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 #include "kernel_worker.h"
  11
  12 using namespace std;
  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     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     void print() const
  75     {
  76         printf("COrphan(hash=%s, dPriority=%.1f, dFeePerKb=%.1f)\n",
  77                ptx->GetHash().ToString().substr(0,10).c_str(), dPriority, dFeePerKb);
  78         BOOST_FOREACH(uint256 hash, setDependsOn)
  79             printf("   setDependsOn %s\n", hash.ToString().substr(0,10).c_str());
  80     }
  81 };
  82
  83
  84 uint64_t nLastBlockTx = 0;
  85 uint64_t nLastBlockSize = 0;
  86 uint32_t nLastCoinStakeSearchInterval = 0;
  87
  88 // We want to sort transactions by priority and fee, so:
  89 typedef boost::tuple<double, double, CTransaction*> TxPriority;
  90 class TxPriorityCompare
  91 {
  92     bool byFee;
  93 public:
  94     TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
  95     bool operator()(const TxPriority& a, const TxPriority& b)
  96     {
  97         if (byFee)
  98         {
  99             if (a.get<1>() == b.get<1>())
 100                 return a.get<0>() < b.get<0>();
 101             return a.get<1>() < b.get<1>();
 102         }
 103         else
 104         {
 105             if (a.get<0>() == b.get<0>())
 106                 return a.get<1>() < b.get<1>();
 107             return a.get<0>() < b.get<0>();
 108         }
 109     }
 110 };
 111
 112 // CreateNewBlock: create new block (without proof-of-work/with provided coinstake)
 113 CBlock* CreateNewBlock(CWallet* pwallet, CTransaction *txCoinStake)
 114 {
 115     bool fProofOfStake = txCoinStake != NULL;
 116
 117     // Create new block
 118     auto_ptr<CBlock> pblock(new CBlock());
 119     if (!pblock.get())
 120         return NULL;
 121
 122     // Create coinbase tx
 123     CTransaction txCoinBase;
 124     txCoinBase.vin.resize(1);
 125     txCoinBase.vin[0].prevout.SetNull();
 126     txCoinBase.vout.resize(1);
 127
 128     if (!fProofOfStake)
 129     {
 130         CReserveKey reservekey(pwallet);
 131         txCoinBase.vout[0].scriptPubKey.SetDestination(reservekey.GetReservedKey().GetID());
 132
 133         // Add our coinbase tx as first transaction
 134         pblock->vtx.push_back(txCoinBase);
 135     }
 136     else
 137     {
 138         // Coinbase output must be empty for Proof-of-Stake block
 139         txCoinBase.vout[0].SetEmpty();
 140
 141         // Syncronize timestamps
 142         pblock->nTime = txCoinBase.nTime = txCoinStake->nTime;
 143
 144         // Add coinbase and coinstake transactions
 145         pblock->vtx.push_back(txCoinBase);
 146         pblock->vtx.push_back(*txCoinStake);
 147     }
 148
 149     // Largest block you're willing to create:
 150     unsigned int nBlockMaxSize = GetArgUInt("-blockmaxsize", MAX_BLOCK_SIZE_GEN/2);
 151     // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
 152     nBlockMaxSize = std::max(1000u, std::min(MAX_BLOCK_SIZE-1000u, nBlockMaxSize));
 153
 154     // How much of the block should be dedicated to high-priority transactions,
 155     // included regardless of the fees they pay
 156     unsigned int nBlockPrioritySize = GetArgUInt("-blockprioritysize", 27000);
 157     nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
 158
 159     // Minimum block size you want to create; block will be filled with free transactions
 160     // until there are no more or the block reaches this size:
 161     unsigned int nBlockMinSize = GetArgUInt("-blockminsize", 0);
 162     nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
 163
 164     // Fee-per-kilobyte amount considered the same as "free"
 165     // Be careful setting this: if you set it to zero then
 166     // a transaction spammer can cheaply fill blocks using
 167     // 1-satoshi-fee transactions. It should be set above the real
 168     // cost to you of processing a transaction.
