chainntnfs/bitcoindnotify: filter out mempool spends from relevant txs

This commit fix a bug within the bitcoind notifier logic, which would
ignore the passed mempool argument, and notify spentness whether the
spending transaction was confirmed or not. The logic used to fix this is
similar to what is already done for the btcd backend.

chainntnfs/bitcoindnotify/bitcoind.go

@@ -352,16 +352,40 @@ func (b *BitcoindNotifier) handleRelevantTx(tx chain.RelevantTx, bestHeight int3
 			// TODO(roasbeef): after change to
 			// loadfilter, only notify on block
 			// inclusion?
+
+			confirmedSpend := false
 			if tx.Block != nil {
+				confirmedSpend = true
 				spendDetails.SpendingHeight = tx.Block.Height
 			} else {
 				spendDetails.SpendingHeight = bestHeight + 1
 			}
 
-			for _, ntfn := range clients {
-				chainntnfs.Log.Infof("Dispatching "+
+			// Keep spendNotifications that are
+			// waiting for a confirmation around.
+			// They will be notified when we find
+			// the spend within a block.
+			rem := make(map[uint64]*spendNotification)
+			for c, ntfn := range clients {
+				// If this is a mempool spend,
+				// and this client didn't want
+				// to be notified on mempool
+				// spends, store it for later.
+				if !confirmedSpend && !ntfn.mempool {
+					rem[c] = ntfn
+					continue
+				}
+
+				confStr := "unconfirmed"
+				if confirmedSpend {
+					confStr = "confirmed"
+				}
+
+				chainntnfs.Log.Infof("Dispatching %s "+
 					"spend notification for "+
-					"outpoint=%v", ntfn.targetOutpoint)
+					"outpoint=%v at height %v",
+					confStr, ntfn.targetOutpoint,
+					spendDetails.SpendingHeight)
 				ntfn.spendChan <- spendDetails
 
 				// Close spendChan to ensure that any calls to Cancel will not
@@ -370,6 +394,12 @@ func (b *BitcoindNotifier) handleRelevantTx(tx chain.RelevantTx, bestHeight int3
 				close(ntfn.spendChan)
 			}
 			delete(b.spendNotifications, prevOut)
+
+			// If we had any clients left, add them
+			// back to the map.
+			if len(rem) > 0 {
+				b.spendNotifications[prevOut] = rem
+			}
 		}
 	}
 }
@@ -530,6 +560,8 @@ type spendNotification struct {
 	spendID uint64
 
 	heightHint uint32
+
+	mempool bool
 }
 
 // spendCancel is a message sent to the BitcoindNotifier when a client wishes
@@ -548,12 +580,13 @@ type spendCancel struct {
 // across the 'Spend' channel. The heightHint should represent the earliest
 // height in the chain where the transaction could have been spent in.
 func (b *BitcoindNotifier) RegisterSpendNtfn(outpoint *wire.OutPoint,
-	heightHint uint32, _ bool) (*chainntnfs.SpendEvent, error) {
+	heightHint uint32, mempool bool) (*chainntnfs.SpendEvent, error) {
 
 	ntfn := &spendNotification{
 		targetOutpoint: outpoint,
 		spendChan:      make(chan *chainntnfs.SpendDetail, 1),
 		spendID:        atomic.AddUint64(&b.spendClientCounter, 1),
+		mempool:        mempool,
 	}
 
 	select {