src/miner.cpp

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2012 The Bitcoin developers
   3 // Copyright (c) 2013 The NovaCoin developers
   4 // Distributed under the MIT/X11 software license, see the accompanying
   5 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   6
   7 #include "txdb-leveldb.h"
   8 #include "miner.h"
   9 #include "kernel.h"
  10 #include "kernel_worker.h"
  11 #include "wallet.h"
  12
  13
  14 //////////////////////////////////////////////////////////////////////////////
  15 //
  16 // BitcoinMiner
  17 //
  18
  19 int64_t nReserveBalance = 0;
  20 static unsigned int nMaxStakeSearchInterval = 60;
  21 uint64_t nStakeInputsMapSize = 0;
  22
  23 int static FormatHashBlocks(void* pbuffer, unsigned int len)
  24 {
  25     unsigned char* pdata = (unsigned char*)pbuffer;
  26     unsigned int blocks = 1 + ((len + 8) / 64);
  27     unsigned char* pend = pdata + 64 * blocks;
  28     memset(pdata + len, 0, 64 * blocks - len);
  29     pdata[len] = 0x80;
  30     unsigned int bits = len * 8;
  31     pend[-1] = (bits >> 0) & 0xff;
  32     pend[-2] = (bits >> 8) & 0xff;
  33     pend[-3] = (bits >> 16) & 0xff;
  34     pend[-4] = (bits >> 24) & 0xff;
  35     return blocks;
  36 }
  37
  38 static const unsigned int pSHA256InitState[8] =
  39 {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
  40
  41 void SHA256Transform(void* pstate, void* pinput, const void* pinit)
  42 {
  43     SHA256_CTX ctx;
  44     unsigned char data[64];
  45
  46     SHA256_Init(&ctx);
  47
  48     for (int i = 0; i < 16; i++)
  49         ((uint32_t*)data)[i] = ByteReverse(((uint32_t*)pinput)[i]);
  50
  51     for (int i = 0; i < 8; i++)
  52         ctx.h[i] = ((uint32_t*)pinit)[i];
  53
  54     SHA256_Update(&ctx, data, sizeof(data));
  55     for (int i = 0; i < 8; i++)
  56         ((uint32_t*)pstate)[i] = ctx.h[i];
  57 }
  58
  59 // Some explaining would be appreciated
  60 class COrphan
  61 {
  62 public:
  63     CTransaction* ptx;
  64     std::set<uint256> setDependsOn;
  65     double dPriority;
  66     double dFeePerKb;
  67
  68     COrphan(CTransaction* ptxIn)
  69     {
  70         ptx = ptxIn;
  71         dPriority = dFeePerKb = 0;
  72     }
  73 };
  74
  75
  76 uint64_t nLastBlockTx = 0;
  77 uint64_t nLastBlockSize = 0;
  78 uint32_t nLastCoinStakeSearchInterval = 0;
  79
  80 // We want to sort transactions by priority and fee, so:
  81 typedef std::tuple<double, double, CTransaction*> TxPriority;
  82 class TxPriorityCompare
  83 {
  84     bool byFee;
  85 public:
  86     TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
  87     bool operator()(const TxPriority& a, const TxPriority& b)
  88     {
  89         if (byFee)
  90         {
  91             if (std::get<1>(a) == std::get<1>(b))
  92                 return std::get<0>(a) < std::get<0>(b);
  93             return std::get<1>(a) < std::get<1>(b);
  94         }
  95         else
  96         {
  97             if (std::get<0>(a) == std::get<0>(b))
  98                 return std::get<1>(a) < std::get<1>(b);
  99             return std::get<0>(a) < std::get<0>(b);
 100         }
 101     }
 102 };
 103
 104 // CreateNewBlock: create new block (without proof-of-work/with provided coinstake)
 105 std::shared_ptr<CBlock> CreateNewBlock(CWallet* pwallet, CTransaction *txCoinStake)
 106 {
 107     bool fProofOfStake = txCoinStake != nullptr;
 108
 109     // Create new block
 110     std::shared_ptr<CBlock> pblock(new CBlock());
 111     if (!pblock.get())
 112         return nullptr;
 113
 114     // Create coinbase tx
 115     CTransaction txCoinBase;
 116     txCoinBase.vin.resize(1);
 117     txCoinBase.vin[0].prevout.SetNull();
 118     txCoinBase.vout.resize(1);
 119
 120     if (!fProofOfStake)
 121     {
 122         CReserveKey reservekey(pwallet);