 169     int64_t nMinTxFee = MIN_TX_FEE;
 170     if (mapArgs.count("-mintxfee"))
 171         ParseMoney(mapArgs["-mintxfee"], nMinTxFee);
 172
 173     CBlockIndex* pindexPrev = pindexBest;
 174
 175     pblock->nBits = GetNextTargetRequired(pindexPrev, fProofOfStake);
 176
 177     // Collect memory pool transactions into the block
 178     int64_t nFees = 0;
 179     {
 180         LOCK2(cs_main, mempool.cs);
 181         CBlockIndex* pindexPrev = pindexBest;
 182         CTxDB txdb("r");
 183
 184         // Priority order to process transactions
 185         list<COrphan> vOrphan; // list memory doesn't move
 186         map<uint256, vector<COrphan*> > mapDependers;
 187
 188         // This vector will be sorted into a priority queue:
 189         vector<TxPriority> vecPriority;
 190         vecPriority.reserve(mempool.mapTx.size());
 191         for (map<uint256, CTransaction>::iterator mi = mempool.mapTx.begin(); mi != mempool.mapTx.end(); ++mi)
 192         {
 193             CTransaction& tx = (*mi).second;
 194             if (tx.IsCoinBase() || tx.IsCoinStake() || !tx.IsFinal())
 195                 continue;
 196
 197             COrphan* porphan = NULL;
 198             double dPriority = 0;
 199             int64_t nTotalIn = 0;
 200             bool fMissingInputs = false;
 201             BOOST_FOREACH(const CTxIn& txin, tx.vin)
 202             {
 203                 // Read prev transaction
 204                 CTransaction txPrev;
 205                 CTxIndex txindex;
 206                 if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
 207                 {
 208                     // This should never happen; all transactions in the memory
 209                     // pool should connect to either transactions in the chain
 210                     // or other transactions in the memory pool.
 211                     if (!mempool.mapTx.count(txin.prevout.hash))
 212                     {
 213                         printf("ERROR: mempool transaction missing input\n");
 214                         if (fDebug) assert("mempool transaction missing input" == 0);
 215                         fMissingInputs = true;
 216                         if (porphan)
 217                             vOrphan.pop_back();
 218                         break;
 219                     }
 220
 221                     // Has to wait for dependencies
 222                     if (!porphan)
 223                     {
 224                         // Use list for automatic deletion
 225                         vOrphan.push_back(COrphan(&tx));
 226                         porphan = &vOrphan.back();
 227                     }
 228                     mapDependers[txin.prevout.hash].push_back(porphan);
 229                     porphan->setDependsOn.insert(txin.prevout.hash);
 230                     nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
 231                     continue;
 232                 }
 233                 int64_t nValueIn = txPrev.vout[txin.prevout.n].nValue;
 234                 nTotalIn += nValueIn;
 235
 236                 int nConf = txindex.GetDepthInMainChain();
 237                 dPriority += (double)nValueIn * nConf;
 238             }
 239             if (fMissingInputs) continue;
 240
 241             // Priority is sum(valuein * age) / txsize
 242             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 243             dPriority /= nTxSize;
 244
 245             // This is a more accurate fee-per-kilobyte than is used by the client code, because the
 246             // client code rounds up the size to the nearest 1K. That's good, because it gives an
 247             // incentive to create smaller transactions.
