Golang Currency.Sub方法代碼示例

// nodeAtWeight grabs an element in the tree that appears at the given weight.
// Though the tree has an arbitrary sorting, a sufficiently random weight will
// pull a random element. The tree is searched through in a post-ordered way.
func (hn *hostNode) nodeAtWeight(weight types.Currency) (*hostNode, error) {
	// Sanity check - weight must be less than the total weight of the tree.
	if weight.Cmp(hn.weight) > 0 {
		return nil, errOverweight
	}

	// Check if the left or right child should be returned.
	if hn.left != nil {
		if weight.Cmp(hn.left.weight) < 0 {
			return hn.left.nodeAtWeight(weight)
		}
		weight = weight.Sub(hn.left.weight) // Search from 0th index of right side.
	}
	if hn.right != nil && weight.Cmp(hn.right.weight) < 0 {
		return hn.right.nodeAtWeight(weight)
	}

	// Sanity check
	if build.DEBUG && !hn.taken {
		build.Critical("nodeAtWeight should not be returning a nil entry")
	}

	// Return the root entry.
	return hn, nil
}

// wallettransactionscmd lists all of the transactions related to the wallet,
// providing a net flow of siacoins and siafunds for each.
func wallettransactionscmd() {
	wtg := new(api.WalletTransactionsGET)
	err := getAPI("/wallet/transactions?startheight=0&endheight=10000000", wtg)
	if err != nil {
		fmt.Println("Could not fetch transaction history:", err)
		return
	}

	fmt.Println("    [height]                                                   [transaction id]    [net siacoins]   [net siafunds]")
	txns := append(wtg.ConfirmedTransactions, wtg.UnconfirmedTransactions...)
	for _, txn := range txns {
		// Determine the number of outgoing siacoins and siafunds.
		var outgoingSiacoins types.Currency
		var outgoingSiafunds types.Currency
		for _, input := range txn.Inputs {
			if input.FundType == types.SpecifierSiacoinInput && input.WalletAddress {
				outgoingSiacoins = outgoingSiacoins.Add(input.Value)
			}
			if input.FundType == types.SpecifierSiafundInput && input.WalletAddress {
				outgoingSiafunds = outgoingSiafunds.Add(input.Value)
			}
		}

		// Determine the number of incoming siacoins and siafunds.
		var incomingSiacoins types.Currency
		var incomingSiafunds types.Currency
		for _, output := range txn.Outputs {
			if output.FundType == types.SpecifierMinerPayout {
				incomingSiacoins = incomingSiacoins.Add(output.Value)
			}
			if output.FundType == types.SpecifierSiacoinOutput && output.WalletAddress {
				incomingSiacoins = incomingSiacoins.Add(output.Value)
			}
			if output.FundType == types.SpecifierSiafundOutput && output.WalletAddress {
				incomingSiafunds = incomingSiafunds.Add(output.Value)
			}
		}

		// Convert the siacoins to a float.
		incomingSiacoinsFloat, _ := new(big.Rat).SetFrac(incomingSiacoins.Big(), types.SiacoinPrecision.Big()).Float64()
		outgoingSiacoinsFloat, _ := new(big.Rat).SetFrac(outgoingSiacoins.Big(), types.SiacoinPrecision.Big()).Float64()

		// Print the results.
		if txn.ConfirmationHeight < 1e9 {
			fmt.Printf("%12v", txn.ConfirmationHeight)
		} else {
			fmt.Printf(" unconfirmed")
		}
		fmt.Printf("%67v%15.2f SC", txn.TransactionID, incomingSiacoinsFloat-outgoingSiacoinsFloat)
		// For siafunds, need to avoid having a negative types.Currency.
		if incomingSiafunds.Cmp(outgoingSiafunds) >= 0 {
			fmt.Printf("%14v SF\n", incomingSiafunds.Sub(outgoingSiafunds))
		} else {
			fmt.Printf("-%14v SF\n", outgoingSiafunds.Sub(incomingSiafunds))
		}
	}
}