 123         txCoinBase.vout[0].scriptPubKey.SetDestination(reservekey.GetReservedKey().GetID());
 124
 125         // Add our coinbase tx as first transaction
 126         pblock->vtx.push_back(txCoinBase);
 127     }
 128     else
 129     {
 130         // Coinbase output must be empty for Proof-of-Stake block
 131         txCoinBase.vout[0].SetEmpty();
 132
 133         // Syncronize timestamps
 134         pblock->nTime = txCoinBase.nTime = txCoinStake->nTime;
 135
 136         // Add coinbase and coinstake transactions
 137         pblock->vtx.push_back(txCoinBase);
 138         pblock->vtx.push_back(*txCoinStake);
 139     }
 140
 141     // Largest block you're willing to create:
 142     unsigned int nBlockMaxSize = GetArgUInt("-blockmaxsize", MAX_BLOCK_SIZE_GEN/2);
 143     // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
 144     nBlockMaxSize = std::max(1000u, std::min(MAX_BLOCK_SIZE-1000u, nBlockMaxSize));
 145
 146     // How much of the block should be dedicated to high-priority transactions,
 147     // included regardless of the fees they pay
 148     unsigned int nBlockPrioritySize = GetArgUInt("-blockprioritysize", 27000);
 149     nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
 150
 151     // Minimum block size you want to create; block will be filled with free transactions
 152     // until there are no more or the block reaches this size:
 153     unsigned int nBlockMinSize = GetArgUInt("-blockminsize", 0);
 154     nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
 155
 156     // Fee-per-kilobyte amount considered the same as "free"
 157     // Be careful setting this: if you set it to zero then
 158     // a transaction spammer can cheaply fill blocks using
 159     // 1-satoshi-fee transactions. It should be set above the real
 160     // cost to you of processing a transaction.
 161     int64_t nMinTxFee = MIN_TX_FEE;
 162     if (mapArgs.count("-mintxfee")) {
 163         bool fResult = ParseMoney(mapArgs["-mintxfee"], nMinTxFee);
 164         if (!fResult) // Parse error
 165             nMinTxFee = MIN_TX_FEE;
 166     }
 167
 168     CBlockIndex* pindexPrev = pindexBest;
 169
 170     pblock->nBits = GetNextTargetRequired(pindexPrev, fProofOfStake);
 171
 172     // Collect memory pool transactions into the block
 173     int64_t nFees = 0;
 174     {
 175         LOCK2(cs_main, mempool.cs);
 176         CBlockIndex* pindexPrev = pindexBest;
 177         CTxDB txdb("r");
 178
 179         // Priority order to process transactions
 180         std::list<COrphan> vOrphan; // list memory doesn't move
 181         std::map<uint256, std::vector<COrphan*> > mapDependers;
 182
 183         // This vector will be sorted into a priority queue:
 184         std::vector<TxPriority> vecPriority;
 185         vecPriority.reserve(mempool.mapTx.size());
 186         for (std::map<uint256, CTransaction>::iterator mi = mempool.mapTx.begin(); mi != mempool.mapTx.end(); ++mi)
 187         {
 188             CTransaction& tx = (*mi).second;
 189             if (tx.IsCoinBase() || tx.IsCoinStake() || !tx.IsFinal())
 190                 continue;
 191
 192             COrphan* porphan = nullptr;
 193             double dPriority = 0;
 194             int64_t nTotalIn = 0;
 195             bool fMissingInputs = false;
 196             for (const CTxIn& txin : tx.vin)
 197             {
 198                 // Read prev transaction
 199                 CTransaction txPrev;
 200                 CTxIndex txindex;
 201                 if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
 202                 {
 203                     // This should never happen; all transactions in the memory
 204                     // pool should connect to either transactions in the chain
 205                     // or other transactions in the memory pool.
