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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <node/miner.h>
#include <chain.h>
#include <chainparams.h>
#include <coins.h>
#include <consensus/amount.h>
#include <consensus/consensus.h>
#include <consensus/merkle.h>
#include <consensus/tx_verify.h>
#include <consensus/validation.h>
#include <deploymentstatus.h>
#include <policy/feerate.h>
#include <policy/policy.h>
#include <pow.h>
#include <primitives/transaction.h>
#include <timedata.h>
#include <util/moneystr.h>
#include <util/system.h>
#include <validation.h>
#include <algorithm>
#include <utility>
namespace node {
int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
{
int64_t nOldTime = pblock->nTime;
int64_t nNewTime = std::max(pindexPrev->GetMedianTimePast() + 1, GetAdjustedTime());
if (nOldTime < nNewTime) {
pblock->nTime = nNewTime;
}
// Updating time can change work required on testnet:
if (consensusParams.fPowAllowMinDifficultyBlocks) {
pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
}
return nNewTime - nOldTime;
}
void RegenerateCommitments(CBlock& block, ChainstateManager& chainman)
{
CMutableTransaction tx{*block.vtx.at(0)};
tx.vout.erase(tx.vout.begin() + GetWitnessCommitmentIndex(block));
block.vtx.at(0) = MakeTransactionRef(tx);
const CBlockIndex* prev_block = WITH_LOCK(::cs_main, return chainman.m_blockman.LookupBlockIndex(block.hashPrevBlock));
chainman.GenerateCoinbaseCommitment(block, prev_block);
block.hashMerkleRoot = BlockMerkleRoot(block);
}
BlockAssembler::Options::Options()
{
blockMinFeeRate = CFeeRate(DEFAULT_BLOCK_MIN_TX_FEE);
nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
}
BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool, const Options& options)
: chainparams{chainstate.m_chainman.GetParams()},
m_mempool(mempool),
m_chainstate(chainstate)
{
blockMinFeeRate = options.blockMinFeeRate;
// Limit weight to between 4K and MAX_BLOCK_WEIGHT-4K for sanity:
nBlockMaxWeight = std::max<size_t>(4000, std::min<size_t>(MAX_BLOCK_WEIGHT - 4000, options.nBlockMaxWeight));
}
static BlockAssembler::Options DefaultOptions()
{
// Block resource limits
// If -blockmaxweight is not given, limit to DEFAULT_BLOCK_MAX_WEIGHT
BlockAssembler::Options options;
options.nBlockMaxWeight = gArgs.GetIntArg("-blockmaxweight", DEFAULT_BLOCK_MAX_WEIGHT);
if (gArgs.IsArgSet("-blockmintxfee")) {
std::optional<CAmount> parsed = ParseMoney(gArgs.GetArg("-blockmintxfee", ""));
options.blockMinFeeRate = CFeeRate{parsed.value_or(DEFAULT_BLOCK_MIN_TX_FEE)};
} else {
options.blockMinFeeRate = CFeeRate{DEFAULT_BLOCK_MIN_TX_FEE};
}
return options;
}
BlockAssembler::BlockAssembler(CChainState& chainstate, const CTxMemPool& mempool)
: BlockAssembler(chainstate, mempool, DefaultOptions()) {}
void BlockAssembler::resetBlock()
{
inBlock.clear();
// Reserve space for coinbase tx
nBlockWeight = 4000;
nBlockSigOpsCost = 400;
// These counters do not include coinbase tx
nBlockTx = 0;
nFees = 0;
}
std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
{
int64_t nTimeStart = GetTimeMicros();
resetBlock();
pblocktemplate.reset(new CBlockTemplate());
if (!pblocktemplate.get()) {
return nullptr;
}
CBlock* const pblock = &pblocktemplate->block; // pointer for convenience
// Add dummy coinbase tx as first transaction
pblock->vtx.emplace_back();
pblocktemplate->vTxFees.push_back(-1); // updated at end
pblocktemplate->vTxSigOpsCost.push_back(-1); // updated at end
LOCK2(cs_main, m_mempool.cs);
CBlockIndex* pindexPrev = m_chainstate.m_chain.Tip();
assert(pindexPrev != nullptr);
nHeight = pindexPrev->nHeight + 1;
pblock->nVersion = m_chainstate.m_chainman.m_versionbitscache.ComputeBlockVersion(pindexPrev, chainparams.GetConsensus());
// -regtest only: allow overriding block.nVersion with
// -blockversion=N to test forking scenarios
if (chainparams.MineBlocksOnDemand()) {
pblock->nVersion = gArgs.GetIntArg("-blockversion", pblock->nVersion);
}
pblock->nTime = GetAdjustedTime();
m_lock_time_cutoff = pindexPrev->GetMedianTimePast();
int nPackagesSelected = 0;
int nDescendantsUpdated = 0;
addPackageTxs(nPackagesSelected, nDescendantsUpdated);
int64_t nTime1 = GetTimeMicros();
m_last_block_num_txs = nBlockTx;
m_last_block_weight = nBlockWeight;
// Create coinbase transaction.
