From 2f0f250d81bb4730c1c05569a724c1ae0039e0a4 Mon Sep 17 00:00:00 2001
From: maciejhirsz <maciej.hirsz@gmail.com>
Date: Thu, 26 Jul 2018 15:26:14 +0200
Subject: [PATCH] Log backend connections

---
 packages/backend/src/Aggregator.ts |  4 ++++
 packages/backend/src/Feed.ts       | 15 +++++++++++++--
 packages/backend/src/Node.ts       |  4 +---
 packages/backend/src/index.ts      |  8 ++++++++
 packages/common/src/helpers.ts     |  2 ++
 5 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/packages/backend/src/Aggregator.ts b/packages/backend/src/Aggregator.ts
index d769b69..175a33d 100644
--- a/packages/backend/src/Aggregator.ts
+++ b/packages/backend/src/Aggregator.ts
@@ -88,5 +88,9 @@ export default class Aggregator {
     for (const chain of this.chains.values()) {
       chain.timeoutCheck(now);
     }
+
+    for (const feed of this.feeds.values()) {
+      feed.ping();
+    }
   }
 }
diff --git a/packages/backend/src/Feed.ts b/packages/backend/src/Feed.ts
index 378188f..48ee35b 100644
--- a/packages/backend/src/Feed.ts
+++ b/packages/backend/src/Feed.ts
@@ -2,7 +2,7 @@ import * as WebSocket from 'ws';
 import * as EventEmitter from 'events';
 import Node from './Node';
 import Chain from './Chain';
-import { VERSION, timestamp, Maybe, FeedMessage, Types, idGenerator } from '@dotstats/common';
+import { VERSION, noop, timestamp, Maybe, FeedMessage, Types, idGenerator } from '@dotstats/common';
 import { Location } from './location';
 
 const nextId = idGenerator<Types.FeedId>();
@@ -16,6 +16,7 @@ export default class Feed {
 
   private socket: WebSocket;
   private messages: Array<FeedMessage.Message> = [];
+  private waitingForPong = false;
 
   constructor(socket: WebSocket) {
     this.id = nextId();
@@ -24,6 +25,7 @@ export default class Feed {
     socket.on('message', (data) => this.handleCommand(data.toString()));
     socket.on('error', () => this.disconnect());
     socket.on('close', () => this.disconnect());
+    socket.on('pong', () => this.waitingForPong = false);
   }
 
   public static feedVersion(): FeedMessage.Message {
@@ -131,6 +133,15 @@ export default class Feed {
     }
   }
 
+  public ping() {
+    if (this.waitingForPong) {
+      this.disconnect();
+      return;
+    }
+    this.waitingForPong = true;
+    this.socket.ping(noop);
+  }
+
   private sendMessages = () => {
     const data = FeedMessage.serialize(this.messages);
     this.messages = [];
@@ -165,7 +176,7 @@ export default class Feed {
 
   private disconnect() {
     this.socket.removeAllListeners();
-    this.socket.close();
+    this.socket.terminate();
 
     this.events.emit('disconnect');
   }
diff --git a/packages/backend/src/Node.ts b/packages/backend/src/Node.ts
index b940c60..5c4b495 100644
--- a/packages/backend/src/Node.ts
+++ b/packages/backend/src/Node.ts
@@ -1,6 +1,6 @@
 import * as WebSocket from 'ws';
 import * as EventEmitter from 'events';
-import { timestamp, Maybe, Types, idGenerator } from '@dotstats/common';
+import { noop, timestamp, Maybe, Types, idGenerator } from '@dotstats/common';
 import { parseMessage, getBestBlock, Message, BestBlock, SystemInterval } from './message';
 import { locate, Location } from './location';
 
@@ -14,8 +14,6 @@ export interface NodeEvents {
   emit(event: 'location', location: Location): void;
 }
 
-function noop() {}
-
 export default class Node {
   public readonly id: Types.NodeId;
   public readonly name: Types.NodeName;
diff --git a/packages/backend/src/index.ts b/packages/backend/src/index.ts
index 2ea5804..86d230a 100644
--- a/packages/backend/src/index.ts
+++ b/packages/backend/src/index.ts
@@ -33,6 +33,14 @@ incomingTelemetry.on('connection', async (socket, req) => {
   }
 });
 
+function logClients() {
+  const feed = telemetryFeed.clients.size;
+  const node = incomingTelemetry.clients.size;
+
+  console.log(`[System] ${feed} open telemetry connections; ${node} open feed connections`);
+}
+
+
 telemetryFeed.on('connection', (socket: WebSocket) => {
   aggregator.addFeed(new Feed(socket));
 });
diff --git a/packages/common/src/helpers.ts b/packages/common/src/helpers.ts
index 4a90ca3..00c76d3 100644
--- a/packages/common/src/helpers.ts
+++ b/packages/common/src/helpers.ts
@@ -33,3 +33,5 @@ export function sleep(time: Milliseconds): Promise<void> {
 }
 
 export const timestamp = Date.now as () => Timestamp;
+
+export function noop() {}