 206                     if (!mempool.mapTx.count(txin.prevout.hash))
 207                     {
 208                         printf("ERROR: mempool transaction missing input\n");
 209                         if (fDebug) assert("mempool transaction missing input" == 0);
 210                         fMissingInputs = true;
 211                         if (porphan)
 212                             vOrphan.pop_back();
 213                         break;
 214                     }
 215
 216                     // Has to wait for dependencies
 217                     if (!porphan)
 218                     {
 219                         // Use list for automatic deletion
 220                         vOrphan.push_back(COrphan(&tx));
 221                         porphan = &vOrphan.back();
 222                     }
 223                     mapDependers[txin.prevout.hash].push_back(porphan);
 224                     porphan->setDependsOn.insert(txin.prevout.hash);
 225                     nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
 226                     continue;
 227                 }
 228                 int64_t nValueIn = txPrev.vout[txin.prevout.n].nValue;
 229                 nTotalIn += nValueIn;
 230
 231                 int nConf = txindex.GetDepthInMainChain();
 232                 dPriority += (double)nValueIn * nConf;
 233             }
 234             if (fMissingInputs) continue;
 235
 236             // Priority is sum(valuein * age) / txsize
 237             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 238             dPriority /= nTxSize;
 239
 240             // This is a more accurate fee-per-kilobyte than is used by the client code, because the
 241             // client code rounds up the size to the nearest 1K. That's good, because it gives an
 242             // incentive to create smaller transactions.
 243             double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);
 244
 245             if (porphan)
 246             {
 247                 porphan->dPriority = dPriority;
 248                 porphan->dFeePerKb = dFeePerKb;
 249             }
 250             else
 251                 vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &(*mi).second));
 252         }
 253
 254         // Collect transactions into block
 255         std::map<uint256, CTxIndex> mapTestPool;
 256         uint64_t nBlockSize = 1000;
 257         uint64_t nBlockTx = 0;
 258         int nBlockSigOps = 100;
 259         bool fSortedByFee = (nBlockPrioritySize <= 0);
 260
 261         TxPriorityCompare comparer(fSortedByFee);
 262         std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 263
 264         while (!vecPriority.empty())
 265         {
 266             // Take highest priority transaction off the priority queue:
 267             double dPriority = std::get<0>(vecPriority.front());
 268             double dFeePerKb = std::get<1>(vecPriority.front());
 269             CTransaction& tx = *(std::get<2>(vecPriority.front()));
 270
 271             std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
 272             vecPriority.pop_back();
 273
 274             // Size limits
 275             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 276             if (nBlockSize + nTxSize >= nBlockMaxSize)
 277                 continue;
 278
 279             // Legacy limits on sigOps:
 280             unsigned int nTxSigOps = tx.GetLegacySigOpCount();
 281             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 282                 continue;
 283
 284             // Timestamp limit
 285             if (tx.nTime > GetAdjustedTime() || (fProofOfStake && tx.nTime > txCoinStake->nTime))
 286                 continue;
 287
 288             // Skip free transactions if we're past the minimum block size:
 289             if (fSortedByFee && (dFeePerKb < nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
 290                 continue;
 291
