Split fees between liquidity ads and swap-in #709
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pm47
commented
Oct 8, 2024
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| serviceFee = 0.msat, | ||
| miningFee = action.fundingTx.sharedTx.tx.localFees.truncateToSatoshi(), |
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Note how we are not using the channelOrigin anymore. There is a certain amount of duplication regarding fee calculation here, I'm not sure how we can simplify. We could revisit later.
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| // If we received or sent funds as part of the splice, we will add a corresponding entry to our incoming/outgoing payments db | ||
| addAll(origins.map { origin -> | ||
| ChannelAction.Storage.StoreIncomingPayment.ViaSpliceIn( | ||
| amountReceived = origin.amountReceived(), | ||
| serviceFee = origin.fees.serviceFee.toMilliSatoshi(), | ||
| miningFee = origin.fees.miningFee, | ||
| localInputs = action.fundingTx.sharedTx.tx.localInputs.map { it.outPoint }.toSet(), | ||
| txId = action.fundingTx.txId, | ||
| origin = origin | ||
| ) | ||
| }) | ||
| // If we added some funds ourselves it's a swap-in |
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There was two separate ViaSpliceIn sections, I'm not sure why.
| if (action.fundingTx.sharedTx.tx.localInputs.isNotEmpty()) add( | ||
| ChannelAction.Storage.StoreIncomingPayment.ViaSpliceIn( | ||
| amountReceived = action.fundingTx.sharedTx.tx.localInputs.map { i -> i.txOut.amount }.sum().toMilliSatoshi() - action.fundingTx.sharedTx.tx.localFees, | ||
| serviceFee = 0.msat, | ||
| miningFee = action.fundingTx.sharedTx.tx.localFees.truncateToSatoshi(), | ||
| localInputs = action.fundingTx.sharedTx.tx.localInputs.map { it.outPoint }.toSet(), | ||
| txId = action.fundingTx.txId, | ||
| origin = null | ||
| origin = origins.filterIsInstance<Origin.OnChainWallet>().firstOrNull() |
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The model allows multiple origins but I don't think we can have several of the OnChainWallet type. We must have an origin otherwise the event will not be stored in db due to
Note that I have a full rework of the incoming payments db on another branch where this particular part is cleaned up.
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I was also wondering whether we should get rid of the multiple origins or not. If you're fixing this on another branch, that's great!
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| // If we purchased liquidity as part of the channel creation, we will add it to our payments db | ||
| liquidityPurchase?.let { purchase -> | ||
| if (channelParams.localParams.isChannelOpener) { | ||
| // We only count fees corresponding to the liquidity purchase (i.e. their inputs). | ||
| add(ChannelAction.Storage.StoreOutgoingPayment.ViaInboundLiquidityRequest(txId = action.fundingTx.txId, purchase = purchase)) | ||
| add(ChannelAction.EmitEvent(LiquidityEvents.Purchased(purchase))) | ||
| } | ||
| } |
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We move this event up because it makes more sense to have it happen "before".
t-bast
reviewed
Oct 9, 2024
src/commonMain/kotlin/fr/acinq/lightning/channel/states/Normal.kt
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When we are purchasing liquidity without any other splice operation (splice-in, splice-out or splice-cpfp), we will have a single entry in our DB: the liquidity purchase itself. In that case, we are paying mining fees for the shared input and output: we must record those in the purchase. This happens during manual liquidity purchases and on-the-fly funding. We cannot easily add tests because we don't implement the liquidity seller side, which makes it hard to trigger those conditions.
t-bast
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Oct 9, 2024
dpad85
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Oct 9, 2024
With ACINQ/lightning-kmp#709 the mining fee is split between local and purchase fees. However, for compat with legacy leases, we do not store the local fee separately in the database. Instead we store the full mining fee and calculate the local fee by subtracting this full fee with the purchase fee.
dpad85
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Oct 10, 2024
With ACINQ/lightning-kmp#709 and ACINQ/lightning-kmp#710, the mining fee for liquidity events is split between local and purchase fee. However, we don't directly store the split fees, for backward compatibility reasons. Thus, to get the local fee from the database, we must compute it back.
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A channel open triggered by a swap-in is technically also a liquidity operation (with 1 sat liquidity required), thus causing two consecutive db events: a liquidity purchase followed by a swap-in. Both actions happen with the same on-chain transaction and we must be careful not to count mining fees twice.