335 lines
11 KiB
TypeScript
335 lines
11 KiB
TypeScript
"use strict";
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import { encode as base64Encode } from "@ethersproject/base64";
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import { shallowCopy } from "@ethersproject/properties";
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import { toUtf8Bytes } from "@ethersproject/strings";
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import { Logger } from "@ethersproject/logger";
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import { version } from "./_version";
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const logger = new Logger(version);
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import { getUrl, GetUrlResponse } from "./geturl";
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function staller(duration: number): Promise<void> {
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return new Promise((resolve) => {
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setTimeout(resolve, duration);
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});
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}
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// Exported Types
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export type ConnectionInfo = {
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url: string,
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headers?: { [key: string]: string | number }
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user?: string,
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password?: string,
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allowInsecureAuthentication?: boolean,
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throttleLimit?: number,
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throttleCallback?: (attempt: number, url: string) => Promise<boolean>,
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timeout?: number,
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};
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export interface OnceBlockable {
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once(eventName: "block", handler: () => void): void;
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}
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export interface OncePollable {
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once(eventName: "poll", handler: () => void): void;
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}
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export type PollOptions = {
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timeout?: number,
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floor?: number,
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ceiling?: number,
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interval?: number,
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retryLimit?: number,
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onceBlock?: OnceBlockable
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oncePoll?: OncePollable
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};
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export type FetchJsonResponse = {
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statusCode: number;
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headers: { [ header: string ]: string };
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};
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type Header = { key: string, value: string };
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export function fetchJson(connection: string | ConnectionInfo, json?: string, processFunc?: (value: any, response: FetchJsonResponse) => any): Promise<any> {
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// How many times to retry in the event of a throttle
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const attemptLimit = (typeof(connection) === "object" && connection.throttleLimit != null) ? connection.throttleLimit: 12;
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logger.assertArgument((attemptLimit > 0 && (attemptLimit % 1) === 0),
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"invalid connection throttle limit", "connection.throttleLimit", attemptLimit);
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const throttleCallback = ((typeof(connection) === "object") ? connection.throttleCallback: null);
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const headers: { [key: string]: Header } = { };
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let url: string = null;
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// @TODO: Allow ConnectionInfo to override some of these values
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const options: any = {
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method: "GET",
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};
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let allow304 = false;
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let timeout = 2 * 60 * 1000;
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if (typeof(connection) === "string") {
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url = connection;
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} else if (typeof(connection) === "object") {
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if (connection == null || connection.url == null) {
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logger.throwArgumentError("missing URL", "connection.url", connection);
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}
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url = connection.url;
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if (typeof(connection.timeout) === "number" && connection.timeout > 0) {
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timeout = connection.timeout;
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}
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if (connection.headers) {
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for (const key in connection.headers) {
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headers[key.toLowerCase()] = { key: key, value: String(connection.headers[key]) };
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if (["if-none-match", "if-modified-since"].indexOf(key.toLowerCase()) >= 0) {
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allow304 = true;
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}
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}
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}
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if (connection.user != null && connection.password != null) {
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if (url.substring(0, 6) !== "https:" && connection.allowInsecureAuthentication !== true) {
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logger.throwError(
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"basic authentication requires a secure https url",
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Logger.errors.INVALID_ARGUMENT,
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{ argument: "url", url: url, user: connection.user, password: "[REDACTED]" }
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);
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}
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const authorization = connection.user + ":" + connection.password;
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headers["authorization"] = {
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key: "Authorization",
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value: "Basic " + base64Encode(toUtf8Bytes(authorization))
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};
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}
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}
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if (json) {
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options.method = "POST";
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options.body = json;
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headers["content-type"] = { key: "Content-Type", value: "application/json" };
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}
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const flatHeaders: { [ key: string ]: string } = { };
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Object.keys(headers).forEach((key) => {
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const header = headers[key];
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flatHeaders[header.key] = header.value;
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});
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options.headers = flatHeaders;
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const runningTimeout = (function() {
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let timer: NodeJS.Timer = null;
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const promise = new Promise(function(resolve, reject) {
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if (timeout) {
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timer = setTimeout(() => {
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if (timer == null) { return; }
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timer = null;
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reject(logger.makeError("timeout", Logger.errors.TIMEOUT, {
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requestBody: (options.body || null),
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requestMethod: options.method,
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timeout: timeout,
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url: url
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}));
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}, timeout);
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}
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});
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const cancel = function() {
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if (timer == null) { return; }
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clearTimeout(timer);
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timer = null;
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}
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return { promise, cancel };
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})();
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const runningFetch = (async function() {
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for (let attempt = 0; attempt < attemptLimit; attempt++) {
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let response: GetUrlResponse = null;
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try {
