From f45350bb6a5ea4d3af4fce00b19f034dfd3135ad Mon Sep 17 00:00:00 2001
From: Nico Krause <post@nicokrause.com>
Date: Sat, 18 Jan 2025 20:34:01 +0500
Subject: [PATCH] fix(block-scanning): improve error handling and server
 selection

- Retry same block on errors with height++ adjustment
- Always reconnect to ElectrumX with random server selection
- Remove error type checking for simpler logic
- Random selection improves load balancing
---
 relay/package.json                           |  2 +-
 relay/src/doichain/connectElectrum.js        | 15 +++++----------
 relay/src/pinner/scanBlockchainForNameOps.js | 15 ++++++++-------
 3 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/relay/package.json b/relay/package.json
index f5ad2a4..821977d 100644
--- a/relay/package.json
+++ b/relay/package.json
@@ -1,6 +1,6 @@
 {
   "name": "libp2p-relay",
-  "version": "0.12.22",
+  "version": "0.12.23",
   "private": true,
   "scripts": {
     "start:no-restart": "node src/relay.js",
diff --git a/relay/src/doichain/connectElectrum.js b/relay/src/doichain/connectElectrum.js
index d905669..2271c1e 100644
--- a/relay/src/doichain/connectElectrum.js
+++ b/relay/src/doichain/connectElectrum.js
@@ -5,7 +5,6 @@ import logger from '../logger.js';
 const MAX_RETRIES = 25;
 const RETRY_DELAY = 5000;
 
-let currentServerIndex = -1;
 let connectedClients = [];
 
 export const useNextElectrum = async (_network, updateStore) => {
@@ -26,10 +25,10 @@ export const useNextElectrum = async (_network, updateStore) => {
     throw new Error('No Electrum servers available for the given network.');
   }
 
-  currentServerIndex = (currentServerIndex + 1) % networkNodes.length;
-  const nextServer = networkNodes[currentServerIndex];
+  // Random server selection
+  const nextServer = networkNodes[Math.floor(Math.random() * networkNodes.length)];
 
-  // Check if we already have a connected client for this server
+  // Check for existing connection
   let existingClient = connectedClients.find(
     (c) =>
       c.host === nextServer.host &&
@@ -41,7 +40,7 @@ export const useNextElectrum = async (_network, updateStore) => {
     return existingClient;
   }
 
-  // If not, create a new client and connect
+  // Create new connection
   const newClient = new ElectrumxClient(
     nextServer.host,
     nextServer.port,
@@ -59,10 +58,6 @@ export const useNextElectrum = async (_network, updateStore) => {
       protocol: nextServer.protocol,
     });
 
-    // Remove this line as it's causing the duplicate server.version request
-    // const serverVersion = await newClient.request('server.version');
-    // updateStore('electrumServerVersion', serverVersion);
-
     const connectedServer = `${nextServer.protocol}://${nextServer.host}:${nextServer.port}`;
     updateStore('connectedServer', connectedServer);
 
@@ -74,7 +69,7 @@ export const useNextElectrum = async (_network, updateStore) => {
       protocol: nextServer.protocol,
       error: error.message,
     });
-    // If connection fails, try the next server
+    // Try another random server
     return useNextElectrum(_network, updateStore);
   }
 };
diff --git a/relay/src/pinner/scanBlockchainForNameOps.js b/relay/src/pinner/scanBlockchainForNameOps.js
index 125310c..12b994f 100644
--- a/relay/src/pinner/scanBlockchainForNameOps.js
+++ b/relay/src/pinner/scanBlockchainForNameOps.js
@@ -242,13 +242,14 @@ async function processBlocks(
     } catch (error) {
       logger.error(`Error processing block at height ${height}:`, { error });
       errorRate.inc(); // Increment the error rate counter
-      if (error.message.includes('ElectrumX connection')) {
-        logger.warn('ElectrumX connection lost, attempting to reconnect...');
-        await reconnectElectrumClient(electrumClient);
-        height++; // Retry the current block
-      } else {
-        await new Promise((resolve) => setTimeout(resolve, 1000)); // Wait before retrying
-      }
+
+      // Always attempt to reconnect to ElectrumX
+      logger.warn('Attempting to reconnect to ElectrumX...');
+      await reconnectElectrumClient(electrumClient);
+
+      // Increase height to retry the same block
+      height++;
+      continue;
     } finally {
       endTimer(); // End timing block processing
     }