Ejemplo n.º 1
// This example demonstrates how to convert the compact "bits" in a block header
// which represent the target difficulty to a big integer and display it using
// the typical hex notation.
func ExampleCompactToBig() {
	// Convert the bits from block 300000 in the main block chain.
	bits := uint32(419465580)
	targetDifficulty := blockchain.CompactToBig(bits)

	// Display it in hex.
	fmt.Printf("%064x\n", targetDifficulty.Bytes())

	// Output:
	// 0000000000000000896c00000000000000000000000000000000000000000000
Ejemplo n.º 2
func TestCompactToBig(t *testing.T) {
	tests := []struct {
		in  uint32
		out int64
		{10000000, 0},

	for x, test := range tests {
		n := blockchain.CompactToBig(test.in)
		want := big.NewInt(test.out)
		if n.Cmp(want) != 0 {
			t.Errorf("TestCompactToBig test #%d failed: got %d want %d\n",
				x, n.Int64(), want.Int64())
Ejemplo n.º 3
// NewBlockTemplate returns a new block template that is ready to be solved
// using the transactions from the passed transaction memory pool and a coinbase
// that either pays to the passed address if it is not nil, or a coinbase that
// is redeemable by anyone if the passed address is nil.  The nil address
// functionality is useful since there are cases such as the getblocktemplate
// RPC where external mining software is responsible for creating their own
// coinbase which will replace the one generated for the block template.  Thus
// the need to have configured address can be avoided.
// 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(mempool *txMemPool, payToAddress btcutil.Address) (*BlockTemplate, error) {
	blockManager := mempool.server.blockManager
	timeSource := mempool.server.timeSource
	chainState := &blockManager.chainState

	// Extend the most recently known best block.
	prevHash := chainState.newestHash
	nextBlockHeight := chainState.newestHeight + 1

	// 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.  The 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).
	extraNonce := uint64(0)
	coinbaseScript, err := standardCoinbaseScript(nextBlockHeight, extraNonce)
	if err != nil {
		return nil, err
	coinbaseTx, err := createCoinbaseTx(coinbaseScript, nextBlockHeight,
	if err != nil {
		return nil, err
	numCoinbaseSigOps := int64(blockchain.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(blockchain.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[wire.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, 0, len(mempoolTxns))
	txSigOpCounts := make([]int64, 0, 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))

	for _, txDesc := range mempoolTxns {
		// A block can't have more than one coinbase or contain
		// non-finalized transactions.
		tx := txDesc.Tx
		if blockchain.IsCoinBase(tx) {
			minrLog.Tracef("Skipping coinbase tx %s", tx.Sha())
		if !blockchain.IsFinalizedTransaction(tx, nextBlockHeight,
			timeSource.AdjustedTime()) {

			minrLog.Tracef("Skipping non-finalized tx %s", tx.Sha())

		// 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 := blockManager.FetchTransactionStore(tx)
		if err != nil {
			minrLog.Warnf("Unable to fetch transaction store for "+
				"tx %s: %v", tx.Sha(), err)

		// Setup dependencies for any transactions which reference
		// other transactions in the mempool so they can be properly
		// ordered below.
		prioItem := &txPrioItem{tx: txDesc.Tx}
		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,
					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
				if prioItem.dependsOn == nil {
					prioItem.dependsOn = make(
				prioItem.dependsOn[*originHash] = struct{}{}

				// Skip the check below. We already know the
				// referenced transaction is available.

			// 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

		// 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
		prioItem.priority = txDesc.CurrentPriority(txStore, nextBlockHeight)

		// 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.
		txSize := tx.MsgTx().SerializeSize()
		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)

		// Enforce maximum signature operations per block.  Also check
		// for overflow.
		numSigOps := int64(blockchain.CountSigOps(tx))
		if blockSigOps+numSigOps < blockSigOps ||
			blockSigOps+numSigOps > blockchain.MaxSigOpsPerBlock {
			minrLog.Tracef("Skipping tx %s because it would "+
				"exceed the maximum sigops per block", tx.Sha())
			logSkippedDeps(tx, deps)
		numP2SHSigOps, err := blockchain.CountP2SHSigOps(tx, false,
		if err != nil {
			minrLog.Tracef("Skipping tx %s due to error in "+
				"CountP2SHSigOps: %v", tx.Sha(), err)
			logSkippedDeps(tx, deps)
		numSigOps += int64(numP2SHSigOps)
		if blockSigOps+numSigOps < blockSigOps ||
			blockSigOps+numSigOps > blockchain.MaxSigOpsPerBlock {
			minrLog.Tracef("Skipping tx %s because it would "+
				"exceed the maximum sigops per block (p2sh)",
			logSkippedDeps(tx, deps)

