src/miner.cpp

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2015 The Bitcoin Core developers
   3 // Distributed under the MIT software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #include "miner.h"
   7
   8 #include "amount.h"
   9 #include "chain.h"
  10 #include "chainparams.h"
  11 #include "coins.h"
  12 #include "consensus/consensus.h"
  13 #include "consensus/merkle.h"
  14 #include "consensus/validation.h"
  15 #include "hash.h"
  16 #include "main.h"
  17 #include "net.h"
  18 #include "policy/policy.h"
  19 #include "pow.h"
  20 #include "primitives/transaction.h"
  21 #include "script/standard.h"
  22 #include "timedata.h"
  23 #include "txmempool.h"
  24 #include "util.h"
  25 #include "utilmoneystr.h"
  26 #include "validationinterface.h"
  27
  28 #include <algorithm>
  29 #include <boost/thread.hpp>
  30 #include <boost/tuple/tuple.hpp>
  31 #include <queue>
  32 #include <utility>
  33
  34 using namespace std;
  35
  36 //////////////////////////////////////////////////////////////////////////////
  37 //
  38 // BitcoinMiner
  39 //
  40
  41 //
  42 // Unconfirmed transactions in the memory pool often depend on other
  43 // transactions in the memory pool. When we select transactions from the
  44 // pool, we select by highest priority or fee rate, so we might consider
  45 // transactions that depend on transactions that aren't yet in the block.
  46
  47 uint64_t nLastBlockTx = 0;
  48 uint64_t nLastBlockSize = 0;
  49 uint64_t nLastBlockWeight = 0;
  50
  51 class ScoreCompare
  52 {
  53 public:
  54     ScoreCompare() {}
  55
  56     bool operator()(const CTxMemPool::txiter a, const CTxMemPool::txiter b)
  57     {
  58         return CompareTxMemPoolEntryByScore()(*b,*a); // Convert to less than
  59     }
  60 };
  61
  62 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
  63 {
  64     int64_t nOldTime = pblock->nTime;
  65     int64_t nNewTime = std::max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
  66
  67     if (nOldTime < nNewTime)
  68         pblock->nTime = nNewTime;
  69
  70     // Updating time can change work required on testnet:
  71     if (consensusParams.fPowAllowMinDifficultyBlocks)
  72         pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
  73
  74     return nNewTime - nOldTime;
  75 }
  76
  77 BlockAssembler::BlockAssembler(const CChainParams& _chainparams)
  78     : chainparams(_chainparams)
  79 {
  80     // Block resource limits
  81     // If neither -blockmaxsize or -blockmaxweight is given, limit to DEFAULT_BLOCK_MAX_*
  82     // If only one is given, only restrict the specified resource.
  83     // If both are given, restrict both.
  84     nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
  85     nBlockMaxSize = DEFAULT_BLOCK_MAX_SIZE;
  86     bool fWeightSet = false;
  87     if (mapArgs.count("-blockmaxweight")) {
  88         nBlockMaxWeight = GetArg("-blockmaxweight", DEFAULT_BLOCK_MAX_WEIGHT);
  89         nBlockMaxSize = MAX_BLOCK_SERIALIZED_SIZE;
  90         fWeightSet = true;
  91     }
  92     if (mapArgs.count("-blockmaxsize")) {
  93         nBlockMaxSize = GetArg("-blockmaxsize", DEFAULT_BLOCK_MAX_SIZE);
  94         if (!fWeightSet) {
  95             nBlockMaxWeight = nBlockMaxSize * WITNESS_SCALE_FACTOR;
  96         }
  97     }
  98
  99     // Limit weight to between 4K and MAX_BLOCK_WEIGHT-4K for sanity:
 100     nBlockMaxWeight = std::max((unsigned int)4000, std::min((unsigned int)(MAX_BLOCK_WEIGHT-4000), nBlockMaxWeight));
 101     // Limit size to between 1K and MAX_BLOCK_SERIALIZED_SIZE-1K for sanity:
 102     nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SERIALIZED_SIZE-1000), nBlockMaxSize));
 103
 104     // Whether we need to account for byte usage (in addition to weight usage)
 105     fNeedSizeAccounting = (nBlockMaxSize < MAX_BLOCK_SERIALIZED_SIZE-1000);
 106 }
 107
 108 void BlockAssembler::resetBlock()
 109 {
 110     inBlock.clear();
 111
 112     // Reserve space for coinbase tx
 113     nBlockSize = 1000;
 114     nBlockWeight = 4000;
 115     nBlockSigOpsCost = 400;
 116     fIncludeWitness = false;
 117
 118     // These counters do not include coinbase tx
 119     nBlockTx = 0;
 120     nFees = 0;
 121
 122     lastFewTxs = 0;
 123     blockFinished = false;
 124 }
 125
