miner.cpp
1 // Copyright (c) 2009-2010 Satoshi Nakamoto 2 // Copyright (c) 2009-present 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 <node/miner.h> 7 8 #include <chain.h> 9 #include <chainparams.h> 10 #include <coins.h> 11 #include <common/args.h> 12 #include <consensus/amount.h> 13 #include <consensus/consensus.h> 14 #include <consensus/merkle.h> 15 #include <consensus/tx_verify.h> 16 #include <consensus/validation.h> 17 #include <deploymentstatus.h> 18 #include <logging.h> 19 #include <node/context.h> 20 #include <node/kernel_notifications.h> 21 #include <policy/feerate.h> 22 #include <policy/policy.h> 23 #include <pow.h> 24 #include <primitives/transaction.h> 25 #include <util/moneystr.h> 26 #include <util/signalinterrupt.h> 27 #include <util/time.h> 28 #include <validation.h> 29 30 #include <algorithm> 31 #include <utility> 32 #include <numeric> 33 34 namespace node { 35 36 int64_t GetMinimumTime(const CBlockIndex* pindexPrev, const int64_t difficulty_adjustment_interval) 37 { 38 int64_t min_time{pindexPrev->GetMedianTimePast() + 1}; 39 // Height of block to be mined. 40 const int height{pindexPrev->nHeight + 1}; 41 // Account for BIP94 timewarp rule on all networks. This makes future 42 // activation safer. 43 if (height % difficulty_adjustment_interval == 0) { 44 min_time = std::max<int64_t>(min_time, pindexPrev->GetBlockTime() - MAX_TIMEWARP); 45 } 46 return min_time; 47 } 48 49 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev) 50 { 51 int64_t nOldTime = pblock->nTime; 52 int64_t nNewTime{std::max<int64_t>(GetMinimumTime(pindexPrev, consensusParams.DifficultyAdjustmentInterval()), 53 TicksSinceEpoch<std::chrono::seconds>(NodeClock::now()))}; 54 55 if (nOldTime < nNewTime) { 56 pblock->nTime = nNewTime; 57 } 58 59 // Updating time can change work required on testnet: 60 if (consensusParams.fPowAllowMinDifficultyBlocks) { 61 pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams); 62 } 63 64 return nNewTime - nOldTime; 65 } 66 67 void RegenerateCommitments(CBlock& block, ChainstateManager& chainman) 68 { 69 CMutableTransaction tx{*block.vtx.at(0)}; 70 tx.vout.erase(tx.vout.begin() + GetWitnessCommitmentIndex(block)); 71 block.vtx.at(0) = MakeTransactionRef(tx); 72 73 const CBlockIndex* prev_block = WITH_LOCK(::cs_main, return chainman.m_blockman.LookupBlockIndex(block.hashPrevBlock)); 74 chainman.GenerateCoinbaseCommitment(block, prev_block); 75 76 block.hashMerkleRoot = BlockMerkleRoot(block); 77 } 78 79 static BlockAssembler::Options ClampOptions(BlockAssembler::Options options) 80 { 81 // Apply DEFAULT_BLOCK_RESERVED_WEIGHT when the caller left it unset. 82 options.block_reserved_weight = std::clamp<size_t>(options.block_reserved_weight.value_or(DEFAULT_BLOCK_RESERVED_WEIGHT), MINIMUM_BLOCK_RESERVED_WEIGHT, MAX_BLOCK_WEIGHT); 83 options.coinbase_output_max_additional_sigops = std::clamp<size_t>(options.coinbase_output_max_additional_sigops, 0, MAX_BLOCK_SIGOPS_COST); 84 // Limit weight to between block_reserved_weight and MAX_BLOCK_WEIGHT for sanity: 85 // block_reserved_weight can safely exceed -blockmaxweight, but the rest of the block template will be empty. 