 248             double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);
 249
 250             if (porphan)
 251             {
 252                 porphan->dPriority = dPriority;
 253                 porphan->dFeePerKb = dFeePerKb;
 254             }
 255             else
 256                 vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &(*mi).second));
 257         }
 258
 259         // Collect transactions into block
 260         map<uint256, CTxIndex> mapTestPool;
 261         uint64_t nBlockSize = 1000;
 262         uint64_t nBlockTx = 0;
 263         int nBlockSigOps = 100;
 264         bool fSortedByFee = (nBlockPrioritySize <= 0);
 265
 266         TxPriorityCompare comparer(fSortedByFee);
 267         std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 268
 269         while (!vecPriority.empty())
 270         {
 271             // Take highest priority transaction off the priority queue:
 272             double dPriority = vecPriority.front().get<0>();
 273             double dFeePerKb = vecPriority.front().get<1>();
 274             CTransaction& tx = *(vecPriority.front().get<2>());
 275
 276             std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
 277             vecPriority.pop_back();
 278
 279             // Size limits
 280             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
 281             if (nBlockSize + nTxSize >= nBlockMaxSize)
 282                 continue;
 283
 284             // Legacy limits on sigOps:
 285             unsigned int nTxSigOps = tx.GetLegacySigOpCount();
 286             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 287                 continue;
 288
 289             // Timestamp limit
 290             if (tx.nTime > GetAdjustedTime() || (fProofOfStake && tx.nTime > txCoinStake->nTime))
 291                 continue;
 292
 293             // Skip free transactions if we're past the minimum block size:
 294             if (fSortedByFee && (dFeePerKb < nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
 295                 continue;
 296
 297             // Prioritize by fee once past the priority size or we run out of high-priority
 298             // transactions:
 299             if (!fSortedByFee &&
 300                 ((nBlockSize + nTxSize >= nBlockPrioritySize) || (dPriority < COIN * 144 / 250)))
 301             {
 302                 fSortedByFee = true;
 303                 comparer = TxPriorityCompare(fSortedByFee);
 304                 std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
 305             }
 306
 307             // Connecting shouldn't fail due to dependency on other memory pool transactions
 308             // because we're already processing them in order of dependency
 309             map<uint256, CTxIndex> mapTestPoolTmp(mapTestPool);
 310             MapPrevTx mapInputs;
 311             bool fInvalid;
 312             if (!tx.FetchInputs(txdb, mapTestPoolTmp, false, true, mapInputs, fInvalid))
 313                 continue;
 314
 315             // Transaction fee
 316             int64_t nTxFees = tx.GetValueIn(mapInputs)-tx.GetValueOut();
 317             int64_t nMinFee = tx.GetMinFee(nBlockSize, true, GMF_BLOCK, nTxSize);
 318             if (nTxFees < nMinFee)
 319                 continue;
 320
 321             // Sigops accumulation
 322             nTxSigOps += tx.GetP2SHSigOpCount(mapInputs);
 323             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
 324                 continue;
 325
 326             if (!tx.ConnectInputs(txdb, mapInputs, mapTestPoolTmp, CDiskTxPos(1,1,1), pindexPrev, false, true, true, MANDATORY_SCRIPT_VERIFY_FLAGS))
 327                 continue;
 328             mapTestPoolTmp[tx.GetHash()] = CTxIndex(CDiskTxPos(1,1,1), tx.vout.size());
 329             swap(mapTestPool, mapTestPoolTmp);
 330
 331             // Added
 332             pblock->vtx.push_back(tx);
 333             nBlockSize += nTxSize;
 334             ++nBlockTx;
 335             nBlockSigOps += nTxSigOps;
 336             nFees += nTxFees;
 337
 338             if (fDebug && GetBoolArg("-printpriority"))
 339             {
 340                 printf("priority %.1f feeperkb %.1f txid %s\n",
 341                        dPriority, dFeePerKb, tx.GetHash().ToString().c_str());
 342             }
 343
 344             // Add transactions that depend on this one to the priority queue