 126 std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
 127 {
 128     resetBlock();
 129
 130     pblocktemplate.reset(new CBlockTemplate());
 131
 132     if(!pblocktemplate.get())
 133         return nullptr;
 134     pblock = &pblocktemplate->block; // pointer for convenience
 135
 136     // Add dummy coinbase tx as first transaction
 137     pblock->vtx.push_back(CTransaction());
 138     pblocktemplate->vTxFees.push_back(-1); // updated at end
 139     pblocktemplate->vTxSigOpsCost.push_back(-1); // updated at end
 140
 141     LOCK2(cs_main, mempool.cs);
 142     CBlockIndex* pindexPrev = chainActive.Tip();
 143     nHeight = pindexPrev->nHeight + 1;
 144
 145     pblock->nVersion = ComputeBlockVersion(pindexPrev, chainparams.GetConsensus());
 146     // -regtest only: allow overriding block.nVersion with
 147     // -blockversion=N to test forking scenarios
 148     if (chainparams.MineBlocksOnDemand())
 149         pblock->nVersion = GetArg("-blockversion", pblock->nVersion);
 150
 151     pblock->nTime = GetAdjustedTime();
 152     const int64_t nMedianTimePast = pindexPrev->GetMedianTimePast();
 153
 154     nLockTimeCutoff = (STANDARD_LOCKTIME_VERIFY_FLAGS & LOCKTIME_MEDIAN_TIME_PAST)
 155                        ? nMedianTimePast
 156                        : pblock->GetBlockTime();
 157
 158     // Decide whether to include witness transactions
 159     // This is only needed in case the witness softfork activation is reverted
 160     // (which would require a very deep reorganization) or when
 161     // -promiscuousmempoolflags is used.
 162     // TODO: replace this with a call to main to assess validity of a mempool
 163     // transaction (which in most cases can be a no-op).
 164     fIncludeWitness = IsWitnessEnabled(pindexPrev, chainparams.GetConsensus());
 165
 166     addPriorityTxs();
 167     addPackageTxs();
 168
 169     nLastBlockTx = nBlockTx;
 170     nLastBlockSize = nBlockSize;
 171     nLastBlockWeight = nBlockWeight;
 172     LogPrintf("CreateNewBlock(): total size %u txs: %u fees: %ld sigops %d\n", nBlockSize, nBlockTx, nFees, nBlockSigOpsCost);
 173
 174     // Create coinbase transaction.
 175     CMutableTransaction coinbaseTx;
 176     coinbaseTx.vin.resize(1);
 177     coinbaseTx.vin[0].prevout.SetNull();
 178     coinbaseTx.vout.resize(1);
 179     coinbaseTx.vout[0].scriptPubKey = scriptPubKeyIn;
 180     coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
 181     coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
 182     pblock->vtx[0] = coinbaseTx;
 183     pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev, chainparams.GetConsensus());
 184     pblocktemplate->vTxFees[0] = -nFees;
 185
 186     // Fill in header
 187     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
 188     UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
 189     pblock->nBits          = GetNextWorkRequired(pindexPrev, pblock, chainparams.GetConsensus());
 190     pblock->nNonce         = 0;
 191     pblocktemplate->vTxSigOpsCost[0] = WITNESS_SCALE_FACTOR * GetLegacySigOpCount(pblock->vtx[0]);
 192
 193     CValidationState state;
 194     if (!TestBlockValidity(state, chainparams, *pblock, pindexPrev, false, false)) {
 195         throw std::runtime_error(strprintf("%s: TestBlockValidity failed: %s", __func__, FormatStateMessage(state)));
 196     }
 197
 198     return std::move(pblocktemplate);
 199 }
 200
 201 bool BlockAssembler::isStillDependent(CTxMemPool::txiter iter)
 202 {
 203     BOOST_FOREACH(CTxMemPool::txiter parent, mempool.GetMemPoolParents(iter))
 204     {
 205         if (!inBlock.count(parent)) {
 206             return true;
 207         }
 208     }
 209     return false;
 210 }
 211
 212 void BlockAssembler::onlyUnconfirmed(CTxMemPool::setEntries& testSet)
 213 {
 214     for (CTxMemPool::setEntries::iterator iit = testSet.begin(); iit != testSet.end(); ) {
 215         // Only test txs not already in the block
 216         if (inBlock.count(*iit)) {
 217             testSet.erase(iit++);
 218         }
 219         else {
 220             iit++;
 221         }
 222     }
 223 }
 224
 225 bool BlockAssembler::TestPackage(uint64_t packageSize, int64_t packageSigOpsCost)
 226 {
 227     // TODO: switch to weight-based accounting for packages instead of vsize-based accounting.
