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Add infrastructure for creating a block template.

Browse Source 
This commit adds a new function named NewBlockTemplate along with
supporting infrastructure which is part of the core functionality needed
to support mining.

In particular the function creates a new block template which contains a
fully populated block with a zero nonce that is ready to be solved as well
as additional information regarding the fees and number of signature
operations for each transaction included in the block.  The specific
transaction selection logic mirrors the reference implementation.

Various cleanup, optimizations, and comment suggestions provided by
@owainga.  Also contains some naming suggestions and comment fixes from
@flammit.
This commit is contained in:
Dave Collins 2014-03-11 00:12:54 -05:00
parent ed45b717e0
commit e98db34ef2
3 changed files with 837 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
blockmanager.go
View File

@ -76,6 +76,28 @@ type getSyncPeerMsg struct {
reply chan *peer
}
// checkConnectBlockMsg is a message type to be sent across the message channel
// for requesting chain to check if a block connects to the end of the current
// main chain.
type checkConnectBlockMsg struct {
block *btcutil.Block
reply chan error
}
// calcNextReqDifficultyResponse is a response sent to the reply channel of a
// calcNextReqDifficultyMsg query.
type calcNextReqDifficultyResponse struct {
difficulty uint32
err error
}
// calcNextReqDifficultyMsg is a message type to be sent across the message
// channel for requesting the required difficulty of the next block.
type calcNextReqDifficultyMsg struct {
timestamp time.Time
reply chan calcNextReqDifficultyResponse
}
// headerNode is used as a node in a list of headers that are linked together
// between checkpoints.
type headerNode struct {
@ -949,6 +971,18 @@ out:
case getSyncPeerMsg:
msg.reply <- b.syncPeer
case checkConnectBlockMsg:
err := b.blockChain.CheckConnectBlock(msg.block)
msg.reply <- err
case calcNextReqDifficultyMsg:
difficulty, err :=
b.blockChain.CalcNextRequiredDifficulty(
msg.timestamp)
msg.reply <- calcNextReqDifficultyResponse{
difficulty: difficulty,
err: err,
}
default:
bmgrLog.Warnf("Invalid message type in block "+
"handler: %T", msg)
@ -1160,6 +1194,28 @@ func (b *blockManager) SyncPeer() *peer {
return <-reply
}
// CheckConnectBlock performs several checks to confirm connecting the passed
// block to the main chain does not violate any rules. This function makes use
// of CheckConnectBlock on an internal instance of a block chain. It is funneled
// through the block manager since btcchain is not safe for concurrent access.
func (b *blockManager) CheckConnectBlock(block *btcutil.Block) error {
reply := make(chan error)
b.msgChan <- checkConnectBlockMsg{block: block, reply: reply}
return <-reply
}
// CalcNextRequiredDifficulty calculates the required difficulty for the next
// block after the current main chain. This function makes use of
// CalcNextRequiredDifficulty on an internal instance of a block chain. It is
// funneled through the block manager since btcchain is not safe for concurrent
// access.
func (b *blockManager) CalcNextRequiredDifficulty(timestamp time.Time) (uint32, error) {
reply := make(chan calcNextReqDifficultyResponse)
b.msgChan <- calcNextReqDifficultyMsg{timestamp: timestamp, reply: reply}
response := <-reply
return response.difficulty, response.err
}
// newBlockManager returns a new bitcoin block manager.
// Use Start to begin processing asynchronous block and inv updates.
func newBlockManager(s *server) (*blockManager, error) {

21
mempool.go
View File

@ -66,10 +66,10 @@ const (
maxStandardMultiSigKeys = 3
// minTxRelayFee is the minimum fee in satoshi that is required for a
// transaction to be treated as free for relay purposes. It is also
// used to help determine if a transaction is considered dust and as a
// base for calculating minimum required fees for larger transactions.
// This value is in Satoshi/KB (kilobyte, not kibibyte).
// transaction to be treated as free for relay and mining purposes. It
// is also used to help determine if a transaction is considered dust
// and as a base for calculating minimum required fees for larger
// transactions. This value is in Satoshi/1000 bytes.
minTxRelayFee = 1000
)
@ -94,7 +94,6 @@ type txMemPool struct {
outpoints map[btcwire.OutPoint]*btcutil.Tx
pennyTotal float64 // exponentially decaying total for penny spends.
lastPennyUnix int64 // unix time of last ``penny spend''
}
// isDust returns whether or not the passed transaction output amount is
@ -148,8 +147,8 @@ func isDust(txOut *btcwire.TxOut) bool {
// The output is considered dust if the cost to the network to spend the
// coins is more than 1/3 of the minimum free transaction relay fee.
