From dac42117ee57baea807a58810210cfd91d645697 Mon Sep 17 00:00:00 2001
From: Edgar Aroutiounian <edgar.factorial@gmail.com>
Date: Fri, 27 Sep 2019 14:14:48 -0700
Subject: [PATCH] [RPC] Expose if current node leader (#1677)

---
 hmy/api_backend.go         | 5 +++++
 hmy/backend.go             | 1 +
 internal/hmyapi/backend.go | 1 +
 internal/hmyapi/harmony.go | 2 ++
 node/rpc.go                | 6 +++++-
 5 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/hmy/api_backend.go b/hmy/api_backend.go
index cfe087a05..2f933558c 100644
--- a/hmy/api_backend.go
+++ b/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()
+}
diff --git a/hmy/backend.go b/hmy/backend.go
index a5609c63a..0bf6a8b23 100644
--- a/hmy/backend.go
+++ b/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
diff --git a/internal/hmyapi/backend.go b/internal/hmyapi/backend.go
index f0a719f1d..70ecb53b6 100644
--- a/internal/hmyapi/backend.go
+++ b/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.
diff --git a/internal/hmyapi/harmony.go b/internal/hmyapi/harmony.go
index 4e0a57f89..f5c7526b9 100644
--- a/internal/hmyapi/harmony.go
+++ b/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(),
 	}
 }
diff --git a/node/rpc.go b/node/rpc.go
index c28192a2b..1877b21ef 100644
--- a/node/rpc.go
+++ b/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()