 228     if (nBlockWeight + WITNESS_SCALE_FACTOR * packageSize >= nBlockMaxWeight)
 229         return false;
 230     if (nBlockSigOpsCost + packageSigOpsCost >= MAX_BLOCK_SIGOPS_COST)
 231         return false;
 232     return true;
 233 }
 234
 235 // Perform transaction-level checks before adding to block:
 236 // - transaction finality (locktime)
 237 // - premature witness (in case segwit transactions are added to mempool before
 238 //   segwit activation)
 239 // - serialized size (in case -blockmaxsize is in use)
 240 bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package)
 241 {
 242     uint64_t nPotentialBlockSize = nBlockSize; // only used with fNeedSizeAccounting
 243     BOOST_FOREACH (const CTxMemPool::txiter it, package) {
 244         if (!IsFinalTx(it->GetTx(), nHeight, nLockTimeCutoff))
 245             return false;
 246         if (!fIncludeWitness && !it->GetTx().wit.IsNull())
 247             return false;
 248         if (fNeedSizeAccounting) {
 249             uint64_t nTxSize = ::GetSerializeSize(it->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
 250             if (nPotentialBlockSize + nTxSize >= nBlockMaxSize) {
 251                 return false;
 252             }
 253             nPotentialBlockSize += nTxSize;
 254         }
 255     }
 256     return true;
 257 }
 258
 259 bool BlockAssembler::TestForBlock(CTxMemPool::txiter iter)
 260 {
 261     if (nBlockWeight + iter->GetTxWeight() >= nBlockMaxWeight) {
 262         // If the block is so close to full that no more txs will fit
 263         // or if we've tried more than 50 times to fill remaining space
 264         // then flag that the block is finished
 265         if (nBlockWeight >  nBlockMaxWeight - 400 || lastFewTxs > 50) {
 266              blockFinished = true;
 267              return false;
 268         }
 269         // Once we're within 4000 weight of a full block, only look at 50 more txs
 270         // to try to fill the remaining space.
 271         if (nBlockWeight > nBlockMaxWeight - 4000) {
 272             lastFewTxs++;
 273         }
 274         return false;
 275     }
 276
 277     if (fNeedSizeAccounting) {
 278         if (nBlockSize + ::GetSerializeSize(iter->GetTx(), SER_NETWORK, PROTOCOL_VERSION) >= nBlockMaxSize) {
 279             if (nBlockSize >  nBlockMaxSize - 100 || lastFewTxs > 50) {
 280                  blockFinished = true;
 281                  return false;
 282             }
 283             if (nBlockSize > nBlockMaxSize - 1000) {
 284                 lastFewTxs++;
 285             }
 286             return false;
 287         }
 288     }
 289
 290     if (nBlockSigOpsCost + iter->GetSigOpCost() >= MAX_BLOCK_SIGOPS_COST) {
 291         // If the block has room for no more sig ops then
 292         // flag that the block is finished
 293         if (nBlockSigOpsCost > MAX_BLOCK_SIGOPS_COST - 8) {
 294             blockFinished = true;
 295             return false;
 296         }
 297         // Otherwise attempt to find another tx with fewer sigops
 298         // to put in the block.
 299         return false;
 300     }
 301
 302     // Must check that lock times are still valid
 303     // This can be removed once MTP is always enforced
 304     // as long as reorgs keep the mempool consistent.
