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sweep: remove dead code and dead tests

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yyforyongyu committed 2024-04-23 04:44:00 +08:00
1 parent 7af195768a
commit 54aaeea491
8 files changed
+32 -3922
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sweep/tx_input_set.go
-454
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@@ -14,23 +14,6 @@ import (
"github.com/lightningnetwork/lnd/lnwallet/chainfee"
)
// addConstraints defines the constraints to apply when adding an input.
type addConstraints uint8
const (
// constraintsRegular is for regular input sweeps that should have a positive
// yield.
constraintsRegular addConstraints = iota
// constraintsWallet is for wallet inputs that are only added to bring up the tx
// output value.
constraintsWallet
// constraintsForce is for inputs that should be swept even with a negative
// yield at the set fee rate.
constraintsForce
)
var (
// ErrNotEnoughInputs is returned when there are not enough wallet
// inputs to construct a non-dust change output for an input set.
@@ -83,443 +66,6 @@ type InputSet interface {
StartingFeeRate() fn.Option[chainfee.SatPerKWeight]
}
type txInputSetState struct {
// feeRate is the fee rate to use for the sweep transaction.
feeRate chainfee.SatPerKWeight
// maxFeeRate is the max allowed fee rate configured by the user.
maxFeeRate chainfee.SatPerKWeight
// inputTotal is the total value of all inputs.
inputTotal btcutil.Amount
// requiredOutput is the sum of the outputs committed to by the inputs.
requiredOutput btcutil.Amount
// changeOutput is the value of the change output. This will be what is
// left over after subtracting the requiredOutput and the tx fee from
// the inputTotal.
//
// NOTE: This might be below the dust limit, or even negative since it
// is the change remaining in csse we pay the fee for a change output.
changeOutput btcutil.Amount
// inputs is the set of tx inputs.
inputs []input.Input
// walletInputTotal is the total value of inputs coming from the wallet.
walletInputTotal btcutil.Amount
// force indicates that this set must be swept even if the total yield
// is negative.
force bool
}
// weightEstimate is the (worst case) tx weight with the current set of
// inputs. It takes a parameter whether to add a change output or not.
func (t *txInputSetState) weightEstimate(change bool) *weightEstimator {
weightEstimate := newWeightEstimator(t.feeRate, t.maxFeeRate)
for _, i := range t.inputs {
// Can ignore error, because it has already been checked when
// calculating the yields.
_ = weightEstimate.add(i)
r := i.RequiredTxOut()
if r != nil {
weightEstimate.addOutput(r)
}
}
// Add a change output to the weight estimate if requested.
if change {
weightEstimate.addP2TROutput()
}
return weightEstimate
}
// totalOutput is the total amount left for us after paying fees.
//
// NOTE: This might be dust.
func (t *txInputSetState) totalOutput() btcutil.Amount {
return t.requiredOutput + t.changeOutput
}
func (t *txInputSetState) clone() txInputSetState {
s := txInputSetState{
feeRate: t.feeRate,
inputTotal: t.inputTotal,
changeOutput: t.changeOutput,
requiredOutput: t.requiredOutput,
walletInputTotal: t.walletInputTotal,
force: t.force,
inputs: make([]input.Input, len(t.inputs)),
}
copy(s.inputs, t.inputs)
return s
}
// txInputSet is an object that accumulates tx inputs and keeps running counters
// on various properties of the tx.
type txInputSet struct {
txInputSetState
// maxInputs is the maximum number of inputs that will be accepted in
// the set.
maxInputs uint32
}
// Compile-time constraint to ensure txInputSet implements InputSet.
var _ InputSet = (*txInputSet)(nil)
// newTxInputSet constructs a new, empty input set.
func newTxInputSet(feePerKW, maxFeeRate chainfee.SatPerKWeight,
maxInputs uint32) *txInputSet {
state := txInputSetState{
feeRate: feePerKW,
maxFeeRate: maxFeeRate,
}
b := txInputSet{
maxInputs: maxInputs,
txInputSetState: state,
}
return &b
}
// Inputs returns the inputs that should be used to create a tx.
func (t *txInputSet) Inputs() []input.Input {
return t.inputs
}
// Budget gives the total amount that can be used as fees by this input set.
//
// NOTE: this field is only used for `BudgetInputSet`.
func (t *txInputSet) Budget() btcutil.Amount {
return t.totalOutput()
}
// DeadlineHeight gives the block height that this set must be confirmed by.
//
// NOTE: this field is only used for `BudgetInputSet`.
func (t *txInputSet) DeadlineHeight() int32 {
return 0
}
// StartingFeeRate returns the max starting fee rate found in the inputs.
