mirror of https://github.com/lightninglabs/loop
liquidity: add swap builder interface
carla
3 years ago
parent
4df6a4e7ca
commit
8bd7ee35be
@ -0,0 +1,162 @@
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package liquidity
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import (
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"context"
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"github.com/btcsuite/btcutil"
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"github.com/lightninglabs/loop"
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"github.com/lightninglabs/loop/labels"
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"github.com/lightninglabs/loop/loopdb"
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"github.com/lightninglabs/loop/swap"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/lightningnetwork/lnd/routing/route"
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)
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// Compile-time assertion that loopOutBuilder satisfies the swapBuilder
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// interface.
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var _ swapBuilder = (*loopOutBuilder)(nil)
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func newLoopOutBuilder(cfg *Config) *loopOutBuilder {
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return &loopOutBuilder{
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cfg: cfg,
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}
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}
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type loopOutBuilder struct {
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// cfg contains all the external functionality we require to create
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// swaps.
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cfg *Config
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}
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// swapType returns the swap type that the builder is responsible for creating.
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func (b *loopOutBuilder) swapType() swap.Type {
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return swap.TypeOut
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}
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// maySwap checks whether we can currently execute a swap, examining the
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// current on-chain fee conditions relevant to our swap type against our fee
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// restrictions.
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//
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// For loop out, we check whether the fees required for our on-chain sweep
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// transaction exceed our fee limits.
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func (b *loopOutBuilder) maySwap(ctx context.Context, params Parameters) error {
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estimate, err := b.cfg.Lnd.WalletKit.EstimateFee(
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ctx, params.SweepConfTarget,
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)
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if err != nil {
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return err
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}
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return params.FeeLimit.mayLoopOut(estimate)
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}
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// inUse examines our current swap traffic to determine whether we should
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// we can perform a swap for the peer/ channels provided.
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func (b *loopOutBuilder) inUse(traffic *swapTraffic, peer route.Vertex,
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channels []lnwire.ShortChannelID) error {
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for _, chanID := range channels {
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lastFail, recentFail := traffic.failedLoopOut[chanID]
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if recentFail {
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log.Debugf("Channel: %v not eligible for suggestions, "+
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"was part of a failed swap at: %v", chanID,
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lastFail)
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return newReasonError(ReasonFailureBackoff)
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}
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if traffic.ongoingLoopOut[chanID] {
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log.Debugf("Channel: %v not eligible for suggestions, "+
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"ongoing loop out utilizing channel", chanID)
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return newReasonError(ReasonLoopOut)
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}
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}
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if traffic.ongoingLoopIn[peer] {
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log.Debugf("Peer: %x not eligible for suggestions ongoing "+
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"loop in utilizing peer", peer)
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return newReasonError(ReasonLoopIn)
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}
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return nil
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}
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// buildSwap creates a swap for the target peer/channels provided. The autoloop
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// boolean indicates whether this swap will actually be executed, because there
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// are some calls we can leave out if this swap is just for a dry run (ie, when
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// we are just demonstrating the actions that autoloop _would_ take, but not
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// actually executing the swap).
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//
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// For loop out, we don't bother generating a new wallet address if this is a
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// dry-run, and we do not add the autoloop label to the recommended swap.
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func (b *loopOutBuilder) buildSwap(ctx context.Context, pubkey route.Vertex,
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channels []lnwire.ShortChannelID, amount btcutil.Amount,
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autoloop bool, params Parameters) (swapSuggestion, error) {
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quote, err := b.cfg.LoopOutQuote(
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ctx, &loop.LoopOutQuoteRequest{
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Amount: amount,
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SweepConfTarget: params.SweepConfTarget,
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SwapPublicationDeadline: b.cfg.Clock.Now(),
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},
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)
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if err != nil {
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return nil, err
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}
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log.Debugf("quote for suggestion: %v, swap fee: %v, "+
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"miner fee: %v, prepay: %v", amount, quote.SwapFee,
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quote.MinerFee, quote.PrepayAmount)
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// Check that the estimated fees for the suggested swap are below the
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// fee limits configured.
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if err := params.FeeLimit.loopOutLimits(amount, quote); err != nil {
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return nil, err
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}
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// Break down our fees into appropriate categories for our swap. Our
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// quote does not provide any off-chain routing estimates for us, so
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// we just set our fees from the amounts that we expect to route. We
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// don't have any off-chain fee estimation, so we just use the exact
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// prepay, swap and miner fee provided by the server and split our
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// remaining fees up from there.
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prepayMaxFee, routeMaxFee, minerFee := params.FeeLimit.loopOutFees(
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amount, quote,
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)
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var chanSet loopdb.ChannelSet
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for _, channel := range channels {
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chanSet = append(chanSet, channel.ToUint64())
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}
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// Create a request with our calculated routing fees. We can use the
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// swap fee, prepay amount and miner fee from the quote because we have
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// already validated them.
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request := loop.OutRequest{
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Amount: amount,
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OutgoingChanSet: chanSet,
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MaxPrepayRoutingFee: prepayMaxFee,
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MaxSwapRoutingFee: routeMaxFee,
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MaxMinerFee: minerFee,
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MaxSwapFee: quote.SwapFee,
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MaxPrepayAmount: quote.PrepayAmount,
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SweepConfTarget: params.SweepConfTarget,
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Initiator: autoloopSwapInitiator,
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}
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if autoloop {
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request.Label = labels.AutoloopLabel(swap.TypeOut)
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addr, err := b.cfg.Lnd.WalletKit.NextAddr(ctx)
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if err != nil {
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return nil, err
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}
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request.DestAddr = addr
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}
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return &loopOutSwapSuggestion{
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OutRequest: request,
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}, nil
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}
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