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mining.go
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mining.go
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// Copyright (c) 2014-2016 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package main
import (
"container/heap"
"container/list"
"encoding/binary"
"fmt"
"math"
"sort"
"time"
"github.com/decred/dcrd/blockchain"
"github.com/decred/dcrd/blockchain/stake"
"github.com/decred/dcrd/chaincfg"
"github.com/decred/dcrd/chaincfg/chainhash"
"github.com/decred/dcrd/mempool"
"github.com/decred/dcrd/mining"
"github.com/decred/dcrd/txscript"
"github.com/decred/dcrd/wire"
"github.com/decred/dcrutil"
)
const (
// minHighPriority is the minimum priority value that allows a
// transaction to be considered high priority.
minHighPriority = dcrutil.AtomsPerCoin * 144.0 / 250
// generatedBlockVersion is the version of the block being generated.
// It is defined as a constant here rather than using the
// wire.BlockVersion constant since a change in the block version
// will require changes to the generated block. Using the wire constant
// for generated block version could allow creation of invalid blocks
// for the updated version.
generatedBlockVersion = 3
// blockHeaderOverhead is the max number of bytes it takes to serialize
// a block header and max possible transaction count.
blockHeaderOverhead = wire.MaxBlockHeaderPayload + wire.MaxVarIntPayload
// coinbaseFlags is some extra data appended to the coinbase script
// sig.
coinbaseFlags = "/dcrd/"
// kilobyte is the size of a kilobyte.
kilobyte = 1000
)
// txPrioItem houses a transaction along with extra information that allows the
// transaction to be prioritized and track dependencies on other transactions
// which have not been mined into a block yet.
type txPrioItem struct {
tx *dcrutil.Tx
txType stake.TxType
fee int64
priority float64
feePerKB float64
// dependsOn holds a map of transaction hashes which this one depends
// on. It will only be set when the transaction references other
// transactions in the source pool and hence must come after them in
// a block.
dependsOn map[chainhash.Hash]struct{}
}
// txPriorityQueueLessFunc describes a function that can be used as a compare
// function for a transation priority queue (txPriorityQueue).
type txPriorityQueueLessFunc func(*txPriorityQueue, int, int) bool
// txPriorityQueue implements a priority queue of txPrioItem elements that
// supports an arbitrary compare function as defined by txPriorityQueueLessFunc.
type txPriorityQueue struct {
lessFunc txPriorityQueueLessFunc
items []*txPrioItem
}
// Len returns the number of items in the priority queue. It is part of the
// heap.Interface implementation.
func (pq *txPriorityQueue) Len() int {
return len(pq.items)
}
// Less returns whether the item in the priority queue with index i should sort
// before the item with index j by deferring to the assigned less function. It
// is part of the heap.Interface implementation.
func (pq *txPriorityQueue) Less(i, j int) bool {
return pq.lessFunc(pq, i, j)
}
// Swap swaps the items at the passed indices in the priority queue. It is
// part of the heap.Interface implementation.
func (pq *txPriorityQueue) Swap(i, j int) {
pq.items[i], pq.items[j] = pq.items[j], pq.items[i]
}
// Push pushes the passed item onto the priority queue. It is part of the
// heap.Interface implementation.
func (pq *txPriorityQueue) Push(x interface{}) {
pq.items = append(pq.items, x.(*txPrioItem))
}
// Pop removes the highest priority item (according to Less) from the priority
// queue and returns it. It is part of the heap.Interface implementation.
func (pq *txPriorityQueue) Pop() interface{} {
n := len(pq.items)
item := pq.items[n-1]
pq.items[n-1] = nil
pq.items = pq.items[0 : n-1]
return item
}
// SetLessFunc sets the compare function for the priority queue to the provided
// function. It also invokes heap.Init on the priority queue using the new
// function so it can immediately be used with heap.Push/Pop.
func (pq *txPriorityQueue) SetLessFunc(lessFunc txPriorityQueueLessFunc) {
pq.lessFunc = lessFunc
heap.Init(pq)
}
// stakePriority is an integer that is used to sort stake transactions
// by importance when they enter the min heap for block construction.