// minFreeTxRelayFee is in Satoshi/KB (kilobyte, not kibibyte), so
// multiply by 1000 to convert bytes.
// minFreeTxRelayFee is in Satoshi/KB, so multiply by 1000 to
// convert to bytes.
//
// Using the typical values for a pay-to-pubkey-hash transaction from
// the breakdown above and the default minimum free transaction relay
@ -379,10 +378,10 @@ func calcMinRelayFee(tx *btcutil.Tx) int64 {
// Calculate the minimum fee for a transaction to be allowed into the
// mempool and relayed by scaling the base fee (which is the minimum
// free transaction relay fee). minTxRelayFee is in Satoshi/KB
// (kilobyte, not kibibyte), so divide the transaction size by 1000 to
// convert to kilobytes. Also, integer division is used so fees only
// increase on full kilobyte boundaries.
// free transaction relay fee). minTxRelayFee is in Satoshi/KB, so
// divide the transaction size by 1000 to convert to kilobytes. Also,
// integer division is used so fees only increase on full kilobyte
// boundaries.
minFee := (1 + serializedLen/1000) * minTxRelayFee
// Set the minimum fee to the maximum possible value if the calculated

771
mining.go Normal file
View File

@ -0,0 +1,771 @@
// Copyright (c) 2014 Conformal Systems LLC.
// 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"
"github.com/conformal/btcchain"
"github.com/conformal/btcdb"
"github.com/conformal/btcscript"
"github.com/conformal/btcutil"
"github.com/conformal/btcwire"
"time"
)
const (
// generatedBlockVersion is the version of the block being generated.
// It is defined as a constant here rather than using the
// btcwire.BlockVersion constant since a change in the block version
// will require changes to the generated block. Using the btcwire
// constant for generated block version could allow creation of invalid
// blocks for the updated version.
generatedBlockVersion = 2
// minHighPriority is the minimum priority value that allows a
// transaction to be considered high priority.
minHighPriority = btcutil.SatoshiPerBitcoin * 144 / 250
// blockHeaderOverhead is the max number of bytes it takes to serialize
// a block header and max possible transaction count.
blockHeaderOverhead = btcwire.MaxBlockHeaderPayload + btcwire.MaxVarIntPayload
// coinbaseFlags is added to the coinbase script of a generated block
// and is used to monitor BIP16 support as well as blocks that are
// generated via btcd.
coinbaseFlags = "/P2SH/btcd/"
)
// 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 *btcutil.Tx
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 memory pool and hence must come after them in
// a block.
dependsOn map[btcwire.ShaHash]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)
}
// 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
}
// 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
}
// newTxPriorityQueue returns a new transaction priority queue that reserves the
// passed amount of space for the elements. The new priority queue uses either
// the txPQByPriority or the txPQByFee compare function depending on the
// sortByFee parameter and is already initialized for use with heap.Push/Pop.
// 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, sortByFee bool) *txPriorityQueue {
pq := &txPriorityQueue{
items: make([]*txPrioItem, 0, reserve),
}
if sortByFee {
pq.SetLessFunc(txPQByFee)
} else {
pq.SetLessFunc(txPQByPriority)
}
return pq
}
// 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 *btcwire.MsgBlock
fees []int64
sigOpCounts []int64
}
// minInt is a helper function to return the minimum of two ints. This avoids
// a math import and the need to cast to floats.
func minInt(a, b int) int {
if a < b {
return a
}
return b
}
// mergeTxStore adds all of the transactions in txStoreB to txStoreA. The
// result is that txStoreA will contain all of its original transactions plus
// all of the transactions in txStoreB.
func mergeTxStore(txStoreA btcchain.TxStore, txStoreB btcchain.TxStore) {
for hash, txDataB := range txStoreB {
if txDataA, exists := txStoreA[hash]; !exists ||
(txDataA.Err == btcdb.TxShaMissing && txDataB.Err !=
btcdb.TxShaMissing) {
txStoreA[hash] = txDataB
}
}
}
// standardCoinbaseScript returns a standard script suitable for use as the
// signature script of the coinbase transaction of a new block. In particular,
// it starts with the block height that is required by version 2 blocks and adds
// the extra nonce as well as additional coinbase flags.
func standardCoinbaseScript(nextBlockHeight int64, extraNonce uint64) []byte {
return btcscript.NewScriptBuilder().AddInt64(nextBlockHeight).
