Create a window resolver extension.

jupyterlab · Apr 25, 2018 · df77d6e · df77d6e
1 parent becb06d
commit df77d6e
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Showing 3 changed files with 47 additions and 145 deletions.
diff --git a/packages/apputils-extension/src/index.ts b/packages/apputils-extension/src/index.ts
@@ -12,7 +12,8 @@ import {
 } from '@jupyterlab/apputils';
 
 import {
-  DataConnector, ISettingRegistry, IStateDB, SettingRegistry, StateDB, URLExt
+  DataConnector, ISettingRegistry, IStateDB, IWindowResolver, SettingRegistry,
+  StateDB, URLExt, WindowResolver
 } from '@jupyterlab/coreutils';
 
 import {
@@ -225,6 +226,23 @@ const themes: JupyterLabPlugin<IThemeManager> = {
 };
 
 
+/**
+ * The default window name resolver provider.
+ */
+const resolver: JupyterLabPlugin<IWindowResolver> = {
+  id: '@jupyterlab/apputils-extension:resolver',
+  autoStart: true,
+  provides: IWindowResolver,
+  activate: app => {
+    const resolver = new WindowResolver({
+      candidate: Promise.resolve('hello')
+    });
+
+    return resolver;
+  }
+};
+
+
 /**
  * The default splash screen provider.
  */
@@ -252,11 +270,15 @@ const state: JupyterLabPlugin<IStateDB> = {
   id: '@jupyterlab/apputils-extension:state',
   autoStart: true,
   provides: IStateDB,
-  requires: [IRouter],
-  activate: (app: JupyterLab, router: IRouter) => {
+  requires: [IRouter, IWindowResolver],
+  activate: (app: JupyterLab, router: IRouter, resolver: IWindowResolver) => {
     let debouncer: number;
     let resolved = false;
 
+    resolver.resolve().then(name => {
+      console.log(`The window resolver returns the name ${name}`);
+    });
+
     const { commands, info, serviceManager } = app;
     const { workspaces } = serviceManager;
     const transform = new PromiseDelegate<StateDB.DataTransform>();
@@ -433,7 +455,7 @@ const state: JupyterLabPlugin<IStateDB> = {
  * Export the plugins as default.
  */
 const plugins: JupyterLabPlugin<any>[] = [
-  palette, settings, state, splash, themes
+  palette, resolver, settings, state, splash, themes
 ];
 export default plugins;
 

diff --git a/packages/coreutils/src/statedb.ts b/packages/coreutils/src/statedb.ts
@@ -98,12 +98,12 @@ class StateDB implements IStateDB {
    * @param options - The instantiation options for a state database.
    */
   constructor(options: StateDB.IOptions) {
-    const { namespace, transform } = options;
+    const { namespace, transform, windowName } = options;
 
     this.namespace = namespace;
 
     // Retrieve the window name, which is used as a namespace prefix.
-    this._ready = Private.windowName().then(name => {
+    this._ready = (windowName || Promise.resolve('')).then(name => {
       this._window = name;
 
       if (!transform) {
@@ -453,6 +453,17 @@ namespace StateDB {
      * client requests.
      */
     transform?: Promise<DataTransform>;
+
+    /**
+     * An optional promise that resolves to a name for the application window.
+     *
+     * #### Notes
+     * In environments where multiple windows can instantiate a state database,
+     * a window name is necessary to prefix all keys that are stored within the
+     * local storage that is shared by all windows. In JupyterLab, this window
+     * name is generated by the `IWindowResolver` extension.
+     */
+    windowName?: Promise<string>;
   }
 }
 