// 2 is for votes (highest), followed by 1 for tickets (2nd highest),
// followed by 0 for regular transactions and revocations (lowest).
type stakePriority int
const (
regOrRevocPriority stakePriority = iota
ticketPriority
votePriority
)
// stakePriority assigns a stake priority based on a transaction type.
func txStakePriority(txType stake.TxType) stakePriority {
prio := regOrRevocPriority
switch txType {
case stake.TxTypeSSGen:
prio = votePriority
case stake.TxTypeSStx:
prio = ticketPriority
}
return prio
}
// compareStakePriority compares the stake priority of two transactions.
// It uses votes > tickets > regular transactions or revocations. It
// returns 1 if i > j, 0 if i == j, and -1 if i < j in terms of stake
// priority.
func compareStakePriority(i, j *txPrioItem) int {
iStakePriority := txStakePriority(i.txType)
jStakePriority := txStakePriority(j.txType)
if iStakePriority > jStakePriority {
return 1
}
if iStakePriority < jStakePriority {
return -1
}
return 0
}
// txPQByPriority sorts a txPriorityQueue by transaction priority and then fees
// per kilobyte.
func txPQByPriority(pq *txPriorityQueue, i, j int) bool {
// Using > here so that pop gives the highest priority item as opposed
// to the lowest. Sort by priority first, then fee.
if pq.items[i].priority == pq.items[j].priority {
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
return pq.items[i].priority > pq.items[j].priority
}
// txPQByStakeAndPriority sorts a txPriorityQueue by stake priority then
// transaction priority, and then fees per kilobyte.
func txPQByStakeAndPriority(pq *txPriorityQueue, i, j int) bool {
// Sort by stake priority, continue if they're the same stake priority.
cmp := compareStakePriority(pq.items[i], pq.items[j])
if cmp == 1 {
return true
}
if cmp == -1 {
return false
}
// Using > here so that pop gives the highest priority item as opposed
// to the lowest. Sort by priority first, then fee.
if pq.items[i].priority == pq.items[j].priority {
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
return pq.items[i].priority > pq.items[j].priority
}
// txPQByFee sorts a txPriorityQueue by fees per kilobyte and then transaction
// priority.
func txPQByFee(pq *txPriorityQueue, i, j int) bool {
// Using > here so that pop gives the highest fee item as opposed
// to the lowest. Sort by fee first, then priority.
if pq.items[i].feePerKB == pq.items[j].feePerKB {
return pq.items[i].priority > pq.items[j].priority
}
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
// txPQByStakeAndFee sorts a txPriorityQueue by stake priority, followed by
// fees per kilobyte, and then transaction priority.
func txPQByStakeAndFee(pq *txPriorityQueue, i, j int) bool {
// Sort by stake priority, continue if they're the same stake priority.
cmp := compareStakePriority(pq.items[i], pq.items[j])
if cmp == 1 {
return true
}
if cmp == -1 {
return false
}
// Using > here so that pop gives the highest fee item as opposed
// to the lowest. Sort by fee first, then priority.
if pq.items[i].feePerKB == pq.items[j].feePerKB {
return pq.items[i].priority > pq.items[j].priority
}
// The stake priorities are equal, so return based on fees
// per KB.
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
// txPQByStakeAndFeeAndThenPriority sorts a txPriorityQueue by stake priority,
// followed by fees per kilobyte, and then if the transaction type is regular
// or a revocation it sorts it by priority.
func txPQByStakeAndFeeAndThenPriority(pq *txPriorityQueue, i, j int) bool {
// Sort by stake priority, continue if they're the same stake priority.
cmp := compareStakePriority(pq.items[i], pq.items[j])
if cmp == 1 {
return true
}
if cmp == -1 {
return false
}
bothAreLowStakePriority :=
txStakePriority(pq.items[i].txType) == regOrRevocPriority &&
txStakePriority(pq.items[j].txType) == regOrRevocPriority
// Use fees per KB on high stake priority transactions.
if !bothAreLowStakePriority {
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
// Both transactions are of low stake importance. Use > here so that
// pop gives the highest priority item as opposed to the lowest.