 305     if (!IsFinalTx(iter->GetTx(), nHeight, nLockTimeCutoff))
 306         return false;
 307
 308     return true;
 309 }
 310
 311 void BlockAssembler::AddToBlock(CTxMemPool::txiter iter)
 312 {
 313     pblock->vtx.push_back(iter->GetTx());
 314     pblocktemplate->vTxFees.push_back(iter->GetFee());
 315     pblocktemplate->vTxSigOpsCost.push_back(iter->GetSigOpCost());
 316     if (fNeedSizeAccounting) {
 317         nBlockSize += ::GetSerializeSize(iter->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
 318     }
 319     nBlockWeight += iter->GetTxWeight();
 320     ++nBlockTx;
 321     nBlockSigOpsCost += iter->GetSigOpCost();
 322     nFees += iter->GetFee();
 323     inBlock.insert(iter);
 324
 325     bool fPrintPriority = GetBoolArg("-printpriority", DEFAULT_PRINTPRIORITY);
 326     if (fPrintPriority) {
 327         double dPriority = iter->GetPriority(nHeight);
 328         CAmount dummy;
 329         mempool.ApplyDeltas(iter->GetTx().GetHash(), dPriority, dummy);
 330         LogPrintf("priority %.1f fee %s txid %s\n",
 331                   dPriority,
 332                   CFeeRate(iter->GetModifiedFee(), iter->GetTxSize()).ToString(),
 333                   iter->GetTx().GetHash().ToString());
 334     }
 335 }
 336
 337 void BlockAssembler::UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded,
 338         indexed_modified_transaction_set &mapModifiedTx)
 339 {
 340     BOOST_FOREACH(const CTxMemPool::txiter it, alreadyAdded) {
 341         CTxMemPool::setEntries descendants;
 342         mempool.CalculateDescendants(it, descendants);
 343         // Insert all descendants (not yet in block) into the modified set
 344         BOOST_FOREACH(CTxMemPool::txiter desc, descendants) {
 345             if (alreadyAdded.count(desc))
 346                 continue;
 347             modtxiter mit = mapModifiedTx.find(desc);
 348             if (mit == mapModifiedTx.end()) {
 349                 CTxMemPoolModifiedEntry modEntry(desc);
 350                 modEntry.nSizeWithAncestors -= it->GetTxSize();
 351                 modEntry.nModFeesWithAncestors -= it->GetModifiedFee();
 352                 modEntry.nSigOpCostWithAncestors -= it->GetSigOpCost();
 353                 mapModifiedTx.insert(modEntry);
 354             } else {
 355                 mapModifiedTx.modify(mit, update_for_parent_inclusion(it));
 356             }
 357         }
 358     }
 359 }
 360
 361 // Skip entries in mapTx that are already in a block or are present
 362 // in mapModifiedTx (which implies that the mapTx ancestor state is
 363 // stale due to ancestor inclusion in the block)
 364 // Also skip transactions that we've already failed to add. This can happen if
 365 // we consider a transaction in mapModifiedTx and it fails: we can then
 366 // potentially consider it again while walking mapTx.  It's currently
 367 // guaranteed to fail again, but as a belt-and-suspenders check we put it in
 368 // failedTx and avoid re-evaluation, since the re-evaluation would be using
 369 // cached size/sigops/fee values that are not actually correct.
 370 bool BlockAssembler::SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set &mapModifiedTx, CTxMemPool::setEntries &failedTx)
 371 {
 372     assert (it != mempool.mapTx.end());
 373     if (mapModifiedTx.count(it) || inBlock.count(it) || failedTx.count(it))
 374         return true;
 375     return false;
 376 }
 377
 378 void BlockAssembler::SortForBlock(const CTxMemPool::setEntries& package, CTxMemPool::txiter entry, std::vector<CTxMemPool::txiter>& sortedEntries)
 379 {
 380     // Sort package by ancestor count
 381     // If a transaction A depends on transaction B, then A's ancestor count
 382     // must be greater than B's.  So this is sufficient to validly order the
 383     // transactions for block inclusion.
 384     sortedEntries.clear();
 385     sortedEntries.insert(sortedEntries.begin(), package.begin(), package.end());
 386     std::sort(sortedEntries.begin(), sortedEntries.end(), CompareTxIterByAncestorCount());
 387 }
 388
 389 // This transaction selection algorithm orders the mempool based
 390 // on feerate of a transaction including all unconfirmed ancestors.
 391 // Since we don't remove transactions from the mempool as we select them
 392 // for block inclusion, we need an alternate method of updating the feerate
 393 // of a transaction with its not-yet-selected ancestors as we go.
 394 // This is accomplished by walking the in-mempool descendants of selected
 395 // transactions and storing a temporary modified state in mapModifiedTxs.
 396 // Each time through the loop, we compare the best transaction in
 397 // mapModifiedTxs with the next transaction in the mempool to decide what
 398 // transaction package to work on next.
