559 lines
18 KiB
TypeScript
559 lines
18 KiB
TypeScript
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import {
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getBigInt, getNumber, hexlify, throwError, throwArgumentError
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} from "../utils/index.js";
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import { AbstractProvider } from "./abstract-provider.js";
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import {
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formatBlock, formatBlockWithTransactions, formatLog, formatTransactionReceipt,
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formatTransactionResponse
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} from "./format.js";
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import { Network } from "./network.js"
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import type { PerformActionRequest } from "./abstract-provider.js";
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import type { Networkish } from "./network.js"
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//const BN_0 = BigInt("0");
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const BN_1 = BigInt("1");
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const BN_2 = BigInt("2");
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function shuffle<T = any>(array: Array<T>): void {
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for (let i = array.length - 1; i > 0; i--) {
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const j = Math.floor(Math.random() * (i + 1));
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const tmp = array[i];
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array[i] = array[j];
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array[j] = tmp;
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}
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}
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function stall(duration: number): Promise<void> {
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return new Promise((resolve) => { setTimeout(resolve, duration); });
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}
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function getTime(): number { return (new Date()).getTime(); }
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export interface FallbackProviderConfig {
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// The provider
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provider: AbstractProvider;
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// How long to wait for a response before getting impatient
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// and ispatching the next provider
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stallTimeout?: number;
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// Lower values are dispatched first
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priority?: number;
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// How much this provider contributes to the quorum
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weight?: number;
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};
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const defaultConfig = { stallTimeout: 400, priority: 1, weight: 1 };
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// We track a bunch of extra stuff that might help debug problems or
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// optimize infrastructure later on.
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export interface FallbackProviderState extends Required<FallbackProviderConfig> {
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// The most recent blockNumber this provider has reported (-2 if none)
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blockNumber: number;
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// The number of total requests ever sent to this provider
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requests: number;
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// The number of responses that errored
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errorResponses: number;
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// The number of responses that occured after the result resolved
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lateResponses: number;
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// How many times syncing was required to catch up the expected block
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outOfSync: number;
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// The number of requests which reported unsupported operation
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unsupportedEvents: number;
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// A rolling average (5% current duration) for response time
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rollingDuration: number;
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// The ratio of quorum-agreed results to total
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score: number;
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}
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interface Config extends FallbackProviderState {
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_updateNumber: null | Promise<any>;
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_network: null | Network;
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_totalTime: number;
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}
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const defaultState = {
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blockNumber: -2, requests: 0, lateResponses: 0, errorResponses: 0,
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outOfSync: -1, unsupportedEvents: 0, rollingDuration: 0, score: 0,
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_network: null, _updateNumber: null, _totalTime: 0
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};
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async function waitForSync(config: Config, blockNumber: number): Promise<void> {
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while (config.blockNumber < 0 || config.blockNumber < blockNumber) {
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if (!config._updateNumber) {
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config._updateNumber = (async () => {
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const blockNumber = await config.provider.getBlockNumber();
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if (blockNumber > config.blockNumber) {
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config.blockNumber = blockNumber;
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}
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config._updateNumber = null;
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})();
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}
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await config._updateNumber;
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config.outOfSync++;
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}
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}
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export type FallbackProviderOptions = {
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// How many providers must agree on a value before reporting
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// back the response
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quorum: number;
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// How many providers must have reported the same event
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// for it to be emitted
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eventQuorum: number;
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// How many providers to dispatch each event to simultaneously.
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// Set this to 0 to use getLog polling, which implies eventQuorum
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// is equal to quorum.