 292             // Prioritize by fee once past the priority size or we run out of high-priority
 293             // transactions:
 294             if (!fSortedByFee &&
 295                 ((nBlockSize + nTxSize >= nBlockPrioritySize) || (dPriority < COIN * 144 / 250)))
 296             {
 297                 fSortedByFee = true;
 298                 comparer = TxPriorityCompare(fSortedByFee);
 299                 std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 300             }
 301
 302             // Connecting shouldn't fail due to dependency on other memory pool transactions
 303             // because we're already processing them in order of dependency
 304             std::map<uint256, CTxIndex> mapTestPoolTmp(mapTestPool);
 305             MapPrevTx mapInputs;
 306             bool fInvalid;
 307             if (!tx.FetchInputs(txdb, mapTestPoolTmp, false, true, mapInputs, fInvalid))
 308                 continue;
 309
 310             // Transaction fee
 311             int64_t nTxFees = tx.GetValueIn(mapInputs)-tx.GetValueOut();
 312             int64_t nMinFee = tx.GetMinFee(nBlockSize, true, GMF_BLOCK, nTxSize);
 313             if (nTxFees < nMinFee)
 314                 continue;
 315
 316             // Sigops accumulation
 317             nTxSigOps += tx.GetP2SHSigOpCount(mapInputs);
 318             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 319                 continue;
 320
 321             if (!tx.ConnectInputs(txdb, mapInputs, mapTestPoolTmp, CDiskTxPos(1,1,1), pindexPrev, false, true, true, MANDATORY_SCRIPT_VERIFY_FLAGS))
 322                 continue;
 323             mapTestPoolTmp[tx.GetHash()] = CTxIndex(CDiskTxPos(1,1,1), tx.vout.size());
 324             swap(mapTestPool, mapTestPoolTmp);
 325
 326             // Added
 327             pblock->vtx.push_back(tx);
 328             nBlockSize += nTxSize;
 329             ++nBlockTx;
 330             nBlockSigOps += nTxSigOps;
 331             nFees += nTxFees;
 332
 333             if (fDebug && GetBoolArg("-printpriority"))
 334             {
 335                 printf("priority %.1f feeperkb %.1f txid %s\n",
 336                        dPriority, dFeePerKb, tx.GetHash().ToString().c_str());
 337             }
 338
 339             // Add transactions that depend on this one to the priority queue
 340             uint256 hash = tx.GetHash();
 341             if (mapDependers.count(hash))
 342             {
 343                 for (COrphan* porphan : mapDependers[hash])
 344                 {
 345                     if (!porphan->setDependsOn.empty())
 346                     {
 347                         porphan->setDependsOn.erase(hash);
 348                         if (porphan->setDependsOn.empty())
 349                         {
 350                             vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
 351                             std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
 352                         }
 353                     }
 354                 }
 355             }
 356         }
 357
 358         nLastBlockTx = nBlockTx;
 359         nLastBlockSize = nBlockSize;
 360
 361         if (!fProofOfStake)
 362         {
 363             pblock->vtx[0].vout[0].nValue = GetProofOfWorkReward(pblock->nBits) + nFees;
 364
 365             if (fDebug)
 366                 printf("CreateNewBlock(): PoW reward %" PRIu64 "\n", pblock->vtx[0].vout[0].nValue);
 367         }
 368
 369         if (fDebug && GetBoolArg("-printpriority"))
 370             printf("CreateNewBlock(): total size %" PRIu64 "\n", nBlockSize);
 371
 372         // Fill in header
 373         pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
 374         if (!fProofOfStake)
 375         {
 376             pblock->nTime          = std::max(pindexPrev->GetMedianTimePast()+1, pblock->GetMaxTransactionTime());
 377             pblock->nTime          = std::max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime()));
