Exit on no ping (#126)

* Exit on no ping

We rely on the heartbeat the server sends to the client to make sure the connection is still alive.
By calling the terminate function on the websocket, the whole process will exit.
Solution based on:
https://github.com/websockets/ws?tab=readme-ov-file#how-to-detect-and-close-broken-connections

* Add log for receiving and submitting opportunities

Author: m30m

scripts/swap-beacon/package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "swap-beacon",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "description": "",
   "main": "index.js",
   "scripts": {

scripts/swap-beacon/package.json

@@ -25,8 +25,10 @@ export function getSwapAdapterConfig(chainId: string) {
 
 export class SwapBeacon {
   private client: Client;
-  private adapters: Adapter[];
-  private chainIds: string[];
+  private pingTimeout: NodeJS.Timeout | undefined;
+  private readonly adapters: Adapter[];
+  private readonly chainIds: string[];
+  private readonly PING_INTERVAL = 30000;
 
   constructor(endpoint: string, _chainIds: string[]) {
     this.client = new Client(
@@ -213,6 +215,7 @@ export class SwapBeacon {
   }
 
   async opportunityHandler(opportunity: Opportunity) {
+    console.log("Received opportunity:", opportunity.opportunityId);
     const swapAdapterConfig = getSwapAdapterConfig(opportunity.chainId);
 
     if (
@@ -235,6 +238,10 @@ export class SwapBeacon {
             return;
           }
           await this.client.submitOpportunity(convertedOpportunity);
+          console.log(
+            "Submitted converted opportunity. Original id:",
+            opportunity.opportunityId
+          );
         } catch (error) {
           console.error(
             `Failed to convert and submit opportunity ${JSON.stringify(
@@ -246,12 +253,25 @@ export class SwapBeacon {
     );
   }
 
+  heartbeat() {
+    if (this.pingTimeout !== undefined) clearTimeout(this.pingTimeout);
+
+    this.pingTimeout = setTimeout(() => {
+      console.error("Received no ping. Terminating connection.");
+      this.client.websocket.terminate();
+    }, this.PING_INTERVAL + 2000); // 2 seconds for latency
+  }
+
   async start() {
     try {
       await this.client.subscribeChains(this.chainIds);
       console.log(
         `Subscribed to chain ${this.chainIds}. Waiting for opportunities...`
       );
+      this.heartbeat();
+      this.client.websocket.on("ping", () => {
+        this.heartbeat();
+      });
     } catch (error) {
       console.error(error);
       this.client.websocket?.close();