// Sort by priority first, then fee.
if pq.items[i].priority == pq.items[j].priority {
return pq.items[i].feePerKB > pq.items[j].feePerKB
}
return pq.items[i].priority > pq.items[j].priority
}
// newTxPriorityQueue returns a new transaction priority queue that reserves the
// passed amount of space for the elements. The new priority queue uses the
// less than function lessFunc to sort the items in the min heap. The priority
// queue can grow larger than the reserved space, but extra copies of the
// underlying array can be avoided by reserving a sane value.
func newTxPriorityQueue(reserve int, lessFunc func(*txPriorityQueue, int,
int) bool) *txPriorityQueue {
pq := &txPriorityQueue{
items: make([]*txPrioItem, 0, reserve),
}
pq.SetLessFunc(lessFunc)
return pq
}
// containsTx is a helper function that checks to see if a list of transactions
// contains any of the TxIns of some transaction.
func containsTxIns(txs []*dcrutil.Tx, tx *dcrutil.Tx) bool {
for _, txToCheck := range txs {
for _, txIn := range tx.MsgTx().TxIn {
if txIn.PreviousOutPoint.Hash.IsEqual(txToCheck.Hash()) {
return true
}
}
}
return false
}
// blockWithNumVotes is a block with the number of votes currently present
// for that block. Just used for sorting.
type blockWithNumVotes struct {
Hash chainhash.Hash
NumVotes uint16
}
// byNumberOfVotes implements sort.Interface to sort a slice of blocks by their
// number of votes.
type byNumberOfVotes []*blockWithNumVotes
// Len returns the number of elements in the slice. It is part of the
// sort.Interface implementation.
func (b byNumberOfVotes) Len() int {
return len(b)
}
// Swap swaps the elements at the passed indices. It is part of the
// sort.Interface implementation.
func (b byNumberOfVotes) Swap(i, j int) {
b[i], b[j] = b[j], b[i]
}
// Less returns whether the block with index i should sort before the block with
// index j. It is part of the sort.Interface implementation.
func (b byNumberOfVotes) Less(i, j int) bool {
return b[i].NumVotes < b[j].NumVotes
}
// SortParentsByVotes takes a list of block header hashes and sorts them
// by the number of votes currently available for them in the votes map of
// mempool. It then returns all blocks that are eligible to be used (have
// at least a majority number of votes) sorted by number of votes, descending.
//
// This function is safe for concurrent access.
func SortParentsByVotes(mp *mempool.TxPool, currentTopBlock chainhash.Hash, blocks []chainhash.Hash, params *chaincfg.Params) []chainhash.Hash {
// Return now when no blocks were provided.
lenBlocks := len(blocks)
if lenBlocks == 0 {
return nil
}
// Fetch the vote metadata for the provided block hashes from the
// mempool and filter out any blocks that do not have the minimum
// required number of votes.
minVotesRequired := (params.TicketsPerBlock / 2) + 1
voteMetadata := mp.VotesForBlocks(blocks)
filtered := make([]*blockWithNumVotes, 0, lenBlocks)
for i := range blocks {
numVotes := uint16(len(voteMetadata[i]))
if numVotes >= minVotesRequired {
filtered = append(filtered, &blockWithNumVotes{
Hash: blocks[i],
NumVotes: numVotes,
})
}
}
// Return now if there are no blocks with enough votes to be eligible to
// build on top of.
if len(filtered) == 0 {
return nil
}
// Blocks with the most votes appear at the top of the list.
sort.Sort(sort.Reverse(byNumberOfVotes(filtered)))
sortedUsefulBlocks := make([]chainhash.Hash, 0, len(filtered))
for _, bwnv := range filtered {
sortedUsefulBlocks = append(sortedUsefulBlocks, bwnv.Hash)
}
// Make sure we don't reorganize the chain needlessly if the top block has
// the same amount of votes as the current leader after the sort. After this
// point, all blocks listed in sortedUsefulBlocks definitely also have the
// minimum number of votes required.
curVoteMetadata := mp.VotesForBlocks([]chainhash.Hash{currentTopBlock})
numTopBlockVotes := uint16(len(curVoteMetadata))
if filtered[0].NumVotes == numTopBlockVotes && filtered[0].Hash !=
currentTopBlock {
// Attempt to find the position of the current block being built
// from in the list.
pos := 0
for i, bwnv := range filtered {
if bwnv.Hash == currentTopBlock {
pos = i
break
}
}
// Swap the top block into the first position. We directly access
// sortedUsefulBlocks useful blocks here with the assumption that
// since the values were accumulated from filtered, they should be
// in the same positions and we shouldn't be able to access anything
// out of bounds.