 399 void BlockAssembler::addPackageTxs()
 400 {
 401     // mapModifiedTx will store sorted packages after they are modified
 402     // because some of their txs are already in the block
 403     indexed_modified_transaction_set mapModifiedTx;
 404     // Keep track of entries that failed inclusion, to avoid duplicate work
 405     CTxMemPool::setEntries failedTx;
 406
 407     // Start by adding all descendants of previously added txs to mapModifiedTx
 408     // and modifying them for their already included ancestors
 409     UpdatePackagesForAdded(inBlock, mapModifiedTx);
 410
 411     CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx.get<ancestor_score>().begin();
 412     CTxMemPool::txiter iter;
 413     while (mi != mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty())
 414     {
 415         // First try to find a new transaction in mapTx to evaluate.
 416         if (mi != mempool.mapTx.get<ancestor_score>().end() &&
 417                 SkipMapTxEntry(mempool.mapTx.project<0>(mi), mapModifiedTx, failedTx)) {
 418             ++mi;
 419             continue;
 420         }
 421
 422         // Now that mi is not stale, determine which transaction to evaluate:
 423         // the next entry from mapTx, or the best from mapModifiedTx?
 424         bool fUsingModified = false;
 425
 426         modtxscoreiter modit = mapModifiedTx.get<ancestor_score>().begin();
 427         if (mi == mempool.mapTx.get<ancestor_score>().end()) {
 428             // We're out of entries in mapTx; use the entry from mapModifiedTx
 429             iter = modit->iter;
 430             fUsingModified = true;
 431         } else {
 432             // Try to compare the mapTx entry to the mapModifiedTx entry
 433             iter = mempool.mapTx.project<0>(mi);
 434             if (modit != mapModifiedTx.get<ancestor_score>().end() &&
 435                     CompareModifiedEntry()(*modit, CTxMemPoolModifiedEntry(iter))) {
 436                 // The best entry in mapModifiedTx has higher score
 437                 // than the one from mapTx.
 438                 // Switch which transaction (package) to consider
 439                 iter = modit->iter;
 440                 fUsingModified = true;
 441             } else {
 442                 // Either no entry in mapModifiedTx, or it's worse than mapTx.
 443                 // Increment mi for the next loop iteration.
 444                 ++mi;
 445             }
 446         }
 447
 448         // We skip mapTx entries that are inBlock, and mapModifiedTx shouldn't
 449         // contain anything that is inBlock.
 450         assert(!inBlock.count(iter));
 451
 452         uint64_t packageSize = iter->GetSizeWithAncestors();
 453         CAmount packageFees = iter->GetModFeesWithAncestors();
 454         int64_t packageSigOpsCost = iter->GetSigOpCostWithAncestors();
 455         if (fUsingModified) {
 456             packageSize = modit->nSizeWithAncestors;
 457             packageFees = modit->nModFeesWithAncestors;
 458             packageSigOpsCost = modit->nSigOpCostWithAncestors;
 459         }
 460
 461         if (packageFees < ::minRelayTxFee.GetFee(packageSize)) {
 462             // Everything else we might consider has a lower fee rate
 463             return;
 464         }
 465
 466         if (!TestPackage(packageSize, packageSigOpsCost)) {
 467             if (fUsingModified) {
 468                 // Since we always look at the best entry in mapModifiedTx,
 469                 // we must erase failed entries so that we can consider the
 470                 // next best entry on the next loop iteration
 471                 mapModifiedTx.get<ancestor_score>().erase(modit);
 472                 failedTx.insert(iter);
 473             }
 474             continue;
 475         }
 476
 477         CTxMemPool::setEntries ancestors;
 478         uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
 479         std::string dummy;
 480         mempool.CalculateMemPoolAncestors(*iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
 481
 482         onlyUnconfirmed(ancestors);
 483         ancestors.insert(iter);
 484
 485         // Test if all tx's are Final
 486         if (!TestPackageTransactions(ancestors)) {
 487             if (fUsingModified) {
 488                 mapModifiedTx.get<ancestor_score>().erase(modit);
 489                 failedTx.insert(iter);
 490             }
 491             continue;
 492         }
 493
 494         // Package can be added. Sort the entries in a valid order.
