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.h"
   8 #include "miner.h"
   9 #include "kernel.h"
  10
  11 using namespace std;
  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     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     void print() const
  74     {
  75         printf("COrphan(hash=%s, dPriority=%.1f, dFeePerKb=%.1f)\n",
  76                ptx->GetHash().ToString().substr(0,10).c_str(), dPriority, dFeePerKb);
  77         BOOST_FOREACH(uint256 hash, setDependsOn)
  78             printf("   setDependsOn %s\n", hash.ToString().substr(0,10).c_str());
  79     }
  80 };
  81
  82
  83 uint64_t nLastBlockTx = 0;
  84 uint64_t nLastBlockSize = 0;
  85 uint32_t nLastCoinStakeSearchInterval = 0;
  86
  87 // We want to sort transactions by priority and fee, so:
  88 typedef boost::tuple<double, double, CTransaction*> TxPriority;
  89 class TxPriorityCompare
  90 {
  91     bool byFee;
  92 public:
  93     TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
  94     bool operator()(const TxPriority& a, const TxPriority& b)
  95     {
  96         if (byFee)
  97         {
  98             if (a.get<1>() == b.get<1>())
  99                 return a.get<0>() < b.get<0>();
 100             return a.get<1>() < b.get<1>();
 101         }
 102         else
 103         {
 104             if (a.get<0>() == b.get<0>())
 105                 return a.get<1>() < b.get<1>();
 106             return a.get<0>() < b.get<0>();
 107         }
 108     }
 109 };
 110
 111 // CreateNewBlock: create new block (without proof-of-work/with provided coinstake)
 112 CBlock* CreateNewBlock(CWallet* pwallet, CTransaction *txCoinStake)
 113 {
 114     bool fProofOfStake = txCoinStake != NULL;
 115
 116     // Create new block
 117     auto_ptr<CBlock> pblock(new CBlock());
 118     if (!pblock.get())
 119         return NULL;
 120
 121     // Create coinbase tx
 122     CTransaction txCoinBase;
 123     txCoinBase.vin.resize(1);
 124     txCoinBase.vin[0].prevout.SetNull();
 125     txCoinBase.vout.resize(1);
 126
 127     if (!fProofOfStake)
 128     {
 129         CReserveKey reservekey(pwallet);
 130         txCoinBase.vout[0].scriptPubKey.SetDestination(reservekey.GetReservedKey().GetID());
 131
 132         // Add our coinbase tx as first transaction
 133         pblock->vtx.push_back(txCoinBase);
 134     }
 135     else
 136     {
 137         // Coinbase output must be empty for Proof-of-Stake block
 138         txCoinBase.vout[0].SetEmpty();
 139
 140         // Syncronize timestamps
 141         pblock->nTime = txCoinBase.nTime = txCoinStake->nTime;
 142
 143         // Add coinbase and coinstake transactions
 144         pblock->vtx.push_back(txCoinBase);
 145         pblock->vtx.push_back(*txCoinStake);
 146     }
 147
 148     // Largest block you're willing to create:
 149     unsigned int nBlockMaxSize = GetArg("-blockmaxsize", MAX_BLOCK_SIZE_GEN/2);
 150     // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
 151     nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SIZE-1000), nBlockMaxSize));
 152
 153     // How much of the block should be dedicated to high-priority transactions,
 154     // included regardless of the fees they pay
 155     unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", 27000);
 156     nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
 157
 158     // Minimum block size you want to create; block will be filled with free transactions
 159     // until there are no more or the block reaches this size:
 160     unsigned int nBlockMinSize = GetArg("-blockminsize", 0);
 161     nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
 162
 163     // Fee-per-kilobyte amount considered the same as "free"
 164     // Be careful setting this: if you set it to zero then
 165     // a transaction spammer can cheaply fill blocks using
 166     // 1-satoshi-fee transactions. It should be set above the real
 167     // cost to you of processing a transaction.
