miner.cpp

#include "miner.h"
#include "hashblock.h"
#include "init.h"
#include "main.h"
#include "util.h"
#include "wallet.h"

#include <cstring>
#include <openssl/sha.h>

int static FormatHashBlocks(void* pbuffer, unsigned int len)
{
    unsigned char* pdata = (unsigned char*)pbuffer;
    unsigned int blocks = 1 + ((len + 8) / 64);
    unsigned char* pend = pdata + 64 * blocks;
    std::memset(pdata + len, 0, 64 * blocks - len);
    pdata[len] = 0x80;
    unsigned int bits = len * 8;
    pend[-1] = (bits >> 0) & 0xff;
    pend[-2] = (bits >> 8) & 0xff;
    pend[-3] = (bits >> 16) & 0xff;
    pend[-4] = (bits >> 24) & 0xff;
    return blocks;
}

static const unsigned int pSHA256InitState[8] =
        {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};

void SHA256Transform(void* pstate, void* pinput, const void* pinit)
{
    SHA256_CTX ctx;
    unsigned char data[64];

    SHA256_Init(&ctx);

    for (int i = 0; i < 16; i++)
        ((uint32_t*)data)[i] = ByteReverse(((uint32_t*)pinput)[i]);

    for (int i = 0; i < 8; i++)
        ctx.h[i] = ((uint32_t*)pinit)[i];

    SHA256_Update(&ctx, data, sizeof(data));
    for (int i = 0; i < 8; i++)
        ((uint32_t*)pstate)[i] = ctx.h[i];
}


uint64 nLastBlockTx = 0;
uint64 nLastBlockSize = 0;
int64 nLastCoinStakeSearchInterval = 0;

// We want to sort transactions by priority and fee, so:
typedef boost::tuple<double, double, CTransaction*> TxPriority;
class TxPriorityCompare
{
    bool byFee;
public:
    TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
    bool operator()(const TxPriority& a, const TxPriority& b)
    {
        if (byFee)
        {
            if (a.get<1>() == b.get<1>())
                return a.get<0>() < b.get<0>();
            return a.get<1>() < b.get<1>();
        }
        else
        {
            if (a.get<0>() == b.get<0>())
                return a.get<1>() < b.get<1>();
            return a.get<0>() < b.get<0>();
        }
    }
};

// Some explaining would be appreciated
class COrphan
{
public:
    CTransaction* ptx;
    std::set<uint256> setDependsOn;
    double dPriority;
    double dFeePerKb;

    COrphan(CTransaction* ptxIn)
    {
        ptx = ptxIn;
        dPriority = dFeePerKb = 0;
    }

    void print() const
    {
        printf("COrphan(hash=%s, dPriority=%.1f, dFeePerKb=%.1f)\n",
               ptx->GetHash().ToString().substr(0,10).c_str(), dPriority, dFeePerKb);
        BOOST_FOREACH(uint256 hash, setDependsOn)
                        printf("   setDependsOn %s\n", hash.ToString().substr(0,10).c_str());
    }
};

// CreateNewBlock:
//   fProofOfStake: try (best effort) to make a proof-of-stake block
CBlock* CreateNewBlock(CWallet* pwallet, bool fProofOfStake)
{
    CReserveKey reservekey(pwallet);

    // Create new block
    std::unique_ptr<CBlock> pblock(new CBlock());
    if (!pblock.get())
        return NULL;

    // Only use the first 4 bits for the version encoding
    pblock->nVersion = CBlock::VOTING_VERSION;

    //Check to see if proposals need to be voted on
    if (mapProposals.size() > 0) {
        std::vector<CVoteObject> votes;

        // Get all the vote objects versions
        std::map<uint256, VoteLocation> mapActiveProposals = proposalManager.GetActive(nBestHeight);
        if (pwalletMain->mapVoteObjects.size() > 0) {
            for (auto it: mapProposals) {
                CTransaction tx;
                uint256 hashBlock;
                if (!GetTransaction(it.first, tx, hashBlock)) {
                    printf("*** failed to get transaction %s!\n", it.first.GetHex().c_str());
                    continue;
                }

                if (!tx.IsProposal()) {
                    printf("*** tx is not a proposal!\n");
                    continue;
                }