// checkSiacoins counts the number of siacoins in the database and verifies
// that it matches the sum of all the coinbases.
func (cs *ConsensusSet) checkSiacoins() error {
	// Calculate the number of expected coins in constant time.
	deflationBlocks := types.InitialCoinbase - types.MinimumCoinbase
	expectedSiacoins := types.CalculateCoinbase(0).Add(types.CalculateCoinbase(cs.height())).Div(types.NewCurrency64(2))
	if cs.height() < types.BlockHeight(deflationBlocks) {
		expectedSiacoins = expectedSiacoins.Mul(types.NewCurrency64(uint64(cs.height()) + 1))
	} else {
		expectedSiacoins = expectedSiacoins.Mul(types.NewCurrency64(deflationBlocks + 1))
		trailingSiacoins := types.NewCurrency64(uint64(cs.height()) - deflationBlocks).Mul(types.CalculateCoinbase(cs.height()))
		expectedSiacoins = expectedSiacoins.Add(trailingSiacoins)
	}

	totalSiacoins := types.ZeroCurrency
	cs.db.forEachSiacoinOutputs(func(scoid types.SiacoinOutputID, sco types.SiacoinOutput) {
		totalSiacoins = totalSiacoins.Add(sco.Value)
	})
	cs.db.forEachFileContracts(func(fcid types.FileContractID, fc types.FileContract) {
		var payout types.Currency
		for _, output := range fc.ValidProofOutputs {
			payout = payout.Add(output.Value)
		}
		totalSiacoins = totalSiacoins.Add(payout)
	})
	cs.db.forEachDelayedSiacoinOutputs(func(v types.SiacoinOutputID, dso types.SiacoinOutput) {
		totalSiacoins = totalSiacoins.Add(dso.Value)
	})
	var siafundPool types.Currency
	err := cs.db.Update(func(tx *bolt.Tx) error {
		siafundPool = getSiafundPool(tx)
		return nil
	})
	if err != nil {
		return err
	}
	cs.db.forEachSiafundOutputs(func(sfoid types.SiafundOutputID, sfo types.SiafundOutput) {
		sfoSiacoins := siafundPool.Sub(sfo.ClaimStart).Div(types.SiafundCount).Mul(sfo.Value)
		totalSiacoins = totalSiacoins.Add(sfoSiacoins)
	})
	if expectedSiacoins.Cmp(totalSiacoins) != 0 {
		return errSiacoinMiscount
	}
	return nil
}

// FundSiacoins will add a siacoin input of exaclty 'amount' to the
// transaction. A parent transaction may be needed to achieve an input with the
// correct value. The siacoin input will not be signed until 'Sign' is called
// on the transaction builder.
func (tb *transactionBuilder) FundSiacoins(amount types.Currency) error {
	tb.wallet.mu.Lock()
	defer tb.wallet.mu.Unlock()

	// Collect a value-sorted set of siacoin outputs.
	var so sortedOutputs
	for scoid, sco := range tb.wallet.siacoinOutputs {
		so.ids = append(so.ids, scoid)
		so.outputs = append(so.outputs, sco)
	}
	// Add all of the unconfirmed outputs as well.
	for _, upt := range tb.wallet.unconfirmedProcessedTransactions {
		for i, sco := range upt.Transaction.SiacoinOutputs {
			// Determine if the output belongs to the wallet.
			_, exists := tb.wallet.keys[sco.UnlockHash]
			if !exists {
				continue
			}
			so.ids = append(so.ids, upt.Transaction.SiacoinOutputID(uint64(i)))
			so.outputs = append(so.outputs, sco)
		}
	}
	sort.Sort(sort.Reverse(so))

	// Create and fund a parent transaction that will add the correct amount of
	// siacoins to the transaction.
	var fund types.Currency
	// potentialFund tracks the balance of the wallet including outputs that
	// have been spent in other unconfirmed transactions recently. This is to
	// provide the user with a more useful error message in the event that they
	// are overspending.
	var potentialFund types.Currency
	parentTxn := types.Transaction{}
	var spentScoids []types.SiacoinOutputID
	for i := range so.ids {
		scoid := so.ids[i]
		sco := so.outputs[i]
		// Check that this output has not recently been spent by the wallet.
		spendHeight := tb.wallet.spentOutputs[types.OutputID(scoid)]
		// Prevent an underflow error.
		allowedHeight := tb.wallet.consensusSetHeight - RespendTimeout
		if tb.wallet.consensusSetHeight < RespendTimeout {
			allowedHeight = 0
		}
		if spendHeight > allowedHeight {
			potentialFund = potentialFund.Add(sco.Value)
			continue
		}
		outputUnlockConditions := tb.wallet.keys[sco.UnlockHash].UnlockConditions
		if tb.wallet.consensusSetHeight < outputUnlockConditions.Timelock {
			continue
		}