86 options.nBlockMaxWeight = std::clamp<size_t>(options.nBlockMaxWeight, *options.block_reserved_weight, MAX_BLOCK_WEIGHT); 87 return options; 88 } 89 90 BlockAssembler::BlockAssembler(Chainstate& chainstate, const CTxMemPool* mempool, const Options& options) 91 : chainparams{chainstate.m_chainman.GetParams()}, 92 m_mempool{options.use_mempool ? mempool : nullptr}, 93 m_chainstate{chainstate}, 94 m_options{ClampOptions(options)} 95 { 96 } 97 98 void ApplyArgsManOptions(const ArgsManager& args, BlockAssembler::Options& options) 99 { 100 // Block resource limits 101 options.nBlockMaxWeight = args.GetIntArg("-blockmaxweight", options.nBlockMaxWeight); 102 if (const auto blockmintxfee{args.GetArg("-blockmintxfee")}) { 103 if (const auto parsed{ParseMoney(*blockmintxfee)}) options.blockMinFeeRate = CFeeRate{*parsed}; 104 } 105 options.print_modified_fee = args.GetBoolArg("-printpriority", options.print_modified_fee); 106 if (!options.block_reserved_weight) { 107 options.block_reserved_weight = args.GetIntArg("-blockreservedweight"); 108 } 109 } 110 111 void BlockAssembler::resetBlock() 112 { 113 // Reserve space for fixed-size block header, txs count, and coinbase tx. 114 nBlockWeight = *Assert(m_options.block_reserved_weight); 115 nBlockSigOpsCost = m_options.coinbase_output_max_additional_sigops; 116 117 // These counters do not include coinbase tx 118 nBlockTx = 0; 119 nFees = 0; 120 } 121 122 std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock() 123 { 124 const auto time_start{SteadyClock::now()}; 125 126 resetBlock(); 127 128 pblocktemplate.reset(new CBlockTemplate()); 129 CBlock* const pblock = &pblocktemplate->block; // pointer for convenience 130 131 // Add dummy coinbase tx as first transaction. It is skipped by the 132 // getblocktemplate RPC and mining interface consumers must not use it. 133 pblock->vtx.emplace_back(); 134 135 LOCK(::cs_main); 136 CBlockIndex* pindexPrev = m_chainstate.m_chain.Tip(); 137 assert(pindexPrev != nullptr); 138 nHeight = pindexPrev->nHeight + 1; 139 140 pblock->nVersion = m_chainstate.m_chainman.m_versionbitscache.ComputeBlockVersion(pindexPrev, chainparams.GetConsensus()); 141 // -regtest only: allow overriding block.nVersion with 142 // -blockversion=N to test forking scenarios 143 if (chainparams.MineBlocksOnDemand()) { 144 pblock->nVersion = gArgs.GetIntArg("-blockversion", pblock->nVersion); 145 } 146 147 pblock->nTime = TicksSinceEpoch<std::chrono::seconds>(NodeClock::now()); 148 m_lock_time_cutoff = pindexPrev->GetMedianTimePast(); 149 150 if (m_mempool) { 151 LOCK(m_mempool->cs); 152 m_mempool->StartBlockBuilding(); 153 addChunks(); 154 m_mempool->StopBlockBuilding(); 155 } 156 157 const auto time_1{SteadyClock::now()}; 158 159 m_last_block_num_txs = nBlockTx; 160 m_last_block_weight = nBlockWeight; 161 162 // Create coinbase transaction. 163 CMutableTransaction coinbaseTx; 164 165 // Construct coinbase transaction struct in parallel 166 CoinbaseTx& coinbase_tx{pblocktemplate->m_coinbase_tx}; 167 coinbase_tx.version = coinbaseTx.version; 168 169 coinbaseTx.vin.resize(1); 170 coinbaseTx.vin[0].prevout.SetNull(); 171 coinbaseTx.vin[0].nSequence = CTxIn::MAX_SEQUENCE_NONFINAL; // Make sure timelock is enforced. 172 coinbase_tx.sequence = coinbaseTx.vin[0].nSequence; 173 174 // Add an output that spends the full coinbase reward. 175 coinbaseTx.vout.resize(1); 176 coinbaseTx.vout[0].scriptPubKey = m_options.coinbase_output_script; 177 // Block subsidy + fees 178 const CAmount block_reward{nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus())}; 179 coinbaseTx.vout[0].nValue = block_reward; 180 coinbase_tx.block_reward_remaining = block_reward; 181 182 // Start the coinbase scriptSig with the block height as required by BIP34. 