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eventWorkers: number;
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};
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type RunningState = {
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config: Config;
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staller: null | Promise<void>;
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didBump: boolean;
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perform: null | Promise<any>;
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done: boolean;
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result: { result: any } | { error: Error }
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}
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// Normalizes a result to a string that can be used to compare against
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// other results using normal string equality
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function normalize(provider: AbstractProvider, value: any, req: PerformActionRequest): string {
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switch (req.method) {
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case "chainId":
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return getBigInt(value).toString();
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case "getBlockNumber":
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return getNumber(value).toString();
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case "getGasPrice":
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return getBigInt(value).toString();
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case "getBalance":
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return getBigInt(value).toString();
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case "getTransactionCount":
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return getNumber(value).toString();
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case "getCode":
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return hexlify(value);
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case "getStorage":
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return hexlify(value);
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case "getBlock":
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if (req.includeTransactions) {
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return JSON.stringify(formatBlockWithTransactions(value));
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}
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return JSON.stringify(formatBlock(value));
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case "getTransaction":
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return JSON.stringify(formatTransactionResponse(value));
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case "getTransactionReceipt":
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return JSON.stringify(formatTransactionReceipt(value));
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case "call":
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return hexlify(value);
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case "estimateGas":
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return getBigInt(value).toString();
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case "getLogs":
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return JSON.stringify(value.map((v: any) => formatLog(v)));
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}
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return throwError("unsupported method", "UNSUPPORTED_OPERATION", {
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operation: `_perform(${ JSON.stringify(req.method) })`
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});
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}
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type TallyResult = {
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result: any;
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normal: string;
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weight: number;
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};
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// This strategy picks the highest wieght result, as long as the weight is
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// equal to or greater than quorum
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function checkQuorum(quorum: number, results: Array<TallyResult>): any {
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const tally: Map<string, { weight: number, result: any }> = new Map();
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for (const { result, normal, weight } of results) {
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const t = tally.get(normal) || { result, weight: 0 };
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t.weight += weight;
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tally.set(normal, t);
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}
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let bestWeight = 0;
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let bestResult = undefined;
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for (const { weight, result } of tally.values()) {
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if (weight >= quorum && weight > bestWeight) {
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bestWeight = weight;
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bestResult = result;
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}
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}
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return bestResult;
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}
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/*
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function getMean(results: Array<TallyResult>): bigint {
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const total = results.reduce((a, r) => (a + BigInt(r.result)), BN_0);
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return total / BigInt(results.length);
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}
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*/
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function getMedian(results: Array<TallyResult>): bigint {
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// Get the sorted values
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const values = results.map((r) => BigInt(r.result));
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values.sort((a, b) => ((a < b) ? -1: (b > a) ? 1: 0));
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const mid = values.length / 2;
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// Odd-length; take the middle value
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if (values.length % 2) { return values[mid]; }
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// Even length; take the ceiling of the mean of the center two values
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return (values[mid - 1] + values[mid] + BN_1) / BN_2;
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}
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function getFuzzyMode(quorum: number, results: Array<TallyResult>): undefined | number {
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if (quorum === 1) { return getNumber(getMedian(results), "%internal"); }
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const tally: Map<number, { result: number, weight: number }> = new Map();
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const add = (result: number, weight: number) => {
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const t = tally.get(result) || { result, weight: 0 };
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t.weight += weight;
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tally.set(result, t);
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};
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for (const { weight, result } of results) {
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const r = getNumber(result);
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add(r - 1, weight);
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add(r, weight);
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add(r + 1, weight);
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}
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let bestWeight = 0;
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let bestResult = undefined;
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for (const { weight, result } of tally.values()) {
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// Use this result, if this result meets quorum and has either:
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// - a better weight
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// - or equal weight, but the result is larger
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if (weight >= quorum && (weight > bestWeight || (bestResult != null && weight === bestWeight && result > bestResult))) {
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bestWeight = weight;
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bestResult = result;
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}
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}
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return bestResult;
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}
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export class FallbackProvider extends AbstractProvider {
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//readonly providerConfigs!: ReadonlyArray<Required<Readonly<ProviderConfig>>>;
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readonly quorum: number;
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readonly eventQuorum: number;
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readonly eventWorkers: number;