//
// NOTE: this field is only used for `BudgetInputSet`.
func (t *txInputSet) StartingFeeRate() fn.Option[chainfee.SatPerKWeight] {
return fn.None[chainfee.SatPerKWeight]()
}
// NeedWalletInput returns true if the input set needs more wallet inputs.
func (t *txInputSet) NeedWalletInput() bool {
return !t.enoughInput()
}
// enoughInput returns true if we've accumulated enough inputs to pay the fees
// and have at least one output that meets the dust limit.
func (t *txInputSet) enoughInput() bool {
// If we have a change output above dust, then we certainly have enough
// inputs to the transaction.
if t.changeOutput >= lnwallet.DustLimitForSize(input.P2TRSize) {
return true
}
// We did not have enough input for a change output. Check if we have
// enough input to pay the fees for a transaction with no change
// output.
fee := t.weightEstimate(false).feeWithParent()
if t.inputTotal < t.requiredOutput+fee {
return false
}
// We could pay the fees, but we still need at least one output to be
// above the dust limit for the tx to be valid (we assume that these
// required outputs only get added if they are above dust)
for _, inp := range t.inputs {
if inp.RequiredTxOut() != nil {
return true
}
}
return false
}
// add adds a new input to the set. It returns a bool indicating whether the
// input was added to the set. An input is rejected if it decreases the tx
// output value after paying fees.
func (t *txInputSet) addToState(inp input.Input,
constraints addConstraints) *txInputSetState {
// Stop if max inputs is reached. Do not count additional wallet inputs,
// because we don't know in advance how many we may need.
if constraints != constraintsWallet &&
uint32(len(t.inputs)) >= t.maxInputs {
return nil
}
// If the input comes with a required tx out that is below dust, we
// won't add it.
//
// NOTE: only HtlcSecondLevelAnchorInput returns non-nil RequiredTxOut.
reqOut := inp.RequiredTxOut()
if reqOut != nil {
// Fetch the dust limit for this output.
dustLimit := lnwallet.DustLimitForSize(len(reqOut.PkScript))
if btcutil.Amount(reqOut.Value) < dustLimit {
log.Errorf("Rejected input=%v due to dust required "+
"output=%v, limit=%v", inp, reqOut.Value,
dustLimit)
// TODO(yy): we should not return here for force
// sweeps. This means when sending sweeping request,
// one must be careful to not create dust outputs. In
// an extreme rare case, where the
// minRelayTxFee/discardfee is increased when sending
// the request, what's considered non-dust at the
// caller side will be dust here, causing a force sweep
// to fail.
return nil
}
}
// Clone the current set state.
newSet := t.clone()
// Add the new input.
newSet.inputs = append(newSet.inputs, inp)
// Add the value of the new input.
value := btcutil.Amount(inp.SignDesc().Output.Value)
newSet.inputTotal += value
// Recalculate the tx fee.
fee := newSet.weightEstimate(true).feeWithParent()
// Calculate the new output value.
if reqOut != nil {
newSet.requiredOutput += btcutil.Amount(reqOut.Value)
}
// NOTE: `changeOutput` could be negative here if this input is using
// constraintsForce.
newSet.changeOutput = newSet.inputTotal - newSet.requiredOutput - fee
// Calculate the yield of this input from the change in total tx output
// value.
inputYield := newSet.totalOutput() - t.totalOutput()
switch constraints {
// Don't sweep inputs that cost us more to sweep than they give us.
case constraintsRegular:
if inputYield <= 0 {
log.Debugf("Rejected regular input=%v due to negative "+
"yield=%v", value, inputYield)
return nil
}
// For force adds, no further constraints apply.
//
// NOTE: because the inputs are sorted with force sweeps being placed
// at the start of the list, we should never see an input with
// constraintsForce come after an input with constraintsRegular. In
// other words, though we may have negative `changeOutput` from
// including force sweeps, `inputYield` should always increase when
// adding regular inputs.
case constraintsForce:
newSet.force = true
// We are attaching a wallet input to raise the tx output value above
// the dust limit.
case constraintsWallet:
// Skip this wallet input if adding it would lower the output
// value.
//
// TODO(yy): change to inputYield < 0 to allow sweeping for
// UTXO aggregation only?
if inputYield <= 0 {
log.Debugf("Rejected wallet input=%v due to negative "+
"yield=%v", value, inputYield)
return nil
}
// Calculate the total value that we spend in this tx from the
// wallet if we'd add this wallet input.
newSet.walletInputTotal += value
// In any case, we don't want to lose money by sweeping. If we
// don't get more out of the tx than we put in ourselves, do not
// add this wallet input. If there is at least one force sweep
// in the set, this does no longer apply.
//
// We should only add wallet inputs to get the tx output value
// above the dust limit, otherwise we'd only burn into fees.
// This is guarded by tryAddWalletInputsIfNeeded.