 345             uint256 hash = tx.GetHash();
 346             if (mapDependers.count(hash))
 347             {
 348                 BOOST_FOREACH(COrphan* porphan, mapDependers[hash])
 349                 {
 350                     if (!porphan->setDependsOn.empty())
 351                     {
 352                         porphan->setDependsOn.erase(hash);
 353                         if (porphan->setDependsOn.empty())
 354                         {
 355                             vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
 356                             std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
 357                         }
 358                     }
 359                 }
 360             }
 361         }
 362
 363         nLastBlockTx = nBlockTx;
 364         nLastBlockSize = nBlockSize;
 365
 366         if (!fProofOfStake)
 367         {
 368             pblock->vtx[0].vout[0].nValue = GetProofOfWorkReward(pblock->nBits, nFees);
 369
 370             if (fDebug)
 371                 printf("CreateNewBlock(): PoW reward %" PRIu64 "\n", pblock->vtx[0].vout[0].nValue);
 372         }
 373
 374         if (fDebug && GetBoolArg("-printpriority"))
 375             printf("CreateNewBlock(): total size %" PRIu64 "\n", nBlockSize);
 376
 377         // Fill in header
 378         pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
 379         if (!fProofOfStake)
 380         {
 381             pblock->nTime          = max(pindexPrev->GetMedianTimePast()+1, pblock->GetMaxTransactionTime());
 382             pblock->nTime          = max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime()));
 383             pblock->UpdateTime(pindexPrev);
 384         }
 385         pblock->nNonce         = 0;
 386     }
 387
 388     return pblock.release();
 389 }
 390
 391
 392 void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
 393 {
 394     // Update nExtraNonce
 395     static uint256 hashPrevBlock;
 396     if (hashPrevBlock != pblock->hashPrevBlock)
 397     {
 398         nExtraNonce = 0;
 399         hashPrevBlock = pblock->hashPrevBlock;
 400     }
 401     ++nExtraNonce;
 402
 403     unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
 404     pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
 405     assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);
 406
 407     pblock->hashMerkleRoot = pblock->BuildMerkleTree();
 408 }
 409
 410
 411 void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1)
 412 {
 413     //
 414     // Pre-build hash buffers
 415     //
 416     struct
 417     {
 418         struct unnamed2
 419         {
 420             int nVersion;
 421             uint256 hashPrevBlock;
 422             uint256 hashMerkleRoot;
 423             unsigned int nTime;
 424             unsigned int nBits;
 425             unsigned int nNonce;
 426         }
 427         block;
 428         unsigned char pchPadding0[64];
 429         uint256 hash1;
 430         unsigned char pchPadding1[64];
 431     }
 432     tmp;
 433     memset(&tmp, 0, sizeof(tmp));
 434
 435     tmp.block.nVersion       = pblock->nVersion;
 436     tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
 437     tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
 438     tmp.block.nTime          = pblock->nTime;
 439     tmp.block.nBits          = pblock->nBits;
 440     tmp.block.nNonce         = pblock->nNonce;
 441
 442     FormatHashBlocks(&tmp.block, sizeof(tmp.block));
 443     FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));
 444
 445     // Byte swap all the input buffer
 446     for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
 447         ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);
 448
 449     // Precalc the first half of the first hash, which stays constant
 450     SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);
 451
 452     memcpy(pdata, &tmp.block, 128);
 453     memcpy(phash1, &tmp.hash1, 64);
 454 }
 455
 456
 457 bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
 458 {
 459     uint256 hashBlock = pblock->GetHash();
 460     uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
 461
 462     if(!pblock->IsProofOfWork())
 463         return error("CheckWork() : %s is not a proof-of-work block", hashBlock.GetHex().c_str());
 464
 465     if (hashBlock > hashTarget)
 466         return error("CheckWork() : proof-of-work not meeting target");
 467
 468     //// debug print