		// Add a siacoin input for this output.
		sci := types.SiacoinInput{
			ParentID:         scoid,
			UnlockConditions: outputUnlockConditions,
		}
		parentTxn.SiacoinInputs = append(parentTxn.SiacoinInputs, sci)
		spentScoids = append(spentScoids, scoid)

		// Add the output to the total fund
		fund = fund.Add(sco.Value)
		potentialFund = potentialFund.Add(sco.Value)
		if fund.Cmp(amount) >= 0 {
			break
		}
	}
	if potentialFund.Cmp(amount) >= 0 && fund.Cmp(amount) < 0 {
		return modules.ErrPotentialDoubleSpend
	}
	if fund.Cmp(amount) < 0 {
		return modules.ErrLowBalance
	}

	// Create and add the output that will be used to fund the standard
	// transaction.
	parentUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
	if err != nil {
		return err
	}
	exactOutput := types.SiacoinOutput{
		Value:      amount,
		UnlockHash: parentUnlockConditions.UnlockHash(),
	}
	parentTxn.SiacoinOutputs = append(parentTxn.SiacoinOutputs, exactOutput)

	// Create a refund output if needed.
	if amount.Cmp(fund) != 0 {
		refundUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
		if err != nil {
			return err
		}
		refundOutput := types.SiacoinOutput{
			Value:      fund.Sub(amount),
			UnlockHash: refundUnlockConditions.UnlockHash(),
//.........這裏部分代碼省略.........

// FundSiafunds will add a siafund input of exaclty 'amount' to the
// transaction. A parent transaction may be needed to achieve an input with the
// correct value. The siafund input will not be signed until 'Sign' is called
// on the transaction builder.
func (tb *transactionBuilder) FundSiafunds(amount types.Currency) error {
	tb.wallet.mu.Lock()
	defer tb.wallet.mu.Unlock()

	// Create and fund a parent transaction that will add the correct amount of
	// siafunds to the transaction.
	var fund types.Currency
	var potentialFund types.Currency
	parentTxn := types.Transaction{}
	var spentSfoids []types.SiafundOutputID
	for sfoid, sfo := range tb.wallet.siafundOutputs {
		// Check that this output has not recently been spent by the wallet.
		spendHeight := tb.wallet.spentOutputs[types.OutputID(sfoid)]
		// Prevent an underflow error.
		allowedHeight := tb.wallet.consensusSetHeight - RespendTimeout
		if tb.wallet.consensusSetHeight < RespendTimeout {
			allowedHeight = 0
		}
		if spendHeight > allowedHeight {
			potentialFund = potentialFund.Add(sfo.Value)
			continue
		}
		outputUnlockConditions := tb.wallet.keys[sfo.UnlockHash].UnlockConditions
		if tb.wallet.consensusSetHeight < outputUnlockConditions.Timelock {
			continue
		}

		// Add a siafund input for this output.
		parentClaimUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
		if err != nil {
			return err
		}
		sfi := types.SiafundInput{
			ParentID:         sfoid,
			UnlockConditions: outputUnlockConditions,
			ClaimUnlockHash:  parentClaimUnlockConditions.UnlockHash(),
		}
		parentTxn.SiafundInputs = append(parentTxn.SiafundInputs, sfi)
		spentSfoids = append(spentSfoids, sfoid)

		// Add the output to the total fund
		fund = fund.Add(sfo.Value)
		potentialFund = potentialFund.Add(sfo.Value)
		if fund.Cmp(amount) >= 0 {
			break
		}
	}
	if potentialFund.Cmp(amount) >= 0 && fund.Cmp(amount) < 0 {
		return modules.ErrPotentialDoubleSpend
	}
	if fund.Cmp(amount) < 0 {
		return modules.ErrLowBalance
	}