//
// TODO(joostjager): Possibly require a max ratio between the
// value of the wallet input and what we get out of this
// transaction. To prevent attaching and locking a big utxo for
// very little benefit.
if newSet.force {
break
}
// TODO(yy): change from `>=` to `>` to allow non-negative
// sweeping - we won't gain more coins from this sweep, but
// aggregating small UTXOs.
if newSet.walletInputTotal >= newSet.totalOutput() {
// TODO(yy): further check this case as it seems we can
// never reach here because it'd mean `inputYield` is
// already <= 0?
log.Debugf("Rejecting wallet input of %v, because it "+
"would make a negative yielding transaction "+
"(%v)", value,
newSet.totalOutput()-newSet.walletInputTotal)
return nil
}
}
return &newSet
}
// add adds a new input to the set. It returns a bool indicating whether the
// input was added to the set. An input is rejected if it decreases the tx
// output value after paying fees.
func (t *txInputSet) add(input input.Input, constraints addConstraints) bool {
newState := t.addToState(input, constraints)
if newState == nil {
return false
}
t.txInputSetState = *newState
return true
}
// addPositiveYieldInputs adds sweepableInputs that have a positive yield to the
// input set. This function assumes that the list of inputs is sorted descending
// by yield.
//
// TODO(roasbeef): Consider including some negative yield inputs too to clean
// up the utxo set even if it costs us some fees up front. In the spirit of
// minimizing any negative externalities we cause for the Bitcoin system as a
// whole.
func (t *txInputSet) addPositiveYieldInputs(sweepableInputs []*SweeperInput) {
for i, inp := range sweepableInputs {
// Apply relaxed constraints for force sweeps.
constraints := constraintsRegular
if inp.parameters().Immediate {
constraints = constraintsForce
}
// Try to add the input to the transaction. If that doesn't
// succeed because it wouldn't increase the output value,
// return. Assuming inputs are sorted by yield, any further
// inputs wouldn't increase the output value either.
if !t.add(inp, constraints) {
var rem []input.Input
for j := i; j < len(sweepableInputs); j++ {
rem = append(rem, sweepableInputs[j])
}
log.Debugf("%d negative yield inputs not added to "+
"input set: %v", len(rem),
inputTypeSummary(rem))
return
}
log.Debugf("Added positive yield input %v to input set",
inputTypeSummary([]input.Input{inp}))
}
// We managed to add all inputs to the set.
}
// AddWalletInputs adds wallet inputs to the set until a non-dust output can be
// made. This non-dust output is either a change output or a required output.
// Return an error if there are not enough wallet inputs.
func (t *txInputSet) AddWalletInputs(wallet Wallet) error {
// Check the current output value and add wallet utxos if needed to
// push the output value to the lower limit.
if err := t.tryAddWalletInputsIfNeeded(wallet); err != nil {
return err
}
// If the output value of this block of inputs does not reach the dust
// limit, stop sweeping. Because of the sorting, continuing with the
// remaining inputs will only lead to sets with an even lower output
// value.
if !t.enoughInput() {
// The change output is always a p2tr here.
dl := lnwallet.DustLimitForSize(input.P2TRSize)
log.Debugf("Input set value %v (required=%v, change=%v) "+
"below dust limit of %v", t.totalOutput(),
t.requiredOutput, t.changeOutput, dl)
return ErrNotEnoughInputs
}
return nil
}
// tryAddWalletInputsIfNeeded retrieves utxos from the wallet and tries adding
// as many as required to bring the tx output value above the given minimum.
func (t *txInputSet) tryAddWalletInputsIfNeeded(wallet Wallet) error {
// If we've already have enough to pay the transaction fees and have at
// least one output materialize, no action is needed.
if t.enoughInput() {
return nil
}
// Retrieve wallet utxos. Only consider confirmed utxos to prevent
// problems around RBF rules for unconfirmed inputs. This currently
// ignores the configured coin selection strategy.
utxos, err := wallet.ListUnspentWitnessFromDefaultAccount(
1, math.MaxInt32,
)
if err != nil {
return err
}
// Sort the UTXOs by putting smaller values at the start of the slice
// to avoid locking large UTXO for sweeping.
//
// TODO(yy): add more choices to CoinSelectionStrategy and use the
// configured value here.
sort.Slice(utxos, func(i, j int) bool {
return utxos[i].Value < utxos[j].Value
})
for _, utxo := range utxos {
input, err := createWalletTxInput(utxo)
if err != nil {
return err
}
// If the wallet input isn't positively-yielding at this fee
// rate, skip it.
if !t.add(input, constraintsWallet) {
continue
}
// Return if we've reached the minimum output amount.
if t.enoughInput() {
return nil
}
}
// We were not able to reach the minimum output amount.
return nil
}
// createWalletTxInput converts a wallet utxo into an object that can be added
// to the other inputs to sweep.
func createWalletTxInput(utxo *lnwallet.Utxo) (input.Input, error) {