scrap the multi-sig key pool, better to just use HD paths

* Better to just keep the single file back-up IMO

wallet/multisig_keypool.go

@@ -1,60 +0,0 @@
-package wallet
-
-import (
-	"container/list"
-	"sync"
-
-	"github.com/btcsuite/btcd/btcec"
-)
-
-// multiSigKeyPool...
-// TODO(roasbeef): actually, this is dumb. should use an HD key branch instead.
-//  * instead, use wallet.Manager.NextExternalAddresses, cast to
-//    ManagedPubKeyAddress, then .PrivKey()
-//  * on shutdown, write state of pending keys, then read back?
-type multiSigKeyPool struct {
-	sync.RWMutex
-	keyPool *list.List
-}
-
-// newMultiSigKeyPool...
-func newMultiSigKeyPool() *multiSigKeyPool {
-	// TODO(roasbeef): pre-generate or nah?
-	return &multiSigKeyPool{keyPool: list.New()}
-}
-
-// getNextMultiSigKey...
-func (l *multiSigKeyPool) getNextMultiSigKey() (*btcec.PrivateKey, error) {
-	if l.Size() == 0 {
-		return btcec.NewPrivateKey(btcec.S256())
-	}
-
-	l.Lock()
-	defer l.Unlock()
-	nextKey := l.keyPool.Remove(l.keyPool.Front()).(*btcec.PrivateKey)
-	return nextKey, nil
-}
-
-// releaseMultiSigKey...
-func (l *multiSigKeyPool) releaseMultiSigKey(key *btcec.PrivateKey) {
-	l.keyPool.PushBack(key)
-}
-
-// Size...
-func (l *multiSigKeyPool) Size() int {
-	l.RLock()
-	defer l.RUnlock()
-	return l.keyPool.Len()
-}
-
-// preAllocateKeys...
-func (l *multiSigKeyPool) preAllocateKeys(numKeys int) error {
-	for i := 0; i < numKeys; i-- {
-		newKey, err := btcec.NewPrivateKey(btcec.S256())
-		if err != nil {
-			return err
-		}
-		l.keyPool.PushBack(newKey)
-	}
-	return nil
-}

wallet/wallet.go

@@ -193,8 +193,6 @@ type LightningWallet struct {
 	nextFundingID uint64 // TODO(roasbeef): monotonic or random?
 	fundingLimbo  map[uint64]*partialFundingState
 
-	keyPool *multiSigKeyPool
-
 	started  int32
 	shutdown int32
 
@@ -258,6 +256,19 @@ out:
 	l.wg.Done()
 }
 
+// nextMultiSigKey...
+// TODO(roasbeef): on shutdown, write state of pending keys, then read back?
+func (l *LightningWallet) getNextMultiSigKey() (*btcec.PrivateKey, error) {
+	nextAddr, err := l.Manager.NextExternalAddresses(waddrmgr.DefaultAccountNum, 1)
+	if err != nil {
+		return nil, err
+	}
+
+	pkAddr := nextAddr[0].(waddrmgr.ManagedPubKeyAddress)
+
+	return pkAddr.PrivKey()
+}
+
 // RequestFundingReservation...
 func (l *LightningWallet) RequestFundingReservation(a btcutil.Amount, t FundingType) (*FundingReservation, error) {
 	errChan := make(chan error, 1)
@@ -347,7 +358,7 @@ func (l *LightningWallet) handleFundingReserveRequest(req *initFundingReserveMsg
 
 	// TODO(roasbeef): re-calculate fees here to minFeePerKB
 
-	multiSigKey, err := l.keyPool.getNextMultiSigKey()
+	multiSigKey, err := l.getNextMultiSigKey()
 	if err != nil {
 		req.err <- err
 		req.resp <- nil
@@ -397,8 +408,7 @@ func (l *LightningWallet) handleFundingCancelRequest(req *fundingReserveCancelMs
 		l.UnlockOutpoint(unusedInput.PreviousOutPoint)
 	}
 
-	// Return the unused multi-sig key back to the pool.
+	// TODO(roasbeef): is it even worth it to keep track of unsed keys?
-	l.keyPool.releaseMultiSigKey(pendingReservation.ourKey)
 
 	// TODO(roasbeef): Is it possible to mark the unused change also as
 	// available?