 168     int64_t nMinTxFee = MIN_TX_FEE;
 169     if (mapArgs.count("-mintxfee"))
 170         ParseMoney(mapArgs["-mintxfee"], nMinTxFee);
 171
 172     CBlockIndex* pindexPrev = pindexBest;
 173
 174     pblock->nBits = GetNextTargetRequired(pindexPrev, fProofOfStake);
 175
 176     // Collect memory pool transactions into the block
 177     int64_t nFees = 0;
 178     {
 179         LOCK2(cs_main, mempool.cs);
 180         CBlockIndex* pindexPrev = pindexBest;
 181         CTxDB txdb("r");
 182
 183         // Priority order to process transactions
 184         list<COrphan> vOrphan; // list memory doesn't move
 185         map<uint256, vector<COrphan*> > mapDependers;
 186
 187         // This vector will be sorted into a priority queue:
 188         vector<TxPriority> vecPriority;
 189         vecPriority.reserve(mempool.mapTx.size());
 190         for (map<uint256, CTransaction>::iterator mi = mempool.mapTx.begin(); mi != mempool.mapTx.end(); ++mi)
 191         {
 192             CTransaction& tx = (*mi).second;
 193             if (tx.IsCoinBase() || tx.IsCoinStake() || !tx.IsFinal())
 194                 continue;
 195
 196             COrphan* porphan = NULL;
 197             double dPriority = 0;
 198             int64_t nTotalIn = 0;
 199             bool fMissingInputs = false;
 200             BOOST_FOREACH(const CTxIn& txin, tx.vin)
 201             {
 202                 // Read prev transaction
 203                 CTransaction txPrev;
 204                 CTxIndex txindex;
 205                 if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
 206                 {
 207                     // This should never happen; all transactions in the memory
 208                     // pool should connect to either transactions in the chain
 209                     // or other transactions in the memory pool.
 210                     if (!mempool.mapTx.count(txin.prevout.hash))
 211                     {
 212                         printf("ERROR: mempool transaction missing input\n");
 213                         if (fDebug) assert("mempool transaction missing input" == 0);
 214                         fMissingInputs = true;
 215                         if (porphan)
 216                             vOrphan.pop_back();
 217                         break;
 218                     }
 219
 220                     // Has to wait for dependencies
 221                     if (!porphan)
 222                     {
 223                         // Use list for automatic deletion
 224                         vOrphan.push_back(COrphan(&tx));
 225                         porphan = &vOrphan.back();
 226                     }
 227                     mapDependers[txin.prevout.hash].push_back(porphan);
 228                     porphan->setDependsOn.insert(txin.prevout.hash);
 229                     nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
 230                     continue;
 231                 }
 232                 int64_t nValueIn = txPrev.vout[txin.prevout.n].nValue;
 233                 nTotalIn += nValueIn;
 234
 235                 int nConf = txindex.GetDepthInMainChain();
 236                 dPriority += (double)nValueIn * nConf;
 237             }
 238             if (fMissingInputs) continue;
 239
 240             // Priority is sum(valuein * age) / txsize
 241             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 242             dPriority /= nTxSize;
 243
 244             // This is a more accurate fee-per-kilobyte than is used by the client code, because the
 245             // client code rounds up the size to the nearest 1K. That's good, because it gives an
 246             // incentive to create smaller transactions.
