services: move blockchain/mempool subscriptions to separate routine

Start of some services is bound to blockchain subscriptions, and thus,
can't be run before the blockchain notifications dispatcher.

Signed-off-by: Ekaterina Pavlova <ekt@morphbits.io>

pkg/consensus/consensus.go

@@ -281,7 +281,6 @@ func (s *service) Start() {
 		b, _ := s.Chain.GetBlock(s.Chain.CurrentBlockHash()) // Can't fail, we have some current block!
 		s.lastTimestamp = b.Timestamp
 		s.dbft.Start(s.lastTimestamp * nsInMs)
-		s.Chain.SubscribeForBlocks(s.blockEvents)
 		go s.eventLoop()
 	}
 }
@@ -299,6 +298,14 @@ func (s *service) Shutdown() {
 }
 
 func (s *service) eventLoop() {
+	s.Chain.SubscribeForBlocks(s.blockEvents)
+
+	// Manually sync up with potentially missed fresh blocks that may be added by blockchain
+	// before the subscription.
+	b, _ := s.Chain.GetBlock(s.Chain.CurrentBlockHash()) // Can't fail, we have some current block!
+	if b.Timestamp >= s.lastTimestamp {
+		s.handleChainBlock(b)
+	}
 events:
 	for {
 		select {

pkg/services/notary/notary.go

@@ -175,13 +175,13 @@ func (n *Notary) Start() {
 		return
 	}
 	n.Config.Log.Info("starting notary service")
-	n.Config.Chain.SubscribeForBlocks(n.blocksCh)
-	n.mp.SubscribeForTransactions(n.reqCh)
 	go n.newTxCallbackLoop()
 	go n.mainLoop()
 }
 
 func (n *Notary) mainLoop() {
+	n.Config.Chain.SubscribeForBlocks(n.blocksCh)
+	n.mp.SubscribeForTransactions(n.reqCh)
 mainloop:
 	for {
 		select {

pkg/services/stateroot/validators.go

@@ -29,11 +29,11 @@ func (s *service) Start() {
 		return
 	}
 	s.log.Info("starting state validation service")
-	s.chain.SubscribeForBlocks(s.blockCh)
 	go s.run()
 }
 
 func (s *service) run() {
+	s.chain.SubscribeForBlocks(s.blockCh)
 runloop:
 	for {
 		select {