mirror of https://github.com/BTCPrivate/lnd.git
lnwallet/channel: move common calculation of balance into computeView
This commit moves common logic used to calculate the state of a commitment after applying a set of HTLC updates, into the new method computeView. This method can be used when calculating the available balance, validating the sanity of a commitment after applying a set of updates, and also when creating a new commitment, reducing the duplication of this logic.
This commit is contained in:
Johan T. Halseth
parent
98d28611e4
commit
1873fe1381
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@ -2023,62 +2023,14 @@ func (lc *LightningChannel) fetchCommitmentView(remoteChain bool,
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commitChain = lc.remoteCommitChain
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}
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ourBalance := commitChain.tip().ourBalance
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theirBalance := commitChain.tip().theirBalance
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// Add the fee from the previous commitment state back to the
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// initiator's balance, so that the fee can be recalculated and
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// re-applied in case fee estimation parameters have changed or the
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// number of outstanding HTLCs has changed.
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if lc.channelState.IsInitiator {
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ourBalance += lnwire.NewMSatFromSatoshis(commitChain.tip().fee)
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} else if !lc.channelState.IsInitiator {
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theirBalance += lnwire.NewMSatFromSatoshis(commitChain.tip().fee)
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}
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nextHeight := commitChain.tip().height + 1
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// Run through all the HTLCs that will be covered by this transaction
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// in order to update their commitment addition height, and to adjust
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// the balances on the commitment transaction accordingly.
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htlcView := lc.fetchHTLCView(theirLogIndex, ourLogIndex)
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filteredHTLCView := lc.evaluateHTLCView(htlcView, &ourBalance,
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&theirBalance, nextHeight, remoteChain)
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// Initiate feePerKw to the last committed fee for this chain as we'll
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// need this to determine which HTLC's are dust, and also the final fee
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// rate.
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feePerKw := commitChain.tail().feePerKw
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// Check if any fee updates have taken place since that last
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// commitment.
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if lc.channelState.IsInitiator {
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switch {
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// We've sent an update_fee message since our last commitment,
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// and now are now creating a commitment that reflects the new
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// fee update.
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case remoteChain && lc.pendingFeeUpdate != nil:
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feePerKw = *lc.pendingFeeUpdate
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// We've created a new commitment for the remote chain that
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// includes a fee update, and have not received a commitment
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// after the fee update has been ACKed.
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case !remoteChain && lc.pendingAckFeeUpdate != nil:
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feePerKw = *lc.pendingAckFeeUpdate
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}
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} else {
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switch {
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// We've received a fee update since the last local commitment,
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// so we'll include the fee update in the current view.
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case !remoteChain && lc.pendingFeeUpdate != nil:
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feePerKw = *lc.pendingFeeUpdate
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// Earlier we received a commitment that signed an earlier fee
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// update, and now we must ACK that update.
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case remoteChain && lc.pendingAckFeeUpdate != nil:
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feePerKw = *lc.pendingAckFeeUpdate
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}
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}
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ourBalance, theirBalance, _, filteredHTLCView, feePerKw :=
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lc.computeView(htlcView, remoteChain, true)
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// Determine how many current HTLCs are over the dust limit, and should
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// be counted for the purpose of fee calculation.
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@ -3072,6 +3024,111 @@ func (lc *LightningChannel) ChanSyncMsg() (*lnwire.ChannelReestablish, error) {
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}, nil
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}
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// computeView takes the given htlcView, and calculates the balances,
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// filtered view (settling unsettled HTLCs), commitment weight and
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// feePerKw, after applying the HTLCs to the latest commitment. The
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// returned balanced are the balances *before* subtracting the
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// commitment fee from the initiator's balance.
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//
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// If the updateState boolean is set true, the add and remove heights
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// of the HTLCs will be set to the next commitment height.
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func (lc *LightningChannel) computeView(view *htlcView, remoteChain bool,
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updateState bool) (lnwire.MilliSatoshi, lnwire.MilliSatoshi, int64,
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*htlcView, btcutil.Amount) {
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commitChain := lc.localCommitChain
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dustLimit := lc.localChanCfg.DustLimit
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if remoteChain {
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commitChain = lc.remoteCommitChain
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dustLimit = lc.remoteChanCfg.DustLimit
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}
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// Since the fetched htlc view will include all updates added
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// after the last committed state, we start with the balances
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// reflecting that state.