183 // Mining clients are expected to append extra data to this prefix, so 184 // increasing its length would reduce the space they can use and may break 185 // existing clients. 186 coinbaseTx.vin[0].scriptSig = CScript() << nHeight; 187 if (m_options.include_dummy_extranonce) { 188 // For blocks at heights <= 16, the BIP34-encoded height alone is only 189 // one byte. Consensus requires coinbase scriptSigs to be at least two 190 // bytes long (bad-cb-length), so tests and regtest include a dummy 191 // extraNonce (OP_0) 192 coinbaseTx.vin[0].scriptSig << OP_0; 193 } 194 coinbase_tx.script_sig_prefix = coinbaseTx.vin[0].scriptSig; 195 Assert(nHeight > 0); 196 coinbaseTx.nLockTime = static_cast<uint32_t>(nHeight - 1); 197 coinbase_tx.lock_time = coinbaseTx.nLockTime; 198 199 pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx)); 200 m_chainstate.m_chainman.GenerateCoinbaseCommitment(*pblock, pindexPrev); 201 202 const CTransactionRef& final_coinbase{pblock->vtx[0]}; 203 if (final_coinbase->HasWitness()) { 204 const auto& witness_stack{final_coinbase->vin[0].scriptWitness.stack}; 205 // Consensus requires the coinbase witness stack to have exactly one 206 // element of 32 bytes. 207 Assert(witness_stack.size() == 1 && witness_stack[0].size() == 32); 208 coinbase_tx.witness = uint256(witness_stack[0]); 209 } 210 if (const int witness_index = GetWitnessCommitmentIndex(*pblock); witness_index != NO_WITNESS_COMMITMENT) { 211 Assert(witness_index >= 0 && static_cast<size_t>(witness_index) < final_coinbase->vout.size()); 212 coinbase_tx.required_outputs.push_back(final_coinbase->vout[witness_index]); 213 } 214 215 LogInfo("CreateNewBlock(): block weight: %u txs: %u fees: %ld sigops %d\n", GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost); 216 217 // Fill in header 218 pblock->hashPrevBlock = pindexPrev->GetBlockHash(); 219 UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev); 220 pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, chainparams.GetConsensus()); 221 pblock->nNonce = 0; 222 223 if (m_options.test_block_validity) { 224 // if nHeight <= 16, and include_dummy_extranonce=false this will fail due to bad-cb-length. 225 if (BlockValidationState state{TestBlockValidity(m_chainstate, *pblock, /*check_pow=*/false, /*check_merkle_root=*/false)}; !state.IsValid()) { 226 throw std::runtime_error(strprintf("TestBlockValidity failed: %s", state.ToString())); 227 } 228 } 229 const auto time_2{SteadyClock::now()}; 230 231 LogDebug(BCLog::BENCH, "CreateNewBlock() chunks: %.2fms, validity: %.2fms (total %.2fms)\n", 232 Ticks<MillisecondsDouble>(time_1 - time_start), 233 Ticks<MillisecondsDouble>(time_2 - time_1), 234 Ticks<MillisecondsDouble>(time_2 - time_start)); 235 236 return std::move(pblocktemplate); 237 } 238 239 bool BlockAssembler::TestChunkBlockLimits(FeePerWeight chunk_feerate, int64_t chunk_sigops_cost) const 240 { 241 if (nBlockWeight + chunk_feerate.size >= m_options.nBlockMaxWeight) { 242 return false; 243 } 244 if (nBlockSigOpsCost + chunk_sigops_cost >= MAX_BLOCK_SIGOPS_COST) { 245 return false; 246 } 247 return true; 248 } 249 250 // Perform transaction-level checks before adding to block: 251 // - transaction finality (locktime) 252 bool BlockAssembler::TestChunkTransactions(const std::vector<CTxMemPoolEntryRef>& txs) const 253 { 254 for (const auto tx : txs) { 255 if (!IsFinalTx(tx.get().GetTx(), nHeight, m_lock_time_cutoff)) { 256 return false; 257 } 258 } 259 return true; 260 } 261 262 void BlockAssembler::AddToBlock(const CTxMemPoolEntry& entry) 