	// Create and add the output that will be used to fund the standard
	// transaction.
	parentUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
	if err != nil {
		return err
	}
	exactOutput := types.SiafundOutput{
		Value:      amount,
		UnlockHash: parentUnlockConditions.UnlockHash(),
	}
	parentTxn.SiafundOutputs = append(parentTxn.SiafundOutputs, exactOutput)

	// Create a refund output if needed.
	if amount.Cmp(fund) != 0 {
		refundUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
		if err != nil {
			return err
		}
		refundOutput := types.SiafundOutput{
			Value:      fund.Sub(amount),
			UnlockHash: refundUnlockConditions.UnlockHash(),
		}
		parentTxn.SiafundOutputs = append(parentTxn.SiafundOutputs, refundOutput)
	}

	// Sign all of the inputs to the parent trancstion.
	for _, sfi := range parentTxn.SiafundInputs {
		_, err := addSignatures(&parentTxn, types.FullCoveredFields, sfi.UnlockConditions, crypto.Hash(sfi.ParentID), tb.wallet.keys[sfi.UnlockConditions.UnlockHash()])
		if err != nil {
			return err
		}
	}

	// Add the exact output.
	claimUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
	if err != nil {
		return err
	}
	newInput := types.SiafundInput{
		ParentID:         parentTxn.SiafundOutputID(0),
		UnlockConditions: parentUnlockConditions,
		ClaimUnlockHash:  claimUnlockConditions.UnlockHash(),
//.........這裏部分代碼省略.........

// FundSiafunds will add a siafund input of exaclty 'amount' to the
// transaction. A parent transaction may be needed to achieve an input with the
// correct value. The siafund input will not be signed until 'Sign' is called
// on the transaction builder.
//
// TODO: The implementation of FundSiacoins is known to have quirks/bugs
// (non-fatal), and has diverged from the implementation of FundSiacoins. The
// implementations should be converged once again.
func (tb *transactionBuilder) FundSiafunds(amount types.Currency) error {
	lockID := tb.wallet.mu.Lock()
	defer tb.wallet.mu.Unlock(lockID)

	// Create and fund a parent transaction that will add the correct amount of
	// siafunds to the transaction.
	var fund types.Currency
	parentTxn := types.Transaction{}
	for scoid, sco := range tb.wallet.siafundOutputs {
		// Check that this output has not recently been spent by the wallet.
		spendHeight := tb.wallet.spentOutputs[types.OutputID(scoid)]
		if spendHeight > tb.wallet.consensusSetHeight-RespendTimeout {
			continue
		}
		outputUnlockConditions := tb.wallet.keys[sco.UnlockHash].unlockConditions
		if tb.wallet.consensusSetHeight < outputUnlockConditions.Timelock {
			continue
		}
		// Mark the output as spent.
		tb.wallet.spentOutputs[types.OutputID(scoid)] = tb.wallet.consensusSetHeight

		// Add a siafund input for this output.
		parentClaimUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
		if err != nil {
			return err
		}
		sci := types.SiafundInput{
			ParentID:         scoid,
			UnlockConditions: outputUnlockConditions,
			ClaimUnlockHash:  parentClaimUnlockConditions.UnlockHash(),
		}
		parentTxn.SiafundInputs = append(parentTxn.SiafundInputs, sci)

		// Add the output to the total fund
		fund = fund.Add(sco.Value)
		if fund.Cmp(amount) >= 0 {
			break
		}
	}

	// Create and add the output that will be used to fund the standard
	// transaction.
	parentUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
	if err != nil {
		return err
	}
	exactOutput := types.SiafundOutput{
		Value:      amount,
		UnlockHash: parentUnlockConditions.UnlockHash(),
	}
	parentTxn.SiafundOutputs = append(parentTxn.SiafundOutputs, exactOutput)

	// Create a refund output if needed.
	if amount.Cmp(fund) != 0 {
		refundUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
		if err != nil {
			return err
		}
		refundOutput := types.SiafundOutput{
			Value:      fund.Sub(amount),
			UnlockHash: refundUnlockConditions.UnlockHash(),
		}
		parentTxn.SiafundOutputs = append(parentTxn.SiafundOutputs, refundOutput)
	}

