransactionsPerDay;
            fWorkBefore = nCheapBefore + nExpensiveBefore*fSigcheckVerificationFactor;
            fWorkAfter = nExpensiveAfter*fSigcheckVerificationFactor;
        }

        return fWorkBefore / (fWorkBefore + fWorkAfter);
    }

    int GetTotalBlocksEstimate()
    {
        if (fTestNet) return 0; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            return 0;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        return checkpoints.rbegin()->first;
    }

    CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
    {
        if (fTestNet) return NULL; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            return NULL;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
        {
            const uint256& hash = i.second;
            std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
            if (t != mapBlockIndex.end())
                return t->second;
        }
        return NULL;
    }
    
    uint256 GetLatestHardenedCheckpoint()
    {
        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;
        return (checkpoints.rbegin()->second);
    }
}