 495         vector<CTxMemPool::txiter> sortedEntries;
 496         SortForBlock(ancestors, iter, sortedEntries);
 497
 498         for (size_t i=0; i<sortedEntries.size(); ++i) {
 499             AddToBlock(sortedEntries[i]);
 500             // Erase from the modified set, if present
 501             mapModifiedTx.erase(sortedEntries[i]);
 502         }
 503
 504         // Update transactions that depend on each of these
 505         UpdatePackagesForAdded(ancestors, mapModifiedTx);
 506     }
 507 }
 508
 509 void BlockAssembler::addPriorityTxs()
 510 {
 511     // How much of the block should be dedicated to high-priority transactions,
 512     // included regardless of the fees they pay
 513     unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", DEFAULT_BLOCK_PRIORITY_SIZE);
 514     nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
 515
 516     if (nBlockPrioritySize == 0) {
 517         return;
 518     }
 519
 520     bool fSizeAccounting = fNeedSizeAccounting;
 521     fNeedSizeAccounting = true;
 522
 523     // This vector will be sorted into a priority queue:
 524     vector<TxCoinAgePriority> vecPriority;
 525     TxCoinAgePriorityCompare pricomparer;
 526     std::map<CTxMemPool::txiter, double, CTxMemPool::CompareIteratorByHash> waitPriMap;
 527     typedef std::map<CTxMemPool::txiter, double, CTxMemPool::CompareIteratorByHash>::iterator waitPriIter;
 528     double actualPriority = -1;
 529
 530     vecPriority.reserve(mempool.mapTx.size());
 531     for (CTxMemPool::indexed_transaction_set::iterator mi = mempool.mapTx.begin();
 532          mi != mempool.mapTx.end(); ++mi)
 533     {
 534         double dPriority = mi->GetPriority(nHeight);
 535         CAmount dummy;
 536         mempool.ApplyDeltas(mi->GetTx().GetHash(), dPriority, dummy);
 537         vecPriority.push_back(TxCoinAgePriority(dPriority, mi));
 538     }
 539     std::make_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 540
 541     CTxMemPool::txiter iter;
 542     while (!vecPriority.empty() && !blockFinished) { // add a tx from priority queue to fill the blockprioritysize
 543         iter = vecPriority.front().second;
 544         actualPriority = vecPriority.front().first;
 545         std::pop_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 546         vecPriority.pop_back();
 547
 548         // If tx already in block, skip
 549         if (inBlock.count(iter)) {
 550             assert(false); // shouldn't happen for priority txs
 551             continue;
 552         }
 553
 554         // cannot accept witness transactions into a non-witness block
 555         if (!fIncludeWitness && !iter->GetTx().wit.IsNull())
 556             continue;
 557
 558         // If tx is dependent on other mempool txs which haven't yet been included
 559         // then put it in the waitSet
 560         if (isStillDependent(iter)) {
 561             waitPriMap.insert(std::make_pair(iter, actualPriority));
 562             continue;
 563         }
 564
 565         // If this tx fits in the block add it, otherwise keep looping
 566         if (TestForBlock(iter)) {
 567             AddToBlock(iter);
 568
 569             // If now that this txs is added we've surpassed our desired priority size
 570             // or have dropped below the AllowFreeThreshold, then we're done adding priority txs
 571             if (nBlockSize >= nBlockPrioritySize || !AllowFree(actualPriority)) {
 572                 break;
 573             }
 574
 575             // This tx was successfully added, so
 576             // add transactions that depend on this one to the priority queue to try again
 577             BOOST_FOREACH(CTxMemPool::txiter child, mempool.GetMemPoolChildren(iter))
 578             {
 579                 waitPriIter wpiter = waitPriMap.find(child);
 580                 if (wpiter != waitPriMap.end()) {
 581                     vecPriority.push_back(TxCoinAgePriority(wpiter->second,child));
 582                     std::push_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 583                     waitPriMap.erase(wpiter);
 584                 }
 585             }
 586         }
 587     }
 588     fNeedSizeAccounting = fSizeAccounting;
 589 }
 590
 591 void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
 592 {
 593     // Update nExtraNonce
 594     static uint256 hashPrevBlock;
 595     if (hashPrevBlock != pblock->hashPrevBlock)
 596     {
 597         nExtraNonce = 0;
 598         hashPrevBlock = pblock->hashPrevBlock;
 599     }
 600     ++nExtraNonce;
 601     unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
 602     CMutableTransaction txCoinbase(pblock->vtx[0]);
 603     txCoinbase.vin[0].scriptSig = (CScript() << nHeight << CScriptNum(nExtraNonce)) + COINBASE_FLAGS;
 604     assert(txCoinbase.vin[0].scriptSig.size() <= 100);
 605
 606     pblock->vtx[0] = txCoinbase;
 607     pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
 608 }