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readonly #configs: Array<Config>;
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#height: number;
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#initialSyncPromise: null | Promise<void>;
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constructor(providers: Array<AbstractProvider | FallbackProviderConfig>, network?: Networkish) {
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super(network);
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this.#configs = providers.map((p) => {
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if (p instanceof AbstractProvider) {
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return Object.assign({ provider: p }, defaultConfig, defaultState );
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} else {
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return Object.assign({ }, defaultConfig, p, defaultState );
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}
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});
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this.#height = -2;
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this.#initialSyncPromise = null;
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this.quorum = 2; //Math.ceil(providers.length / 2);
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this.eventQuorum = 1;
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this.eventWorkers = 1;
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if (this.quorum > this.#configs.reduce((a, c) => (a + c.weight), 0)) {
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throwArgumentError("quorum exceed provider wieght", "quorum", this.quorum);
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}
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}
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// @TOOD: Copy these and only return public values
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get providerConfigs(): Array<FallbackProviderState> {
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return this.#configs.slice();
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}
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async _detectNetwork(): Promise<Network> {
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return Network.from(getBigInt(await this._perform({ method: "chainId" })));
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}
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// @TODO: Add support to select providers to be the event subscriber
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//_getSubscriber(sub: Subscription): Subscriber {
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// throw new Error("@TODO");
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//}
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// Grab the next (random) config that is not already part of configs
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#getNextConfig(configs: Array<Config>): null | Config {
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// Shuffle the states, sorted by priority
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const allConfigs = this.#configs.slice();
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shuffle(allConfigs);
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allConfigs.sort((a, b) => (b.priority - a.priority));
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for (const config of allConfigs) {
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if (configs.indexOf(config) === -1) { return config; }
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}
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return null;
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}
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// Adds a new runner (if available) to running.
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#addRunner(running: Set<RunningState>, req: PerformActionRequest): null | RunningState {
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const config = this.#getNextConfig(Array.from(running).map((r) => r.config));
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if (config == null) {
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return null;
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}
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const result: any = { };
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const runner: RunningState = {
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config, result, didBump: false, done: false,
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perform: null, staller: null
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};
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const now = getTime();
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runner.perform = (async () => {
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try {
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config.requests++;
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result.result = await config.provider._perform(req);
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} catch (error) {
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config.errorResponses++;
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result.error = error;
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}
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if (runner.done) { config.lateResponses++; }
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const dt = (getTime() - now);
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config._totalTime += dt;
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config.rollingDuration = 0.95 * config.rollingDuration + 0.05 * dt;
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runner.perform = null;
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})();
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runner.staller = (async () => {
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await stall(config.stallTimeout);
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runner.staller = null;
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})();
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running.add(runner);
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return runner;
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}
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// Initializes the blockNumber and network for each runner and
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// blocks until initialized
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async #initialSync(): Promise<void> {
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let initialSync = this.#initialSyncPromise;
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if (!initialSync) {
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const promises: Array<Promise<any>> = [ ];
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this.#configs.forEach((config) => {
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promises.push(waitForSync(config, 0));
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promises.push((async () => {
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config._network = await config.provider.getNetwork();
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})());
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});
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this.#initialSyncPromise = initialSync = (async () => {
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// Wait for all providers to have a block number and network
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await Promise.all(promises);
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// Check all the networks match
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let chainId: null | bigint = null;
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for (const config of this.#configs) {
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const network = <Network>(config._network);
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if (chainId == null) {
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chainId = network.chainId;
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} else if (network.chainId !== chainId) {
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throwError("cannot mix providers on different networks", "UNSUPPORTED_OPERATION", {
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operation: "new FallbackProvider"
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});
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}
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}
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})();
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}
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await initialSync
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}
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async #checkQuorum(running: Set<RunningState>, req: PerformActionRequest): Promise<any> {
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// Get all the result objects
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const results: Array<TallyResult> = [ ];
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for (const runner of running) {
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if ("result" in runner.result) {
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const result = runner.result.result;
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results.push({
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result,
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normal: normalize(runner.config.provider, result, req),
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weight: runner.config.weight
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});
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}
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}
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// Are there enough results to event meet quorum?