AddUint64(extraNonce).AddData([]byte(coinbaseFlags)).Script()
}
// createCoinbaseTx returns a coinbase transaction paying an appropriate subsidy
// based on the passed block height to the passed public key. It also accepts
// an extra nonce value for the signature script. This extra nonce helps ensure
// the transaction is not a duplicate transaction (paying the same value to the
// same public key address would otherwise be an identical transaction for
// block version 1).
func createCoinbaseTx(coinbaseScript []byte, nextBlockHeight int64, addr btcutil.Address) (*btcutil.Tx, error) {
// Create a script to pay to the specific address.
pkScript, err := btcscript.PayToAddrScript(addr)
if err != nil {
return nil, err
}
tx := btcwire.NewMsgTx()
tx.AddTxIn(&btcwire.TxIn{
// Coinbase transactions have no inputs, so previous outpoint is
// zero hash and max index.
PreviousOutpoint: *btcwire.NewOutPoint(&btcwire.ShaHash{},
btcwire.MaxPrevOutIndex),
SignatureScript: coinbaseScript,
Sequence: btcwire.MaxTxInSequenceNum,
})
tx.AddTxOut(&btcwire.TxOut{
Value: btcchain.CalcBlockSubsidy(nextBlockHeight,
activeNetParams.btcnet),
PkScript: pkScript,
})
return btcutil.NewTx(tx), nil
}
// calcPriority returns a transaction priority given a transaction and the sum
// of each of its input values multiplied by their age (# of confirmations).
// Thus, the final formula for the priority is:
// sum(inputValue * inputAge) / adjustedTxSize
func calcPriority(tx *btcutil.Tx, serializedTxSize int, inputValueAge float64) float64 {
// In order to encourage spending multiple old unspent transaction
// outputs thereby reducing the total set, don't count the constant
// overhead for each input as well as enough bytes of the signature
// script to cover a pay-to-script-hash redemption with a compressed
// pubkey. This makes additional inputs free by boosting the priority
// of the transaction accordingly. No more incentive is given to avoid
// encouraging gaming future transactions through the use of junk
// outputs. This is the same logic used in the reference
// implementation.
//
// The constant overhead for a txin is 41 bytes since the previous
// outpoint is 36 bytes + 4 bytes for the sequence + 1 byte the
// signature script length.
//
// A compressed pubkey pay-to-script-hash redemption with a maximum len
// signature is of the form:
// [OP_DATA_73 <73-byte sig> + OP_DATA_35 + {OP_DATA_33
// <33 byte compresed pubkey> + OP_CHECKSIG}]
//
// Thus 1 + 73 + 1 + 1 + 33 + 1 = 110
overhead := 0
for _, txIn := range tx.MsgTx().TxIn {
// Max inputs + size can't possibly overflow here.
overhead += 41 + minInt(110, len(txIn.SignatureScript))
}
if overhead >= serializedTxSize {
return 0.0
}
return inputValueAge / float64(serializedTxSize-overhead)
}
// spendTransaction updates the passed transaction store by marking the inputs
// to the passed transaction as spent. It also adds the passed transaction to
// the store at the provided height.
func spendTransaction(txStore btcchain.TxStore, tx *btcutil.Tx, height int64) error {
for _, txIn := range tx.MsgTx().TxIn {
originHash := &txIn.PreviousOutpoint.Hash
originIndex := txIn.PreviousOutpoint.Index
if originTx, exists := txStore[*originHash]; exists {
originTx.Spent[originIndex] = true
}
}
txStore[*tx.Sha()] = &btcchain.TxData{
Tx: tx,
Hash: tx.Sha(),
BlockHeight: height,
Spent: make([]bool, len(tx.MsgTx().TxOut)),
Err: nil,
}
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 *btcutil.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.Sha(), tx.Sha())
}
}
// 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) (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 := time.Unix(time.Now().Unix(), 0)
minTimestamp := chainState.pastMedianTime.Add(time.Second)
if newTimestamp.Before(minTimestamp) {
newTimestamp = minTimestamp
}
return newTimestamp, nil
}
// NewBlockTemplate returns a new block template using the transactions from the
// passed transaction memory pool with a coinbase that pays to the passed
// address and is ready to be solved. The transactions selected and included
// are prioritized according to several factors. First, each transaction has a
// priority calculated based on its value, age of inputs, and size.
