From 49f78bf8a0f5c6e5d107d02a9e4923d7df821de4 Mon Sep 17 00:00:00 2001
From: Lars <larsjohnsen@gmail.com>
Date: Mon, 29 Mar 2021 18:36:20 +0200
Subject: [PATCH] Fix race condition which broke API access in some
 circumstances

The function `r2WatcherContentStart` did exit in some circumstances (e.g. when there are few posts on the page), causing `Context.establish` to not run.
---
 lib/core/init.js                      |  3 ---
 lib/environment/foreground/context.js |  5 ++---
 lib/utils/watchers.js                 | 28 ++++++++++++++-------------
 3 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/lib/core/init.js b/lib/core/init.js
index 6de2a6c95b..5afa7cdb53 100644
--- a/lib/core/init.js
+++ b/lib/core/init.js
@@ -2,7 +2,6 @@
 
 import { once } from 'lodash-es';
 import { _loadI18n } from '../environment';
-import * as Context from '../environment/foreground/context';
 import {
 	BodyClasses,
 	PagePhases,
@@ -69,5 +68,3 @@ export const afterLoad: Promise<void> = Promise.all([go, PagePhases.loadComplete
 
 // BodyClasses may have been added before document.body was ready
 Promise.all([onInit, PagePhases.bodyStart]).then(BodyClasses.addMissing);
-
-Promise.all([onInit, PagePhases.bodyStart]).then(() => { Context.establish(contentStart); });
diff --git a/lib/environment/foreground/context.js b/lib/environment/foreground/context.js
index afa31cdca6..2b7649f94a 100644
--- a/lib/environment/foreground/context.js
+++ b/lib/environment/foreground/context.js
@@ -4,6 +4,7 @@ import {
 	loggedInUser,
 	loggedInUserHash,
 } from '../../utils/user';
+import { contentStart } from '../../utils/pagePhases';
 import { waitForEvent } from '../../utils/dom';
 
 export const data: {|
@@ -18,9 +19,7 @@ export const data: {|
 	pathname: location.pathname,
 };
 
-export function establish(contentStart: *) {
-	if (!location.protocol.startsWith('http')) return;
-
+if (location.protocol.startsWith('http')) {
 	data.origin = location.origin;
 
 	contentStart.then(() => {
diff --git a/lib/utils/watchers.js b/lib/utils/watchers.js
index 80e5759c81..c045248342 100644
--- a/lib/utils/watchers.js
+++ b/lib/utils/watchers.js
@@ -4,6 +4,7 @@ import { memoize, once } from 'lodash-es';
 import { Thing } from './Thing';
 import { isPageType } from './location';
 import { isLastNodeInDOM, watchForFutureChildren, watchForFutureDescendants, waitForAttach, waitForDescendantChange, waitForSelectorMatch, watchForChildren } from './dom';
+import { contentLoaded } from './pagePhases';
 import { MINUTE } from './time';
 
 type WatcherOptions = {| immediate?: boolean, id?: mixed |};
@@ -119,7 +120,6 @@ export function registerPage(page: HTMLElement) {
 }
 
 const HIDE_FOLLOWING_CLASS = 'res-hide-following';
-let contentLoaded = false;
 
 const cleanHideClasses = () => {
 	for (const ele of [...document.getElementsByClassName(HIDE_FOLLOWING_CLASS)]) ele.classList.remove(HIDE_FOLLOWING_CLASS);
@@ -151,7 +151,7 @@ export async function r2WatcherContentStart() {
 		const queue = [];
 		let i = 0;
 		// Reset every half minute so new things are processed fast when loading additional things via neverEndingReddit / "more comments" etc
-		setInterval(() => { if (contentLoaded) { queue.length = 0; i = 0; } }, 0.5 * MINUTE);
+		contentLoaded.then(() => { setInterval(() => { queue.length = 0; i = 0; }, 0.5 * MINUTE); });
 		return thing => {
 			const n = i++;
 			const check = queue[n] = async () => {
@@ -209,7 +209,6 @@ export async function r2WatcherContentStart() {
 			}
 
 			cleanHideClasses();
-			// console.log('hiding',last,  _last)
 			// Hide the following elements until 'contentLoaded',
 			// to prevent them being painted without the 'immediate' watchers having been invoked on them
 			do { _last.classList.add(HIDE_FOLLOWING_CLASS); } while ((_last = _last.parentElement) && _last !== container);
@@ -219,25 +218,28 @@ export async function r2WatcherContentStart() {
 	};
 
 	while (true) { // eslint-disable-line no-constant-condition
-		// Stop if the next phase has started by now
-		if (contentLoaded) return;
-
 		const thingElements = getReadyThingElements();
 		for (const e of thingElements) registerThing(e);
 
 		if (thingElements.length >= initialProcessSize) return;
 
-		await Promise.all([ // eslint-disable-line no-await-in-loop
-			// Give the browser some time to load additional posts into the DOM before continuing if we've already processed some
-			thingElements.length ? (new Promise(res => { setTimeout(res, 100); })) : Promise.resolve(),
-			waitForDescendantChange(container, Thing.thingSelector),
-		]);
+		try {
+			await Promise.race([ // eslint-disable-line no-await-in-loop
+				contentLoaded.then(() => Promise.reject()), // eslint-disable-line prefer-promise-reject-errors
+				Promise.all([
+					// Give the browser some time to load additional posts into the DOM before continuing if we've already processed some
+					thingElements.length ? (new Promise(res => { setTimeout(res, 100); })) : Promise.resolve(),
+					waitForDescendantChange(container, Thing.thingSelector),
+				]),
+			]);
+		} catch (e) {
+			// `r2WatcherContentLoaded` has run by now
+			break;
+		}
 	}
 }
 
 export function r2WatcherContentLoaded() {
-	contentLoaded = true;
-
 	cleanHideClasses();
 
 	// Things may be edited/loaded using the Reddit interface