263 { 264 pblocktemplate->block.vtx.emplace_back(entry.GetSharedTx()); 265 pblocktemplate->vTxFees.push_back(entry.GetFee()); 266 pblocktemplate->vTxSigOpsCost.push_back(entry.GetSigOpCost()); 267 nBlockWeight += entry.GetTxWeight(); 268 ++nBlockTx; 269 nBlockSigOpsCost += entry.GetSigOpCost(); 270 nFees += entry.GetFee(); 271 272 if (m_options.print_modified_fee) { 273 LogInfo("fee rate %s txid %s\n", 274 CFeeRate(entry.GetModifiedFee(), entry.GetTxSize()).ToString(), 275 entry.GetTx().GetHash().ToString()); 276 } 277 } 278 279 void BlockAssembler::addChunks() 280 { 281 // Limit the number of attempts to add transactions to the block when it is 282 // close to full; this is just a simple heuristic to finish quickly if the 283 // mempool has a lot of entries. 284 const int64_t MAX_CONSECUTIVE_FAILURES = 1000; 285 constexpr int32_t BLOCK_FULL_ENOUGH_WEIGHT_DELTA = 4000; 286 int64_t nConsecutiveFailed = 0; 287 288 std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef> selected_transactions; 289 selected_transactions.reserve(MAX_CLUSTER_COUNT_LIMIT); 290 FeePerWeight chunk_feerate; 291 292 // This fills selected_transactions 293 chunk_feerate = m_mempool->GetBlockBuilderChunk(selected_transactions); 294 FeePerVSize chunk_feerate_vsize = ToFeePerVSize(chunk_feerate); 295 296 while (selected_transactions.size() > 0) { 297 // Check to see if min fee rate is still respected. 298 if (ByRatio{chunk_feerate_vsize} < ByRatio{m_options.blockMinFeeRate.GetFeePerVSize()}) { 299 // Everything else we might consider has a lower feerate 300 return; 301 } 302 303 int64_t chunk_sig_ops = 0; 304 for (const auto& tx : selected_transactions) { 305 chunk_sig_ops += tx.get().GetSigOpCost(); 306 } 307 308 // Check to see if this chunk will fit. 309 if (!TestChunkBlockLimits(chunk_feerate, chunk_sig_ops) || !TestChunkTransactions(selected_transactions)) { 310 // This chunk won't fit, so we skip it and will try the next best one. 311 m_mempool->SkipBuilderChunk(); 312 ++nConsecutiveFailed; 313 314 if (nConsecutiveFailed > MAX_CONSECUTIVE_FAILURES && nBlockWeight + 315 BLOCK_FULL_ENOUGH_WEIGHT_DELTA > m_options.nBlockMaxWeight) { 316 // Give up if we're close to full and haven't succeeded in a while 317 return; 318 } 319 } else { 320 m_mempool->IncludeBuilderChunk(); 321 322 // This chunk will fit, so add it to the block. 323 nConsecutiveFailed = 0; 324 for (const auto& tx : selected_transactions) { 325 AddToBlock(tx); 326 } 327 pblocktemplate->m_package_feerates.emplace_back(chunk_feerate_vsize); 328 } 329 330 selected_transactions.clear(); 331 chunk_feerate = m_mempool->GetBlockBuilderChunk(selected_transactions); 332 chunk_feerate_vsize = ToFeePerVSize(chunk_feerate); 333 } 334 } 335 336 void AddMerkleRootAndCoinbase(CBlock& block, CTransactionRef coinbase, uint32_t version, uint32_t timestamp, uint32_t nonce) 337 { 338 if (block.vtx.size() == 0) { 339 block.vtx.emplace_back(coinbase); 340 } else { 341 block.vtx[0] = coinbase; 342 } 343 block.nVersion = version; 344 block.nTime = timestamp; 345 block.nNonce = nonce; 346 block.hashMerkleRoot = BlockMerkleRoot(block); 347 348 // Reset cached checks 349 block.m_checked_witness_commitment = false; 350 block.m_checked_merkle_root = false; 351 block.fChecked = false; 352 } 353 354 void InterruptWait(KernelNotifications& kernel_notifications, bool& interrupt_wait) 355 { 356 LOCK(kernel_notifications.m_tip_block_mutex); 357 interrupt_wait = true; 358 kernel_notifications.m_tip_block_cv.notify_all(); 