lnwallet: expose relay fee on fee estimators

htlcswitch/mock.go

@@ -75,6 +75,10 @@ func (m *mockFeeEstimator) EstimateFeePerKW(
 	}
 }
 
+func (m *mockFeeEstimator) RelayFeePerKW() lnwallet.SatPerKWeight {
+	return 1e3
+}
+
 func (m *mockFeeEstimator) Start() error {
 	return nil
 }

lnwallet/fee_estimator.go

@@ -59,6 +59,11 @@ type FeeEstimator interface {
 	// Stop stops any spawned goroutines and cleans up the resources used
 	// by the fee estimator.
 	Stop() error
+
+	// RelayFeePerKW returns the minimum fee rate required for transactions
+	// to be relayed. This is also the basis for calculation of the dust
+	// limit.
+	RelayFeePerKW() SatPerKWeight
 }
 
 // StaticFeeEstimator will return a static value for all fee calculation
@@ -68,6 +73,10 @@ type StaticFeeEstimator struct {
 	// FeePerKW is the static fee rate in satoshis-per-vbyte that will be
 	// returned by this fee estimator.
 	FeePerKW SatPerKWeight
+
+	// RelayFee is the minimum fee rate required for transactions to be
+	// relayed.
+	RelayFee SatPerKWeight
 }
 
 // EstimateFeePerKW will return a static value for fee calculations.
@@ -77,6 +86,14 @@ func (e StaticFeeEstimator) EstimateFeePerKW(numBlocks uint32) (SatPerKWeight, e
 	return e.FeePerKW, nil
 }
 
+// RelayFeePerKW returns the minimum fee rate required for transactions to be
+// relayed.
+//
+// NOTE: This method is part of the FeeEstimator interface.
+func (e StaticFeeEstimator) RelayFeePerKW() SatPerKWeight {
+	return e.RelayFee
+}
+
 // Start signals the FeeEstimator to start any processes or goroutines
 // it needs to perform its duty.
 //
@@ -206,6 +223,14 @@ func (b *BtcdFeeEstimator) EstimateFeePerKW(numBlocks uint32) (SatPerKWeight, er
 	return feeEstimate, nil
 }
 
+// RelayFeePerKW returns the minimum fee rate required for transactions to be
+// relayed.
+//
+// NOTE: This method is part of the FeeEstimator interface.
+func (b *BtcdFeeEstimator) RelayFeePerKW() SatPerKWeight {
+	return b.minFeePerKW
+}
+
 // fetchEstimate returns a fee estimate for a transaction to be confirmed in
 // confTarget blocks. The estimate is returned in sat/kw.
 func (b *BtcdFeeEstimator) fetchEstimate(confTarget uint32) (SatPerKWeight, error) {
@@ -359,6 +384,14 @@ func (b *BitcoindFeeEstimator) EstimateFeePerKW(numBlocks uint32) (SatPerKWeight
 	return feeEstimate, nil
 }
 
+// RelayFeePerKW returns the minimum fee rate required for transactions to be
+// relayed.
+//
+// NOTE: This method is part of the FeeEstimator interface.
+func (b *BitcoindFeeEstimator) RelayFeePerKW() SatPerKWeight {
+	return b.minFeePerKW
+}
+
 // fetchEstimate returns a fee estimate for a transaction to be confirmed in
 // confTarget blocks. The estimate is returned in sat/kw.
 func (b *BitcoindFeeEstimator) fetchEstimate(confTarget uint32) (SatPerKWeight, error) {