 378             pblock->UpdateTime(pindexPrev);
 379         }
 380         pblock->nNonce         = 0;
 381     }
 382
 383     return pblock;
 384 }
 385
 386
 387 void IncrementExtraNonce(std::shared_ptr<CBlock>& pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
 388 {
 389     // Update nExtraNonce
 390     static uint256 hashPrevBlock;
 391     if (hashPrevBlock != pblock->hashPrevBlock)
 392     {
 393         nExtraNonce = 0;
 394         hashPrevBlock = pblock->hashPrevBlock;
 395     }
 396     ++nExtraNonce;
 397
 398     unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
 399     pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
 400     assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);
 401
 402     pblock->hashMerkleRoot = pblock->BuildMerkleTree();
 403 }
 404
 405
 406 void FormatHashBuffers(const std::shared_ptr<CBlock>& pblock, char* pmidstate, char* pdata, char* phash1)
 407 {
 408     //
 409     // Pre-build hash buffers
 410     //
 411     struct
 412     {
 413         struct unnamed2
 414         {
 415             int nVersion;
 416             uint256 hashPrevBlock;
 417             uint256 hashMerkleRoot;
 418             unsigned int nTime;
 419             unsigned int nBits;
 420             unsigned int nNonce;
 421         }
 422         block;
 423         unsigned char pchPadding0[64];
 424         uint256 hash1;
 425         unsigned char pchPadding1[64];
 426     }
 427     tmp;
 428     memset(&tmp, 0, sizeof(tmp));
 429
 430     tmp.block.nVersion       = pblock->nVersion;
 431     tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
 432     tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
 433     tmp.block.nTime          = pblock->nTime;
 434     tmp.block.nBits          = pblock->nBits;
 435     tmp.block.nNonce         = pblock->nNonce;
 436
 437     FormatHashBlocks(&tmp.block, sizeof(tmp.block));
 438     FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));
 439
 440     // Byte swap all the input buffer
 441     for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
 442         ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);
 443
 444     // Precalc the first half of the first hash, which stays constant
 445     SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);
 446
 447     memcpy(pdata, &tmp.block, 128);
 448     memcpy(phash1, &tmp.hash1, 64);
 449 }
 450
 451
 452 bool CheckWork(const std::shared_ptr<CBlock>& pblock, CWallet& wallet, CReserveKey& reservekey)
 453 {
 454     uint256 hashBlock = pblock->GetHash();
 455     uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
 456
 457     if(!pblock->IsProofOfWork())
 458         return error("CheckWork() : %s is not a proof-of-work block", hashBlock.GetHex().c_str());
 459
 460     if (hashBlock > hashTarget)
 461         return error("CheckWork() : proof-of-work not meeting target");
 462
 463     //// debug print
 464     printf("CheckWork() : new proof-of-work block found  \n  hash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), hashTarget.GetHex().c_str());
 465     pblock->print();
 466     printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());
 467
 468     // Found a solution
 469     {
 470         LOCK(cs_main);
 471         if (pblock->hashPrevBlock != hashBestChain)
 472             return error("CheckWork() : generated block is stale");
 473
 474         // Remove key from key pool
 475         reservekey.KeepKey();
 476
 477         // Track how many getdata requests this block gets
 478         {
 479             LOCK(wallet.cs_wallet);
 480             wallet.mapRequestCount[hashBlock] = 0;
 481         }
 482
 483         // Process this block the same as if we had received it from another node
 484         if (!ProcessBlock(nullptr, pblock.get()))
 485             return error("CheckWork() : ProcessBlock, block not accepted");
 486     }
 487
 488     return true;
 489 }
 490
