Subscribe and handle eth notifications about new block

bchain/coins/eth/ethrpc.go

@@ -30,16 +30,18 @@ const (
 
 // EthRPC is an interface to JSON-RPC eth service.
 type EthRPC struct {
-	client       *ethclient.Client
-	rpc          *rpc.Client
-	timeout      time.Duration
-	rpcURL       string
-	Parser       *EthParser
-	Testnet      bool
-	Network      string
-	Mempool      *bchain.Mempool
-	bestHeaderMu sync.Mutex
-	bestHeader   *ethtypes.Header
+	client               *ethclient.Client
+	rpc                  *rpc.Client
+	timeout              time.Duration
+	rpcURL               string
+	Parser               *EthParser
+	Testnet              bool
+	Network              string
+	Mempool              *bchain.UTXOMempool
+	bestHeaderMu         sync.Mutex
+	bestHeader           *ethtypes.Header
+	chanNewBlock         chan *ethtypes.Header
+	newBlockSubscription *rpc.ClientSubscription
 }
 
 type configuration struct {
@@ -71,9 +73,29 @@ func NewEthRPC(config json.RawMessage, pushHandler func(bchain.NotificationType)
 	s.Parser = &EthParser{}
 	s.timeout = time.Duration(c.RPCTimeout) * time.Second
 
+	// new blocks notifications handling
+	// the subscription is done in Initialize
+	s.chanNewBlock = make(chan *ethtypes.Header)
+	go func() {
+		for {
+			h, ok := <-s.chanNewBlock
+			if !ok {
+				break
+			}
+			glog.V(2).Info("rpc: new block header ", h.Number)
+			// update best header to the new header
+			s.bestHeaderMu.Lock()
+			s.bestHeader = h
+			s.bestHeaderMu.Unlock()
+			// notify blockbook
+			pushHandler(bchain.NotificationNewBlock)
+		}
+	}()
+
 	return s, nil
 }
 
+// Initialize initializes ethereum rpc interface
 func (b *EthRPC) Initialize() error {
 	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
 	defer cancel()
@@ -98,11 +120,26 @@ func (b *EthRPC) Initialize() error {
 	}
 	glog.Info("rpc: block chain ", b.Network)
 
+	// Subscribe to new blocks
+	sub, err := b.rpc.EthSubscribe(ctx, b.chanNewBlock, "newHeads")
+	if err != nil {
+		return errors.Annotatef(err, "EthSubscribe newHeads")
+	}
+	b.newBlockSubscription = sub
 	// b.Mempool = bchain.NewMempool(s, metrics)
 	return nil
 }
 
+// Shutdown cleans up rpc interface to ethereum
 func (b *EthRPC) Shutdown() error {
+	if b.newBlockSubscription != nil {
+		b.newBlockSubscription.Unsubscribe()
+	}
+	if b.rpc != nil {
+		b.rpc.Close()
+	}
+	close(b.chanNewBlock)
+	glog.Info("rpc: shutdown")
 	return nil
 }
 
@@ -409,23 +446,24 @@ func (b *EthRPC) EstimateSmartFee(blocks int, conservative bool) (float64, error
 
 // SendRawTransaction sends raw transaction.
 func (b *EthRPC) SendRawTransaction(tx string) (string, error) {
-	panic("not implemented")
+	return "", errors.New("SendRawTransaction: not implemented")
 }
 
 func (b *EthRPC) ResyncMempool(onNewTxAddr func(txid string, addr string)) error {
-	panic("not implemented")
+	return nil
+	return errors.New("ResyncMempool: not implemented")
 }
 
 func (b *EthRPC) GetMempoolTransactions(address string) ([]string, error) {
-	panic("not implemented")
+	return nil, errors.New("ResyncMempool: not implemented")
 }
 
 func (b *EthRPC) GetMempoolSpentOutput(outputTxid string, vout uint32) string {
-	panic("not implemented")
+	return ""
 }
 
 func (b *EthRPC) GetMempoolEntry(txid string) (*bchain.MempoolEntry, error) {
-	panic("not implemented")
+	return nil, errors.New("ResyncMempool: not implemented")
 }
 
 func (b *EthRPC) GetChainParser() bchain.BlockChainParser {