 247             double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);
 248
 249             if (porphan)
 250             {
 251                 porphan->dPriority = dPriority;
 252                 porphan->dFeePerKb = dFeePerKb;
 253             }
 254             else
 255                 vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &(*mi).second));
 256         }
 257
 258         // Collect transactions into block
 259         map<uint256, CTxIndex> mapTestPool;
 260         uint64_t nBlockSize = 1000;
 261         uint64_t nBlockTx = 0;
 262         int nBlockSigOps = 100;
 263         bool fSortedByFee = (nBlockPrioritySize <= 0);
 264
 265         TxPriorityCompare comparer(fSortedByFee);
 266         std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 267
 268         while (!vecPriority.empty())
 269         {
 270             // Take highest priority transaction off the priority queue:
 271             double dPriority = vecPriority.front().get<0>();
 272             double dFeePerKb = vecPriority.front().get<1>();
 273             CTransaction& tx = *(vecPriority.front().get<2>());
 274
 275             std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
 276             vecPriority.pop_back();
 277
 278             // Size limits
 279             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 280             if (nBlockSize + nTxSize >= nBlockMaxSize)
 281                 continue;
 282
 283             // Legacy limits on sigOps:
 284             unsigned int nTxSigOps = tx.GetLegacySigOpCount();
 285             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 286                 continue;
 287
 288             // Timestamp limit
 289             if (tx.nTime > GetAdjustedTime() || (fProofOfStake && tx.nTime > txCoinStake->nTime))
 290                 continue;
 291
 292             // Skip free transactions if we're past the minimum block size:
 293             if (fSortedByFee && (dFeePerKb < nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
 294                 continue;
 295
 296             // Prioritize by fee once past the priority size or we run out of high-priority
 297             // transactions:
 298             if (!fSortedByFee &&
 299                 ((nBlockSize + nTxSize >= nBlockPrioritySize) || (dPriority < COIN * 144 / 250)))
 300             {
 301                 fSortedByFee = true;
 302                 comparer = TxPriorityCompare(fSortedByFee);
 303                 std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 304             }
 305
 306             // Connecting shouldn't fail due to dependency on other memory pool transactions
 307             // because we're already processing them in order of dependency
 308             map<uint256, CTxIndex> mapTestPoolTmp(mapTestPool);
 309             MapPrevTx mapInputs;
 310             bool fInvalid;
 311             if (!tx.FetchInputs(txdb, mapTestPoolTmp, false, true, mapInputs, fInvalid))
 312                 continue;
 313
 314             // Transaction fee
 315             int64_t nTxFees = tx.GetValueIn(mapInputs)-tx.GetValueOut();
 316             int64_t nMinFee = tx.GetMinFee(nBlockSize, true, GMF_BLOCK, nTxSize);
 317             if (nTxFees < nMinFee)
 318                 continue;
 319
 320             // Sigops accumulation
 321             nTxSigOps += tx.GetP2SHSigOpCount(mapInputs);
 322             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 323                 continue;
 324
 325             if (!tx.ConnectInputs(txdb, mapInputs, mapTestPoolTmp, CDiskTxPos(1,1,1), pindexPrev, false, true, true, MANDATORY_SCRIPT_VERIFY_FLAGS))
 326                 continue;
 327             mapTestPoolTmp[tx.GetHash()] = CTxIndex(CDiskTxPos(1,1,1), tx.vout.size());
 328             swap(mapTestPool, mapTestPoolTmp);
 329
 330             // Added
 331             pblock->vtx.push_back(tx);
 332             nBlockSize += nTxSize;
 333             ++nBlockTx;
 334             nBlockSigOps += nTxSigOps;
 335             nFees += nTxFees;
 336
 337             if (fDebug && GetBoolArg("-printpriority"))
 338             {
 339                 printf("priority %.1f feeperkb %.1f txid %s\n",
 340                        dPriority, dFeePerKb, tx.GetHash().ToString().c_str());
 341             }
 342
 343             // Add transactions that depend on this one to the priority queue