CMutableTransaction coinbaseTx;
coinbaseTx.vin.resize(1);
coinbaseTx.vin[0].prevout.SetNull();
coinbaseTx.vout.resize(1);
coinbaseTx.vout[0].scriptPubKey = scriptPubKeyIn;
coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx));
pblocktemplate->vchCoinbaseCommitment = m_chainstate.m_chainman.GenerateCoinbaseCommitment(*pblock, pindexPrev);
pblocktemplate->vTxFees[0] = -nFees;
LogPrintf("CreateNewBlock(): block weight: %u txs: %u fees: %ld sigops %d\n", GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost);
// Fill in header
pblock->hashPrevBlock = pindexPrev->GetBlockHash();
UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, chainparams.GetConsensus());
pblock->nNonce = 0;
pblocktemplate->vTxSigOpsCost[0] = WITNESS_SCALE_FACTOR * GetLegacySigOpCount(*pblock->vtx[0]);
BlockValidationState state;
if (!TestBlockValidity(state, chainparams, m_chainstate, *pblock, pindexPrev, GetAdjustedTime, false, false)) {
throw std::runtime_error(strprintf("%s: TestBlockValidity failed: %s", __func__, state.ToString()));
}
int64_t nTime2 = GetTimeMicros();
LogPrint(BCLog::BENCH, "CreateNewBlock() packages: %.2fms (%d packages, %d updated descendants), validity: %.2fms (total %.2fms)\n", 0.001 * (nTime1 - nTimeStart), nPackagesSelected, nDescendantsUpdated, 0.001 * (nTime2 - nTime1), 0.001 * (nTime2 - nTimeStart));
return std::move(pblocktemplate);
}
void BlockAssembler::onlyUnconfirmed(CTxMemPool::setEntries& testSet)
{
for (CTxMemPool::setEntries::iterator iit = testSet.begin(); iit != testSet.end(); ) {
// Only test txs not already in the block
if (inBlock.count(*iit)) {
testSet.erase(iit++);
} else {
iit++;
}
}
}
bool BlockAssembler::TestPackage(uint64_t packageSize, int64_t packageSigOpsCost) const
{
// TODO: switch to weight-based accounting for packages instead of vsize-based accounting.
