Return num of nodes instead of the nodes list connection info

Author: moshababo

Diff for: docs/api.md

@@ -568,19 +568,10 @@ class GrpcService {
    */
   public discoverNodes: grpc.handleUnaryCall<xudrpc.DiscoverNodesRequest, xudrpc.DiscoverNodesResponse> = async (call, callback) => {
     try {
-      const nodes = await this.service.discoverNodes(call.request.toObject());
+      const numNodes = await this.service.discoverNodes(call.request.toObject());
+
       const response = new xudrpc.DiscoverNodesResponse();
-      response.setNodesList(nodes.map((node) => {
-        const grpcNode = new xudrpc.NodeConnectionInfo();
-        grpcNode.setNodepubkey(node.nodePubKey);
-        grpcNode.setAddressesList(node.addresses.map((address) => {
-          const grpcAddress = new xudrpc.Address();
-          grpcAddress.setHost(address.host);
-          grpcAddress.setPort(address.port);
-          return grpcAddress;
-        }));
-        return grpcNode;
-      }));
+      response.setNumNodes(numNodes);
 
       callback(null, response);
     } catch (err) {

Diff for: lib/grpc/GrpcService.ts

@@ -809,10 +809,10 @@ class Peer extends EventEmitter {
     return packet;
   }
 
-  public discoverNodes = async (): Promise<NodeConnectionInfo[]> => {
+  public discoverNodes = async (): Promise<number> => {
     const packet = await this.sendGetNodes();
     const res = await this.wait(packet.header.id, packet.responseType);
-    return res.body;
+    return res.body.length;
   }
 
   private sendPong = async (pingId: string): Promise<void> => {

Diff for: lib/p2p/Peer.ts

@@ -502,7 +502,7 @@ class Pool extends EventEmitter {
     }
   }
 
-  public discoverNodes = async (peerPubKey: string): Promise<NodeConnectionInfo[]> => {
+  public discoverNodes = async (peerPubKey: string): Promise<number> => {
     const peer = this.peers.get(peerPubKey);
     if (!peer) {
       throw errors.NOT_CONNECTED(peerPubKey);