if pos != 0 {
sortedUsefulBlocks[0], sortedUsefulBlocks[pos] =
sortedUsefulBlocks[pos], sortedUsefulBlocks[0]
}
}
return sortedUsefulBlocks
}
// BlockTemplate houses a block that has yet to be solved along with additional
// details about the fees and the number of signature operations for each
// transaction in the block.
type BlockTemplate struct {
// Block is a block that is ready to be solved by miners. Thus, it is
// completely valid with the exception of satisfying the proof-of-work
// requirement.
Block *wire.MsgBlock
// Fees contains the amount of fees each transaction in the generated
// template pays in base units. Since the first transaction is the
// coinbase, the first entry (offset 0) will contain the negative of the
// sum of the fees of all other transactions.
Fees []int64
// SigOpCounts contains the number of signature operations each
// transaction in the generated template performs.
SigOpCounts []int64
// Height is the height at which the block template connects to the main
// chain.
Height int64
// ValidPayAddress indicates whether or not the template coinbase pays
// to an address or is redeemable by anyone. See the documentation on
// NewBlockTemplate for details on which this can be useful to generate
// templates without a coinbase payment address.
ValidPayAddress bool
}
// mergeUtxoView adds all of the entries in view to viewA. The result is that
// viewA will contain all of its original entries plus all of the entries
// in viewB. It will replace any entries in viewB which also exist in viewA
// if the entry in viewA is fully spent.
func mergeUtxoView(viewA *blockchain.UtxoViewpoint, viewB *blockchain.UtxoViewpoint) {
viewAEntries := viewA.Entries()
for hash, entryB := range viewB.Entries() {
if entryA, exists := viewAEntries[hash]; !exists ||
entryA == nil || entryA.IsFullySpent() {
viewAEntries[hash] = entryB
}
}
}
// hashExistsInList checks if a hash exists in a list of hash pointers.
func hashInSlice(h chainhash.Hash, list []chainhash.Hash) bool {
for i := range list {
if h == list[i] {
return true
}
}
return false
}
// txIndexFromTxList returns a transaction's index in a list, or -1 if it
// can not be found.
func txIndexFromTxList(hash chainhash.Hash, list []*dcrutil.Tx) int {
for i, tx := range list {
h := tx.Hash()
if hash == *h {
return i
}
}
return -1
}
// standardCoinbaseOpReturn creates a standard OP_RETURN output to insert into
// coinbase to use as extranonces. The OP_RETURN pushes 32 bytes.
func standardCoinbaseOpReturn(height uint32, extraNonces []uint64) ([]byte,
error) {
if len(extraNonces) != 4 {
return nil, fmt.Errorf("extranonces has wrong num uint64s")
}
enData := make([]byte, 36, 36)
binary.LittleEndian.PutUint32(enData[0:4], height)
binary.LittleEndian.PutUint64(enData[4:12], extraNonces[0])
binary.LittleEndian.PutUint64(enData[12:20], extraNonces[1])
binary.LittleEndian.PutUint64(enData[20:28], extraNonces[2])
binary.LittleEndian.PutUint64(enData[28:36], extraNonces[3])
extraNonceScript, err := txscript.GenerateProvablyPruneableOut(enData)
if err != nil {
return nil, err
}
return extraNonceScript, nil
}
// getCoinbaseExtranonce extracts the extranonce from a block template's
// coinbase transaction.
func (bt *BlockTemplate) getCoinbaseExtranonces() []uint64 {
if len(bt.Block.Transactions[0].TxOut) < 2 {
return []uint64{0, 0, 0, 0}
}
if len(bt.Block.Transactions[0].TxOut[1].PkScript) < 38 {
return []uint64{0, 0, 0, 0}
}
ens := make([]uint64, 4, 4) // 32-bytes
ens[0] = binary.LittleEndian.Uint64(
bt.Block.Transactions[0].TxOut[1].PkScript[6:14])
ens[1] = binary.LittleEndian.Uint64(
bt.Block.Transactions[0].TxOut[1].PkScript[14:22])
ens[2] = binary.LittleEndian.Uint64(
bt.Block.Transactions[0].TxOut[1].PkScript[22:30])
ens[3] = binary.LittleEndian.Uint64(
bt.Block.Transactions[0].TxOut[1].PkScript[30:38])
return ens
}
// getCoinbaseExtranonce extracts the extranonce from a block template's
// coinbase transaction.