359 } 360 361 std::unique_ptr<CBlockTemplate> WaitAndCreateNewBlock(ChainstateManager& chainman, 362 KernelNotifications& kernel_notifications, 363 CTxMemPool* mempool, 364 const std::unique_ptr<CBlockTemplate>& block_template, 365 const BlockWaitOptions& options, 366 const BlockAssembler::Options& assemble_options, 367 bool& interrupt_wait) 368 { 369 // Delay calculating the current template fees, just in case a new block 370 // comes in before the next tick. 371 CAmount current_fees = -1; 372 373 // Alternate waiting for a new tip and checking if fees have risen. 374 // The latter check is expensive so we only run it once per second. 375 auto now{NodeClock::now()}; 376 const auto deadline = now + options.timeout; 377 const MillisecondsDouble tick{1000}; 378 const bool allow_min_difficulty{chainman.GetParams().GetConsensus().fPowAllowMinDifficultyBlocks}; 379 380 do { 381 bool tip_changed{false}; 382 { 383 WAIT_LOCK(kernel_notifications.m_tip_block_mutex, lock); 384 // Note that wait_until() checks the predicate before waiting 385 kernel_notifications.m_tip_block_cv.wait_until(lock, std::min(now + tick, deadline), [&]() EXCLUSIVE_LOCKS_REQUIRED(kernel_notifications.m_tip_block_mutex) { 386 AssertLockHeld(kernel_notifications.m_tip_block_mutex); 387 const auto tip_block{kernel_notifications.TipBlock()}; 388 // We assume tip_block is set, because this is an instance 389 // method on BlockTemplate and no template could have been 390 // generated before a tip exists. 391 tip_changed = Assume(tip_block) && tip_block != block_template->block.hashPrevBlock; 392 return tip_changed || chainman.m_interrupt || interrupt_wait; 393 }); 394 if (interrupt_wait) { 395 interrupt_wait = false; 396 return nullptr; 397 } 398 } 399 400 if (chainman.m_interrupt) return nullptr; 401 // At this point the tip changed, a full tick went by or we reached 402 // the deadline. 403 404 // Must release m_tip_block_mutex before locking cs_main, to avoid deadlocks. 405 LOCK(::cs_main); 406 407 // On test networks return a minimum difficulty block after 20 minutes 408 if (!tip_changed && allow_min_difficulty) { 409 const NodeClock::time_point tip_time{std::chrono::seconds{chainman.ActiveChain().Tip()->GetBlockTime()}}; 410 if (now > tip_time + 20min) { 411 tip_changed = true; 412 } 413 } 414 415 /** 416 * We determine if fees increased compared to the previous template by generating 417 * a fresh template. There may be more efficient ways to determine how much 418 * (approximate) fees for the next block increased, perhaps more so after 419 * Cluster Mempool. 420 * 421 * We'll also create a new template if the tip changed during this iteration. 422 */ 423 if (options.fee_threshold < MAX_MONEY || tip_changed) { 424 auto new_tmpl{BlockAssembler{ 425 chainman.ActiveChainstate(), 426 mempool, 427 assemble_options} 428 .CreateNewBlock()}; 429 430 // If the tip changed, return the new template regardless of its fees. 431 if (tip_changed) return new_tmpl; 432 433 // Calculate the original template total fees if we haven't already 434 if (current_fees == -1) { 435 current_fees = std::accumulate(block_template->vTxFees.begin(), block_template->vTxFees.end(), CAmount{0}); 436 } 437 438 // Check if fees increased enough to return the new template 439 const CAmount new_fees = std::accumulate(new_tmpl->vTxFees.begin(), new_tmpl->vTxFees.end(), CAmount{0}); 440 Assume(options.fee_threshold != MAX_MONEY); 441 if (new_fees >= current_fees + options.fee_threshold) return