                CVoteProposal proposal;
                if (!ProposalFromTransaction(tx, proposal)) {
                    printf("*** failed to deserialize!\n");
                    continue;
                }

                if (!mapActiveProposals.count(proposal.GetHash())) {
                    continue;
                }

                if (pwalletMain->mapVoteObjects.count(proposal.GetHash()) == 0) {
                    //printf("*** mapVoteObjects does not have proposal hash\n");
                    continue;
                }

                CVoteObject voteObject = pwalletMain->mapVoteObjects[proposal.GetHash()];
                votes.emplace_back(voteObject);
                //printf("*** added vote for %s\n", proposal.GetName().c_str());
            }
        }

        // Update the block version to have all votes
        pblock->nVersion |= CVoteObject::GetCombinedVotes(votes);
    }

    // Create coinbase tx
    CTransaction txNew;
    txNew.vin.resize(1);
    txNew.vin[0].prevout.SetNull();
    txNew.vout.resize(1);
    txNew.vout[0].scriptPubKey << reservekey.GetReservedKey() << OP_CHECKSIG;

    // Add our coinbase tx as first transaction
    pblock->vtx.push_back(txNew);

    // Largest block you're willing to create:
    unsigned int nBlockMaxSize = GetArg("-blockmaxsize", MAX_BLOCK_SIZE_GEN/2);
    // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
    nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SIZE-1000), nBlockMaxSize));

    // How much of the block should be dedicated to high-priority transactions,
    // included regardless of the fees they pay
    unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", 27000);
    nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);

    // Minimum block size you want to create; block will be filled with free transactions
    // until there are no more or the block reaches this size:
    unsigned int nBlockMinSize = GetArg("-blockminsize", 0);
    nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);

    // Fee-per-kilobyte amount considered the same as "free"
    // Be careful setting this: if you set it to zero then
    // a transaction spammer can cheaply fill blocks using
    // 1-satoshi-fee transactions. It should be set above the real
    // cost to you of processing a transaction.
    int64 nMinTxFee = MIN_TX_FEE;
    if (mapArgs.count("-mintxfee"))
        ParseMoney(mapArgs["-mintxfee"], nMinTxFee);

    // ppcoin: if coinstake available add coinstake tx
    static int64 nLastCoinStakeSearchTime = GetAdjustedTime();  // only initialized at startup
    CBlockIndex* pindexPrev = pindexBest;

    if (fProofOfStake && !pwalletMain->fDisableStake)  // attempt to find a coinstake && make sure settings allow PoS (presstab HyperStake)
    {
        pblock->nBits = GetNextTargetRequired(pindexPrev, true);
        CTransaction txCoinStake;
        int64 nSearchTime = txCoinStake.nTime; // search to current time
        if (nSearchTime > nLastCoinStakeSearchTime)
        {
            // printf(">>> OK1\n");
            if (pwallet->CreateCoinStake(*pwallet, pblock->nBits, nSearchTime-nLastCoinStakeSearchTime, txCoinStake))
            {
                if (txCoinStake.nTime >= std::max(pindexPrev->GetMedianTimePast()+1, pindexPrev->GetBlockTime() - GetClockDrift(pindexPrev->GetBlockTime())))
                {   // make sure coinstake would meet timestamp protocol
                    // as it would be the same as the block timestamp
                    pblock->vtx[0].vout[0].SetEmpty();
                    pblock->vtx[0].nTime = txCoinStake.nTime;
                    pblock->vtx.push_back(txCoinStake);
                }
            }
            nLastCoinStakeSearchInterval = nSearchTime - nLastCoinStakeSearchTime;
            nLastCoinStakeSearchTime = nSearchTime;
        }
    }

    pblock->nBits = GetNextTargetRequired(pindexPrev, pblock->IsProofOfStake());

    // Collect memory pool transactions into the block
    int64 nFees = 0;
    {
        LOCK2(cs_main, mempool.cs);
        CBlockIndex* pindexPrev = pindexBest;
        CTxDB txdb("r");

