Background listener cleanup (#3040)

* rename environment/_helpers.js -> environment/_messaging.js

* environment: move duplicated background listeners to environment/_common.js

* Cache subclasses Map

chrome/background.entry.js

@@ -30,8 +30,8 @@
 
 */
 
-import { createMessageHandler } from '../lib/environment/_helpers';
-import Cache from '../lib/utils/Cache';
+import { addCommonBackgroundListeners } from '../lib/environment/_common';
+import { createMessageHandler } from '../lib/environment/_messaging';
 
 import cssOff from './images/css-off.png';
 import cssOffSmall from './images/css-off-small.png';
@@ -60,6 +60,8 @@ chrome.runtime.onMessage.addListener(({ type, ...obj }, sender, sendResponse) =>
 
 // Listeners
 
+addCommonBackgroundListeners(addListener);
+
 addListener('ajax', async ({ method, url, headers, data, credentials }) => {
 	const request = new XMLHttpRequest();
 
@@ -127,24 +129,6 @@ addListener('permissions', async ({ operation, permissions, origins }, { id: tab
 	}
 })();
 
-const session = new Map();
-
-addListener('session', ([operation, key, value]) => {
-	switch (operation) {
-		case 'get':
-			return session.get(key);
-		case 'set':
-			session.set(key, value);
-			break;
-		case 'delete':
-			return session.delete(key);
-		case 'clear':
-			return session.clear();
-		default:
-			throw new Error(`Invalid session operation: ${operation}`);
-	}
-});
-
 addListener('deleteCookies', cookies =>
 	cookies.forEach(({ url, name }) => chrome.cookies.remove({ url, name }))
 );
@@ -162,23 +146,6 @@ addListener('addURLToHistory', url => {
 	chrome.history.addUrl({ url });
 });
 
-const cache = new Cache();
-
-addListener('XHRCache', ({ operation, key, value, maxAge }) => {
-	switch (operation) {
-		case 'set':
-			return cache.set(key, value);
-		case 'check':
-			return cache.check(key, maxAge);
-		case 'delete':
-			return cache.delete(key);
-		case 'clear':
-			return cache.clear();
-		default:
-			throw new Error(`Invalid XHRCache operation: ${operation}`);
-	}
-});
-
 chrome.pageAction.onClicked.addListener(({ id: tabId }) =>
 	sendMessage('pageActionClick', undefined, { tabId })
 );

chrome/environment.js

@@ -1,4 +1,4 @@
-import { createMessageHandler } from '../lib/environment/_helpers';
+import { createMessageHandler } from '../lib/environment/_messaging';
 import { extendDeep, keyedMutex, waitForEvent } from '../lib/utils';
 import { apiToPromise } from './_helpers';
 

firefox/background.entry.js

@@ -1,9 +1,9 @@
 import mainEntry from '../lib/main.entry'; // eslint-disable-line import/default
 import resCss from '../lib/css/res.scss';
 
-import { createMessageHandler } from '../lib/environment/_helpers';
+import { addCommonBackgroundListeners } from '../lib/environment/_common';
+import { createMessageHandler } from '../lib/environment/_messaging';
 import { nativeRequire } from '../lib/environment/_nativeRequire';
-import Cache from '../lib/utils/Cache';
 import { extendDeep } from '../lib/utils/object';
 
 import cssDisabled from './images/css-disabled.png';
@@ -67,6 +67,8 @@ const {
 
 // Listeners
 
+addCommonBackgroundListeners(addListener);
+
 addListener('deleteCookies', cookies =>
 	cookies.forEach(({ name }) => cookieManager.remove('.reddit.com', name, '/', false, false))
 );
@@ -236,41 +238,6 @@ addListener('storage', ([operation, key, value]) => {
 	}
 });
 