 344             uint256 hash = tx.GetHash();
 345             if (mapDependers.count(hash))
 346             {
 347                 BOOST_FOREACH(COrphan* porphan, mapDependers[hash])
 348                 {
 349                     if (!porphan->setDependsOn.empty())
 350                     {
 351                         porphan->setDependsOn.erase(hash);
 352                         if (porphan->setDependsOn.empty())
 353                         {
 354                             vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
 355                             std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
 356                         }
 357                     }
 358                 }
 359             }
 360         }
 361
 362         nLastBlockTx = nBlockTx;
 363         nLastBlockSize = nBlockSize;
 364
 365         if (!fProofOfStake)
 366         {
 367             pblock->vtx[0].vout[0].nValue = GetProofOfWorkReward(pblock->nBits, nFees);
 368
 369             if (fDebug)
 370                 printf("CreateNewBlock(): PoW reward %" PRIu64 "\n", pblock->vtx[0].vout[0].nValue);
 371         }
 372
 373         if (fDebug && GetBoolArg("-printpriority"))
 374             printf("CreateNewBlock(): total size %" PRIu64 "\n", nBlockSize);
 375
 376         // Fill in header
 377         pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
 378         if (!fProofOfStake)
 379         {
 380             pblock->nTime          = max(pindexPrev->GetMedianTimePast()+1, pblock->GetMaxTransactionTime());
 381             pblock->nTime          = max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime()));
 382             pblock->UpdateTime(pindexPrev);
 383         }
 384         pblock->nNonce         = 0;
 385     }
 386
 387     return pblock.release();
 388 }
 389
 390
 391 void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
 392 {
 393     // Update nExtraNonce
 394     static uint256 hashPrevBlock;
 395     if (hashPrevBlock != pblock->hashPrevBlock)
 396     {
 397         nExtraNonce = 0;
 398         hashPrevBlock = pblock->hashPrevBlock;
 399     }
 400     ++nExtraNonce;
 401
 402     unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
 403     pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
 404     assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);
 405
 406     pblock->hashMerkleRoot = pblock->BuildMerkleTree();
 407 }
 408
 409
 410 void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1)
 411 {
 412     //
 413     // Pre-build hash buffers
 414     //
 415     struct
 416     {
 417         struct unnamed2
 418         {
 419             int nVersion;
 420             uint256 hashPrevBlock;
 421             uint256 hashMerkleRoot;
 422             unsigned int nTime;
 423             unsigned int nBits;
 424             unsigned int nNonce;
 425         }
 426         block;
 427         unsigned char pchPadding0[64];
 428         uint256 hash1;
 429         unsigned char pchPadding1[64];
 430     }
 431     tmp;
 432     memset(&tmp, 0, sizeof(tmp));
 433
 434     tmp.block.nVersion       = pblock->nVersion;
 435     tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
 436     tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
 437     tmp.block.nTime          = pblock->nTime;
 438     tmp.block.nBits          = pblock->nBits;
 439     tmp.block.nNonce         = pblock->nNonce;
 440
 441     FormatHashBlocks(&tmp.block, sizeof(tmp.block));
 442     FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));
 443
 444     // Byte swap all the input buffer
 445     for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
 446         ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);
 447
 448     // Precalc the first half of the first hash, which stays constant
 449     SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);
 450
 451     memcpy(pdata, &tmp.block, 128);
 452     memcpy(phash1, &tmp.hash1, 64);
 453 }
 454
 455
 456 bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
 457 {
 458     uint256 hashBlock = pblock->GetHash();
 459     uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
 460
 461     if(!pblock->IsProofOfWork())
 462         return error("CheckWork() : %s is not a proof-of-work block", hashBlock.GetHex().c_str());
 463
 464     if (hashBlock > hashTarget)