        // Priority order to process transactions
        std::list<COrphan> vOrphan; // list memory doesn't move
        std::map<uint256, std::vector<COrphan*> > mapDependers;

        // This vector will be sorted into a priority queue:
        std::vector<TxPriority> vecPriority;
        vecPriority.reserve(mempool.mapTx.size());
        for (auto mi = mempool.mapTx.begin(); mi != mempool.mapTx.end(); ++mi)
        {
            CTransaction& tx = (*mi).second;
            if (tx.IsCoinBase() || tx.IsCoinStake() || !tx.IsFinal())
                continue;

            COrphan* porphan = NULL;
            double dPriority = 0;
            int64 nTotalIn = 0;
            bool fMissingInputs = false;
            BOOST_FOREACH(const CTxIn& txin, tx.vin)
            {
                // Read prev transaction
                CTransaction txPrev;
                CTxIndex txindex;
                if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
                {
                    // This should never happen; all transactions in the memory
                    // pool should connect to either transactions in the chain
                    // or other transactions in the memory pool.
                    if (!mempool.mapTx.count(txin.prevout.hash))
                    {
                        printf("ERROR: mempool transaction missing input\n");
                        if (fDebug) assert("mempool transaction missing input" == 0);
                        fMissingInputs = true;
                        if (porphan)
                            vOrphan.pop_back();
                        break;
                    }

                    // Has to wait for dependencies
                    if (!porphan)
                    {
                        // Use list for automatic deletion
                        vOrphan.push_back(COrphan(&tx));
                        porphan = &vOrphan.back();
                    }
                    mapDependers[txin.prevout.hash].push_back(porphan);
                    porphan->setDependsOn.insert(txin.prevout.hash);
                    nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
                    continue;
                }
                int64 nValueIn = txPrev.vout[txin.prevout.n].nValue;
                nTotalIn += nValueIn;

                int nConf = txindex.GetDepthInMainChain();
                dPriority += (double)nValueIn * nConf;
            }
            if (fMissingInputs) continue;

            // Priority is sum(valuein * age) / txsize
            unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
            dPriority /= nTxSize;

            // This is a more accurate fee-per-kilobyte than is used by the client code, because the
            // client code rounds up the size to the nearest 1K. That's good, because it gives an
            // incentive to create smaller transactions.
            double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);

            if (porphan)
            {
                porphan->dPriority = dPriority;
                porphan->dFeePerKb = dFeePerKb;
            }
            else
                vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &(*mi).second));
        }

        // Collect transactions into block
        std::map<uint256, CTxIndex> mapTestPool;
        uint64 nBlockSize = 1000;
        uint64 nBlockTx = 0;
        int nBlockSigOps = 100;
        bool fSortedByFee = (nBlockPrioritySize <= 0);

        TxPriorityCompare comparer(fSortedByFee);
        std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);

        while (!vecPriority.empty())
        {
            // Take highest priority transaction off the priority queue:
            double dPriority = vecPriority.front().get<0>();
            double dFeePerKb = vecPriority.front().get<1>();
            CTransaction& tx = *(vecPriority.front().get<2>());

            std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
            vecPriority.pop_back();

            // Size limits
            unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
            if (nBlockSize + nTxSize >= nBlockMaxSize)
                continue;

            // Legacy limits on sigOps:
            unsigned int nTxSigOps = tx.GetLegacySigOpCount();
            if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                continue;

            // Timestamp limit
            if (tx.nTime > GetAdjustedTime() || (pblock->IsProofOfStake() && tx.nTime > pblock->vtx[1].nTime))
                continue;

            // ppcoin: simplify transaction fee - allow free = false
            int64 nMinFee = tx.GetMinFee(nBlockSize, false, GMF_BLOCK);

            // Skip free transactions if we're past the minimum block size:
            if (fSortedByFee && (dFeePerKb < nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
                continue;