 469     printf("CheckWork() : new proof-of-work block found  \n  hash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), hashTarget.GetHex().c_str());
 470     pblock->print();
 471     printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());
 472
 473     // Found a solution
 474     {
 475         LOCK(cs_main);
 476         if (pblock->hashPrevBlock != hashBestChain)
 477             return error("CheckWork() : generated block is stale");
 478
 479         // Remove key from key pool
 480         reservekey.KeepKey();
 481
 482         // Track how many getdata requests this block gets
 483         {
 484             LOCK(wallet.cs_wallet);
 485             wallet.mapRequestCount[hashBlock] = 0;
 486         }
 487
 488         // Process this block the same as if we had received it from another node
 489         if (!ProcessBlock(NULL, pblock))
 490             return error("CheckWork() : ProcessBlock, block not accepted");
 491     }
 492
 493     return true;
 494 }
 495
 496 bool CheckStake(CBlock* pblock, CWallet& wallet)
 497 {
 498     uint256 proofHash = 0, hashTarget = 0;
 499     uint256 hashBlock = pblock->GetHash();
 500
 501     if(!pblock->IsProofOfStake())
 502         return error("CheckStake() : %s is not a proof-of-stake block", hashBlock.GetHex().c_str());
 503
 504     // verify hash target and signature of coinstake tx
 505     if (!CheckProofOfStake(pblock->vtx[1], pblock->nBits, proofHash, hashTarget))
 506         return error("CheckStake() : proof-of-stake checking failed");
 507
 508     //// debug print
 509     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());
 510     pblock->print();
 511     printf("out %s\n", FormatMoney(pblock->vtx[1].GetValueOut()).c_str());
 512
 513     // Found a solution
 514     {
 515         LOCK(cs_main);
 516         if (pblock->hashPrevBlock != hashBestChain)
 517             return error("CheckStake() : generated block is stale");
 518
 519         // Track how many getdata requests this block gets
 520         {
 521             LOCK(wallet.cs_wallet);
 522             wallet.mapRequestCount[hashBlock] = 0;
 523         }
 524
 525         // Process this block the same as if we had received it from another node
 526         if (!ProcessBlock(NULL, pblock))
 527             return error("CheckStake() : ProcessBlock, block not accepted");
 528     }
 529
 530     return true;
 531 }
 532
 533 // Precalculated SHA256 contexts and metadata
 534 // (txid, vout.n) => (kernel, (tx.nTime, nAmount))
 535 typedef std::map<std::pair<uint256, unsigned int>, std::pair<std::vector<unsigned char>, std::pair<uint32_t, uint64_t> > > MidstateMap;
 536
 537 // Fill the inputs map with precalculated contexts and metadata
 538 bool FillMap(CWallet *pwallet, uint32_t nUpperTime, MidstateMap &inputsMap)
 539 {
 540     // Choose coins to use
 541     int64_t nBalance = pwallet->GetBalance();
 542
 543     if (nBalance <= nReserveBalance)
 544         return false;
 545
 546     uint32_t nTime = GetAdjustedTime();
 547
 548     CTxDB txdb("r");
 549     {
 550         LOCK2(cs_main, pwallet->cs_wallet);
 551
 552         CoinsSet setCoins;
 553         int64_t nValueIn = 0;
 554         if (!pwallet->SelectCoinsSimple(nBalance - nReserveBalance, MIN_TX_FEE, MAX_MONEY, nUpperTime, nCoinbaseMaturity * 10, setCoins, nValueIn))
 555             return error("FillMap() : SelectCoinsSimple failed");
 556
 557         if (setCoins.empty())
 558             return false;
 559
 560         CBlock block;
 561         CTxIndex txindex;
 562
 563         for(CoinsSet::const_iterator pcoin = setCoins.begin(); pcoin != setCoins.end(); pcoin++)
 564         {
 565             pair<uint256, uint32_t> key = make_pair(pcoin->first->GetHash(), pcoin->second);
 566
 567             // Skip existent inputs
 568             if (inputsMap.find(key) != inputsMap.end())
 569                 continue;
 570
 571             // Trying to parse scriptPubKey
 572             txnouttype whichType;
 573             vector<valtype> vSolutions;
 574             if (!Solver(pcoin->first->vout[pcoin->second].scriptPubKey, whichType, vSolutions))
 575                 continue;
 576
 577             // Only support pay to public key and pay to address
 578             if (whichType != TX_PUBKEY && whichType != TX_PUBKEYHASH)
 579                 continue;
 580
 581             // Load transaction index item
