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