            // Prioritize by fee once past the priority size or we run out of high-priority
            // transactions:
            if (!fSortedByFee &&
                ((nBlockSize + nTxSize >= nBlockPrioritySize) || (dPriority < COIN * 144 / 250)))
            {
                fSortedByFee = true;
                comparer = TxPriorityCompare(fSortedByFee);
                std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
            }

            // Connecting shouldn't fail due to dependency on other memory pool transactions
            // because we're already processing them in order of dependency
            std::map<uint256, CTxIndex> mapTestPoolTmp(mapTestPool);
            MapPrevTx mapInputs;
            bool fInvalid;
            if (!tx.FetchInputs(txdb, mapTestPoolTmp, false, true, mapInputs, fInvalid))
                continue;

            int64 nTxFees = tx.GetValueIn(mapInputs)-tx.GetValueOut();
            if (nTxFees < nMinFee)
                continue;

            nTxSigOps += tx.GetP2SHSigOpCount(mapInputs);
            if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                continue;

            if (!tx.ConnectInputs(txdb, mapInputs, mapTestPoolTmp, CDiskTxPos(1,1,1), pindexPrev, false, true))
                continue;
            mapTestPoolTmp[tx.GetHash()] = CTxIndex(CDiskTxPos(1,1,1), tx.vout.size());
            swap(mapTestPool, mapTestPoolTmp);

            // Added
            pblock->vtx.push_back(tx);
            nBlockSize += nTxSize;
            ++nBlockTx;
            nBlockSigOps += nTxSigOps;
            nFees += nTxFees;

            if (fDebug && GetBoolArg("-printpriority"))
            {
                printf("priority %.1f feeperkb %.1f txid %s\n",
                       dPriority, dFeePerKb, tx.GetHash().ToString().c_str());
            }

            // Add transactions that depend on this one to the priority queue
            uint256 hash = tx.GetHash();
            if (mapDependers.count(hash))
            {
                BOOST_FOREACH(COrphan* porphan, mapDependers[hash])
                {
                    if (!porphan->setDependsOn.empty())
                    {
                        porphan->setDependsOn.erase(hash);
                        if (porphan->setDependsOn.empty())
                        {
                            vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
                            std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
                        }
                    }
                }
            }
        }

        // TODO: ADD BLOCK HEIGHT FOR VOTING HARD FORK
        // TODO: MIGHT NEED TO CHECK BLOCK SIZE CONSTRAINTS
        // TODO: PUT THIS IN ANOTHER METHOD TO IMPROVE MODULARIZATION AND CODE REUSE
        if(pindexPrev->nHeight >= VOTING_START) {
            std::vector<CTransaction> vProposalTransactions;
            for(CTransaction tx: pblock->vtx) {
                if(tx.IsProposal()) {
                    vProposalTransactions.emplace_back(tx);
                }
            }

            std::vector <CTransaction> vOrderedProposalTransactions;
            proposalManager.GetDeterministicOrdering(pindexPrev->hashProofOfStake, vProposalTransactions,
                                                     vOrderedProposalTransactions);
            for (CTransaction txProposal: vOrderedProposalTransactions) {
                // output variables
                int nRequiredFee;
                CVoteProposal proposal;
                VoteLocation location;
                CTransaction txCoinBase = pblock->vtx[0];

                // Skip this txProposal if a proposal object cannot be extracted from it
                if (!ProposalFromTransaction(txProposal, proposal)) {
                    continue;
                }

                // input variables
                int nTxFee = CVoteProposal::BASE_FEE; //TODO: DETERMINE THE BEST VALUE FROM TRIALS
                int nBitCount = proposal.GetBitCount();
                int nStartHeight = proposal.GetStartHeight();
                int nCheckSpan = proposal.GetCheckSpan();

                // If a valid voting location cannot be found then create an unaccepted proposal refund
                if (!proposalManager.GetNextLocation(nBitCount, nStartHeight, nCheckSpan, location)) {
                    proposalManager.AddRefundToCoinBase(proposal, nRequiredFee, nTxFee, false, txCoinBase);
                } else {
                    // If a fee cannot be calculated then skip this proposal without creating a refund tx
                    proposal.SetLocation(location);
                    if (!proposalManager.GetFee(proposal, nRequiredFee)) continue;