if (nBlockWeight + WITNESS_SCALE_FACTOR * packageSize >= nBlockMaxWeight) {
return false;
}
if (nBlockSigOpsCost + packageSigOpsCost >= MAX_BLOCK_SIGOPS_COST) {
return false;
}
return true;
}
// Perform transaction-level checks before adding to block:
// - transaction finality (locktime)
bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package) const
{
for (CTxMemPool::txiter it : package) {
if (!IsFinalTx(it->GetTx(), nHeight, m_lock_time_cutoff)) {
return false;
}
}
return true;
}
void BlockAssembler::AddToBlock(CTxMemPool::txiter iter)
{
pblocktemplate->block.vtx.emplace_back(iter->GetSharedTx());
pblocktemplate->vTxFees.push_back(iter->GetFee());
pblocktemplate->vTxSigOpsCost.push_back(iter->GetSigOpCost());
nBlockWeight += iter->GetTxWeight();
++nBlockTx;
nBlockSigOpsCost += iter->GetSigOpCost();
nFees += iter->GetFee();
inBlock.insert(iter);
bool fPrintPriority = gArgs.GetBoolArg("-printpriority", DEFAULT_PRINTPRIORITY);
if (fPrintPriority) {
LogPrintf("fee rate %s txid %s\n",
CFeeRate(iter->GetModifiedFee(), iter->GetTxSize()).ToString(),
iter->GetTx().GetHash().ToString());
}
}
int BlockAssembler::UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded,
indexed_modified_transaction_set &mapModifiedTx)
{
AssertLockHeld(m_mempool.cs);
int nDescendantsUpdated = 0;
for (CTxMemPool::txiter it : alreadyAdded) {
CTxMemPool::setEntries descendants;
m_mempool.CalculateDescendants(it, descendants);
// Insert all descendants (not yet in block) into the modified set
for (CTxMemPool::txiter desc : descendants) {
if (alreadyAdded.count(desc)) {
continue;
}
++nDescendantsUpdated;
modtxiter mit = mapModifiedTx.find(desc);
if (mit == mapModifiedTx.end()) {
CTxMemPoolModifiedEntry modEntry(desc);
modEntry.nSizeWithAncestors -= it->GetTxSize();
modEntry.nModFeesWithAncestors -= it->GetModifiedFee();
modEntry.nSigOpCostWithAncestors -= it->GetSigOpCost();
mapModifiedTx.insert(modEntry);
} else {
mapModifiedTx.modify(mit, update_for_parent_inclusion(it));
}
}
}
return nDescendantsUpdated;
}
// Skip entries in mapTx that are already in a block or are present
// in mapModifiedTx (which implies that the mapTx ancestor state is
// stale due to ancestor inclusion in the block)
// Also skip transactions that we've already failed to add. This can happen if
// we consider a transaction in mapModifiedTx and it fails: we can then
// potentially consider it again while walking mapTx. It's currently
// guaranteed to fail again, but as a belt-and-suspenders check we put it in
// failedTx and avoid re-evaluation, since the re-evaluation would be using
// cached size/sigops/fee values that are not actually correct.
bool BlockAssembler::SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set& mapModifiedTx, CTxMemPool::setEntries& failedTx)
{
AssertLockHeld(m_mempool.cs);
assert(it != m_mempool.mapTx.end());
return mapModifiedTx.count(it) || inBlock.count(it) || failedTx.count(it);
}
void BlockAssembler::SortForBlock(const CTxMemPool::setEntries& package, std::vector<CTxMemPool::txiter>& sortedEntries)
{
// Sort package by ancestor count
// If a transaction A depends on transaction B, then A's ancestor count
// must be greater than B's. So this is sufficient to validly order the
// transactions for block inclusion.
sortedEntries.clear();
sortedEntries.insert(sortedEntries.begin(), package.begin(), package.end());
std::sort(sortedEntries.begin(), sortedEntries.end(), CompareTxIterByAncestorCount());
}
// This transaction selection algorithm orders the mempool based
// on feerate of a transaction including all unconfirmed ancestors.
// Since we don't remove transactions from the mempool as we select them
// for block inclusion, we need an alternate method of updating the feerate
// of a transaction with its not-yet-selected ancestors as we go.
// This is accomplished by walking the in-mempool descendants of selected
// transactions and storing a temporary modified state in mapModifiedTxs.