 491 bool CheckStake(const std::shared_ptr<CBlock>& pblock, CWallet& wallet)
 492 {
 493     uint256 proofHash = 0, hashTarget = 0;
 494     uint256 hashBlock = pblock->GetHash();
 495
 496     if(!pblock->IsProofOfStake())
 497         return error("CheckStake() : %s is not a proof-of-stake block", hashBlock.GetHex().c_str());
 498
 499     // verify hash target and signature of coinstake tx
 500     if (!CheckProofOfStake(pblock->vtx[1], pblock->nBits, proofHash, hashTarget))
 501         return error("CheckStake() : proof-of-stake checking failed");
 502
 503     //// debug print
 504     printf("CheckStake() : new proof-of-stake block found  \n  hash: %s \nproofhash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), proofHash.GetHex().c_str(), hashTarget.GetHex().c_str());
 505     pblock->print();
 506     printf("out %s\n", FormatMoney(pblock->vtx[1].GetValueOut()).c_str());
 507
 508     // Found a solution
 509     {
 510         LOCK(cs_main);
 511         if (pblock->hashPrevBlock != hashBestChain)
 512             return error("CheckStake() : generated block is stale");
 513
 514         // Track how many getdata requests this block gets
 515         {
 516             LOCK(wallet.cs_wallet);
 517             wallet.mapRequestCount[hashBlock] = 0;
 518         }
 519
 520         // Process this block the same as if we had received it from another node
 521         if (!ProcessBlock(nullptr, pblock.get()))
 522             return error("CheckStake() : ProcessBlock, block not accepted");
 523     }
 524
 525     return true;
 526 }
 527
 528 // Precalculated SHA256 contexts and metadata
 529 // (txid, vout.n) => (kernel, (tx.nTime, nAmount))
 530 typedef std::map<std::pair<uint256, unsigned int>, std::pair<std::vector<unsigned char>, std::pair<uint32_t, uint64_t> > > MidstateMap;
 531
 532 // Fill the inputs map with precalculated contexts and metadata
 533 bool FillMap(CWallet *pwallet, uint32_t nUpperTime, MidstateMap &inputsMap)
 534 {
 535     // Choose coins to use
 536     int64_t nBalance = pwallet->GetBalance();
 537
 538     if (nBalance <= nReserveBalance)
 539         return false;
 540
 541     uint32_t nTime = GetAdjustedTime();
 542
 543     CTxDB txdb("r");
 544     {
 545         LOCK2(cs_main, pwallet->cs_wallet);
 546
 547         CoinsSet setCoins;
 548         int64_t nValueIn = 0;
 549         if (!pwallet->SelectCoinsSimple(nBalance - nReserveBalance, MIN_TX_FEE, MAX_MONEY, nUpperTime, nCoinbaseMaturity * 10, setCoins, nValueIn))
 550             return error("FillMap() : SelectCoinsSimple failed");
 551
 552         if (setCoins.empty())
 553             return false;
 554
 555         CBlock block;
 556         CTxIndex txindex;
 557
 558         for(CoinsSet::const_iterator pcoin = setCoins.begin(); pcoin != setCoins.end(); pcoin++)
 559         {
 560             std::pair<uint256, uint32_t> key = {pcoin->first->GetHash(), pcoin->second};
 561
 562             // Skip existent inputs
 563             if (inputsMap.find(key) != inputsMap.end())
 564                 continue;
 565
 566             // Trying to parse scriptPubKey
 567             txnouttype whichType;
 568             std::vector<valtype> vSolutions;
 569             if (!Solver(pcoin->first->vout[pcoin->second].scriptPubKey, whichType, vSolutions))
 570                 continue;
 571
 572             // Only support pay to public key and pay to address
 573             if (whichType != TX_PUBKEY && whichType != TX_PUBKEYHASH)
 574                 continue;
 575
 576             // Load transaction index item
 577             if (!txdb.ReadTxIndex(pcoin->first->GetHash(), txindex))
 578                 continue;
 579
 580             // Read block header
 581             if (!block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
 582                 continue;
 583
 584             // Only load coins meeting min age requirement
 585             if (nStakeMinAge + block.nTime > nTime - nMaxStakeSearchInterval)
 586                 continue;
