mining模块 ​

// IsCoinBaseTx determines whether or not a transaction is a coinbase.  A coinbase
// is a special transaction created by miners that has no inputs.  This is
// represented in the block chain by a transaction with a single input that has
// a previous output transaction index set to the maximum value along with a
// zero hash.
//
// This function only differs from IsCoinBase in that it works with a raw wire
// transaction as opposed to a higher level util transaction.
func IsCoinBaseTx(msgTx *wire.MsgTx) bool {
	// A coin base must only have one transaction input.
	if len(msgTx.TxIn) != 1 {
		return false
	}

	// The previous output of a coin base must have a max value index and
	// a zero hash.
	prevOut := &msgTx.TxIn[0].PreviousOutPoint
	if prevOut.Index != math.MaxUint32 || !prevOut.Hash.IsEqual(zeroHash) {
		return false
	}

	return true
}

// 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(params *chaincfg.Params, coinbaseScript []byte, nextBlockHeight int32, addr btcutil.Address) (*btcutil.Tx, error) {
	// 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 pkScript []byte
	if addr != nil {
		var err error
		pkScript, err = txscript.PayToAddrScript(addr)
		if err != nil {
			return nil, err
		}
	} else {
		var err error
		scriptBuilder := txscript.NewScriptBuilder()
		pkScript, err = scriptBuilder.AddOp(txscript.OP_TRUE).Script()
		if err != nil {
			return nil, err
		}
	}

	tx := wire.NewMsgTx(wire.TxVersion)
	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),
		SignatureScript: coinbaseScript,
		Sequence:        wire.MaxTxInSequenceNum,
	})
	tx.AddTxOut(&wire.TxOut{
		Value:    blockchain.CalcBlockSubsidy(nextBlockHeight, params),
		PkScript: pkScript,
	})
	return btcutil.NewTx(tx), nil
}

// 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 {
		log.Errorf("Unexpected error while generating random "+
			"extra nonce offset: %v", err)
		enOffset = 0
	}

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

	// Initial state.
	lastGenerated := time.Now()
	lastTxUpdate := m.g.TxSource().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.
		m.g.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.
				best := m.g.BestSnapshot()
				if !header.PrevBlock.IsEqual(&best.Hash) {
					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.g.TxSource().LastUpdated() &&
					time.Now().After(lastGenerated.Add(time.Minute)) {

					return false
				}

				m.g.UpdateBlockTime(msgBlock)

			default:
				// 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.BlockHash()
			hashesCompleted += 2

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

	return false
}