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More robust FallbackProvider broadcast (ethers-io#4186, ethers-io#4297,
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ricmoo authored and Woodpile37 committed Jan 14, 2024
1 parent 8cb891d commit 256e59a
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95 changes: 95 additions & 0 deletions src.ts/_tests/test-providers-fallback.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,95 @@
import assert from "assert";

import {
isError, makeError,

AbstractProvider, FallbackProvider, Network,
} from "../index.js";

import type {
PerformActionRequest
} from "../index.js";



const network = Network.from("mainnet");

function stall(duration: number): Promise<void> {
return new Promise((resolve) => { setTimeout(resolve, duration); });
}


export type Performer = (req: PerformActionRequest) => Promise<any>;

export class MockProvider extends AbstractProvider {
readonly _perform: Performer;

constructor(perform: Performer) {
super(network, { cacheTimeout: -1 });
this._perform = perform;
}

async _detectNetwork(): Promise<Network> { return network; }

async perform(req: PerformActionRequest): Promise<any> {
return await this._perform(req);
}
}

describe("Test Fallback broadcast", function() {

const txHash = "0x33017397ef7c7943dee3b422aec52b0a210de58d73d49c1b3ce455970f01c83a";

async function test(actions: Array<{ timeout: number, error?: Error }>): Promise<any> {
// https://sepolia.etherscan.io/tx/0x33017397ef7c7943dee3b422aec52b0a210de58d73d49c1b3ce455970f01c83a
const tx = "0x02f87683aa36a7048459682f00845d899ef982520894b5bdaa442bb34f27e793861c456cd5bdc527ac8c89056bc75e2d6310000080c001a07503893743e94445b2361a444343757e6f59d52e19e9b3f65eb138d802eaa972a06e4e9bc10ff55474f9aac0a4c284733b4195cb7b273de5e7465ce75a168e0c38";

const providers: Array<MockProvider> = actions.map(({ timeout, error }) => {
return new MockProvider(async (r) => {
if (r.method === "getBlockNumber") { return 1; }
if (r.method === "broadcastTransaction") {
await stall(timeout);
if (error) { throw error; }
return txHash;
}
throw new Error(`unhandled method: ${ r.method }`);
});
});;

const provider = new FallbackProvider(providers);
return await provider.broadcastTransaction(tx);
}

it("picks late non-failed broadcasts", async function() {
const result = await test([
{ timeout: 200, error: makeError("already seen", "UNKNOWN_ERROR") },
{ timeout: 4000, error: makeError("already seen", "UNKNOWN_ERROR") },
{ timeout: 400 },
]);
assert(result.hash === txHash, "result.hash === txHash");
});

it("picks late non-failed broadcasts with quorum-met red-herrings", async function() {
const result = await test([
{ timeout: 200, error: makeError("bad nonce", "NONCE_EXPIRED") },
{ timeout: 400, error: makeError("bad nonce", "NONCE_EXPIRED") },
{ timeout: 1000 },
]);
assert(result.hash === txHash, "result.hash === txHash");
});

it("insufficient funds short-circuit broadcast", async function() {
await assert.rejects(async function() {
const result = await test([
{ timeout: 200, error: makeError("is broke", "INSUFFICIENT_FUNDS") },
{ timeout: 400, error: makeError("is broke", "INSUFFICIENT_FUNDS") },
{ timeout: 800 },
{ timeout: 1000 },
]);
console.log(result);
}, function(error: unknown) {
assert(isError(error, "INSUFFICIENT_FUNDS"));
return true;
});
});
});
42 changes: 36 additions & 6 deletions src.ts/providers/provider-fallback.ts
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
* @_section: api/providers/fallback-provider:Fallback Provider [about-fallback-provider]
*/
import {
getBigInt, getNumber, assert, assertArgument
assert, assertArgument, getBigInt, getNumber, isError
} from "../utils/index.js";

import { AbstractProvider } from "./abstract-provider.js";
Expand Down Expand Up @@ -707,16 +707,46 @@ export class FallbackProvider extends AbstractProvider {
// a cost on the user, so spamming is safe-ish. Just send it to
// every backend.
if (req.method === "broadcastTransaction") {
const results = await Promise.all(this.#configs.map(async ({ provider, weight }) => {
// Once any broadcast provides a positive result, use it. No
// need to wait for anyone else
const results: Array<null | TallyResult> = this.#configs.map((c) => null);
const broadcasts = this.#configs.map(async ({ provider, weight }, index) => {
try {
const result = await provider._perform(req);
return Object.assign(normalizeResult({ result }), { weight });
results[index] = Object.assign(normalizeResult({ result }), { weight });
} catch (error: any) {
return Object.assign(normalizeResult({ error }), { weight });
results[index] = Object.assign(normalizeResult({ error }), { weight });
}
}));
});

// As each promise finishes...
while (true) {
// Check for a valid broadcast result
const done = <Array<any>>results.filter((r) => (r != null));
for (const { value } of done) {
if (!(value instanceof Error)) { return value; }
}

// Check for a legit broadcast error (one which we cannot
// recover from; some nodes may return the following red
// herring events:
// - alredy seend (UNKNOWN_ERROR)
// - NONCE_EXPIRED
// - REPLACEMENT_UNDERPRICED
const result = checkQuorum(this.quorum, <Array<any>>results.filter((r) => (r != null)));
if (isError(result, "INSUFFICIENT_FUNDS")) {
throw result;
}

// Kick off the next provider (if any)
const waiting = broadcasts.filter((b, i) => (results[i] == null));
if (waiting.length === 0) { break; }
await Promise.race(waiting);
}

const result = getAnyResult(this.quorum, results);
// Use standard quorum results; any result was returned above,
// so this will find any error that met quorum if any
const result = getAnyResult(this.quorum, <Array<any>>results);
assert(result !== undefined, "problem multi-broadcasting", "SERVER_ERROR", {
request: "%sub-requests",
info: { request: req, results: results.map(stringify) }
Expand Down

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