From 984f6fa155fca08ebec2353c75ee0a0b974e8568 Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Thu, 18 May 2023 16:52:47 -0400
Subject: [PATCH] More robust defaultProvider start-up when a backend fails on
 bootstrap (#3979).

---
 src.ts/providers/provider-fallback.ts | 28 ++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/src.ts/providers/provider-fallback.ts b/src.ts/providers/provider-fallback.ts
index 6be29c95da..624c8a4e02 100644
--- a/src.ts/providers/provider-fallback.ts
+++ b/src.ts/providers/provider-fallback.ts
@@ -97,12 +97,15 @@ interface Config extends FallbackProviderState {
     _updateNumber: null | Promise<any>;
     _network: null | Network;
     _totalTime: number;
+    _lastFatalError: null | Error;
+    _lastFatalErrorTimestamp: number;
 }
 
 const defaultState = {
     blockNumber: -2, requests: 0, lateResponses: 0, errorResponses: 0,
     outOfSync: -1, unsupportedEvents: 0, rollingDuration: 0, score: 0,
-    _network: null, _updateNumber: null, _totalTime: 0
+    _network: null, _updateNumber: null, _totalTime: 0,
+    _lastFatalError: null, _lastFatalErrorTimestamp: 0
 };
 
 
@@ -110,15 +113,22 @@ async function waitForSync(config: Config, blockNumber: number): Promise<void> {
     while (config.blockNumber < 0 || config.blockNumber < blockNumber) {
         if (!config._updateNumber) {
             config._updateNumber = (async () => {
-                const blockNumber = await config.provider.getBlockNumber();
-                if (blockNumber > config.blockNumber) {
-                    config.blockNumber = blockNumber;
+                try {
+                    const blockNumber = await config.provider.getBlockNumber();
+                    if (blockNumber > config.blockNumber) {
+                        config.blockNumber = blockNumber;
+                    }
+                } catch (error: any) {
+                    config.blockNumber = -2;
+                    config._lastFatalError = error;
+                    config._lastFatalErrorTimestamp = getTime();
                 }
                 config._updateNumber = null;
             })();
         }
         await config._updateNumber;
         config.outOfSync++;
+        if (config._lastFatalError) { break; }
     }
 }
 
@@ -413,6 +423,7 @@ export class FallbackProvider extends AbstractProvider {
         allConfigs.sort((a, b) => (b.priority - a.priority));
 
         for (const config of allConfigs) {
+            if (config._lastFatalError) { continue; }
             if (configs.indexOf(config) === -1) { return config; }
         }
 
@@ -471,9 +482,11 @@ export class FallbackProvider extends AbstractProvider {
         if (!initialSync) {
             const promises: Array<Promise<any>> = [ ];
             this.#configs.forEach((config) => {
-                promises.push(waitForSync(config, 0));
                 promises.push((async () => {
-                    config._network = await config.provider.getNetwork();
+                    await waitForSync(config, 0);
+                    if (!config._lastFatalError) {
+                        config._network = await config.provider.getNetwork();
+                    }
                 })());
             });
 
@@ -484,6 +497,7 @@ export class FallbackProvider extends AbstractProvider {
                 // Check all the networks match
                 let chainId: null | bigint = null;
                 for (const config of this.#configs) {
+                    if (config._lastFatalError) { continue; }
                     const network = <Network>(config._network);
                     if (chainId == null) {
                         chainId = network.chainId;
@@ -519,7 +533,7 @@ export class FallbackProvider extends AbstractProvider {
             case "getBlockNumber": {
                 // We need to get the bootstrap block height
                 if (this.#height === -2) {
-                    this.#height = Math.ceil(getNumber(<bigint>getMedian(this.quorum, this.#configs.map((c) => ({
+                    this.#height = Math.ceil(getNumber(<bigint>getMedian(this.quorum, this.#configs.filter((c) => (!c._lastFatalError)).map((c) => ({
                         value: c.blockNumber,
                         tag: getNumber(c.blockNumber).toString(),
                         weight: c.weight