chainntnfs: dispatch conf/spend notifications after blocks

In this commit, we alter the different ChainNotifier implementations to
dispatch confirmation and spend notifications after blocks. We do this
to ensure the external consistency of our registered clients.

chainntnfs/btcdnotify/btcd.go

@@ -622,14 +622,13 @@ func (b *BtcdNotifier) confDetailsManually(txid *chainhash.Hash, startHeight,
 // TODO(halseth): this is reusing the neutrino notifier implementation, unify
 // them.
 func (b *BtcdNotifier) handleBlockConnected(epoch chainntnfs.BlockEpoch) error {
-	// First process the block for our internal state. A new block has
-	// been connected to the main chain. Send out any N confirmation
-	// notifications which may have been triggered by this new block.
+	// First, we'll fetch the raw block as we'll need to gather all the
+	// transactions to determine whether any are relevant to our registered
+	// clients.
 	rawBlock, err := b.chainConn.GetBlock(epoch.Hash)
 	if err != nil {
 		return fmt.Errorf("unable to get block: %v", err)
 	}
-
 	newBlock := &filteredBlock{
 		hash:    *epoch.Hash,
 		height:  uint32(epoch.Height),
@@ -637,6 +636,9 @@ func (b *BtcdNotifier) handleBlockConnected(epoch chainntnfs.BlockEpoch) error {
 		connect: true,
 	}
 
+	// We'll then extend the txNotifier's height with the information of
+	// this new block, which will handle all of the notification logic for
+	// us.
 	err = b.txNotifier.ConnectTip(
 		&newBlock.hash, newBlock.height, newBlock.txns,
 	)
@@ -647,13 +649,15 @@ func (b *BtcdNotifier) handleBlockConnected(epoch chainntnfs.BlockEpoch) error {
 	chainntnfs.Log.Infof("New block: height=%v, sha=%v", epoch.Height,
 		epoch.Hash)
 
-	// We want to set the best block before dispatching notifications so if
-	// any subscribers make queries based on their received block epoch, our
-	// state is fully updated in time.
+	// Now that we've guaranteed the new block extends the txNotifier's
+	// current tip, we'll proceed to dispatch notifications to all of our
+	// registered clients whom have had notifications fulfilled. Before
+	// doing so, we'll make sure update our in memory state in order to
+	// satisfy any client requests based upon the new block.
 	b.bestBlock = epoch
-	b.notifyBlockEpochs(int32(newBlock.height), &newBlock.hash)
 
-	return nil
+	b.notifyBlockEpochs(epoch.Height, epoch.Hash)
+	return b.txNotifier.NotifyHeight(uint32(epoch.Height))
 }
 
 // notifyBlockEpochs notifies all registered block epoch clients of the newly