// Transactions which consist of larger amounts, older inputs, and small sizes
// have the highest priority. Second, a fee per kilobyte is calculated for each
// transaction. Transactions with a higher fee per kilobyte are preferred.
// Finally, the block generation related configuration options are all taken
// into account.
//
// Transactions which only spend outputs from other transactions already in the
// block chain are immediately added to a priority queue which either
// prioritizes based on the priority (then fee per kilobyte) or the fee per
// kilobyte (then priority) depending on whether or not the BlockPrioritySize
// configuration option allots space for high-priority transactions.
// Transactions which spend outputs from other transactions in the memory pool
// are added to a dependency map so they can be added to the priority queue once
// the transactions they depend on have been included.
//
// Once the high-priority area (if configured) has been filled with transactions,
// or the priority falls below what is considered high-priority, the priority
// queue is updated to prioritize by fees per kilobyte (then priority).
//
// When the fees per kilobyte drop below the TxMinFreeFee configuration option,
// the transaction will be skipped unless there is a BlockMinSize set, in which
// case the block will be filled with the low-fee/free transactions until the
// block size reaches that minimum size.
//
// Any transactions which would cause the block to exceed the BlockMaxSize
// configuration option, exceed the maximum allowed signature operations per
// block, or otherwise cause the block to be invalid are skipped.
//
// Given the above, a block generated by this function is of the following form:
//
// ----------------------------------- -- --
// | Coinbase Transaction | | |
// |-----------------------------------| | |
// | | | | ----- cfg.BlockPrioritySize
// | High-priority Transactions | | |
// | | | |
// |-----------------------------------| | --
// | | |
// | | |
// | | |--- cfg.BlockMaxSize
// | Transactions prioritized by fee | |
// | until <= cfg.TxMinFreeFee | |
// | | |
// | | |
// | | |
// |-----------------------------------| |
// | Low-fee/Non high-priority (free) | |
// | transactions (while block size | |
// | <= cfg.BlockMinSize) | |
// ----------------------------------- --
func NewBlockTemplate(payToAddress btcutil.Address, mempool *txMemPool) (*BlockTemplate, error) {
blockManager := mempool.server.blockManager
chainState := &blockManager.chainState
chain := blockManager.blockChain
// Extend the most recently known best block.
chainState.Lock()
prevHash := chainState.newestHash
nextBlockHeight := chainState.newestHeight + 1
chainState.Unlock()
// Create a standard coinbase transaction paying to the provided
// address. NOTE: The coinbase value will be updated to include the
// fees from the selected transactions later after they have actually
// been selected. It is created here to detect any errors early
// before potentially doing a lot of work below.
extraNonce := uint64(0)
coinbaseScript := standardCoinbaseScript(nextBlockHeight, extraNonce)
coinbaseTx, err := createCoinbaseTx(coinbaseScript, nextBlockHeight,
payToAddress)
if err != nil {
return nil, err
}
numCoinbaseSigOps := int64(btcchain.CountSigOps(coinbaseTx))
// Get the current memory pool transactions and create a priority queue
// to hold the transactions which are ready for inclusion into a block
// along with some priority related and fee metadata. Reserve the same
// number of items that are in the memory pool for the priority queue.
// Also, choose the initial sort order for the priority queue based on
// whether or not there is an area allocated for high-priority
// transactions.
mempoolTxns := mempool.TxDescs()
sortedByFee := cfg.BlockPrioritySize == 0
priorityQueue := newTxPriorityQueue(len(mempoolTxns), sortedByFee)
// Create a slice to hold the transactions to be included in the
// generated block with reserved space. Also create a transaction
// store to house all of the input transactions so multiple lookups
// can be avoided.
blockTxns := make([]*btcutil.Tx, 0, len(mempoolTxns))
blockTxns = append(blockTxns, coinbaseTx)
blockTxStore := make(btcchain.TxStore)
// dependers is used to track transactions which depend on another
// transaction in the memory pool. This, in conjunction with the
// dependsOn map kept with each dependent transaction helps quickly
// determine which dependent transactions are now eligible for inclusion
// in the block once each transaction has been included.
dependers := make(map[btcwire.ShaHash]*list.List)
// Create slices to hold the fees and number of signature operations
// for each of the selected transactions and add an entry for the
// coinbase. This allows the code below to simply append details about
// a transaction as it is selected for inclusion in the final block.