		// 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,
			logSkippedDeps(tx, deps)

		// 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 <= minHighPriority) {

			minrLog.Tracef("Switching to sort by fees per "+
				"kilobyte blockSize %d >= BlockPrioritySize "+
				"%d || priority %.2f <= minHighPriority %.2f",
				blockPlusTxSize, cfg.BlockPrioritySize,
				prioItem.priority, minHighPriority)

			sortedByFee = true

			// 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 < minHighPriority {

				heap.Push(priorityQueue, prioItem)

		// Ensure the transaction inputs pass all of the necessary
		// preconditions before allowing it to be added to the block.
		_, err = blockchain.CheckTransactionInputs(tx, nextBlockHeight,
		if err != nil {
			minrLog.Tracef("Skipping tx %s due to error in "+
				"CheckTransactionInputs: %v", tx.Sha(), err)
			logSkippedDeps(tx, deps)
		err = blockchain.ValidateTransactionScripts(tx, blockTxStore,
		if err != nil {
			minrLog.Tracef("Skipping tx %s due to error in "+
				"ValidateTransactionScripts: %v", tx.Sha(), err)
			logSkippedDeps(tx, deps)

		// 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 -= wire.MaxVarIntPayload -
	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, timeSource)
	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 := blockchain.BuildMerkleTreeStore(blockTxns)
	var msgBlock wire.MsgBlock
	msgBlock.Header = wire.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)
	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, blockchain.CompactToBig(msgBlock.Header.Bits))

	return &BlockTemplate{
		block:           &msgBlock,
		fees:            txFees,
		sigOpCounts:     txSigOpCounts,
		height:          nextBlockHeight,
		validPayAddress: payToAddress != nil,
	}, nil
Ejemplo n.º 4
// solveBlock attempts to find some combination of a nonce, extra nonce, and
// current timestamp which makes the passed block hash to a value less than the
// target difficulty.  The timestamp is updated periodically and the passed
// block is modified with all tweaks during this process.  This means that
// when the function returns true, the block is ready for submission.
// This function will return early with false when conditions that trigger a
// stale block such as a new block showing up or periodically when there are
// new transactions and enough time has elapsed without finding a solution.
func (m *CPUMiner) solveBlock(msgBlock *wire.MsgBlock, blockHeight int32,
	ticker *time.Ticker, quit chan struct{}) bool {

	// Choose a random extra nonce offset for this block template and
	// worker.
	enOffset, err := wire.RandomUint64()
	if err != nil {
		minrLog.Errorf("Unexpected error while generating random "+
			"extra nonce offset: %v", err)
		enOffset = 0

	// Create a couple of convenience variables.
	header := &msgBlock.Header
	targetDifficulty := blockchain.CompactToBig(header.Bits)

	// Initial state.
	lastGenerated := time.Now()
	lastTxUpdate := m.server.txMemPool.LastUpdated()
	hashesCompleted := uint64(0)

	// Note that the entire extra nonce range is iterated and the offset is
	// added relying on the fact that overflow will wrap around 0 as
	// provided by the Go spec.
	for extraNonce := uint64(0); extraNonce < maxExtraNonce; extraNonce++ {
		// Update the extra nonce in the block template with the
		// new value by regenerating the coinbase script and
		// setting the merkle root to the new value.  The
		UpdateExtraNonce(msgBlock, blockHeight, extraNonce+enOffset)

		// Search through the entire nonce range for a solution while
		// periodically checking for early quit and stale block
		// conditions along with updates to the speed monitor.
		for i := uint32(0); i <= maxNonce; i++ {
			select {
			case <-quit:
				return false

			case <-ticker.C:
				m.updateHashes <- hashesCompleted
				hashesCompleted = 0

				// The current block is stale if the best block
				// has changed.
				bestHash, _ := m.server.blockManager.chainState.Best()
				if !header.PrevBlock.IsEqual(bestHash) {
					return false

				// The current block is stale if the memory pool
				// has been updated since the block template was
				// generated and it has been at least one
				// minute.
				if lastTxUpdate != m.server.txMemPool.LastUpdated() &&
					time.Now().After(lastGenerated.Add(time.Minute)) {

					return false

				UpdateBlockTime(msgBlock, m.server.blockManager)

				// Non-blocking select to fall through

			// Update the nonce and hash the block header.  Each
			// hash is actually a double sha256 (two hashes), so
			// increment the number of hashes completed for each
			// attempt accordingly.
			header.Nonce = i
			hash := header.BlockSha()
			hashesCompleted += 2

			// The block is solved when the new block hash is less
			// than the target difficulty.  Yay!
			if blockchain.ShaHashToBig(&hash).Cmp(targetDifficulty) <= 0 {
				m.updateHashes <- hashesCompleted
				return true

	return false