add option to only consider the mining fee for the absolute fee check

ACINQ · Oct 10, 2024 · e087cbe · e087cbe
1 parent 78f6449
commit e087cbe
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Showing 3 changed files with 17 additions and 2 deletions.
diff --git a/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt b/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt
@@ -239,6 +239,7 @@ data class NodeParams(
                 maxAbsoluteFee = 2_000.sat,
                 maxRelativeFeeBasisPoints = 3_000 /* 3000 = 30 % */,
                 skipAbsoluteFeeCheck = false,
+                considerOnlyMiningFeeForAbsoluteFeeCheck = false,
                 maxAllowedFeeCredit = 0.msat
             )
         ),

diff --git a/src/commonMain/kotlin/fr/acinq/lightning/payment/LiquidityPolicy.kt b/src/commonMain/kotlin/fr/acinq/lightning/payment/LiquidityPolicy.kt
@@ -20,9 +20,10 @@ sealed class LiquidityPolicy {
      * @param maxAbsoluteFee max absolute fee
      * @param maxRelativeFeeBasisPoints max relative fee (all included: service fee and mining fee) (1_000 bips = 10 %)
      * @param skipAbsoluteFeeCheck only applies for off-chain payments, being more lax may make sense when the sender doesn't retry payments
+     * @param considerOnlyMiningFeeForAbsoluteFeeCheck only consider the mining fee for the absolute fee check. This makes sense in `inboundLiquidityTarget` is used, and the funding rate predictable
      * @param maxAllowedFeeCredit maximum amount that can be added to fee credit (see [fr.acinq.lightning.Feature.FundingFeeCredit])
      */
-    data class Auto(val inboundLiquidityTarget: Satoshi?, val maxAbsoluteFee: Satoshi, val maxRelativeFeeBasisPoints: Int, val skipAbsoluteFeeCheck: Boolean, val maxAllowedFeeCredit: MilliSatoshi) : LiquidityPolicy()
+    data class Auto(val inboundLiquidityTarget: Satoshi?, val maxAbsoluteFee: Satoshi, val maxRelativeFeeBasisPoints: Int, val skipAbsoluteFeeCheck: Boolean, val maxAllowedFeeCredit: MilliSatoshi, val considerOnlyMiningFeeForAbsoluteFeeCheck: Boolean = false) : LiquidityPolicy()
 
     /** Make a decision for a particular liquidity event. */
     fun maybeReject(amount: MilliSatoshi, fee: ChannelManagementFees, source: LiquidityEvents.Source, logger: MDCLogger): LiquidityEvents.Rejected? {
@@ -34,7 +35,8 @@ sealed class LiquidityPolicy {
                 logger.info { "liquidity policy check: amount=$amount liquidityTarget=${inboundLiquidityTarget ?: 0.sat} fee=$fee maxAbsoluteFee=$maxAbsoluteFee maxRelativeFee=$maxRelativeFee policy=$this" }
                 when {
                     fee.total.toMilliSatoshi() > maxRelativeFee -> LiquidityEvents.Rejected.Reason.TooExpensive.OverRelativeFee(maxRelativeFeeBasisPoints)
-                    fee.total.toMilliSatoshi() > maxAbsoluteFee -> LiquidityEvents.Rejected.Reason.TooExpensive.OverAbsoluteFee(this.maxAbsoluteFee)
+                    considerOnlyMiningFeeForAbsoluteFeeCheck && fee.miningFee.toMilliSatoshi() > maxAbsoluteFee -> LiquidityEvents.Rejected.Reason.TooExpensive.OverAbsoluteFee(this.maxAbsoluteFee)
+                    !considerOnlyMiningFeeForAbsoluteFeeCheck && fee.total.toMilliSatoshi() > maxAbsoluteFee -> LiquidityEvents.Rejected.Reason.TooExpensive.OverAbsoluteFee(this.maxAbsoluteFee)
                     else -> null // accept
                 }
             }

diff --git a/src/commonTest/kotlin/fr/acinq/lightning/payment/LiquidityPolicyTestsCommon.kt b/src/commonTest/kotlin/fr/acinq/lightning/payment/LiquidityPolicyTestsCommon.kt
@@ -46,4 +46,16 @@ class LiquidityPolicyTestsCommon : LightningTestSuite() {
             actual = policy.maybeReject(amount = 4_000_000.msat, fee = ChannelManagementFees(miningFee = 2_000.sat, serviceFee = 0.sat), source = LiquidityEvents.Source.OnChainWallet, logger)?.reason
         )
     }
+
+    @Test
+    fun `policy rejection mining fee check`() {
+        val policy = LiquidityPolicy.Auto(maxAbsoluteFee = 1_000.sat, maxRelativeFeeBasisPoints = 5_000 /* 3000 = 30 % */, skipAbsoluteFeeCheck = false, inboundLiquidityTarget = null, maxAllowedFeeCredit = 0.msat, considerOnlyMiningFeeForAbsoluteFeeCheck = true)
+        // total fee is over absolute, but mining fee is below and we only consider the mining fee
+        assertNull(policy.maybeReject(amount = 10_000_000.msat, fee = ChannelManagementFees(miningFee = 900.sat, serviceFee = 2_000.sat), source = LiquidityEvents.Source.OnChainWallet, logger))
+        // the mining fee is over absolute
+        assertEquals(
+            expected = LiquidityEvents.Rejected.Reason.TooExpensive.OverAbsoluteFee(policy.maxAbsoluteFee),
+            actual = policy.maybeReject(amount = 10_000_000.msat, fee = ChannelManagementFees(miningFee = 2_000.sat, serviceFee = 0.sat), source = LiquidityEvents.Source.OnChainWallet, logger)?.reason
+        )
+    }
 }