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if (results.reduce((a, r) => (a + r.weight), 0) < this.quorum) {
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return undefined;
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}
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switch (req.method) {
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case "getBlockNumber": {
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// We need to get the bootstrap block height
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if (this.#height === -2) {
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const height = Math.ceil(getNumber(getMedian(this.#configs.map((c) => ({
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result: c.blockNumber,
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normal: getNumber(c.blockNumber).toString(),
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weight: c.weight
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}))), "%internal"));
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this.#height = height;
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}
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const mode = getFuzzyMode(this.quorum, results);
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if (mode === undefined) { return undefined; }
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if (mode > this.#height) { this.#height = mode; }
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return this.#height;
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}
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case "getGasPrice":
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case "estimateGas":
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return getMedian(results);
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case "getBlock":
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// Pending blocks are mempool dependant and already
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// quite untrustworthy
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if ("blockTag" in req && req.blockTag === "pending") {
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return results[0].result;
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}
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return checkQuorum(this.quorum, results);
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case "chainId":
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case "getBalance":
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case "getTransactionCount":
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case "getCode":
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case "getStorage":
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case "getTransaction":
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case "getTransactionReceipt":
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case "getLogs":
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return checkQuorum(this.quorum, results);
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case "call":
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// @TODO: Check errors
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return checkQuorum(this.quorum, results);
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case "broadcastTransaction":
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throw new Error("TODO");
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}
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return throwError("unsupported method", "UNSUPPORTED_OPERATION", {
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operation: `_perform(${ JSON.stringify((<any>req).method) })`
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});
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}
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async #waitForQuorum(running: Set<RunningState>, req: PerformActionRequest): Promise<any> {
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if (running.size === 0) { throw new Error("no runners?!"); }
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// Any promises that are interesting to watch for; an expired stall
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// or a successful perform
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const interesting: Array<Promise<void>> = [ ];
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//const results: Array<any> = [ ];
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//const errors: Array<Error> = [ ];
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let newRunners = 0;
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for (const runner of running) {
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// @TODO: use runner.perfom != null
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/*
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if ("result" in runner.result) {
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results.push(runner.result.result);
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} else if ("error" in runner.result) {
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errors.push(runner.result.error);
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}
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*/
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// No responses, yet; keep an eye on it
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if (runner.perform) {
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interesting.push(runner.perform);
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}
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// Still stalling...
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if (runner.staller) {
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interesting.push(runner.staller);
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continue;
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}
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// This runner has already triggered another runner
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if (runner.didBump) { continue; }
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// Got a response (result or error) or stalled; kick off another runner
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runner.didBump = true;
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newRunners++;
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}
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// Check for quorum
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/*
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console.log({ results, errors } );
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if (results.length >= this.quorum) {
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return results[0];
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}
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if (errors.length >= this.quorum) {
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return errors[0];
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}
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*/
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const value = await this.#checkQuorum(running, req);
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if (value !== undefined) {
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if (value instanceof Error) { throw value; }
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return value;
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}
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// Add any new runners, because a staller timed out or a result
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// or error response came in.
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for (let i = 0; i < newRunners; i++) {
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this.#addRunner(running, req)
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}
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if (interesting.length === 0) {
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throw new Error("quorum not met");
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// return logger.throwError("failed to meet quorum", "", {
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// });
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}
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// Wait for someone to either complete its perform or trigger a stall
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await Promise.race(interesting);
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return await this.#waitForQuorum(running, req);
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}
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async _perform<T = any>(req: PerformActionRequest): Promise<T> {
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await this.#initialSync();
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// Bootstrap enough to meet quorum
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const running: Set<RunningState> = new Set();
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for (let i = 0; i < this.quorum; i++) {
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this.#addRunner(running, req);
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}
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const result = this.#waitForQuorum(running, req);
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for (const runner of running) { runner.done = true; }
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return result;
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}
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}
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