fix #1857: throttle update requests for same site

Author: tophf

src/background/update-manager.js

@@ -4,10 +4,10 @@ import {API} from '/js/msg';
 import * as prefs from '/js/prefs';
 import {calcStyleDigest, styleSectionsEqual} from '/js/sections-util';
 import {chromeLocal} from '/js/storage-util';
-import {extractUsoaId, isLocalhost, usoApi} from '/js/urls';
-import {debounce, deepMerge} from '/js/util';
+import {extractUsoaId, isCdnUrl, isLocalhost, usoApi} from '/js/urls';
+import {debounce, deepMerge, getHost, resolvedPromise, sleep} from '/js/util';
 import {ignoreChromeError} from '/js/util-webext';
-import {bgBusy, safeTimeout} from './common';
+import {bgBusy} from './common';
 import {db} from './db';
 import download from './download';
 import * as styleMan from './style-manager';
@@ -27,6 +27,7 @@ const STATES = /** @namespace UpdaterStates */ {
   ERROR_VERSION: 'error: version is older than installed style',
 };
 export const getStates = () => STATES;
+const safeSleep = __.MV3 ? ms => __.KEEP_ALIVE(sleep(ms)) : sleep;
 const RH_ETAG = {responseHeaders: ['etag']}; // a hashsum of file contents
 const RX_DATE2VER = new RegExp([
   /^(\d{4})/,
@@ -41,6 +42,8 @@ const RETRY_ERRORS = [
   503, // service unavailable
   429, // too many requests
 ];
+const HOST_THROTTLE = 1000; // ms
+const hostJobs = {};
 let lastUpdateTime;
 let checkingAll = false;
 let logQueue = [];
@@ -227,19 +230,28 @@ export async function checkStyle(opts) {
 
 }
 
-async function tryDownload(url, params, {retryDelay = 1000} = {}) {
+async function tryDownload(url, params, {retryDelay = HOST_THROTTLE} = {}) {
   while (true) {
+    let host, job;
     try {
       params = deepMerge(params || {}, {headers: {'Cache-Control': 'no-cache'}});
-      return await download(url, params);
+      host = getHost(url);
+      job = hostJobs[host];
+      job = hostJobs[host] = (job
+        ? job.then(() => safeSleep(HOST_THROTTLE / (isCdnUrl(url) ? 4 : 1)))
+        : resolvedPromise()
+      ).then(() => download(url, params));
+      return await job;
     } catch (code) {
       if (!RETRY_ERRORS.includes(code) ||
           retryDelay > MIN_INTERVAL_MS) {
-        return Promise.reject(code);
+        throw code;
       }
+    } finally {
+      if (hostJobs[host] === job) delete hostJobs[host];
     }
     retryDelay *= 1.25;
-    await new Promise(resolve => safeTimeout(resolve, retryDelay));
+    await safeSleep(retryDelay);
   }
 }
 

src/js/urls.js

@@ -59,3 +59,7 @@ export const supported = /*@__PURE__*/ regExpTest.bind(new RegExp(
 export const isLocalhost = /*@__PURE__*/ regExpTest.bind(
   /^file:|^https?:\/\/([^/]+@)?(localhost|127\.0\.0\.1)(:\d+)?\//
 );
+
+export const isCdnUrl = /*@__PURE__*/ regExpTest.bind(
+  /^https:\/\/((\w+-)?cdn(js)?(-\w+)?\.[^/]+|[^/]+?\.github(usercontent)?\.(io|com))\//i
+);

src/js/util.js

@@ -9,10 +9,12 @@ export const clamp = (value, min, max) => value < min ? min : value > max ? max
 export const clipString = (str, limit = 100) => str.length > limit
   ? str.substr(0, limit) + '...'
   : str;
+export const getHost = url => url.split('/', 3)[2];
 export const hasOwn = /*@__PURE__*/Object.call.bind({}.hasOwnProperty);
 /** FYI, matchMedia's onchange doesn't work in bg context, so we use it in our content script */
 export const isCssDarkScheme = () => matchMedia('(prefers-color-scheme:dark)').matches;
 export const isObject = val => typeof val === 'object' && val;
+export const resolvedPromise = async val => val;
 export const sleep = ms => new Promise(ms > 0 ? cb => setTimeout(cb, ms) : setTimeout);
 export const stringAsRegExpStr = s => s.replace(/[{}()[\]\\.+*?^$|]/g, '\\$&');
 export const stringAsRegExp = (s, flags) => new RegExp(stringAsRegExpStr(s), flags);