-const session = new Map();
-
-addListener('session', ([operation, key, value]) => {
-	switch (operation) {
-		case 'get':
-			return session.get(key);
-		case 'set':
-			session.set(key, value);
-			break;
-		case 'delete':
-			return session.delete(key);
-		case 'clear':
-			return session.clear();
-		default:
-			throw new Error(`Invalid session operation: ${operation}`);
-	}
-});
-
-const cache = new Cache();
-
-addListener('XHRCache', ({ operation, key, value, maxAge }) => {
-	switch (operation) {
-		case 'set':
-			return cache.set(key, value);
-		case 'check':
-			return cache.check(key, maxAge);
-		case 'delete':
-			return cache.delete(key);
-		case 'clear':
-			return cache.clear();
-		default:
-			throw new Error(`Invalid XHRCache operation: ${operation}`);
-	}
-});
-
 const pageAction = ActionButton({
 	id: 'res-styletoggle',
 	label: 'toggle subreddit CSS',

firefox/environment.js

@@ -1,4 +1,4 @@
-import { createMessageHandler } from '../lib/environment/_helpers';
+import { createMessageHandler } from '../lib/environment/_messaging';
 
 const {
 	_handleMessage,

lib/environment/_common.js

@@ -0,0 +1,38 @@
+import Cache from '../utils/Cache';
+
+export function addCommonBackgroundListeners(addListener) {
+	const session = new Map();
+
+	addListener('session', ([operation, key, value]) => {
+		switch (operation) {
+			case 'get':
+				return session.get(key);
+			case 'set':
+				session.set(key, value);
+				break;
+			case 'delete':
+				return session.delete(key);
+			case 'clear':
+				return session.clear();
+			default:
+				throw new Error(`Invalid session operation: ${operation}`);
+		}
+	});
+
+	const cache = new Cache();
+
+	addListener('XHRCache', ([operation, key, value]) => {
+		switch (operation) {
+			case 'set':
+				return cache.set(key, value);
+			case 'check':
+				return cache.get(key, value);
+			case 'delete':
+				return cache.delete(key);
+			case 'clear':
+				return cache.clear();
+			default:
+				throw new Error(`Invalid XHRCache operation: ${operation}`);
+		}
+	});
+}

lib/environment/xhrCache.js

@@ -6,7 +6,7 @@ import { sendMessage } from 'browserEnvironment';
  * @returns {Promise<void, *>}
  */
 export function set(key, value) {
-	return sendMessage('XHRCache', { operation: 'set', key, value });
+	return sendMessage('XHRCache', ['set', key, value]);
 }
 
 /**
@@ -15,21 +15,21 @@ export function set(key, value) {
  * @returns {Promise<*|void, *>}
  */
 export function check(key, maxAge) {
-	return sendMessage('XHRCache', { operation: 'check', key, maxAge });
+	return sendMessage('XHRCache', ['check', key, maxAge]);
 }
 
 /**
  * @param {string} key
  * @returns {Promise<void, *>}
  */
 export function _delete(key) {
-	return sendMessage('XHRCache', { operation: 'delete', key });
+	return sendMessage('XHRCache', ['delete', key]);
 }
 export { _delete as delete };
 
 /**
  * @returns {Promise<void, *>}
  */
 export function clear() {
-	return sendMessage('XHRCache', { operation: 'clear' });
+	return sendMessage('XHRCache', ['clear']);
 }

lib/utils/Cache.js

@@ -1,43 +1,27 @@
-export default class Cache {
-	entries = new Map();
-
-	constructor(capacity = 250) {
+export default class Cache extends Map {
+	constructor(capacity = 500) {
+		super();
 		this.capacity = capacity;
 	}
 
-	check(key, maxAge = Infinity) {
-		const entry = this.entries.get(key);
+	get(key, maxAge = Infinity) {
+		const entry = super.get(key);
 		const now = Date.now();
 		if (entry && (now - entry.timestamp < maxAge)) {
 			entry.timestamp = now;
-			return entry.data;
+			return entry.value;
 		}
 	}
 
 	set(key, value) {
-		this.entries.set(key, {
-			data: value,
-			timestamp: Date.now(),
-		});
+		super.set(key, { value, timestamp: Date.now() });
 