 465         return error("CheckWork() : proof-of-work not meeting target");
 466
 467     //// debug print
 468     printf("CheckWork() : new proof-of-work block found  \n  hash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), hashTarget.GetHex().c_str());
 469     pblock->print();
 470     printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());
 471
 472     // Found a solution
 473     {
 474         LOCK(cs_main);
 475         if (pblock->hashPrevBlock != hashBestChain)
 476             return error("CheckWork() : generated block is stale");
 477
 478         // Remove key from key pool
 479         reservekey.KeepKey();
 480
 481         // Track how many getdata requests this block gets
 482         {
 483             LOCK(wallet.cs_wallet);
 484             wallet.mapRequestCount[hashBlock] = 0;
 485         }
 486
 487         // Process this block the same as if we had received it from another node
 488         if (!ProcessBlock(NULL, pblock))
 489             return error("CheckWork() : ProcessBlock, block not accepted");
 490     }
 491
 492     return true;
 493 }
 494
 495 bool CheckStake(CBlock* pblock, CWallet& wallet)
 496 {
 497     uint256 proofHash = 0, hashTarget = 0;
 498     uint256 hashBlock = pblock->GetHash();
 499
 500     if(!pblock->IsProofOfStake())
 501         return error("CheckStake() : %s is not a proof-of-stake block", hashBlock.GetHex().c_str());
 502
 503     // verify hash target and signature of coinstake tx
 504     if (!CheckProofOfStake(pblock->vtx[1], pblock->nBits, proofHash, hashTarget))
 505         return error("CheckStake() : proof-of-stake checking failed");
 506
 507     //// debug print
 508     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());
 509     pblock->print();
 510     printf("out %s\n", FormatMoney(pblock->vtx[1].GetValueOut()).c_str());
 511
 512     // Found a solution
 513     {
 514         LOCK(cs_main);
 515         if (pblock->hashPrevBlock != hashBestChain)
 516             return error("CheckStake() : generated block is stale");
 517
 518         // Track how many getdata requests this block gets
 519         {
 520             LOCK(wallet.cs_wallet);
 521             wallet.mapRequestCount[hashBlock] = 0;
 522         }
 523
 524         // Process this block the same as if we had received it from another node
 525         if (!ProcessBlock(NULL, pblock))
 526             return error("CheckStake() : ProcessBlock, block not accepted");
 527     }
 528
 529     return true;
 530 }
 531
 532 // Precalculated SHA256 contexts and metadata
 533 // (txid, vout.n) => (SHA256_CTX, (tx.nTime, nAmount))
 534 typedef std::map<std::pair<uint256, unsigned int>, std::pair<SHA256_CTX, std::pair<uint32_t, uint64_t> > > MidstateMap;
 535
 536 // Fill the inputs map with precalculated states and metadata
 537 bool FillMap(CWallet *pwallet, uint32_t nUpperTime, MidstateMap &inputsMap)
 538 {
 539     // Choose coins to use
 540     int64_t nBalance = pwallet->GetBalance();
 541
 542     if (nBalance <= nReserveBalance)
 543         return false;
 544
 545     uint32_t nTime = GetAdjustedTime();
 546
 547     CTxDB txdb("r");
 548     {
 549         LOCK2(cs_main, pwallet->cs_wallet);
 550
 551         CoinsSet setCoins;
 552         int64_t nValueIn = 0;
 553         if (!pwallet->SelectCoinsSimple(nBalance - nReserveBalance, MIN_TX_FEE, MAX_MONEY, nUpperTime, nCoinbaseMaturity * 10, setCoins, nValueIn))
 554             return error("FillMap() : SelectCoinsSimple failed");
 555
 556         if (setCoins.empty())
 557             return false;
 558
 559         CBlock block;
 560         CTxIndex txindex;
 561
 562         for(CoinsSet::const_iterator pcoin = setCoins.begin(); pcoin != setCoins.end(); pcoin++)
 563         {
 564             pair<uint256, uint32_t> key = make_pair(pcoin->first->GetHash(), pcoin->second);
 565
 566             // Skip existent inputs
 567             if (inputsMap.find(key) != inputsMap.end())
 568                 continue;
 569
 570             // Trying to parse scriptPubKey
 571             txnouttype whichType;
 572             vector<valtype> vSolutions;
 573             if (!Solver(pcoin->first->vout[pcoin->second].scriptPubKey, whichType, vSolutions))
 574                 continue;
 575
 576             // Only support pay to public key and pay to address
 577             if (whichType != TX_PUBKEY && whichType != TX_PUBKEYHASH)