 582             if (!txdb.ReadTxIndex(pcoin->first->GetHash(), txindex))
 583                 continue;
 584
 585             // Read block header
 586             if (!block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
 587                 continue;
 588
 589             // Only load coins meeting min age requirement
 590             if (nStakeMinAge + block.nTime > nTime - nMaxStakeSearchInterval)
 591                 continue;
 592
 593             // Get stake modifier
 594             uint64_t nStakeModifier = 0;
 595             if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
 596                 continue;
 597
 598             // Build static part of kernel
 599             CDataStream ssKernel(SER_GETHASH, 0);
 600             ssKernel << nStakeModifier;
 601             ssKernel << block.nTime << (txindex.pos.nTxPos - txindex.pos.nBlockPos) << pcoin->first->nTime << pcoin->second;
 602
 603             // (txid, vout.n) => (kernel, (tx.nTime, nAmount))
 604             inputsMap[key] = make_pair(std::vector<unsigned char>(ssKernel.begin(), ssKernel.end()), make_pair(pcoin->first->nTime, pcoin->first->vout[pcoin->second].nValue));
 605         }
 606
 607         nStakeInputsMapSize = inputsMap.size();
 608
 609         if (fDebug)
 610             printf("FillMap() : Map of %" PRIu64 " precalculated contexts has been created by stake miner\n", nStakeInputsMapSize);
 611     }
 612
 613     return true;
 614 }
 615
 616 // Scan inputs map in order to find a solution
 617 bool ScanMap(const MidstateMap &inputsMap, uint32_t nBits, MidstateMap::key_type &LuckyInput, std::pair<uint256, uint32_t> &solution)
 618 {
 619     static uint32_t nLastCoinStakeSearchTime = GetAdjustedTime(); // startup timestamp
 620     uint32_t nSearchTime = GetAdjustedTime();
 621
 622     if (inputsMap.size() > 0 && nSearchTime > nLastCoinStakeSearchTime)
 623     {
 624         // Scanning interval (begintime, endtime)
 625         std::pair<uint32_t, uint32_t> interval;
 626
 627         interval.first = nSearchTime;
 628         interval.second = nSearchTime - min(nSearchTime-nLastCoinStakeSearchTime, nMaxStakeSearchInterval);
 629
 630         // (txid, nout) => (kernel, (tx.nTime, nAmount))
 631         for(MidstateMap::const_iterator input = inputsMap.begin(); input != inputsMap.end(); input++)
 632         {
 633             unsigned char *kernel = (unsigned char *) &input->second.first[0];
 634
 635             // scan(State, Bits, Time, Amount, ...)
 636             if (ScanKernelBackward(kernel, nBits, input->second.second.first, input->second.second.second, interval, solution))
 637             {
 638                 // Solution found
 639                 LuckyInput = input->first; // (txid, nout)
 640
 641                 return true;
 642             }
 643         }
 644
 645         // Inputs map iteration can be big enough to consume few seconds while scanning.
 646         // We're using dynamical calculation of scanning interval in order to compensate this delay.
 647         nLastCoinStakeSearchInterval = nSearchTime - nLastCoinStakeSearchTime;
 648         nLastCoinStakeSearchTime = nSearchTime;
 649     }
 650
 651     // No solutions were found
 652     return false;
 653 }
 654
 655 // Stake miner thread
 656 void ThreadStakeMiner(void* parg)
 657 {
 658     SetThreadPriority(THREAD_PRIORITY_LOWEST);
 659
 660     // Make this thread recognisable as the mining thread
 661     RenameThread("novacoin-miner");
 662     CWallet* pwallet = (CWallet*)parg;
 663
 664     MidstateMap inputsMap;
 665     if (!FillMap(pwallet, GetAdjustedTime(), inputsMap))
 666         return;
 667
 668     bool fTrySync = true;
 669
 670     CBlockIndex* pindexPrev = pindexBest;
 671     uint32_t nBits = GetNextTargetRequired(pindexPrev, true);
 672
 673     printf("ThreadStakeMinter started\n");
 674
 675     try
 676     {
 677         vnThreadsRunning[THREAD_MINTER]++;
 678
 679         MidstateMap::key_type LuckyInput;
 680         std::pair<uint256, uint32_t> solution;
 681
 682         // Main miner loop
 683         do
 684         {
 685             if (fShutdown)
 686                 goto _endloop;
 687
 688             while (pwallet->IsLocked())
 689             {
 690                 Sleep(1000);
 691                 if (fShutdown)
 692                     goto _endloop; // Don't be afraid to use a goto if that's the best option.
