import * as fs from 'fs'; import * as events from 'events'; import { getToken } from '../database/config.js'; import { PriorityQueue } from './priority_queue.js'; // queue processor module variables const bus = new events.EventEmitter(); // a bus to notify the queue processor to start processing messages let busy = false; // true if we are already sending api requests. let backoffSeconds = 0; let running = false; // other module variables let headers = undefined; // a file scope variable so that we only evaluate these once. let queue = new PriorityQueue(); // a priority queue to hold api calls we want to send, allows for throttling. // a single queue processor should be running at any time, otherwise there will be trouble! async function queue_processor() { if (running) { throw 'refusing to start a second queue processor'; } running = true; while(true) { try { if (backoffSeconds > 0) { await sleep(backoffSeconds * 1000); backoffSeconds = 0; } if (queue.isEmpty()) { busy = false; await new Promise(resolve => bus.once('send', resolve)); busy = true; } const before = new Date(); await send_this(queue.dequeue().element); const duration = new Date() - before; if (duration < 400) { // 333 should work, but 400 should still allow some manual requests to go through during development await sleep(400 - duration); } } catch (e) { running = false; throw e; } } } queue_processor(); // send takes a request object as argument and an optional context ctx // example request: { // endpoint: the path part of the url to call, // method: HTTP method for `fetch` call, defaults to 'GET', // payload: optional json object that will be send along with the request, // priority: optional priority value (defaults to 10, lower than 10 means the message will be sent faster) // } export function send(request, ctx) { return new Promise((resolve, reject) => { let data = { ctx: ctx, reject: reject, request: request, resolve: resolve, }; queue.enqueue(data, request.priority ? request.priority : 10); if (!busy) { bus.emit('send'); // the queue was previously empty, let's wake up the queue_processor } }); } // send_this take a data object as argument built in the send function above async function send_this(data) { if (headers === undefined) { const token = getToken(); if (token === null) { throw 'Could not get token from the database. Did you init or register yet?'; } headers = { 'Content-Type': 'application/json', 'Authorization': `Bearer ${token}` }; } let options = { headers: headers, }; if (data.request.method !== undefined) { options['method'] = data.request.method; } if (data.request.payload !== undefined) { options['body'] = JSON.stringify(data.request.payload); } fs.writeFileSync('log', JSON.stringify({event: 'send', date: new Date(), data: data}) + '\n', {flag: 'a+'}); try { let response = await fetch(`https://api.spacetraders.io/v2${data.request.endpoint}`, options); response = await response.json(); switch(response.error?.code) { //case 401: // TODO 401 means a server reset happened // TODO reject all promises in queue // close database file // rm database file // logrotate // spawnSync // break; case 429: // 429 means rate limited, let's hold back as instructed backoffSeconds = response.error.data.retryAfter; queue.enqueue(data, 1); break; case 503: // 503 means maintenance mode, let's hold back for 1 minute backoffSeconds = 60; queue.enqueue(data, 1); break; default: // no error! fs.writeFileSync('log', JSON.stringify({event: 'response', date: new Date(), data: response}) + '\n', {flag: 'a+'}); return data.resolve(response); } } catch (err) { fs.writeFileSync('log', JSON.stringify({event: 'error', date: new Date(), data: err}) + '\n', {flag: 'a+'}); switch(err.cause?.code) { case 'EAI_AGAIN': // DNS lookup timed out error, let's hold back for 5 seconds backoffSeconds = 5; queue.enqueue(data, 1); break; case 'ECONNRESET': queue.enqueue(data, 1); break; case 'UND_ERR_CONNECT_TIMEOUT': queue.enqueue(data, 1); break; default: data.reject(response); } } } export function debugLog(ctx) { console.log(`--- ${Date()} -----------------------------------------------------------------------------`); console.log(JSON.stringify(ctx, null, 2)); } export function sleep(delay) { return new Promise((resolve) => setTimeout(resolve, delay)) }