 578                 continue;
 579
 580             // Load transaction index item
 581             if (!txdb.ReadTxIndex(pcoin->first->GetHash(), txindex))
 582                 continue;
 583
 584             // Read block header
 585             if (!block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
 586                 continue;
 587
 588             // Only load coins meeting min age requirement
 589             if (nStakeMinAge + block.nTime > nTime - nMaxStakeSearchInterval)
 590                 continue;
 591
 592             uint64_t nStakeModifier = 0;
 593             if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
 594                 continue;
 595
 596             SHA256_CTX ctx;
 597             // Calculate midstate using (modifier, block time, tx offset, tx time, output number)
 598             GetKernelMidstate(nStakeModifier, block.nTime, txindex.pos.nTxPos - txindex.pos.nBlockPos, pcoin->first->nTime, pcoin->second, ctx);
 599
 600             // (txid, vout.n) => (SHA256_CTX, (tx.nTime, nAmount))
 601             inputsMap[key] = make_pair(ctx, make_pair(pcoin->first->nTime, pcoin->first->vout[pcoin->second].nValue));
 602         }
 603
 604         nStakeInputsMapSize = inputsMap.size();
 605
 606         if (fDebug)
 607             printf("Stake miner: map of %" PRIu64 " precalculated contexts has been created\n", nStakeInputsMapSize);
 608     }
 609
 610     return true;
 611 }
 612
 613 // Scan inputs map in order to find a solution
 614 bool ScanMap(const MidstateMap &inputsMap, uint32_t nBits, MidstateMap::key_type &LuckyInput, std::pair<uint256, uint32_t> &solution)
 615 {
 616     static uint32_t nLastCoinStakeSearchTime = GetAdjustedTime(); // startup timestamp
 617     uint32_t nSearchTime = GetAdjustedTime();
 618
 619     if (inputsMap.size() > 0 && nSearchTime > nLastCoinStakeSearchTime)
 620     {
 621         // Scanning interval (begintime, endtime)
 622         std::pair<uint32_t, uint32_t> interval;
 623
 624         interval.first = nSearchTime;
 625         interval.second = nSearchTime - min(nSearchTime-nLastCoinStakeSearchTime, nMaxStakeSearchInterval);
 626
 627         // (txid, nout) => (SHA256_CTX, (tx.nTime, nAmount))
 628         for(MidstateMap::const_iterator input = inputsMap.begin(); input != inputsMap.end(); input++)
 629         {
 630             SHA256_CTX ctx = input->second.first;
 631
 632             // scan(State, Bits, Time, Amount, ...)
 633             if (ScanMidstateBackward(ctx, nBits, input->second.second.first, input->second.second.second, interval, solution))
 634             {
 635                 // Solution found
 636                 LuckyInput = input->first; // (txid, nout)
 637
 638                 return true;
 639             }
 640         }
 641
 642         // Inputs map iteration can be big enough to consume few seconds while scanning.
 643         // We're using dynamical calculation of scanning interval in order to compensate this delay.
 644         nLastCoinStakeSearchInterval = nSearchTime - nLastCoinStakeSearchTime;
 645         nLastCoinStakeSearchTime = nSearchTime;
 646     }
 647
 648     // No solutions were found
 649     return false;
 650 }
 651
 652 // Stake miner thread
 653 void ThreadStakeMiner(void* parg)
 654 {
 655     SetThreadPriority(THREAD_PRIORITY_LOWEST);
 656
 657     // Make this thread recognisable as the mining thread
 658     RenameThread("novacoin-miner");
 659     CWallet* pwallet = (CWallet*)parg;
 660
 661     MidstateMap inputsMap;
 662     if (!FillMap(pwallet, GetAdjustedTime(), inputsMap))
 663         return;
 664
 665     bool fTrySync = true;
 666
 667     CBlockIndex* pindexPrev = pindexBest;
 668     uint32_t nBits = GetNextTargetRequired(pindexPrev, true);
 669
 670     printf("ThreadStakeMinter started\n");
 671
 672     try
 673     {
 674         vnThreadsRunning[THREAD_MINTER]++;
 675
 676         MidstateMap::key_type LuckyInput;
 677         std::pair<uint256, uint32_t> solution;
 678
 679         // Main miner loop
 680         do
 681         {
 682             if (fShutdown)
 683                 goto _endloop;
 684
 685             while (pwallet->IsLocked())
 686             {
 687                 Sleep(1000);
 688                 if (fShutdown)
 689                     goto _endloop; // Don't be afraid to use a goto if that's the best option.