func getCoinbaseExtranonces(msgBlock *wire.MsgBlock) []uint64 {
if len(msgBlock.Transactions[0].TxOut) < 2 {
return []uint64{0, 0, 0, 0}
}
if len(msgBlock.Transactions[0].TxOut[1].PkScript) < 38 {
return []uint64{0, 0, 0, 0}
}
ens := make([]uint64, 4, 4) // 32-bytes
ens[0] = binary.LittleEndian.Uint64(
msgBlock.Transactions[0].TxOut[1].PkScript[6:14])
ens[1] = binary.LittleEndian.Uint64(
msgBlock.Transactions[0].TxOut[1].PkScript[14:22])
ens[2] = binary.LittleEndian.Uint64(
msgBlock.Transactions[0].TxOut[1].PkScript[22:30])
ens[3] = binary.LittleEndian.Uint64(
msgBlock.Transactions[0].TxOut[1].PkScript[30:38])
return ens
}
// UpdateExtraNonce updates the extra nonce in the coinbase script of the passed
// block by regenerating the coinbase script with the passed value and block
// height. It also recalculates and updates the new merkle root that results
// from changing the coinbase script.
func UpdateExtraNonce(msgBlock *wire.MsgBlock, blockHeight int64,
extraNonces []uint64) error {
// First block has no extranonce.
if blockHeight == 1 {
return nil
}
if len(extraNonces) != 4 {
return fmt.Errorf("not enough nonce information passed")
}
coinbaseOpReturn, err := standardCoinbaseOpReturn(uint32(blockHeight),
extraNonces)
if err != nil {
return err
}
msgBlock.Transactions[0].TxOut[1].PkScript = coinbaseOpReturn
// TODO(davec): A dcrutil.Block should use saved in the state to avoid
// recalculating all of the other transaction hashes.
// block.Transactions[0].InvalidateCache()
// Recalculate the merkle root with the updated extra nonce.
block := dcrutil.NewBlockDeepCopyCoinbase(msgBlock)
merkles := blockchain.BuildMerkleTreeStore(block.Transactions())
msgBlock.Header.MerkleRoot = *merkles[len(merkles)-1]
return nil
}
// createCoinbaseTx returns a coinbase transaction paying an appropriate subsidy
// based on the passed block height to the provided address. When the address
// is nil, the coinbase transaction will instead be redeemable by anyone.
//
// See the comment for NewBlockTemplate for more information about why the nil
// address handling is useful.
func createCoinbaseTx(subsidyCache *blockchain.SubsidyCache,
coinbaseScript []byte,
opReturnPkScript []byte,
nextBlockHeight int64,
addr dcrutil.Address,
voters uint16,
params *chaincfg.Params) (*dcrutil.Tx, error) {
tx := wire.NewMsgTx()
tx.AddTxIn(&wire.TxIn{
// Coinbase transactions have no inputs, so previous outpoint is
// zero hash and max index.
PreviousOutPoint: *wire.NewOutPoint(&chainhash.Hash{},
wire.MaxPrevOutIndex, wire.TxTreeRegular),
Sequence: wire.MaxTxInSequenceNum,
BlockHeight: wire.NullBlockHeight,
BlockIndex: wire.NullBlockIndex,
SignatureScript: coinbaseScript,
})
// Block one is a special block that might pay out tokens to a ledger.
if nextBlockHeight == 1 && len(params.BlockOneLedger) != 0 {
// Convert the addresses in the ledger into useable format.
addrs := make([]dcrutil.Address,
len(params.BlockOneLedger),
len(params.BlockOneLedger))
for i, payout := range params.BlockOneLedger {
addr, err := dcrutil.DecodeAddress(payout.Address, params)
if err != nil {
return nil, err
}
addrs[i] = addr
}
for i, payout := range params.BlockOneLedger {
// Make payout to this address.