@@ -466,138 +477,4 @@ namespace Private {
    */
   export
   type Envelope = { readonly v: ReadonlyJSONValue };
-
-  /**
-   * The timeout (in ms) to wait for beacon responders.
-   */
-  const TIMEOUT = 100;
-
-  /**
-   * The internal prefix for private local storage keys.
-   */
-  const PREFIX = '@jupyterlab/coreutils:StateDB';
-
-  /**
-   * The local storage beacon key.
-   */
-  const BEACON = `${PREFIX}:beacon`;
-
-  /**
-   * The local storage window prefix.
-   */
-  const WINDOW = `${PREFIX}:window-`;
-
-  /**
-   * The window name.
-   */
-  let name: string;
-
-  /**
-   * The window name promise.
-   */
-  let promise: Promise<string>;
-
-  /**
-   * Wait until a window name is available and resolve.
-   */
-  function awaitName(resolve: (value: string) => void): void {
-    window.setTimeout(() => {
-      if (name) {
-        return resolve(name);
-      }
-
-      createName().then(value => {
-        name = value;
-        resolve(name);
-      });
-    }, TIMEOUT);
-  }
-
-  /**
-   * Create a name for this window.
-   */
-  function createName(): Promise<string> {
-    console.log('I should generate a name');
-    return Promise.resolve('');
-  }
-
-  /**
-   * Fetch the known window names.
-   */
-  function fetchWindowNames(): { [name: string]: number } {
-      const names: { [name: string]: number } = { };
-      const { localStorage } = window;
-      let i = localStorage.length;
-
-      while (i) {
-        let key = localStorage.key(--i);
-
-        if (key && key.indexOf(WINDOW) === 0) {
-          let name = key.replace(WINDOW, '');
-
-          names[name] = parseInt(localStorage.getItem(key), 10);
-        }
-      }
-
-      return names;
-  }
-
-  /**
-   * Fire off the signal beacon to solicit pings from other JupyterLab windows.
-   */
-  function beacon(): void {
-    window.localStorage.setItem(BEACON, `${(new Date()).getTime()}`);
-  }
-
-  /**
-   * Respond to a signal beacon.
-   */
-  function ping(): void {
-    if (name) {
-      window.localStorage.setItem(name, `${(new Date()).getTime()}`);
-    }
-  }
-
-  /**
-   * The window storage event handler.
-   */
-  function storageHandler(event: StorageEvent) {
-    const { key } = event;
-
-    console.log('event key', key);
-
-    if (key === BEACON) {
-      console.log('The beacon has been fired');
-      return ping();
-    }
-
-    if (key.indexOf(WINDOW) !== 0) {
-      return;
-    }
-
-    const windows = fetchWindowNames();
-    const name = key.replace(WINDOW, '');
-
-    if (name in windows) {
-      console.log(`Window ${name} is a known window.`);
-    } else {
-      console.log(`Window ${name} is an unknown window.`);
-    }
-  }
-
-  /**
-   * Returns a promise that resolves with the window name used for restoration.
-   */
-  export
-  function windowName(): Promise<string> {
-    return promise || (promise = new Promise((resolve) => {
-      beacon();
-      awaitName(resolve);
-    }));
-  }
-
-  /**
-   * Start the storage event handler immediately.
-   */
-  window.addEventListener('storage', storageHandler);
 }
diff --git a/packages/coreutils/src/windowresolver.ts b/packages/coreutils/src/windowresolver.ts
@@ -34,7 +34,7 @@ interface IWindowResolver {
  */
 export
 class WindowResolver implements IWindowResolver {
-  constructor(options: WindowResolver.IOptions = { candidate: '' }) {
+  constructor(options: WindowResolver.IOptions = { candidate: Promise.resolve('') }) {
     this._candidate = options.candidate;
   }
 
@@ -44,11 +44,14 @@ class WindowResolver implements IWindowResolver {
    * @returns A promise that resolves to a window name.
    */
   resolve(): Promise<string> {
-    console.log('Start with candidate:', this._candidate);
-    return Private.windowName();
+    return this._candidate.then(name => {
+      console.log('Start with candidate:', name);
+      return Private.windowName();
+    });
+
   }
 
-  private _candidate: string;
+  private _candidate: Promise<string>;
 }
 
 
@@ -65,7 +68,7 @@ namespace WindowResolver {
     /**
      * A potential preferred default window name.
      */
-    candidate: string;
+    candidate: Promise<string>;
   }
 }