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/bitcoindnotify/bitcoind.go

@@ -568,14 +568,19 @@ func (b *BitcoindNotifier) confDetailsManually(txid *chainhash.Hash,
 // transactions included this block will processed to either send notifications
 // now or after numConfirmations confs.
 func (b *BitcoindNotifier) handleBlockConnected(block chainntnfs.BlockEpoch) error {
+	// 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(block.Hash)
 	if err != nil {
 		return fmt.Errorf("unable to get block: %v", err)
 	}
-
 	txns := btcutil.NewBlock(rawBlock).Transactions()
-	err = b.txNotifier.ConnectTip(
-		block.Hash, uint32(block.Height), txns)
+
+	// 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(block.Hash, uint32(block.Height), txns)
 	if err != nil {
 		return fmt.Errorf("unable to connect tip: %v", err)
 	}
@@ -583,15 +588,15 @@ func (b *BitcoindNotifier) handleBlockConnected(block chainntnfs.BlockEpoch) err
 	chainntnfs.Log.Infof("New block: height=%v, sha=%v", block.Height,
 		block.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 = block
 
-	// Lastly we'll notify any subscribed clients of the block.
 	b.notifyBlockEpochs(block.Height, block.Hash)
-
-	return nil
+	return b.txNotifier.NotifyHeight(uint32(block.Height))
 }
 
 // notifyBlockEpochs notifies all registered block epoch clients of the newly

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

chainntnfs/neutrinonotify/neutrino.go

@@ -542,9 +542,8 @@ func (n *NeutrinoNotifier) historicalConfDetails(targetHash *chainhash.Hash,
 // transactions included this block will processed to either send notifications
 // now or after numConfirmations confs.
 func (n *NeutrinoNotifier) handleBlockConnected(newBlock *filteredBlock) 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.
+	// We'll extend the txNotifier's height with the information of this new
+	// block, which will handle all of the notification logic for us.
 	err := n.txNotifier.ConnectTip(
 		&newBlock.hash, newBlock.height, newBlock.txns,
 	)
@@ -555,16 +554,15 @@ func (n *NeutrinoNotifier) handleBlockConnected(newBlock *filteredBlock) error {
 	chainntnfs.Log.Infof("New block: height=%v, sha=%v", newBlock.height,
 		newBlock.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.
 	n.bestHeight = newBlock.height
 
-	// With all persistent changes committed, notify any subscribed clients
-	// of the block.
 	n.notifyBlockEpochs(int32(newBlock.height), &newBlock.hash)
-
-	return nil
+	return n.txNotifier.NotifyHeight(newBlock.height)
 }
 
 // getFilteredBlock is a utility to retrieve the full filtered block from a block epoch.