pks, err := txscript.PayToAddrScript(addrs[i])
if err != nil {
return nil, err
}
tx.AddTxOut(&wire.TxOut{
Value: payout.Amount,
PkScript: pks,
})
}
tx.TxIn[0].ValueIn = params.BlockOneSubsidy()
return dcrutil.NewTx(tx), nil
}
// Create a coinbase with correct block subsidy and extranonce.
subsidy := blockchain.CalcBlockWorkSubsidy(subsidyCache,
nextBlockHeight,
voters,
activeNetParams.Params)
tax := blockchain.CalcBlockTaxSubsidy(subsidyCache,
nextBlockHeight,
voters,
activeNetParams.Params)
// Tax output.
if params.BlockTaxProportion > 0 {
tx.AddTxOut(&wire.TxOut{
Value: tax,
PkScript: params.OrganizationPkScript,
})
} else {
// Tax disabled.
scriptBuilder := txscript.NewScriptBuilder()
trueScript, err := scriptBuilder.AddOp(txscript.OP_TRUE).Script()
if err != nil {
return nil, err
}
tx.AddTxOut(&wire.TxOut{
Value: tax,
PkScript: trueScript,
})
}
// Extranonce.
tx.AddTxOut(&wire.TxOut{
Value: 0,
PkScript: opReturnPkScript,
})
// ValueIn.
tx.TxIn[0].ValueIn = subsidy + tax
// Create the script to pay to the provided payment address if one was
// specified. Otherwise create a script that allows the coinbase to be
// redeemable by anyone.
var pksSubsidy []byte
if addr != nil {
var err error
pksSubsidy, err = txscript.PayToAddrScript(addr)
if err != nil {
return nil, err
}
} else {
var err error
scriptBuilder := txscript.NewScriptBuilder()
pksSubsidy, err = scriptBuilder.AddOp(txscript.OP_TRUE).Script()
if err != nil {
return nil, err
}
}
// Subsidy paid to miner.
tx.AddTxOut(&wire.TxOut{
Value: subsidy,
PkScript: pksSubsidy,
})
return dcrutil.NewTx(tx), nil
}
// spendTransaction updates the passed view by marking the inputs to the passed
// transaction as spent. It also adds all outputs in the passed transaction
// which are not provably unspendable as available unspent transaction outputs.
func spendTransaction(utxoView *blockchain.UtxoViewpoint, tx *dcrutil.Tx,
height int64) error {
for _, txIn := range tx.MsgTx().TxIn {
originHash := &txIn.PreviousOutPoint.Hash
originIndex := txIn.PreviousOutPoint.Index
entry := utxoView.LookupEntry(originHash)
if entry != nil {
entry.SpendOutput(originIndex)
}
}
utxoView.AddTxOuts(tx, height, wire.NullBlockIndex)
return nil
}
// logSkippedDeps logs any dependencies which are also skipped as a result of
// skipping a transaction while generating a block template at the trace level.
func logSkippedDeps(tx *dcrutil.Tx, deps *list.List) {
if deps == nil {
return
}
for e := deps.Front(); e != nil; e = e.Next() {
item := e.Value.(*txPrioItem)
minrLog.Tracef("Skipping tx %s since it depends on %s\n",
item.tx.Hash(), tx.Hash())
}
}
// minimumMedianTime returns the minimum allowed timestamp for a block building
// on the end of the current best chain. In particular, it is one second after
// the median timestamp of the last several blocks per the chain consensus
// rules.
func minimumMedianTime(chainState *chainState) (time.Time, error) {
chainState.Lock()
defer chainState.Unlock()
if chainState.pastMedianTimeErr != nil {
return time.Time{}, chainState.pastMedianTimeErr
}
return chainState.pastMedianTime.Add(time.Second), nil
}
// medianAdjustedTime returns the current time adjusted to ensure it is at least
// one second after the median timestamp of the last several blocks per the
// chain consensus rules.
func medianAdjustedTime(chainState *chainState,
timeSource blockchain.MedianTimeSource) (time.Time, error) {
chainState.Lock()
defer chainState.Unlock()
if chainState.pastMedianTimeErr != nil {
return time.Time{}, chainState.pastMedianTimeErr
}
// The timestamp for the block must not be before the median timestamp
// of the last several blocks. Thus, choose the maximum between the
// current time and one second after the past median time. The current
// timestamp is truncated to a second boundary before comparison since a
// block timestamp does not supported a precision greater than one
// second.