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response = await getUrl(url, options);
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// Exponential back-off throttling (interval = 100ms)
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if (response.statusCode === 429 && attempt < attemptLimit) {
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let tryAgain = true;
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if (throttleCallback) {
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tryAgain = await throttleCallback(attempt, url);
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}
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if (tryAgain) {
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const timeout = 100 * parseInt(String(Math.random() * Math.pow(2, attempt)));
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await staller(timeout);
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continue;
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}
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}
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} catch (error) {
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response = (<any>error).response;
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if (response == null) {
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runningTimeout.cancel();
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logger.throwError("missing response", Logger.errors.SERVER_ERROR, {
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requestBody: (options.body || null),
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requestMethod: options.method,
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serverError: error,
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url: url
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});
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}
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}
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let body = response.body;
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if (allow304 && response.statusCode === 304) {
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body = null;
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} else if (response.statusCode < 200 || response.statusCode >= 300) {
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runningTimeout.cancel();
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logger.throwError("bad response", Logger.errors.SERVER_ERROR, {
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status: response.statusCode,
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headers: response.headers,
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body: body,
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requestBody: (options.body || null),
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requestMethod: options.method,
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url: url
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});
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}
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let json: any = null;
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if (body != null) {
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try {
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json = JSON.parse(body);
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} catch (error) {
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runningTimeout.cancel();
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logger.throwError("invalid JSON", Logger.errors.SERVER_ERROR, {
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body: body,
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error: error,
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requestBody: (options.body || null),
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requestMethod: options.method,
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url: url
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});
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}
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}
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if (processFunc) {
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try {
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json = await processFunc(json, response);
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} catch (error) {
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// Allow the processFunc to trigger a throttle
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if (error.throttleRetry && attempt < attemptLimit) {
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let tryAgain = true;
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if (throttleCallback) {
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tryAgain = await throttleCallback(attempt, url);
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}
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if (tryAgain) {
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const timeout = 100 * parseInt(String(Math.random() * Math.pow(2, attempt)));
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await staller(timeout);
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continue;
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}
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}
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runningTimeout.cancel();
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logger.throwError("processing response error", Logger.errors.SERVER_ERROR, {
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body: json,
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error: error,
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requestBody: (options.body || null),
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requestMethod: options.method,
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url: url
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});
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}
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}
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runningTimeout.cancel();
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return json;
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}
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})();
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return Promise.race([ runningTimeout.promise, runningFetch ]);
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}
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export function poll<T>(func: () => Promise<T>, options?: PollOptions): Promise<T> {
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if (!options) { options = {}; }
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options = shallowCopy(options);
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if (options.floor == null) { options.floor = 0; }
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if (options.ceiling == null) { options.ceiling = 10000; }
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if (options.interval == null) { options.interval = 250; }
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return new Promise(function(resolve, reject) {
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let timer: NodeJS.Timer = null;
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let done: boolean = false;
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// Returns true if cancel was successful. Unsuccessful cancel means we're already done.
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const cancel = (): boolean => {
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if (done) { return false; }
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done = true;
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if (timer) { clearTimeout(timer); }
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return true;
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};
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if (options.timeout) {
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timer = setTimeout(() => {
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if (cancel()) { reject(new Error("timeout")); }
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}, options.timeout)
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}
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const retryLimit = options.retryLimit;
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let attempt = 0;
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function check() {
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return func().then(function(result) {
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// If we have a result, or are allowed null then we're done
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if (result !== undefined) {
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if (cancel()) { resolve(result); }
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} else if (options.oncePoll) {
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options.oncePoll.once("poll", check);
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} else if (options.onceBlock) {
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options.onceBlock.once("block", check);
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// Otherwise, exponential back-off (up to 10s) our next request
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} else if (!done) {
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attempt++;
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if (attempt > retryLimit) {
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if (cancel()) { reject(new Error("retry limit reached")); }
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return;
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}
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let timeout = options.interval * parseInt(String(Math.random() * Math.pow(2, attempt)));
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if (timeout < options.floor) { timeout = options.floor; }
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if (timeout > options.ceiling) { timeout = options.ceiling; }
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setTimeout(check, timeout);
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}
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return null;
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}, function(error) {
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if (cancel()) { reject(error); }
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});
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}
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check();
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});
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}
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