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