lnwallet: move FeeEstimator into distinct file

In this commit, we move the FeeEstimator interface into a distinct file
as follow up commits will begin to flesh out the interface with
additional implementations.

lnwallet/fee_estimator.go

@@ -0,0 +1,40 @@
+package lnwallet
+
+// FeeEstimator provides the ability to estimate on-chain transaction fees for
+// various combinations of transaction sizes and desired confirmation time
+// (measured by number of blocks).
+type FeeEstimator interface {
+	// EstimateFeePerByte takes in a target for the number of blocks until
+	// an initial confirmation and returns the estimated fee expressed in
+	// satoshis/byte.
+	EstimateFeePerByte(numBlocks uint32) uint64
+
+	// EstimateFeePerWeight takes in a target for the number of blocks
+	// until an initial confirmation and returns the estimated fee
+	// expressed in satoshis/weight.
+	EstimateFeePerWeight(numBlocks uint32) uint64
+}
+
+// StaticFeeEstimator will return a static value for all fee calculation
+// requests. It is designed to be replaced by a proper fee calculation
+// implementation.
+type StaticFeeEstimator struct {
+	// FeeRate is the static fee rate in satoshis-per-byte that will be
+	// returned by this fee estimator. Queries for the fee rate in weight
+	// units will be scaled accordingly.
+	FeeRate uint64
+}
+
+// EstimateFeePerByte will return a static value for fee calculations.
+func (e StaticFeeEstimator) EstimateFeePerByte(numBlocks uint32) uint64 {
+	return e.FeeRate
+}
+
+// EstimateFeePerWeight will return a static value for fee calculations.
+func (e StaticFeeEstimator) EstimateFeePerWeight(numBlocks uint32) uint64 {
+	return e.FeeRate / 4
+}
+
+// A compile-time assertion to ensure that StaticFeeEstimator implements the
+// FeeEstimator interface.
+var _ FeeEstimator = (*StaticFeeEstimator)(nil)

lnwallet/interface.go

@@ -268,26 +268,6 @@ type MessageSigner interface {
 	SignMessage(pubKey *btcec.PublicKey, msg []byte) (*btcec.Signature, error)
 }
 
-// FeeEstimator provides the ability to estimate on-chain transaction fees for
-// various combinations of transaction sizes and desired confirmation time
-// (measured by number of blocks).
-type FeeEstimator interface {
-	// EstimateFeePerByte takes in a target for the number of blocks until
-	// an initial confirmation and returns the estimated fee expressed in
-	// satoshis/byte.
-	EstimateFeePerByte(numBlocks uint32) uint64
-
-	// EstimateFeePerWeight takes in a target for the number of blocks until
-	// an initial confirmation and returns the estimated fee expressed in
-	// satoshis/weight.
-	EstimateFeePerWeight(numBlocks uint32) uint64
-
-	// EstimateConfirmation will return the number of blocks expected for a
-	// transaction to be confirmed given a fee rate in satoshis per
-	// byte.
-	EstimateConfirmation(satPerByte int64) uint32
-}
-
 // WalletDriver represents a "driver" for a particular concrete
 // WalletController implementation. A driver is identified by a globally unique
 // string identifier along with a 'New()' method which is responsible for

lnwallet/wallet.go

@@ -1445,28 +1445,3 @@ func coinSelect(feeRatePerWeight uint64, amt btcutil.Amount,
 		return selectedUtxos, changeAmt, nil
 	}
 }
-
-// StaticFeeEstimator will return a static value for all fee calculation
-// requests. It is designed to be replaced by a proper fee calculation
-// implementation.
-type StaticFeeEstimator struct {
-	FeeRate      uint64
-	Confirmation uint32
-}
-
-// EstimateFeePerByte will return a static value for fee calculations.
-func (e StaticFeeEstimator) EstimateFeePerByte(numBlocks uint32) uint64 {
-	return e.FeeRate
-}
-
-// EstimateFeePerWeight will return a static value for fee calculations.
-func (e StaticFeeEstimator) EstimateFeePerWeight(numBlocks uint32) uint64 {
-	return e.FeeRate / 4
-}
-
-// EstimateConfirmation will return a static value representing the estimated
-// number of blocks that will be required to confirm a transaction for the
-// given fee rate.
-func (e StaticFeeEstimator) EstimateConfirmation(satPerByte int64) uint32 {
-	return e.Confirmation
-}