Cache localStorage objects for SettingsStore

src/settings/handlers/AbstractLocalStorageSettingsHandler.ts

@@ -0,0 +1,87 @@
+/*
+Copyright 2019 - 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import SettingsHandler from "./SettingsHandler";
+
+/**
+ * Abstract settings handler wrapping around localStorage making getValue calls cheaper
+ * by caching the values and listening for localStorage updates from other tabs.
+ */
+export default abstract class AbstractLocalStorageSettingsHandler extends SettingsHandler {
+    private itemCache = new Map<string, any>();
+    private objectCache = new Map<string, object>();
+
+    protected constructor() {
+        super();
+
+        // Listen for storage changes from other tabs to bust the cache
+        window.addEventListener("storage", (e: StorageEvent) => {
+            if (e.key === null) {
+                this.itemCache.clear();
+                this.objectCache.clear();
+            } else {
+                this.itemCache.delete(e.key);
+                this.objectCache.delete(e.key);
+            }
+        });
+    }
+
+    protected getItem(key: string): any {
+        if (!this.itemCache.has(key)) {
+            const value = localStorage.getItem(key);
+            this.itemCache.set(key, value);
+            return value;
+        }
+
+        return this.itemCache.get(key);
+    }
+
+    protected getObject<T extends object>(key: string): T | null {
+        if (!this.objectCache.has(key)) {
+            try {
+                const value = JSON.parse(localStorage.getItem(key));
+                this.objectCache.set(key, value);
+                return value;
+            } catch (err) {
+                console.error("Failed to parse localStorage object", err);
+                return null;
+            }
+        }
+
+        return this.objectCache.get(key) as T;
+    }
+
+    protected setItem(key: string, value: any): void {
+        this.itemCache.set(key, value);
+        localStorage.setItem(key, value);
+    }
+
+    protected setObject(key: string, value: object): void {
+        this.objectCache.set(key, value);
+        localStorage.setItem(key, JSON.stringify(value));
+    }
+
+    // handles both items and objects
+    protected removeItem(key: string): void {
+        localStorage.removeItem(key);
+        this.itemCache.delete(key);
+        this.objectCache.delete(key);
+    }
+
+    public isSupported(): boolean {
+        return localStorage !== undefined && localStorage !== null;
+    }
+}

src/settings/handlers/DeviceSettingsHandler.ts

@@ -1,7 +1,7 @@
 /*
 Copyright 2017 Travis Ralston
 Copyright 2019 New Vector Ltd.
-Copyright 2019 The Matrix.org Foundation C.I.C.
+Copyright 2019 - 2022 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -16,17 +16,17 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import SettingsHandler from "./SettingsHandler";
 import { MatrixClientPeg } from "../../MatrixClientPeg";
 import { SettingLevel } from "../SettingLevel";
 import { CallbackFn, WatchManager } from "../WatchManager";
+import AbstractLocalStorageSettingsHandler from "./AbstractLocalStorageSettingsHandler";
 
 /**
  * Gets and sets settings at the "device" level for the current device.
  * This handler does not make use of the roomId parameter. This handler
  * will special-case features to support legacy settings.
  */
-export default class DeviceSettingsHandler extends SettingsHandler {
+export default class DeviceSettingsHandler extends AbstractLocalStorageSettingsHandler {
     /**
      * Creates a new device settings handler
      * @param {string[]} featureNames The names of known features.
@@ -43,15 +43,15 @@ export default class DeviceSettingsHandler extends SettingsHandler {
 
         // Special case notifications
         if (settingName === "notificationsEnabled") {
-            const value = localStorage.getItem("notifications_enabled");
+            const value = this.getItem("notifications_enabled");
             if (typeof(value) === "string") return value === "true";
             return null; // wrong type or otherwise not set
         } else if (settingName === "notificationBodyEnabled") {
-            const value = localStorage.getItem("notifications_body_enabled");
+            const value = this.getItem("notifications_body_enabled");
             if (typeof(value) === "string") return value === "true";
             return null; // wrong type or otherwise not set
         } else if (settingName === "audioNotificationsEnabled") {
-            const value = localStorage.getItem("audio_notifications_enabled");
+            const value = this.getItem("audio_notifications_enabled");
             if (typeof(value) === "string") return value === "true";
             return null; // wrong type or otherwise not set
         }
@@ -68,15 +68,15 @@ export default class DeviceSettingsHandler extends SettingsHandler {
 
         // Special case notifications
         if (settingName === "notificationsEnabled") {
-            localStorage.setItem("notifications_enabled", newValue);
+            this.setItem("notifications_enabled", newValue);
             this.watchers.notifyUpdate(settingName, null, SettingLevel.DEVICE, newValue);
             return Promise.resolve();
         } else if (settingName === "notificationBodyEnabled") {
-            localStorage.setItem("notifications_body_enabled", newValue);
+            this.setItem("notifications_body_enabled", newValue);
             this.watchers.notifyUpdate(settingName, null, SettingLevel.DEVICE, newValue);
             return Promise.resolve();
         } else if (settingName === "audioNotificationsEnabled") {
-            localStorage.setItem("audio_notifications_enabled", newValue);
+            this.setItem("audio_notifications_enabled", newValue);
             this.watchers.notifyUpdate(settingName, null, SettingLevel.DEVICE, newValue);
             return Promise.resolve();
         }
@@ -87,15 +87,15 @@ export default class DeviceSettingsHandler extends SettingsHandler {
 