                    // If the maximum fee provided by the proposal creator is less than the required fee
                    // then create an unaccepted proposal refund
                    if (nRequiredFee > proposal.GetMaxFee()) {
                        proposalManager.AddRefundToCoinBase(proposal, nRequiredFee, nTxFee, false, txCoinBase);
                    } else {
                        proposalManager.AddRefundToCoinBase(proposal, nRequiredFee, nTxFee, true, txCoinBase);
                    }
                }
            }
        }

        nLastBlockTx = nBlockTx;
        nLastBlockSize = nBlockSize;

        if (fDebug && GetBoolArg("-printpriority"))
            printf("CreateNewBlock(): total size %llu\n", nBlockSize);

        if (pblock->IsProofOfWork())
            pblock->vtx[0].vout[0].nValue = GetProofOfWorkReward(pindexPrev->nHeight+1, nFees, pindexPrev->GetBlockHash());

        // Fill in header
        pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
        if (pblock->IsProofOfStake())
            pblock->nTime      = pblock->vtx[1].nTime; //same as coinstake timestamp
        pblock->nTime          = std::max(pindexPrev->GetMedianTimePast()+1, pblock->GetMaxTransactionTime());
        pblock->nTime          = std::max(pblock->GetBlockTime(), pindexPrev->GetBlockTime() - GetClockDrift(pindexPrev->GetBlockTime()));
        if (pblock->IsProofOfWork())
            pblock->UpdateTime(pindexPrev);
        pblock->nNonce         = 0;
    }

    return pblock.release();
}


void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
{
    // Update nExtraNonce
    static uint256 hashPrevBlock;
    if (hashPrevBlock != pblock->hashPrevBlock)
    {
        nExtraNonce = 0;
        hashPrevBlock = pblock->hashPrevBlock;
    }
    ++nExtraNonce;
    unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
    pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
    assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);

    pblock->hashMerkleRoot = pblock->BuildMerkleTree();
}


void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1)
{
    //
    // Pre-build hash buffers
    //
    struct
    {
        struct unnamed2
        {
            int nVersion;
            uint256 hashPrevBlock;
            uint256 hashMerkleRoot;
            unsigned int nTime;
            unsigned int nBits;
            unsigned int nNonce;
        }
                block;
        unsigned char pchPadding0[64];
        uint256 hash1;
        unsigned char pchPadding1[64];
    }
            tmp;
    memset(&tmp, 0, sizeof(tmp));

    tmp.block.nVersion       = pblock->nVersion;
    tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
    tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
    tmp.block.nTime          = pblock->nTime;
    tmp.block.nBits          = pblock->nBits;
    tmp.block.nNonce         = pblock->nNonce;

    FormatHashBlocks(&tmp.block, sizeof(tmp.block));
    FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));

    // Byte swap all the input buffer
    for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
        ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);

    // Precalc the first half of the first hash, which stays constant
    SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);

    memcpy(pdata, &tmp.block, 128);
    memcpy(phash1, &tmp.hash1, 64);
}


bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
{
    uint256 hash = pblock->GetHash();
    uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();

    if (hash > hashTarget && pblock->IsProofOfWork())
        return error("BitcoinMiner : proof-of-work not meeting target");

    //// debug print
    printf("BitcoinMiner:\n");
    printf("new block found  \n  hash: %s  \ntarget: %s\n", hash.GetHex().c_str(), hashTarget.GetHex().c_str());
    pblock->print();
    printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());

    // Found a solution
    {
        LOCK(cs_main);
        if (pblock->hashPrevBlock != hashBestChain)
            return error("BitcoinMiner : generated block is stale");

        // Remove key from key pool
        reservekey.KeepKey();

        // Track how many getdata requests this block gets
        {
            LOCK(wallet.cs_wallet);
            wallet.mapRequestCount[pblock->GetHash()] = 0;
        }