// However, since the total fees aren't known yet, use a dummy value for
// the coinbase fee which will be updated later.
txFees := make([]int64, len(mempoolTxns))
txSigOpCounts := make([]int64, len(mempoolTxns))
txFees = append(txFees, -1) // Updated once known
txSigOpCounts = append(txSigOpCounts, numCoinbaseSigOps)
minrLog.Debugf("Considering %d mempool transactions for inclusion to "+
"new block", len(mempoolTxns))
mempoolLoop:
for _, txDesc := range mempoolTxns {
// A block can't have more than one coinbase or contain
// non-finalized transactions.
tx := txDesc.Tx
if btcchain.IsCoinBase(tx) {
minrLog.Tracef("Skipping coinbase tx %s", tx.Sha())
continue
}
if !btcchain.IsFinalizedTransaction(tx, nextBlockHeight, time.Now()) {
minrLog.Tracef("Skipping non-finalized tx %s", tx.Sha())
continue
}
// Fetch all of the transactions referenced by the inputs to
// this transaction. NOTE: This intentionally does not fetch
// inputs from the mempool since a transaction which depends on
// other transactions in the mempool must come after those
// dependencies in the final generated block.
txStore, err := chain.FetchTransactionStore(tx)
if err != nil {
minrLog.Warnf("Unable to fetch transaction store for "+
"tx %s: %v", tx.Sha(), err)
continue
}
// Calculate the input value age sum for the transaction. This
// is comprised of the sum all of input amounts multiplied by
// their respective age (number of confirmations since the
// referenced input transaction). While doing the above, also
// setup dependencies for any transactions which reference other
// transactions in the mempool so they can be properly ordered
// below.
prioItem := &txPrioItem{tx: txDesc.Tx}
inputValueAge := float64(0.0)
for _, txIn := range tx.MsgTx().TxIn {
originHash := &txIn.PreviousOutpoint.Hash
originIndex := txIn.PreviousOutpoint.Index
txData, exists := txStore[*originHash]
if !exists || txData.Err != nil || txData.Tx == nil {
if !mempool.HaveTransaction(originHash) {
minrLog.Tracef("Skipping tx %s because "+
"it references tx %s which is "+
"not available", tx.Sha,
originHash)
continue mempoolLoop
}
// The transaction is referencing another
// transaction in the memory pool, so setup an
// ordering dependency.
depList, exists := dependers[*originHash]
if !exists {
depList = list.New()
dependers[*originHash] = depList
}
depList.PushBack(prioItem)
if prioItem.dependsOn == nil {
prioItem.dependsOn = make(
map[btcwire.ShaHash]struct{})
}
prioItem.dependsOn[*originHash] = struct{}{}
// No need to calculate or sum input value age
// for this input since it's zero due to
// the input age multiplier of 0.
continue
}
// Ensure the output index in the referenced transaction
// is available.
msgTx := txData.Tx.MsgTx()
if originIndex > uint32(len(msgTx.TxOut)) {
minrLog.Tracef("Skipping tx %s because "+
"it references output %d of tx %s "+
"which is out of bounds", tx.Sha,
originIndex, originHash)
continue mempoolLoop
}
// Sum the input value times age.
originTxOut := txData.Tx.MsgTx().TxOut[originIndex]
inputValue := originTxOut.Value
inputAge := nextBlockHeight - txData.BlockHeight
inputValueAge += float64(inputValue * inputAge)
}
// Calculate the final transaction priority using the input
// value age sum as well as the adjusted transaction size. The
// formula is: sum(inputValue * inputAge) / adjustedTxSize
txSize := tx.MsgTx().SerializeSize()
prioItem.priority = calcPriority(tx, txSize, inputValueAge)
// Calculate the fee in Satoshi/KB.