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ourBalance := commitChain.tip().ourBalance
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theirBalance := commitChain.tip().theirBalance
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// Add the fee from the previous commitment state back to the
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// initiator's balance, so that the fee can be recalculated and
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// re-applied in case fee estimation parameters have changed or
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// the number of outstanding HTLCs has changed.
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if lc.channelState.IsInitiator {
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ourBalance += lnwire.NewMSatFromSatoshis(
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commitChain.tip().fee)
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} else if !lc.channelState.IsInitiator {
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theirBalance += lnwire.NewMSatFromSatoshis(
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commitChain.tip().fee)
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}
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nextHeight := commitChain.tip().height + 1
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// We evaluate the view at this stage, meaning settled and
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// failed HTLCs will remove their corresponding added HTLCs.
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// The resulting filtered view will only have Add entries left,
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// making it easy to compare the channel constraints to the
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// final commitment state.
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filteredHTLCView := lc.evaluateHTLCView(view, &ourBalance,
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&theirBalance, nextHeight, remoteChain, updateState)
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// Initiate feePerKw to the last committed fee for this chain as we'll
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// need this to determine which HTLCs are dust, and also the final fee
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// rate.
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feePerKw := commitChain.tip().feePerKw
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// Check if any fee updates have taken place since that last
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// commitment.
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if lc.channelState.IsInitiator {
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switch {
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// We've sent an update_fee message since our last commitment,
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// and now are now creating a commitment that reflects the new
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// fee update.
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case remoteChain && lc.pendingFeeUpdate != nil:
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feePerKw = *lc.pendingFeeUpdate
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// We've created a new commitment for the remote chain that
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// includes a fee update, and have not received a commitment
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// after the fee update has been ACKed.
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case !remoteChain && lc.pendingAckFeeUpdate != nil:
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feePerKw = *lc.pendingAckFeeUpdate
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}
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} else {
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switch {
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// We've received a fee update since the last local commitment,
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// so we'll include the fee update in the current view.
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case !remoteChain && lc.pendingFeeUpdate != nil:
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feePerKw = *lc.pendingFeeUpdate
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// Earlier we received a commitment that signed an earlier fee
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// update, and now we must ACK that update.
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case remoteChain && lc.pendingAckFeeUpdate != nil:
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feePerKw = *lc.pendingAckFeeUpdate
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}
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}
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// Now go through all HTLCs at this stage, to calculate the total
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// weight, needed to calculate the transaction fee.
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var totalHtlcWeight int64
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for _, htlc := range filteredHTLCView.ourUpdates {
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if htlcIsDust(remoteChain, !remoteChain, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit) {
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continue
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}
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totalHtlcWeight += HtlcWeight
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}
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for _, htlc := range filteredHTLCView.theirUpdates {
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if htlcIsDust(!remoteChain, !remoteChain, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit) {
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continue
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}
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totalHtlcWeight += HtlcWeight
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}
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totalCommitWeight := CommitWeight + totalHtlcWeight
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return ourBalance, theirBalance, totalCommitWeight, filteredHTLCView, feePerKw
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}
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// validateCommitmentSanity is used to validate that on current state the commitment
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// transaction is valid in terms of propagating it over Bitcoin network, and
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// also that all outputs are meet Bitcoin spec requirements and they are
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@ -4975,124 +5032,24 @@ func (lc *LightningChannel) AvailableBalance() lnwire.MilliSatoshi {
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// this method. Additionally, the total weight of the next to be created
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// commitment is returned for accounting purposes.
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func (lc *LightningChannel) availableBalance() (lnwire.MilliSatoshi, int64) {
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// First, we'll grab the current local balance. If we're the initiator
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// of the channel then we paid the fees on the last commitment state,
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// so we'll re-apply those.
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settledBalance := lc.channelState.LocalCommitment.LocalBalance
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if lc.channelState.IsInitiator {
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settledBalance += lnwire.NewMSatFromSatoshis(
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lc.localCommitChain.tip().fee,
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)
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}
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// Next we'll grab the current set of log updates that are still active
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// and haven't been garbage collected.
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// We'll grab the current set of log updates that the remote has
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// ACKed.