        // Process this block the same as if we had received it from another node
        if (!ProcessBlock(NULL, pblock))
            return error("BitcoinMiner : ProcessBlock, block not accepted");
    }

    return true;
}

bool fGenerateBitcoins = false;
static bool fLimitProcessors = false;
static int nLimitProcessors = -1;

bool fMintableCoins = false;
int nMintableLastCheck = 0;

void BitcoinMiner(CWallet *pwallet, bool fProofOfStake)
{
    printf("CPUMiner started for proof-of-%s\n", fProofOfStake? "stake" : "work");
    SetThreadPriority(THREAD_PRIORITY_LOWEST);

    // If we are minting, then make sure fGenerateBitcoins knows that
    if(fProofOfStake)
        fGenerateBitcoins = true;

    // Make this thread recognisable as the mining thread
    RenameThread("bitcoin-miner");

    // Each thread has its own key and counter
    CReserveKey reservekey(pwallet);
    unsigned int nExtraNonce = 0;

    while (fGenerateBitcoins || fProofOfStake)
    {
        if (fShutdown)
            return;

        fWalletStaking = false;

        while (vNodes.empty() || IsInitialBlockDownload() || pwallet->IsLocked()  ||  !fMintableCoins)
        {
            nLastCoinStakeSearchInterval = 0;
            Sleep(1000);
            if (fShutdown)
                return;

            //control the amount of times the client will check for mintable coins
            if (GetTime() - nMintableLastCheck > 60) //check for mintable coins every 60 seconds
            {
                nMintableLastCheck = GetTime();
                fMintableCoins = pwallet->MintableCoins();
            }

            if (!fGenerateBitcoins && !fProofOfStake)
                return;
        }

        if(mapHashedBlocks.count(nBestHeight)) //search our map of hashed blocks, see if bestblock has been hashed yet
        {
            fWalletStaking = true;
            if(GetTime() - mapHashedBlocks[nBestHeight] < std::max(pwallet->nHashInterval, (unsigned int)1)) // wait a 'hash interval' until trying to hash again
            {
                Sleep(1000); // 2.5 second sleep for this thread
                continue;
            }
        }

        //
        // Create new block
        //
        unsigned int nTransactionsUpdatedLast = nTransactionsUpdated;
        CBlockIndex* pindexPrev = pindexBest;

        std::unique_ptr<CBlock> pblock(CreateNewBlock(pwallet, fProofOfStake));
        if (!pblock.get())
            return;
        IncrementExtraNonce(pblock.get(), pindexPrev, nExtraNonce);

        if (fProofOfStake)
        {
            // ppcoin: if proof-of-stake block found then process block
            if (pblock->IsProofOfStake())
            {
                printf("CPUMiner : proof-of-stake block found %s\n", pblock->GetHash().ToString().c_str());

                if (!pblock->SignBlock(*pwalletMain))
                {
                    continue;
                }

                printf("CPUMiner : proof-of-stake block was signed %s\n", pblock->GetHash().ToString().c_str());
                SetThreadPriority(THREAD_PRIORITY_NORMAL);
                CheckWork(pblock.get(), *pwalletMain, reservekey);
                SetThreadPriority(THREAD_PRIORITY_LOWEST);
            }
            continue;
        }

        printf("Running BitcoinMiner with %lu transactions in block (%u bytes)\n", pblock->vtx.size(),
               ::GetSerializeSize(*pblock, SER_NETWORK, PROTOCOL_VERSION));

        //
        // Pre-build hash buffers
        //
        char pmidstatebuf[32+16]; char* pmidstate = alignup<16>(pmidstatebuf);
        char pdatabuf[128+16];    char* pdata     = alignup<16>(pdatabuf);
        char phash1buf[64+16];    char* phash1    = alignup<16>(phash1buf);

        FormatHashBuffers(pblock.get(), pmidstate, pdata, phash1);

        unsigned int& nBlockTime = *(unsigned int*)(pdata + 64 + 4);
        unsigned int& nBlockBits = *(unsigned int*)(pdata + 64 + 8);

        //
        // Search
        //
        int64 nStart = GetTime();
        uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();

        while (true)
        {
            unsigned int nHashesDone = 0;

            uint256 thash;
            while (true)
            {
                thash = pblock->GetHash();
                if (thash <= hashTarget)
                {

                    if (!pblock->SignBlock(*pwalletMain))
                    {
                        break;
                    }