newTimestamp := timeSource.AdjustedTime()
minTimestamp := chainState.pastMedianTime.Add(time.Second)
if newTimestamp.Before(minTimestamp) {
newTimestamp = minTimestamp
}
// Adjust by the amount requested from the command line argument.
newTimestamp = newTimestamp.Add(
time.Duration(-cfg.MiningTimeOffset) * time.Second)
return newTimestamp, nil
}
// maybeInsertStakeTx checks to make sure that a stake tx is
// valid from the perspective of the mainchain (not necessarily
// the mempool or block) before inserting into a tx tree.
// If it fails the check, it returns false; otherwise true.
func maybeInsertStakeTx(bm *blockManager, stx *dcrutil.Tx, treeValid bool) bool {
missingInput := false
view, err := bm.chain.FetchUtxoView(stx, treeValid)
if err != nil {
minrLog.Warnf("Unable to fetch transaction store for "+
"stx %s: %v", stx.Hash(), err)
return false
}
mstx := stx.MsgTx()
isSSGen, _ := stake.IsSSGen(mstx)
for i, txIn := range mstx.TxIn {
// Evaluate if this is a stakebase input or not. If it
// is, continue without evaluation of the input.
// if isStakeBase
if isSSGen && (i == 0) {
txIn.BlockHeight = wire.NullBlockHeight
txIn.BlockIndex = wire.NullBlockIndex
continue
}
originHash := &txIn.PreviousOutPoint.Hash
utxIn := view.LookupEntry(originHash)
if utxIn == nil {
missingInput = true
break
} else {
originIdx := txIn.PreviousOutPoint.Index
txIn.ValueIn = utxIn.AmountByIndex(originIdx)
txIn.BlockHeight = uint32(utxIn.BlockHeight())
txIn.BlockIndex = utxIn.BlockIndex()
}
}
return !missingInput
}
// deepCopyBlockTemplate returns a deeply copied block template that copies all
// data except a block's references to transactions, which are kept as pointers
// in the block. This is considered safe because transaction data is generally
// immutable, with the exception of coinbases which we alternatively also
// deep copy.
func deepCopyBlockTemplate(blockTemplate *BlockTemplate) *BlockTemplate {
if blockTemplate == nil {
return nil
}
// Deep copy the header, which we hash on.
headerCopy := blockTemplate.Block.Header
// Copy transactions pointers. Duplicate the coinbase
// transaction, because it might update it by modifying
// the extra nonce.
transactionsCopy := make([]*wire.MsgTx, len(blockTemplate.Block.Transactions),
len(blockTemplate.Block.Transactions))
coinbaseCopy :=
dcrutil.NewTxDeep(blockTemplate.Block.Transactions[0])
for i, mtx := range blockTemplate.Block.Transactions {
if i == 0 {
transactionsCopy[i] = coinbaseCopy.MsgTx()
} else {
transactionsCopy[i] = mtx
}
}
sTransactionsCopy := make([]*wire.MsgTx,
len(blockTemplate.Block.STransactions),
len(blockTemplate.Block.STransactions))
for i, mtx := range blockTemplate.Block.STransactions {
sTransactionsCopy[i] = mtx
}
msgBlockCopy := &wire.MsgBlock{
Header: headerCopy,
Transactions: transactionsCopy,
STransactions: sTransactionsCopy,
}
fees := make([]int64, len(blockTemplate.Fees), len(blockTemplate.Fees))
for i, f := range blockTemplate.Fees {
fees[i] = f
}
sigOps := make([]int64, len(blockTemplate.SigOpCounts),
len(blockTemplate.SigOpCounts))
for i, s := range blockTemplate.SigOpCounts {
sigOps[i] = s
}
return &BlockTemplate{
Block: msgBlockCopy,
Fees: fees,
SigOpCounts: sigOps,
Height: blockTemplate.Height,
ValidPayAddress: blockTemplate.ValidPayAddress,
}
}
// handleTooFewVoters handles the situation in which there are too few voters on
// of the blockchain. If there are too few voters and a cached parent template to
// work off of is present, it will return a copy of that template to pass to the
// miner.