new_tmpl; 442 } 443 444 now = NodeClock::now(); 445 } while (now < deadline); 446 447 return nullptr; 448 } 449 450 std::optional<BlockRef> GetTip(ChainstateManager& chainman) 451 { 452 LOCK(::cs_main); 453 CBlockIndex* tip{chainman.ActiveChain().Tip()}; 454 if (!tip) return {}; 455 return BlockRef{tip->GetBlockHash(), tip->nHeight}; 456 } 457 458 bool CooldownIfHeadersAhead(ChainstateManager& chainman, KernelNotifications& kernel_notifications, const BlockRef& last_tip, bool& interrupt_mining) 459 { 460 uint256 last_tip_hash{last_tip.hash}; 461 462 while (const std::optional<int> remaining = chainman.BlocksAheadOfTip()) { 463 const int cooldown_seconds = std::clamp(*remaining, 3, 20); 464 const auto cooldown_deadline{MockableSteadyClock::now() + std::chrono::seconds{cooldown_seconds}}; 465 466 { 467 WAIT_LOCK(kernel_notifications.m_tip_block_mutex, lock); 468 kernel_notifications.m_tip_block_cv.wait_until(lock, cooldown_deadline, [&]() EXCLUSIVE_LOCKS_REQUIRED(kernel_notifications.m_tip_block_mutex) { 469 const auto tip_block = kernel_notifications.TipBlock(); 470 return chainman.m_interrupt || interrupt_mining || (tip_block && *tip_block != last_tip_hash); 471 }); 472 if (chainman.m_interrupt || interrupt_mining) { 473 interrupt_mining = false; 474 return false; 475 } 476 477 // If the tip changed during the wait, extend the deadline 478 const auto tip_block = kernel_notifications.TipBlock(); 479 if (tip_block && *tip_block != last_tip_hash) { 480 last_tip_hash = *tip_block; 481 continue; 482 } 483 } 484 485 // No tip change and the cooldown window has expired. 486 if (MockableSteadyClock::now() >= cooldown_deadline) break; 487 } 488 489 return true; 490 } 491 492 std::optional<BlockRef> WaitTipChanged(ChainstateManager& chainman, KernelNotifications& kernel_notifications, const uint256& current_tip, MillisecondsDouble& timeout, bool& interrupt) 493 { 494 Assume(timeout >= 0ms); // No internal callers should use a negative timeout 495 if (timeout < 0ms) timeout = 0ms; 496 if (timeout > std::chrono::years{100}) timeout = std::chrono::years{100}; // Upper bound to avoid UB in std::chrono 497 auto deadline{std::chrono::steady_clock::now() + timeout}; 498 { 499 WAIT_LOCK(kernel_notifications.m_tip_block_mutex, lock); 500 // For callers convenience, wait longer than the provided timeout 501 // during startup for the tip to be non-null. That way this function 502 // always returns valid tip information when possible and only 503 // returns null when shutting down, not when timing out. 504 kernel_notifications.m_tip_block_cv.wait(lock, [&]() EXCLUSIVE_LOCKS_REQUIRED(kernel_notifications.m_tip_block_mutex) { 505 return kernel_notifications.TipBlock() || chainman.m_interrupt || interrupt; 506 }); 507 if (chainman.m_interrupt || interrupt) { 508 interrupt = false; 509 return {}; 510 } 511 // At this point TipBlock is set, so continue to wait until it is 512 // different then `current_tip` provided by caller. 513 kernel_notifications.m_tip_block_cv.wait_until(lock, deadline, [&]() EXCLUSIVE_LOCKS_REQUIRED(kernel_notifications.m_tip_block_mutex) { 514 return Assume(kernel_notifications.TipBlock()) != current_tip || chainman.m_interrupt || interrupt; 515 }); 516 if (chainman.m_interrupt || interrupt) { 517 interrupt = false; 518 return {}; 519 } 520 } 521 522 // Must release m_tip_block_mutex before getTip() locks cs_main, to 523 // avoid deadlocks. 524 return GetTip(chainman); 525 } 526 527 } // namespace node