// NOTE: This is a more precise value than the one calculated
// during calcMinRelayFee which rounds up to the nearest full
// kilobyte boundary. This is beneficial since it provides an
// incentive to create smaller transactions.
prioItem.feePerKB = float64(txDesc.Fee) / (float64(txSize) / 1000)
prioItem.fee = txDesc.Fee
// Add the transaction to the priority queue to mark it ready
// for inclusion in the block unless it has dependencies.
if prioItem.dependsOn == nil {
heap.Push(priorityQueue, prioItem)
}
// Merge the store which contains all of the input transactions
// for this transaction into the input transaction store. This
// allows the code below to avoid a second lookup.
mergeTxStore(blockTxStore, txStore)
}
minrLog.Tracef("Priority queue len %d, dependers len %d",
priorityQueue.Len(), len(dependers))
// The starting block size is the size of the block header plus the max
// possible transaction count size, plus the size of the coinbase
// transaction.
blockSize := blockHeaderOverhead + uint32(coinbaseTx.MsgTx().SerializeSize())
blockSigOps := numCoinbaseSigOps
totalFees := int64(0)
// Choose which transactions make it into the block.
for priorityQueue.Len() > 0 {
// Grab the highest priority (or highest fee per kilobyte
// depending on the sort order) transaction.
prioItem := heap.Pop(priorityQueue).(*txPrioItem)
tx := prioItem.tx
// Grab the list of transactions which depend on this one (if
// any) and remove the entry for this transaction as it will
// either be included or skipped, but in either case the deps
// are no longer needed.
deps := dependers[*tx.Sha()]
delete(dependers, *tx.Sha())
// Enforce maximum block size. Also check for overflow.
txSize := uint32(tx.MsgTx().SerializeSize())
blockPlusTxSize := blockSize + txSize
if blockPlusTxSize < blockSize || blockPlusTxSize >= cfg.BlockMaxSize {
minrLog.Tracef("Skipping tx %s because it would exceed "+
"the max block size", tx.Sha())
logSkippedDeps(tx, deps)
continue
}
// Enforce maximum signature operations per block. Also check
// for overflow.
numSigOps := int64(btcchain.CountSigOps(tx))
if blockSigOps+numSigOps < blockSigOps ||
blockSigOps+numSigOps > btcchain.MaxSigOpsPerBlock {
minrLog.Tracef("Skipping tx %s because it would "+
"exceed the maximum sigops per block", tx.Sha())
logSkippedDeps(tx, deps)
continue
}
numP2SHSigOps, err := btcchain.CountP2SHSigOps(tx, false,
blockTxStore)
if err != nil {
minrLog.Tracef("Skipping tx %s due to error in "+
"CountP2SHSigOps: %v", tx.Sha(), err)
logSkippedDeps(tx, deps)
continue
}
numSigOps += int64(numP2SHSigOps)
if blockSigOps+numSigOps < blockSigOps ||
blockSigOps+numSigOps > btcchain.MaxSigOpsPerBlock {
minrLog.Tracef("Skipping tx %s because it would "+
"exceed the maximum sigops per block (p2sh)",
tx.Sha())
logSkippedDeps(tx, deps)
continue
}
// Skip free transactions once the block is larger than the
// minimum block size.
if sortedByFee && prioItem.feePerKB < minTxRelayFee &&
blockPlusTxSize >= cfg.BlockMinSize {
minrLog.Tracef("Skipping tx %s with feePerKB %.2f "+
"< minTxRelayFee %d and block size %d >= "+
"minBlockSize %d", tx.Sha(), prioItem.feePerKB,
minTxRelayFee, blockPlusTxSize,
cfg.BlockMinSize)
logSkippedDeps(tx, deps)
continue
}
// Prioritize by fee per kilobyte once the block is larger than
// the priority size or there are no more high-priority
// transactions.
if !sortedByFee && (blockPlusTxSize >= cfg.BlockPrioritySize ||
prioItem.priority <= float64(minHighPriority)) {
minrLog.Tracef("Switching to sort by fees per "+
"kilobyte blockSize %d >= BlockPrioritySize "+
"%d || priority %.2f <= minHighPriority %.2f",
blockPlusTxSize, cfg.BlockPrioritySize,
prioItem.priority, float64(minHighPriority))
sortedByFee = true
priorityQueue.SetLessFunc(txPQByFee)
// Put the transaction back into the priority queue and
// skip it so it is re-priortized by fees if it won't
// fit into the high-priority section or the priority is
// too low. Otherwise this transaction will be the
// final one in the high-priority section, so just fall
// though to the code below so it is added now.
if blockPlusTxSize > cfg.BlockPrioritySize ||
prioItem.priority < float64(minHighPriority) {
heap.Push(priorityQueue, prioItem)
continue
}
}
// Ensure the transaction inputs pass all of the necessary
// preconditions before allowing it to be added to the block.