// Safe for concurrent access.
func handleTooFewVoters(subsidyCache *blockchain.SubsidyCache,
nextHeight int64,
miningAddress dcrutil.Address,
bm *blockManager) (*BlockTemplate, error) {
timeSource := bm.server.timeSource
chainState := &bm.chainState
stakeValidationHeight := bm.server.chainParams.StakeValidationHeight
curTemplate := bm.GetCurrentTemplate()
// Check to see if we've fallen off the chain, for example if a
// reorganization had recently occurred. If this is the case,
// nuke the templates.
bestHeader := chainState.GetTopBlockHeader()
if curTemplate != nil {
if !bestHeader.PrevBlock.IsEqual(
&curTemplate.Block.Header.PrevBlock) {
minrLog.Debugf("Cached mining templates are no longer current, " +
"resetting")
bm.SetCurrentTemplate(nil)
bm.SetParentTemplate(nil)
}
}
// Handle not enough voters being present if we're set to mine aggressively
// (default behaviour).
if nextHeight >= stakeValidationHeight {
if bm.AggressiveMining {
if curTemplate != nil {
cptCopy := deepCopyBlockTemplate(curTemplate)
// Update the timestamp of the old template.
ts, err := medianAdjustedTime(chainState, timeSource)
if err != nil {
return nil, err
}
cptCopy.Block.Header.Timestamp = ts
// If we're on testnet, the time since this last block
// listed as the parent must be taken into consideration.
if bm.server.chainParams.ReduceMinDifficulty {
parentHash := cptCopy.Block.Header.PrevBlock
requiredDifficulty, err :=
bm.CalcNextRequiredDiffNode(&parentHash, ts)
if err != nil {
return nil, miningRuleError(ErrGettingDifficulty,
err.Error())
}
cptCopy.Block.Header.Bits = requiredDifficulty
}
// Choose a new extranonce value that is one greater
// than the previous extranonce, so we don't remine the
// same block and choose the same winners as before.
ens := cptCopy.getCoinbaseExtranonces()
ens[0]++
err = UpdateExtraNonce(cptCopy.Block, cptCopy.Height, ens)
if err != nil {
return nil, err
}
// Update extranonce of the original template too, so
// we keep getting unique numbers.
err = UpdateExtraNonce(curTemplate.Block, curTemplate.Height, ens)
if err != nil {
return nil, err
}
// Make sure the block validates.
block := dcrutil.NewBlockDeepCopyCoinbase(cptCopy.Block)
block.SetHeight(cptCopy.Height)
if err := blockchain.CheckWorklessBlockSanity(block,
bm.server.timeSource,
bm.server.chainParams); err != nil {
return nil, miningRuleError(ErrCheckConnectBlock,
err.Error())
}
if err := bm.CheckConnectBlock(block); err != nil {
minrLog.Errorf("failed to check template while "+
"duplicating a parent: %v", err.Error())
return nil, miningRuleError(ErrCheckConnectBlock,
err.Error())
}
return cptCopy, nil
}
// We may have just started mining and stored the current block
// template, so we don't have a parent.
if curTemplate == nil {
// Fetch the latest block and head and begin working
// off of it with an empty transaction tree regular
// and the contents of that stake tree. In the future
// we should have the option of readding some
// transactions from this block, too.
topBlock, err :=
bm.GetTopBlockFromChain()
if err != nil {
return nil, fmt.Errorf("failed to get top block from " +
"chain")
}
btMsgBlock := new(wire.MsgBlock)
rand, err := wire.RandomUint64()
if err != nil {
return nil, err
}
opReturnPkScript, err :=
standardCoinbaseOpReturn(topBlock.MsgBlock().Header.Height,
[]uint64{0, 0, 0, rand})
if err != nil {
return nil, err
}
coinbaseTx, err := createCoinbaseTx(subsidyCache,
[]byte{0x01, 0x02},
opReturnPkScript,
topBlock.Height(),
miningAddress,
topBlock.MsgBlock().Header.Voters,
bm.server.chainParams)
if err != nil {
return nil, err
}
btMsgBlock.AddTransaction(coinbaseTx.MsgTx())
for _, stx := range topBlock.STransactions() {
btMsgBlock.AddSTransaction(stx.MsgTx())
}
// Copy the rest of the header.