 587
 588             // Get stake modifier
 589             uint64_t nStakeModifier = 0;
 590             if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
 591                 continue;
 592
 593             // Build static part of kernel
 594             CDataStream ssKernel(SER_GETHASH, 0);
 595             ssKernel << nStakeModifier;
 596             ssKernel << block.nTime << (txindex.pos.nTxPos - txindex.pos.nBlockPos) << pcoin->first->nTime << pcoin->second;
 597
 598             // (txid, vout.n) => (kernel, (tx.nTime, nAmount))
 599             inputsMap[key] = {std::vector<unsigned char>(ssKernel.begin(), ssKernel.end()), {pcoin->first->nTime, pcoin->first->vout[pcoin->second].nValue}};
 600         }
 601
 602         nStakeInputsMapSize = inputsMap.size();
 603
 604         if (fDebug)
 605             printf("FillMap() : Map of %" PRIu64 " precalculated contexts has been created by stake miner\n", nStakeInputsMapSize);
 606     }
 607
 608     return true;
 609 }
 610
 611 // Scan inputs map in order to find a solution
 612 bool ScanMap(const MidstateMap &inputsMap, uint32_t nBits, MidstateMap::key_type &LuckyInput, std::pair<uint256, uint32_t> &solution)
 613 {
 614     static uint32_t nLastCoinStakeSearchTime = GetAdjustedTime(); // startup timestamp
 615     uint32_t nSearchTime = GetAdjustedTime();
 616
 617     if (inputsMap.size() > 0 && nSearchTime > nLastCoinStakeSearchTime)
 618     {
 619         // Scanning interval (begintime, endtime)
 620         std::pair<uint32_t, uint32_t> interval;
 621
 622         interval.first = nSearchTime;
 623         interval.second = nSearchTime - std::min(nSearchTime-nLastCoinStakeSearchTime, nMaxStakeSearchInterval);
 624
 625         // (txid, nout) => (kernel, (tx.nTime, nAmount))
 626         for(MidstateMap::const_iterator input = inputsMap.begin(); input != inputsMap.end(); input++)
 627         {
 628             unsigned char *kernel = (unsigned char *) &input->second.first[0];
 629
 630             // scan(State, Bits, Time, Amount, ...)
 631             if (ScanKernelBackward(kernel, nBits, input->second.second.first, input->second.second.second, interval, solution))
 632             {
 633                 // Solution found
 634                 LuckyInput = input->first; // (txid, nout)
 635
 636                 return true;
 637             }
 638         }
 639
 640         // Inputs map iteration can be big enough to consume few seconds while scanning.
 641         // We're using dynamical calculation of scanning interval in order to compensate this delay.
 642         nLastCoinStakeSearchInterval = nSearchTime - nLastCoinStakeSearchTime;
 643         nLastCoinStakeSearchTime = nSearchTime;
 644     }
 645
 646     // No solutions were found
 647     return false;
 648 }
 649
 650 // Stake miner thread
 651 void ThreadStakeMiner(void* parg)
 652 {
 653     SetThreadPriority(THREAD_PRIORITY_LOWEST);
 654
 655     // Make this thread recognisable as the mining thread
 656     RenameThread("novacoin-miner");
 657     CWallet* pwallet = (CWallet*)parg;
 658
 659     MidstateMap inputsMap;
 660     if (!FillMap(pwallet, GetAdjustedTime(), inputsMap))
 661         return;
 662
 663     bool fTrySync = true;
 664
 665     CBlockIndex* pindexPrev = pindexBest;
 666     uint32_t nBits = GetNextTargetRequired(pindexPrev, true);
 667
 668     printf("ThreadStakeMinter started\n");
 669
 670     try
 671     {
 672         vnThreadsRunning[THREAD_MINTER]++;
 673
 674         MidstateMap::key_type LuckyInput;
 675         std::pair<uint256, uint32_t> solution;
 676
 677         // Main miner loop
 678         do
 679         {
 680             if (fShutdown)
 681                 goto _endloop;
 682
 683             while (pwallet->IsLocked())
 684             {
 685                 Sleep(1000);
 686                 if (fShutdown)
 687                     goto _endloop; // Don't be afraid to use a goto if that's the best option.