-		if (this.entries.size > this.capacity) {
-			this._prune();
+		if (this.size > this.capacity) {
+			// evict least-recently used
+			Array.from(this.entries())
+				.sort(([, a], [, b]) => b.timestamp - a.timestamp)
+				.slice((this.capacity / 2) | 0)
+				.forEach(([key]) => this.delete(key));
 		}
 	}
-
-	delete(key) {
-		this.entries.delete(key);
-	}
-
-	clear() {
-		this.entries.clear();
-	}
-
-	_prune() {
-		// evict least-recently used
-		Array.from(this.entries.entries())
-			.sort(([, a], [, b]) => b.timestamp - a.timestamp)
-			.slice((this.capacity / 2) | 0)
-			.forEach(([key]) => this.entries.delete(key));
-	}
 }

node/environment.js

@@ -1,4 +1,4 @@
-import { createMessageHandler } from '../lib/environment/_helpers';
+import { createMessageHandler } from '../lib/environment/_messaging';
 import { extendDeep } from '../lib/utils';
 
 const {

safari/background.entry.js

@@ -2,8 +2,8 @@
 
 import 'babel-polyfill';
 
-import { createMessageHandler } from '../lib/environment/_helpers';
-import Cache from '../lib/utils/Cache';
+import { addCommonBackgroundListeners } from '../lib/environment/_common';
+import { createMessageHandler } from '../lib/environment/_messaging';
 import { extendDeep } from '../lib/utils/object';
 
 const {
@@ -18,6 +18,8 @@ safari.application.addEventListener('message', ({ name: type, message: obj, targ
 
 // Listeners
 
+addCommonBackgroundListeners(addListener);
+
 addListener('ajax', async ({ method, url, headers, data, credentials }) => {
 	const request = new XMLHttpRequest();
 
@@ -105,24 +107,6 @@ addListener('storage', ([operation, key, value]) => {
 	}
 });
 
-const session = new Map();
-
-addListener('session', ([operation, key, value]) => {
-	switch (operation) {
-		case 'get':
-			return session.get(key);
-		case 'set':
-			session.set(key, value);
-			break;
-		case 'delete':
-			return session.delete(key);
-		case 'clear':
-			return session.clear();
-		default:
-			throw new Error(`Invalid session operation: ${operation}`);
-	}
-});
-
 addListener('openNewTabs', ({ urls, focusIndex }, tab) => {
 	// Really? No SafariBrowserTab::index?
 	let currentIndex = Array.from(tab.browserWindow.tabs).findIndex(t => t === tab);
@@ -135,23 +119,6 @@ addListener('openNewTabs', ({ urls, focusIndex }, tab) => {
 	));
 });
 
-const cache = new Cache();
-
-addListener('XHRCache', ({ operation, key, value, maxAge }) => {
-	switch (operation) {
-		case 'set':
-			return cache.set(key, value);
-		case 'check':
-			return cache.check(key, maxAge);
-		case 'delete':
-			return cache.delete(key);
-		case 'clear':
-			return cache.clear();
-		default:
-			throw new Error(`Invalid XHRCache operation: ${operation}`);
-	}
-});
-
 addListener('isPrivateBrowsing', (request, tab) => tab.private);
 
 addListener('multicast', async (request, senderTab) =>

safari/environment.js

@@ -4,7 +4,7 @@ import 'babel-polyfill';
 
 import resCss from '../lib/css/res.scss';
 
-import { createMessageHandler } from '../lib/environment/_helpers';
+import { createMessageHandler } from '../lib/environment/_messaging';
 import { nonNull } from '../lib/utils';
 
 // Safari has a ridiculous bug that causes it to lose access to safari.self.tab if you click the back button.