// Each time through the loop, we compare the best transaction in
// mapModifiedTxs with the next transaction in the mempool to decide what
// transaction package to work on next.
void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpdated)
{
AssertLockHeld(m_mempool.cs);
// mapModifiedTx will store sorted packages after they are modified
// because some of their txs are already in the block
indexed_modified_transaction_set mapModifiedTx;
// Keep track of entries that failed inclusion, to avoid duplicate work
CTxMemPool::setEntries failedTx;
CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = m_mempool.mapTx.get<ancestor_score>().begin();
CTxMemPool::txiter iter;
// Limit the number of attempts to add transactions to the block when it is
// close to full; this is just a simple heuristic to finish quickly if the
// mempool has a lot of entries.
const int64_t MAX_CONSECUTIVE_FAILURES = 1000;
int64_t nConsecutiveFailed = 0;
while (mi != m_mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty()) {
// First try to find a new transaction in mapTx to evaluate.
if (mi != m_mempool.mapTx.get<ancestor_score>().end() &&
SkipMapTxEntry(m_mempool.mapTx.project<0>(mi), mapModifiedTx, failedTx)) {
++mi;
continue;
}
// Now that mi is not stale, determine which transaction to evaluate:
// the next entry from mapTx, or the best from mapModifiedTx?
bool fUsingModified = false;
modtxscoreiter modit = mapModifiedTx.get<ancestor_score>().begin();
if (mi == m_mempool.mapTx.get<ancestor_score>().end()) {
// We're out of entries in mapTx; use the entry from mapModifiedTx
iter = modit->iter;
fUsingModified = true;
} else {
// Try to compare the mapTx entry to the mapModifiedTx entry
iter = m_mempool.mapTx.project<0>(mi);
if (modit != mapModifiedTx.get<ancestor_score>().end() &&
CompareTxMemPoolEntryByAncestorFee()(*modit, CTxMemPoolModifiedEntry(iter))) {
// The best entry in mapModifiedTx has higher score
// than the one from mapTx.
// Switch which transaction (package) to consider
iter = modit->iter;
fUsingModified = true;
} else {
// Either no entry in mapModifiedTx, or it's worse than mapTx.
// Increment mi for the next loop iteration.
++mi;
}
}
// We skip mapTx entries that are inBlock, and mapModifiedTx shouldn't
// contain anything that is inBlock.
assert(!inBlock.count(iter));
uint64_t packageSize = iter->GetSizeWithAncestors();
CAmount packageFees = iter->GetModFeesWithAncestors();
int64_t packageSigOpsCost = iter->GetSigOpCostWithAncestors();
if (fUsingModified) {
packageSize = modit->nSizeWithAncestors;
packageFees = modit->nModFeesWithAncestors;
packageSigOpsCost = modit->nSigOpCostWithAncestors;
}
if (packageFees < blockMinFeeRate.GetFee(packageSize)) {
// Everything else we might consider has a lower fee rate
return;
}
if (!TestPackage(packageSize, packageSigOpsCost)) {
if (fUsingModified) {
// Since we always look at the best entry in mapModifiedTx,
// we must erase failed entries so that we can consider the
// next best entry on the next loop iteration
mapModifiedTx.get<ancestor_score>().erase(modit);
failedTx.insert(iter);
}
++nConsecutiveFailed;
if (nConsecutiveFailed > MAX_CONSECUTIVE_FAILURES && nBlockWeight >
nBlockMaxWeight - 4000) {
// Give up if we're close to full and haven't succeeded in a while
break;
}
continue;
}
CTxMemPool::setEntries ancestors;
uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
std::string dummy;
m_mempool.CalculateMemPoolAncestors(*iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
onlyUnconfirmed(ancestors);
ancestors.insert(iter);
// Test if all tx's are Final
if (!TestPackageTransactions(ancestors)) {
if (fUsingModified) {
mapModifiedTx.get<ancestor_score>().erase(modit);
failedTx.insert(iter);
}
continue;
}
// This transaction will make it in; reset the failed counter.
nConsecutiveFailed = 0;
// Package can be added. Sort the entries in a valid order.
std::vector<CTxMemPool::txiter> sortedEntries;
SortForBlock(ancestors, sortedEntries);
for (size_t i = 0; i < sortedEntries.size(); ++i) {
AddToBlock(sortedEntries[i]);
// Erase from the modified set, if present
mapModifiedTx.erase(sortedEntries[i]);
}
++nPackagesSelected;
// Update transactions that depend on each of these
nDescendantsUpdated += UpdatePackagesForAdded(ancestors, mapModifiedTx);
}
}
} // namespace node
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