 688             }
 689
 690             while (vNodes.empty() || IsInitialBlockDownload())
 691             {
 692                 fTrySync = true;
 693
 694                 Sleep(1000);
 695                 if (fShutdown)
 696                     goto _endloop;
 697             }
 698
 699             if (fTrySync)
 700             {
 701                 // Don't try mine blocks unless we're at the top of chain and have at least three p2p connections.
 702                 fTrySync = false;
 703                 if (vNodes.size() < 3 || nBestHeight < GetNumBlocksOfPeers())
 704                 {
 705                     Sleep(1000);
 706                     continue;
 707                 }
 708             }
 709
 710             if (ScanMap(inputsMap, nBits, LuckyInput, solution))
 711             {
 712                 SetThreadPriority(THREAD_PRIORITY_NORMAL);
 713
 714                 // Remove lucky input from the map
 715                 inputsMap.erase(inputsMap.find(LuckyInput));
 716
 717                 CKey key;
 718                 CTransaction txCoinStake;
 719
 720                 // Create new coinstake transaction
 721                 if (!pwallet->CreateCoinStake(LuckyInput.first, LuckyInput.second, solution.second, nBits, txCoinStake, key))
 722                 {
 723                     std::string strMessage = _("Warning: Unable to create coinstake transaction, see debug.log for the details. Mining thread has been stopped.");
 724                     strMiscWarning = strMessage;
 725                     printf("*** %s\n", strMessage.c_str());
 726
 727                     break;
 728                 }
 729
 730                 // Now we have new coinstake, it's time to create the block ...
 731                 std::shared_ptr<CBlock> pblock = CreateNewBlock(pwallet, &txCoinStake);
 732                 if (!pblock)
 733                 {
 734                     std::string strMessage = _("Warning: Unable to allocate memory for the new block object. Mining thread has been stopped.");
 735                     strMiscWarning = strMessage;
 736                     printf("*** %s\n", strMessage.c_str());
 737
 738                     break;
 739                 }
 740
 741                 unsigned int nExtraNonce = 0;
 742                 IncrementExtraNonce(pblock, pindexPrev, nExtraNonce);
 743
 744                 // ... and sign it
 745                 if (!key.Sign(pblock->GetHash(), pblock->vchBlockSig))
 746                 {
 747                     std::string strMessage = _("Warning: Proof-of-Stake miner is unable to sign the block (locked wallet?). Mining thread has been stopped.");
 748                     strMiscWarning = strMessage;
 749                     printf("*** %s\n", strMessage.c_str());
 750
 751                     break;
 752                 }
 753
 754                 CheckStake(pblock, *pwallet);
 755                 SetThreadPriority(THREAD_PRIORITY_LOWEST);
 756                 Sleep(500);
 757             }
 758
 759             if (pindexPrev != pindexBest)
 760             {
 761                 // The best block has been changed, we need to refill the map
 762                 if (FillMap(pwallet, GetAdjustedTime(), inputsMap))
 763                 {
 764                     pindexPrev = pindexBest;
 765                     nBits = GetNextTargetRequired(pindexPrev, true);
 766                 }
 767                 else
 768                 {
 769                     // Clear existent data if FillMap failed
 770                     inputsMap.clear();
 771                 }
 772             }
 773
 774             Sleep(500);
 775
 776             _endloop:
 777                 (void)0; // do nothing
 778         }
 779         while(!fShutdown);
 780
 781         vnThreadsRunning[THREAD_MINTER]--;
 782     }
 783     catch (std::exception& e) {
 784         vnThreadsRunning[THREAD_MINTER]--;
 785         PrintException(&e, "ThreadStakeMinter()");
 786     } catch (...) {
 787         vnThreadsRunning[THREAD_MINTER]--;
 788         PrintException(nullptr, "ThreadStakeMinter()");
 789     }
 790     printf("ThreadStakeMinter exiting, %d threads remaining\n", vnThreadsRunning[THREAD_MINTER]);
 791 }