 693             }
 694
 695             while (vNodes.empty() || IsInitialBlockDownload())
 696             {
 697                 fTrySync = true;
 698
 699                 Sleep(1000);
 700                 if (fShutdown)
 701                     goto _endloop;
 702             }
 703
 704             if (fTrySync)
 705             {
 706                 // Don't try mine blocks unless we're at the top of chain and have at least three p2p connections.
 707                 fTrySync = false;
 708                 if (vNodes.size() < 3 || nBestHeight < GetNumBlocksOfPeers())
 709                 {
 710                     Sleep(1000);
 711                     continue;
 712                 }
 713             }
 714
 715             if (ScanMap(inputsMap, nBits, LuckyInput, solution))
 716             {
 717                 SetThreadPriority(THREAD_PRIORITY_NORMAL);
 718
 719                 // Remove lucky input from the map
 720                 inputsMap.erase(inputsMap.find(LuckyInput));
 721
 722                 CKey key;
 723                 CTransaction txCoinStake;
 724
 725                 // Create new coinstake transaction
 726                 if (!pwallet->CreateCoinStake(LuckyInput.first, LuckyInput.second, solution.second, nBits, txCoinStake, key))
 727                 {
 728                     string strMessage = _("Warning: Unable to create coinstake transaction, see debug.log for the details. Mining thread has been stopped.");
 729                     strMiscWarning = strMessage;
 730                     printf("*** %s\n", strMessage.c_str());
 731
 732                     break;
 733                 }
 734
 735                 // Now we have new coinstake, it's time to create the block ...
 736                 CBlock* pblock;
 737                 pblock = CreateNewBlock(pwallet, &txCoinStake);
 738                 if (!pblock)
 739                 {
 740                     string strMessage = _("Warning: Unable to allocate memory for the new block object. Mining thread has been stopped.");
 741                     strMiscWarning = strMessage;
 742                     printf("*** %s\n", strMessage.c_str());
 743
 744                     break;
 745                 }
 746
 747                 unsigned int nExtraNonce = 0;
 748                 IncrementExtraNonce(pblock, pindexPrev, nExtraNonce);
 749
 750                 // ... and sign it
 751                 if (!key.Sign(pblock->GetHash(), pblock->vchBlockSig))
 752                 {
 753                     string strMessage = _("Warning: Proof-of-Stake miner is unable to sign the block (locked wallet?). Mining thread has been stopped.");
 754                     strMiscWarning = strMessage;
 755                     printf("*** %s\n", strMessage.c_str());
 756
 757                     break;
 758                 }
 759
 760                 CheckStake(pblock, *pwallet);
 761                 SetThreadPriority(THREAD_PRIORITY_LOWEST);
 762                 Sleep(500);
 763             }
 764
 765             if (pindexPrev != pindexBest)
 766             {
 767                 // The best block has been changed, we need to refill the map
 768                 if (FillMap(pwallet, GetAdjustedTime(), inputsMap))
 769                 {
 770                     pindexPrev = pindexBest;
 771                     nBits = GetNextTargetRequired(pindexPrev, true);
 772                 }
 773                 else
 774                 {
 775                     // Clear existent data if FillMap failed
 776                     inputsMap.clear();
 777                 }
 778             }
 779
 780             Sleep(500);
 781
 782             _endloop:
 783                 (void)0; // do nothing
 784         }
 785         while(!fShutdown);
 786
 787         vnThreadsRunning[THREAD_MINTER]--;
 788     }
 789     catch (std::exception& e) {
 790         vnThreadsRunning[THREAD_MINTER]--;
 791         PrintException(&e, "ThreadStakeMinter()");
 792     } catch (...) {
 793         vnThreadsRunning[THREAD_MINTER]--;
 794         PrintException(NULL, "ThreadStakeMinter()");
 795     }
 796     printf("ThreadStakeMinter exiting, %d threads remaining\n", vnThreadsRunning[THREAD_MINTER]);
 797 }