	// Sign all of the inputs to the parent trancstion.
	for _, sfi := range parentTxn.SiafundInputs {
		err := addSignatures(&parentTxn, types.FullCoveredFields, sfi.UnlockConditions, crypto.Hash(sfi.ParentID), tb.wallet.keys[sfi.UnlockConditions.UnlockHash()])
		if err != nil {
			return err
		}
	}

	// Add the exact output.
	claimUnlockConditions, err := tb.wallet.nextPrimarySeedAddress()
	if err != nil {
		return err
	}
	newInput := types.SiafundInput{
		ParentID:         parentTxn.SiafundOutputID(0),
		UnlockConditions: parentUnlockConditions,
		ClaimUnlockHash:  claimUnlockConditions.UnlockHash(),
	}
	tb.parents = append(tb.parents, parentTxn)
	tb.siafundInputs = append(tb.siafundInputs, len(tb.transaction.SiafundInputs))
	tb.transaction.SiafundInputs = append(tb.transaction.SiafundInputs, newInput)
	return nil
}

//.........這裏部分代碼省略.........
		return types.Transaction{}, ErrInsufficientSiafunds
	}

	// Truncate the keys to exactly the number needed.
	skps = skps[:skps[0].UnlockConditions.SignaturesRequired]

	// Assemble the base transction, including a 10 siacoin fee if possible.
	id, err := w.RegisterTransaction(types.Transaction{})
	if err != nil {
		return types.Transaction{}, err
	}
	// Add a miner fee - if funding the transaction fails, we'll just send a
	// transaction with no fee.
	txn, err := w.FundTransaction(id, types.NewCurrency64(TransactionFee))
	if err == nil {
		txn, _, err = w.AddMinerFee(id, types.NewCurrency64(TransactionFee))
		if err != nil {
			return types.Transaction{}, err
		}
	}
	// Add the siafund inputs to the transcation.
	for _, sfoid := range sfoids {
		// Get an address for the siafund claims.
		lockID := w.mu.Lock()
		claimDest, _, err := w.coinAddress(false)
		w.mu.Unlock(lockID)
		if err != nil {
			return types.Transaction{}, err
		}

		// Assemble the SiafundInput to spend this output.
		sfi := types.SiafundInput{
			ParentID:         sfoid,
			UnlockConditions: skps[0].UnlockConditions,
			ClaimUnlockHash:  claimDest,
		}
		txn, _, err = w.AddSiafundInput(id, sfi)
		if err != nil {
			return types.Transaction{}, err
		}
	}
	// Add the siafund output to the transaction.
	sfo := types.SiafundOutput{
		Value:      amount,
		UnlockHash: dest,
	}
	txn, _, err = w.AddSiafundOutput(id, sfo)
	if err != nil {
		return types.Transaction{}, err
	}
	// Add a refund siafund output if needed.
	if amount.Cmp(availableSiafunds) != 0 {
		refund := availableSiafunds.Sub(amount)
		sfo := types.SiafundOutput{
			Value:      refund,
			UnlockHash: baseUnlockHash,
		}
		txn, _, err = w.AddSiafundOutput(id, sfo)
		if err != nil {
			return types.Transaction{}, err
		}
	}
	// Add signatures for the siafund inputs.
	sigIndex := 0
	for _, sfoid := range sfoids {
		for _, key := range skps {
			txnSig := types.TransactionSignature{
				ParentID:       crypto.Hash(sfoid),
				CoveredFields:  types.CoveredFields{WholeTransaction: true},
				PublicKeyIndex: uint64(key.Index),
			}
			txn.TransactionSignatures = append(txn.TransactionSignatures, txnSig)
			sigHash := txn.SigHash(sigIndex)
			encodedSig, err := crypto.SignHash(sigHash, key.SecretKey)
			if err != nil {
				return types.Transaction{}, err
			}
			txn.TransactionSignatures[sigIndex].Signature = encodedSig[:]

			txn, _, err = w.AddTransactionSignature(id, txn.TransactionSignatures[sigIndex])
			if err != nil {
				return types.Transaction{}, err
			}

			sigIndex++
		}
	}

	// Sign the transaction.
	txn, err = w.SignTransaction(id, true)
	if err != nil {
		return types.Transaction{}, err
	}

	err = w.tpool.AcceptTransaction(txn)
	if err != nil {
		return types.Transaction{}, err
	}
	return txn, nil
}