lnwallet: add FeeEstimator interface, StaticFeeEstimator implementation

This commit adds the FeeEstimator interface, which can be used for
future fee calculation implementations. Currently, there is only the
StaticFeeEstimator implementation, which returns the same fee rate for
any transaction.

server.go

@@ -62,8 +62,9 @@ type server struct {
 
 	chainNotifier chainntnfs.ChainNotifier
 
-	bio      lnwallet.BlockChainIO
-	lnwallet *lnwallet.LightningWallet
+	bio          lnwallet.BlockChainIO
+	lnwallet     *lnwallet.LightningWallet
+	feeEstimator lnwallet.FeeEstimator
 
 	fundingMgr *fundingManager
 	chanDB     *channeldb.DB
@@ -108,8 +109,8 @@ type server struct {
 // passed listener address.
 func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 	bio lnwallet.BlockChainIO, fundingSigner lnwallet.MessageSigner,
-	wallet *lnwallet.LightningWallet, chanDB *channeldb.DB,
-	chainView chainview.FilteredChainView) (*server, error) {
+	wallet *lnwallet.LightningWallet, estimator lnwallet.FeeEstimator,
+	chanDB *channeldb.DB, chainView chainview.FilteredChainView) (*server, error) {
 
 	privKey, err := wallet.GetIdentitykey()
 	if err != nil {
@@ -131,6 +132,7 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 		bio:           bio,
 		chainNotifier: notifier,
 		chanDB:        chanDB,
+		feeEstimator:  estimator,
 
 		invoices:    newInvoiceRegistry(chanDB),
 		utxoNursery: newUtxoNursery(chanDB, notifier, wallet),
@@ -264,7 +266,7 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 
 	s.rpcServer = newRPCServer(s)
 	s.breachArbiter = newBreachArbiter(wallet, chanDB, notifier,
-		s.htlcSwitch, s.bio)
+		s.htlcSwitch, s.bio, s.feeEstimator)
 
 	var chanIDSeed [32]byte
 	if _, err := rand.Read(chanIDSeed[:]); err != nil {
@@ -272,10 +274,11 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 	}
 
 	s.fundingMgr, err = newFundingManager(fundingConfig{
-		IDKey:    s.identityPriv.PubKey(),
-		Wallet:   wallet,
-		ChainIO:  s.bio,
-		Notifier: s.chainNotifier,
+		IDKey:        s.identityPriv.PubKey(),
+		Wallet:       wallet,
+		ChainIO:      s.bio,
+		Notifier:     s.chainNotifier,
+		FeeEstimator: s.feeEstimator,
 		SignMessage: func(pubKey *btcec.PublicKey, msg []byte) (*btcec.Signature, error) {
 			if pubKey.IsEqual(s.identityPriv.PubKey()) {
 				return s.nodeSigner.SignMessage(pubKey, msg)
@@ -300,8 +303,10 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 
 			for _, channel := range dbChannels {
 				if chanID.IsChanPoint(channel.ChanID) {
-					return lnwallet.NewLightningChannel(wallet.Signer,
-						notifier, channel)
+					return lnwallet.NewLightningChannel(
+						wallet.Signer, notifier,
+						lnwallet.StaticFeeEstimator{FeeRate: 250},
+						channel)
 				}
 			}