lnwallet: expose output leases on WalletController interface

lnwallet/btcwallet/btcwallet.go

@@ -19,6 +19,7 @@ import (
 	"github.com/btcsuite/btcwallet/wallet/txauthor"
 	"github.com/btcsuite/btcwallet/wallet/txrules"
 	"github.com/btcsuite/btcwallet/walletdb"
+	"github.com/btcsuite/btcwallet/wtxmgr"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
@@ -367,6 +368,27 @@ func (b *BtcWallet) UnlockOutpoint(o wire.OutPoint) {
 	b.wallet.UnlockOutpoint(o)
 }
 
+// LeaseOutput locks an output to the given ID, preventing it from being
+// available for any future coin selection attempts. The absolute time of the
+// lock's expiration is returned. The expiration of the lock can be extended by
+// successive invocations of this call. Outputs can be unlocked before their
+// expiration through `ReleaseOutput`.
+//
+// If the output is not known, wtxmgr.ErrUnknownOutput is returned. If the
+// output has already been locked to a different ID, then
+// wtxmgr.ErrOutputAlreadyLocked is returned.
+func (b *BtcWallet) LeaseOutput(id wtxmgr.LockID, op wire.OutPoint) (time.Time,
+	error) {
+	return b.wallet.LeaseOutput(id, op)
+}
+
+// ReleaseOutput unlocks an output, allowing it to be available for coin
+// selection if it remains unspent. The ID should match the one used to
+// originally lock the output.
+func (b *BtcWallet) ReleaseOutput(id wtxmgr.LockID, op wire.OutPoint) error {
+	return b.wallet.ReleaseOutput(id, op)
+}
+
 // ListUnspentWitness returns a slice of all the unspent outputs the wallet
 // controls which pay to witness programs either directly or indirectly.
 //