[RPC] Expose if current node leader (#1677)

hmy/api_backend.go

@@ -275,3 +275,8 @@ func (b *APIBackend) ResendCx(ctx context.Context, txID common.Hash) (uint64, bo
 	success := b.hmy.CxPool().Add(entry)
 	return blockNum, success
 }
+
+// IsLeader exposes if node is currently leader
+func (b *APIBackend) IsLeader() bool {
+	return b.hmy.nodeAPI.IsCurrentlyLeader()
+}

hmy/backend.go

@@ -49,6 +49,7 @@ type NodeAPI interface {
 	GetBalanceOfAddress(address common.Address) (*big.Int, error)
 	GetNonceOfAddress(address common.Address) uint64
 	GetTransactionsHistory(address string) ([]common.Hash, error)
+	IsCurrentlyLeader() bool
 }
 
 // New creates a new Harmony object (including the

internal/hmyapi/backend.go

@@ -71,6 +71,7 @@ type Backend interface {
 	GetTransactionsHistory(address string) ([]common.Hash, error)
 	// retrieve the blockHash using txID and add blockHash to CxPool for resending
 	ResendCx(ctx context.Context, txID common.Hash) (uint64, bool)
+	IsLeader() bool
 }
 
 // GetAPIs returns all the APIs.

internal/hmyapi/harmony.go

@@ -49,6 +49,7 @@ type NodeMetadata struct {
 	Version      string `json:"version"`
 	NetworkType  string `json:"network"`
 	ChainID      string `json:"chainid"`
+	IsLeader     bool   `json:"is-leader"`
 }
 
 // GetNodeMetadata produces a NodeMetadata record. Note the data is from the answering RPC
@@ -59,5 +60,6 @@ func (s *PublicHarmonyAPI) GetNodeMetadata() NodeMetadata {
 		nodeconfig.GetVersion(),
 		string(cfg.GetNetworkType()),
 		s.b.ChainConfig().ChainID.String(),
+		s.b.IsLeader(),
 	}
 }

node/rpc.go

@@ -44,6 +44,11 @@ var (
 	harmony *hmy.Harmony
 )
 
+// IsCurrentlyLeader exposes if node is currently the leader node
+func (node *Node) IsCurrentlyLeader() bool {
+	return node.Consensus.IsLeader()
+}
+
 // StartRPC start RPC service
 func (node *Node) StartRPC(nodePort string) error {
 	// Gather all the possible APIs to surface
@@ -66,7 +71,6 @@ func (node *Node) StartRPC(nodePort string) error {
 	if err := node.startHTTP(httpEndpoint, apis, httpModules, httpOrigins, httpVirtualHosts, httpTimeouts); err != nil {
 		return err
 	}
-
 	wsEndpoint = fmt.Sprintf("%v:%v", ip, port+rpcWSPortOffset)
 	if err := node.startWS(wsEndpoint, apis, wsModules, wsOrigins, true); err != nil {
 		node.stopHTTP()