             delete settings["useIRCLayout"];
             settings["layout"] = newValue;
-            localStorage.setItem("mx_local_settings", JSON.stringify(settings));
+            this.setObject("mx_local_settings", settings);
 
             this.watchers.notifyUpdate(settingName, null, SettingLevel.DEVICE, newValue);
             return Promise.resolve();
         }
 
         const settings = this.getSettings() || {};
         settings[settingName] = newValue;
-        localStorage.setItem("mx_local_settings", JSON.stringify(settings));
+        this.setObject("mx_local_settings", settings);
         this.watchers.notifyUpdate(settingName, null, SettingLevel.DEVICE, newValue);
 
         return Promise.resolve();
@@ -105,10 +105,6 @@ export default class DeviceSettingsHandler extends SettingsHandler {
         return true; // It's their device, so they should be able to
     }
 
-    public isSupported(): boolean {
-        return localStorage !== undefined && localStorage !== null;
-    }
-
     public watchSetting(settingName: string, roomId: string, cb: CallbackFn) {
         this.watchers.watchSetting(settingName, roomId, cb);
     }
@@ -118,9 +114,7 @@ export default class DeviceSettingsHandler extends SettingsHandler {
     }
 
     private getSettings(): any { // TODO: [TS] Type return
-        const value = localStorage.getItem("mx_local_settings");
-        if (!value) return null;
-        return JSON.parse(value);
+        return this.getObject("mx_local_settings");
     }
 
     // Note: features intentionally don't use the same key as settings to avoid conflicts
@@ -132,15 +126,15 @@ export default class DeviceSettingsHandler extends SettingsHandler {
             return false;
         }
 
-        const value = localStorage.getItem("mx_labs_feature_" + featureName);
+        const value = this.getItem("mx_labs_feature_" + featureName);
         if (value === "true") return true;
         if (value === "false") return false;
         // Try to read the next config level for the feature.
         return null;
     }
 
     private writeFeature(featureName: string, enabled: boolean | null) {
-        localStorage.setItem("mx_labs_feature_" + featureName, `${enabled}`);
+        this.setItem("mx_labs_feature_" + featureName, `${enabled}`);
         this.watchers.notifyUpdate(featureName, null, SettingLevel.DEVICE, enabled);
     }
 }

src/settings/handlers/RoomDeviceSettingsHandler.ts

@@ -1,6 +1,6 @@
 /*
 Copyright 2017 Travis Ralston
-Copyright 2019, 2020 The Matrix.org Foundation C.I.C.
+Copyright 2019, 2020 - 2022 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -15,15 +15,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import SettingsHandler from "./SettingsHandler";
 import { SettingLevel } from "../SettingLevel";
 import { WatchManager } from "../WatchManager";
+import AbstractLocalStorageSettingsHandler from "./AbstractLocalStorageSettingsHandler";
 
 /**
  * Gets and sets settings at the "room-device" level for the current device in a particular
  * room.
  */
-export default class RoomDeviceSettingsHandler extends SettingsHandler {
+export default class RoomDeviceSettingsHandler extends AbstractLocalStorageSettingsHandler {
     constructor(public readonly watchers: WatchManager) {
         super();
     }
@@ -32,7 +32,7 @@ export default class RoomDeviceSettingsHandler extends SettingsHandler {
         // Special case blacklist setting to use legacy values
         if (settingName === "blacklistUnverifiedDevices") {
             const value = this.read("mx_local_settings");
-            if (value && value['blacklistUnverifiedDevicesPerRoom']) {
+            if (value?.['blacklistUnverifiedDevicesPerRoom']) {
                 return value['blacklistUnverifiedDevicesPerRoom'][roomId];
             }
         }
@@ -49,16 +49,15 @@ export default class RoomDeviceSettingsHandler extends SettingsHandler {
             if (!value) value = {};
             if (!value["blacklistUnverifiedDevicesPerRoom"]) value["blacklistUnverifiedDevicesPerRoom"] = {};
             value["blacklistUnverifiedDevicesPerRoom"][roomId] = newValue;
-            localStorage.setItem("mx_local_settings", JSON.stringify(value));
+            this.setObject("mx_local_settings", value);
             this.watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
             return Promise.resolve();
         }
 
         if (newValue === null) {
-            localStorage.removeItem(this.getKey(settingName, roomId));
+            this.removeItem(this.getKey(settingName, roomId));
         } else {
-            newValue = JSON.stringify({ value: newValue });
-            localStorage.setItem(this.getKey(settingName, roomId), newValue);
+            this.setObject(this.getKey(settingName, roomId), { value: newValue });
         }
 
         this.watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
@@ -69,14 +68,8 @@ export default class RoomDeviceSettingsHandler extends SettingsHandler {
         return true; // It's their device, so they should be able to
     }
 
-    public isSupported(): boolean {
-        return localStorage !== undefined && localStorage !== null;
-    }
-
     private read(key: string): any {
-        const rawValue = localStorage.getItem(key);
-        if (!rawValue) return null;
-        return JSON.parse(rawValue);
+        return this.getItem(key);
     }
 
     private getKey(settingName: string, roomId: string): string {