 690             }
 691
 692             while (vNodes.empty() || IsInitialBlockDownload())
 693             {
 694                 fTrySync = true;
 695
 696                 Sleep(1000);
 697                 if (fShutdown)
 698                     goto _endloop;
 699             }
 700
 701             if (fTrySync)
 702             {
 703                 // Don't try mine blocks unless we're at the top of chain and have at least three p2p connections.
 704                 fTrySync = false;
 705                 if (vNodes.size() < 3 || nBestHeight < GetNumBlocksOfPeers())
 706                 {
 707                     Sleep(1000);
 708                     continue;
 709                 }
 710             }
 711
 712             if (ScanMap(inputsMap, nBits, LuckyInput, solution))
 713             {
 714                 SetThreadPriority(THREAD_PRIORITY_NORMAL);
 715
 716                 // Remove lucky input from the map
 717                 inputsMap.erase(inputsMap.find(LuckyInput));
 718
 719                 CKey key;
 720                 CTransaction txCoinStake;
 721
 722                 // Create new coinstake transaction
 723                 if (!pwallet->CreateCoinStake(LuckyInput.first, LuckyInput.second, solution.second, nBits, txCoinStake, key))
 724                 {
 725                     string strMessage = _("Warning: Unable to create coinstake transaction, see debug.log for the details. Mining thread has been stopped.");
 726                     strMiscWarning = strMessage;
 727                     printf("*** %s\n", strMessage.c_str());
 728
 729                     break;
 730                 }
 731
 732                 // Now we have new coinstake, it's time to create the block ...
 733                 CBlock* pblock;
 734                 pblock = CreateNewBlock(pwallet, &txCoinStake);
 735                 if (!pblock)
 736                 {
 737                     string strMessage = _("Warning: Unable to allocate memory for the new block object. Mining thread has been stopped.");
 738                     strMiscWarning = strMessage;
 739                     printf("*** %s\n", strMessage.c_str());
 740
 741                     break;
 742                 }
 743
 744                 unsigned int nExtraNonce = 0;
 745                 IncrementExtraNonce(pblock, pindexPrev, nExtraNonce);
 746
 747                 // ... and sign it
 748                 if (!key.Sign(pblock->GetHash(), pblock->vchBlockSig))
 749                 {
 750                     string strMessage = _("Warning: Proof-of-Stake miner is unable to sign the block (locked wallet?). Mining thread has been stopped.");
 751                     strMiscWarning = strMessage;
 752                     printf("*** %s\n", strMessage.c_str());
 753
 754                     break;
 755                 }
 756
 757                 CheckStake(pblock, *pwallet);
 758                 SetThreadPriority(THREAD_PRIORITY_LOWEST);
 759                 Sleep(500);
 760             }
 761
 762             if (pindexPrev != pindexBest)
 763             {
 764                 // The best block has been changed, we need to refill the map
 765                 if (FillMap(pwallet, GetAdjustedTime(), inputsMap))
 766                 {
 767                     pindexPrev = pindexBest;
 768                     nBits = GetNextTargetRequired(pindexPrev, true);
 769                 }
 770                 else
 771                 {
 772                     // Clear existent data if FillMap failed
 773                     inputsMap.clear();
 774                 }
 775             }
 776
 777             Sleep(500);
 778
 779             _endloop:
 780                 (void)0; // do nothing
 781         }
 782         while(!fShutdown);
 783
 784         vnThreadsRunning[THREAD_MINTER]--;
 785     }
 786     catch (std::exception& e) {
 787         vnThreadsRunning[THREAD_MINTER]--;
 788         PrintException(&e, "ThreadStakeMinter()");
 789     } catch (...) {
 790         vnThreadsRunning[THREAD_MINTER]--;
 791         PrintException(NULL, "ThreadStakeMinter()");
 792     }
 793     printf("ThreadStakeMinter exiting, %d threads remaining\n", vnThreadsRunning[THREAD_MINTER]);
 794 }