                    SetThreadPriority(THREAD_PRIORITY_NORMAL);
                    CheckWork(pblock.get(), *pwallet, reservekey);
                    SetThreadPriority(THREAD_PRIORITY_LOWEST);
                    break;
                }
                pblock->nNonce += 1;
                nHashesDone += 1;
                if ((pblock->nNonce & 0xFF) == 0)
                    break;
            }

            // Meter hashes/sec
            static int64 nHashCounter;
            if (nHPSTimerStart == 0)
            {
                nHPSTimerStart = GetTimeMillis();
                nHashCounter = 0;
            }
            else
                nHashCounter += nHashesDone;
            if (GetTimeMillis() - nHPSTimerStart > 4000)
            {
                static CCriticalSection cs;
                {
                    LOCK(cs);
                    if (GetTimeMillis() - nHPSTimerStart > 4000)
                    {
                        dHashesPerSec = 1000.0 * nHashCounter / (GetTimeMillis() - nHPSTimerStart);
                        nHPSTimerStart = GetTimeMillis();
                        nHashCounter = 0;
                        static int64 nLogTime;
                        if (GetTime() - nLogTime > 30 * 60)
                        {
                            nLogTime = GetTime();
                            printf("hashmeter %6.0f khash/s\n", dHashesPerSec/1000.0);
                        }
                    }
                }
            }

            // Check for stop or if block needs to be rebuilt
            boost::this_thread::interruption_point();
            if (vNodes.empty())
                break;
            if (pblock->nNonce >= 0xffff0000)
                break;
            if (nTransactionsUpdated != nTransactionsUpdatedLast && GetTime() - nStart > 60)
                break;
            if (pindexPrev != pindexBest)
                break;

            // Update nTime every few seconds
            pblock->UpdateTime(pindexPrev);
            nBlockTime = ByteReverse(pblock->nTime);
            if (fTestNet)
            {
                // Changing pblock->nTime can change work required on testnet:
                nBlockBits = ByteReverse(pblock->nBits);
                hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
            }
        }
    }
}


void ThreadBitcoinMiner(void* parg)
{
    CWallet* pwallet = (CWallet*)parg;
    try
    {
        vnThreadsRunning[THREAD_MINER]++;
        BitcoinMiner(pwallet, false);
        vnThreadsRunning[THREAD_MINER]--;
    }
    catch (std::exception& e) {
        vnThreadsRunning[THREAD_MINER]--;
        PrintException(&e, "ThreadBitcoinMiner()");
    } catch (...) {
        vnThreadsRunning[THREAD_MINER]--;
        PrintException(NULL, "ThreadBitcoinMiner()");
    }
    nHPSTimerStart = 0;
    if (vnThreadsRunning[THREAD_MINER] == 0)
        dHashesPerSec = 0;
    printf("ThreadBitcoinMiner exiting, %d threads remaining\n", vnThreadsRunning[THREAD_MINER]);
}


void GenerateBitcoins(bool fGenerate, CWallet* pwallet)
{
    fGenerateBitcoins = fGenerate;
    nLimitProcessors = GetArg("-genproclimit", -1);
    if (nLimitProcessors == 0)
        fGenerateBitcoins = false;
    fLimitProcessors = (nLimitProcessors != -1);

    if (fGenerate)
    {
        int nProcessors = boost::thread::hardware_concurrency();
        printf("%d processors\n", nProcessors);
        if (nProcessors < 1)
            nProcessors = 1;
        if (fLimitProcessors && nProcessors > nLimitProcessors)
            nProcessors = nLimitProcessors;
        int nAddThreads = nProcessors - vnThreadsRunning[THREAD_MINER];
        printf("Starting %d BitcoinMiner threads\n", nAddThreads);
        for (int i = 0; i < nAddThreads; i++)
        {
            if (!NewThread(ThreadBitcoinMiner, pwallet))
                printf("Error: NewThread(ThreadBitcoinMiner) failed\n");
            Sleep(10);
        }
    }
}