_, err = btcchain.CheckTransactionInputs(tx, nextBlockHeight,
blockTxStore)
if err != nil {
minrLog.Tracef("Skipping tx %s due to error in "+
"CheckTransactionInputs: %v", tx.Sha(), err)
logSkippedDeps(tx, deps)
continue
}
flags := btcscript.ScriptBip16 | btcscript.ScriptCanonicalSignatures
err = btcchain.ValidateTransactionScripts(tx, blockTxStore, flags)
if err != nil {
minrLog.Tracef("Skipping tx %s due to error in "+
"ValidateTransactionScripts: %v", tx.Sha(), err)
logSkippedDeps(tx, deps)
continue
}
// Spend the transaction inputs in the block transaction store
// and add an entry for it to ensure any transactions which
// reference this one have it available as an input and can
// ensure they aren't double spending.
spendTransaction(blockTxStore, tx, nextBlockHeight)
// Add the transaction to the block, increment counters, and
// save the fees and signature operation counts to the block
// template.
blockTxns = append(blockTxns, tx)
blockSize += txSize
blockSigOps += numSigOps
totalFees += prioItem.fee
txFees = append(txFees, prioItem.fee)
txSigOpCounts = append(txSigOpCounts, numSigOps)
minrLog.Tracef("Adding tx %s (priority %.2f, feePerKB %.2f)",
prioItem.tx.Sha(), prioItem.priority, prioItem.feePerKB)
// Add transactions which depend on this one (and also do not
// have any other unsatisified dependencies) to the priority
// queue.
if deps != nil {
for e := deps.Front(); e != nil; e = e.Next() {
// Add the transaction to the priority queue if
// there are no more dependencies after this
// one.
item := e.Value.(*txPrioItem)
delete(item.dependsOn, *tx.Sha())
if len(item.dependsOn) == 0 {
heap.Push(priorityQueue, item)
}
}
}
}
// Now that the actual transactions have been selected, update the
// block size for the real transaction count and coinbase value with
// the total fees accordingly.
blockSize -= btcwire.MaxVarIntPayload -
uint32(btcwire.VarIntSerializeSize(uint64(len(blockTxns))))
coinbaseTx.MsgTx().TxOut[0].Value += totalFees
txFees[0] = -totalFees
// Calculate the required difficulty for the block. The timestamp
// is potentially adjusted to ensure it comes after the median time of
// the last several blocks per the chain consensus rules.
ts, err := medianAdjustedTime(chainState)
if err != nil {
return nil, err
}
requiredDifficulty, err := blockManager.CalcNextRequiredDifficulty(ts)
if err != nil {
return nil, err
}
// Create a new block ready to be solved.
merkles := btcchain.BuildMerkleTreeStore(blockTxns)
var msgBlock btcwire.MsgBlock
msgBlock.Header = btcwire.BlockHeader{
Version: generatedBlockVersion,
PrevBlock: *prevHash,
MerkleRoot: *merkles[len(merkles)-1],
Timestamp: ts,
Bits: requiredDifficulty,
}
for _, tx := range blockTxns {
if err := msgBlock.AddTransaction(tx.MsgTx()); err != nil {
return nil, err
}
}
// Finally, perform a full check on the created block against the chain
// consensus rules to ensure it properly connects to the current best
// chain with no issues.
block := btcutil.NewBlock(&msgBlock)
block.SetHeight(nextBlockHeight)
if err := blockManager.CheckConnectBlock(block); err != nil {
return nil, err
}
minrLog.Debugf("Created new block template (%d transactions, %d in "+
"fees, %d signature operations, %d bytes, target difficulty "+
"%064x)", len(msgBlock.Transactions), totalFees, blockSigOps,
blockSize, btcchain.CompactToBig(msgBlock.Header.Bits))
return &BlockTemplate{
block: &msgBlock,
fees: txFees,
sigOpCounts: txSigOpCounts,
}, nil
}