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remoteACKedIndex := lc.localCommitChain.tip().theirMessageIndex
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htlcView := lc.fetchHTLCView(remoteACKedIndex,
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lc.localUpdateLog.logIndex)
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feePerKw := lc.channelState.LocalCommitment.FeePerKw
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dustLimit := lc.channelState.LocalChanCfg.DustLimit
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// We'll now re-compute the current weight of all the active HTLC's. We
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// make sure to skip any HTLC's that would be dust on our version of
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// the commitment transaction.
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var totalHtlcWeight int64
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for _, htlc := range lc.channelState.LocalCommitment.Htlcs {
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if htlcIsDust(false, true, feePerKw, htlc.Amt.ToSatoshis(),
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dustLimit) {
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continue
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}
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// Then compute our current balance for that view.
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ourBalance, _, commitWeight, _, feePerKw :=
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lc.computeView(htlcView, false, false)
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totalHtlcWeight += HtlcWeight
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}
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// Next we'll run through our set of updates and modify the
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// settledBalance and totalHtlcWeight fields accordingly.
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for _, entry := range htlcView.ourUpdates {
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switch {
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// For any new HTLC's added as a part of this state, we'll
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// subtract the total balance, and tally the weight increase if
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// it isn't dust.
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case entry.EntryType == Add && entry.addCommitHeightLocal == 0:
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settledBalance -= entry.Amount
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if htlcIsDust(false, true, feePerKw, entry.Amount.ToSatoshis(),
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dustLimit) {
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continue
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}
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totalHtlcWeight += HtlcWeight
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// For any new HTLC's we newly settled as part of this state,
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// we'll subtract the HTLC weight and increase our balance
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// accordingly.
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case entry.EntryType == Settle && entry.removeCommitHeightLocal == 0:
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totalHtlcWeight -= HtlcWeight
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settledBalance += entry.Amount
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// For any new fails added as a part of this state, we'll
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// subtract the weight of the HTLC we're failing.
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case entry.EntryType == Fail && entry.removeCommitHeightLocal == 0:
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fallthrough
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case entry.EntryType == MalformedFail && entry.removeCommitHeightLocal == 0:
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totalHtlcWeight -= HtlcWeight
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}
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}
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for _, entry := range htlcView.theirUpdates {
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switch {
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// If the remote party has an HTLC that will be included as
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// part of this state, then we'll account for the additional
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// weight of the HTLC.
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case entry.EntryType == Add && entry.addCommitHeightLocal == 0:
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if htlcIsDust(true, true, feePerKw, entry.Amount.ToSatoshis(),
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dustLimit) {
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continue
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}
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totalHtlcWeight += HtlcWeight
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// If the remote party is settling one of our HTLC's for the
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// first time as part of this state, then we'll subtract the
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// weight of the HTLC.
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case entry.EntryType == Settle && entry.removeCommitHeightLocal == 0:
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totalHtlcWeight -= HtlcWeight
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// For any HTLC's that they're failing as a part of the next,
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// state, we'll subtract the weight of the HTLC and also credit
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// ourselves back the value of the HTLC.
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case entry.EntryType == Fail && entry.removeCommitHeightLocal == 0:
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fallthrough
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case entry.EntryType == MalformedFail && entry.removeCommitHeightLocal == 0:
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totalHtlcWeight -= HtlcWeight
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settledBalance += entry.Amount
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}
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}
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// If we subtracted dust HTLC's, then we'll need to reset the weight of
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// the HTLCs back to zero.
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if totalHtlcWeight < 0 {
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totalHtlcWeight = 0
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}
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// If we're the initiator then we need to pay fees for this state, so
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// taking into account the number of active HTLC's we'll calculate the
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// fee that must be paid.
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totalCommitWeight := CommitWeight + totalHtlcWeight
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// If we are the channel initiator, we must remember to subtract the
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// commitment fee from our available balance.
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commitFee := btcutil.Amount((int64(feePerKw) * commitWeight) / 1000)
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if lc.channelState.IsInitiator {
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additionalFee := lnwire.NewMSatFromSatoshis(
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btcutil.Amount((int64(feePerKw) * totalCommitWeight) / 1000),
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)
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settledBalance -= additionalFee
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ourBalance -= lnwire.NewMSatFromSatoshis(commitFee)
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}
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return settledBalance, totalCommitWeight
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return ourBalance, commitWeight
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}
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// StateSnapshot returns a snapshot of the current fully committed state within
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