Implement persistence of last used using stateDB

src/index.ts

@@ -9,6 +9,7 @@ import { ICommandPalette, MainAreaWidget } from '@jupyterlab/apputils';
 import { FileBrowserModel, IDefaultFileBrowser } from '@jupyterlab/filebrowser';
 import { ILauncher, LauncherModel } from '@jupyterlab/launcher';
 import { ISettingRegistry } from '@jupyterlab/settingregistry';
+import { IStateDB } from '@jupyterlab/statedb';
 import { ITranslator } from '@jupyterlab/translation';
 import { addIcon, launcherIcon } from '@jupyterlab/ui-components';
 import { find } from '@lumino/algorithm';
@@ -33,7 +34,7 @@ const plugin: JupyterFrontEndPlugin<ILauncher> = {
   description: 'A redesigned JupyterLab launcher',
   provides: ILauncher,
   autoStart: true,
-  requires: [ITranslator],
+  requires: [ITranslator, IStateDB],
   optional: [ILabShell, ICommandPalette, IDefaultFileBrowser, ISettingRegistry],
   activate
 };
@@ -46,6 +47,7 @@ export default plugin;
 function activate(
   app: JupyterFrontEnd,
   translator: ITranslator,
+  stateDB: IStateDB,
   labShell: ILabShell | null,
   palette: ICommandPalette | null,
   defaultBrowser: IDefaultFileBrowser | null,
@@ -74,7 +76,10 @@ function activate(
       });
   }
 
-  const lastUsedDatabase = new LastUsedDatabase();
+  const lastUsedDatabase = new LastUsedDatabase({
+    stateDB,
+    fetchInterval: 10000
+  });
   const favoritesDatabase = new FavoritesDatabase();
 
   commands.addCommand(CommandIDs.create, {

src/last_used.ts

@@ -1,24 +1,52 @@
 import { ILauncher } from '@jupyterlab/launcher';
+import { IStateDB } from '@jupyterlab/statedb';
 
 export interface ILastUsedDatabase {
   get(item: ILauncher.IItemOptions): Date | null;
-  recordAsUsedNow(item: ILauncher.IItemOptions): void;
+  recordAsUsedNow(item: ILauncher.IItemOptions): Promise<void>;
 }
 
+type DatabaseLayout = Record<string, string>;
+
 export class LastUsedDatabase implements ILastUsedDatabase {
-  constructor() {
-    // TODO: use settings registry, or state db, or server to persist this info
-    this._db = new Map();
+  constructor(options: { stateDB: IStateDB; fetchInterval: number }) {
+    this._stateDB = options.stateDB;
+    this._updateDB();
+    window.setInterval(this._updateDB, options.fetchInterval);
   }
   get(item: ILauncher.IItemOptions) {
-    const date = this._db.get(this._itemKey(item));
+    if (!this._db) {
+      return null;
+    }
+    const date = this._db[this._itemKey(item)];
     return date ? new Date(date) : null;
   }
-  recordAsUsedNow(item: ILauncher.IItemOptions) {
-    this._db.set(this._itemKey(item), new Date().toUTCString());
+  async recordAsUsedNow(item: ILauncher.IItemOptions) {
+    const db = await this._fetch();
+    this._db = db;
+    db[this._itemKey(item)] = new Date().toUTCString();
+    await this._stateDB.save(this._stateDBKey, db);
+  }
+  private _updateDB = () => {
+    this._fetch()
+      .then(db => {
+        this._db = db;
+      })
+      .catch(console.warn);
+  };
+  private async _fetch(): Promise<DatabaseLayout> {
+    const db = (await this._stateDB.fetch(this._stateDBKey)) as
+      | DatabaseLayout
+      | undefined;
+    if (typeof db === 'undefined') {
+      return {};
+    }
+    return db;
   }
   private _itemKey(item: ILauncher.IItemOptions): string {
     return item.command + '_' + JSON.stringify(item.args);
   }
-  private _db: Map<string, string>;
+  private _db: DatabaseLayout | null = null;
+  private _stateDB: IStateDB;
+  private _stateDBKey = 'new-launcher:last-used';
 }

src/launcher.tsx

@@ -418,7 +418,7 @@ class Item implements IItem {
   async execute() {
     const { item, commands, lastUsedDatabase } = this._options;
     await commands.execute(item.command, this.args);
-    lastUsedDatabase.recordAsUsedNow(item);
+    await lastUsedDatabase.recordAsUsedNow(item);
     this.lastUsed = lastUsedDatabase.get(item);
     this._refreshLastUsed.emit();
   }