Refactor auto save mechanism

packages/core/src/browser/frontend-application-module.ts

@@ -450,6 +450,8 @@ export const frontendApplicationModule = new ContainerModule((bind, _unbind, _is
     bindBackendStopwatch(bind);
 
     bind(SaveResourceService).toSelf().inSingletonScope();
+    bind(FrontendApplicationContribution).toService(SaveResourceService);
+
     bind(UserWorkingDirectoryProvider).toSelf().inSingletonScope();
     bind(FrontendApplicationContribution).toService(UserWorkingDirectoryProvider);
 

packages/core/src/browser/index.ts

@@ -46,3 +46,4 @@ export * from './tooltip-service';
 export * from './decoration-style';
 export * from './styling-service';
 export * from './hover-service';
+export * from './save-resource-service';

packages/core/src/browser/save-resource-service.ts

@@ -14,15 +14,153 @@
  * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
  ********************************************************************************/
 
-import { inject, injectable } from 'inversify';
-import { MessageService, UNTITLED_SCHEME, URI } from '../common';
+import type { ApplicationShell } from './shell';
+import { injectable } from 'inversify';
+import { UNTITLED_SCHEME, URI, Disposable, DisposableCollection } from '../common';
 import { Navigatable, NavigatableWidget } from './navigatable-types';
-import { Saveable, SaveableSource, SaveOptions } from './saveable';
+import { AutoSaveMode, Saveable, SaveableSource, SaveOptions, SaveReason } from './saveable';
 import { Widget } from './widgets';
+import { FrontendApplicationContribution } from './frontend-application-contribution';
+import { FrontendApplication } from './frontend-application';
+import throttle = require('lodash.throttle');
 
 @injectable()
-export class SaveResourceService {
-    @inject(MessageService) protected readonly messageService: MessageService;
+export class SaveResourceService implements FrontendApplicationContribution {
+
+    protected saveThrottles = new Map<Saveable, AutoSaveThrottle>();
+    protected saveMode: AutoSaveMode = 'off';
+    protected saveDelay = 1000;
+    protected shell: ApplicationShell;
+
+    get autoSave(): AutoSaveMode {
+        return this.saveMode;
+    }
+
+    set autoSave(value: AutoSaveMode) {
+        this.updateAutoSaveMode(value);
+    }
+
+    get autoSaveDelay(): number {
+        return this.saveDelay;
+    }
+
+    set autoSaveDelay(value: number) {
+        this.updateAutoSaveDelay(value);
+    }
+
+    onDidInitializeLayout(app: FrontendApplication): void {
+        this.shell = app.shell;
+        // Register restored editors first
+        for (const widget of this.shell.widgets) {
+            const saveable = Saveable.get(widget);
+            if (saveable) {
+                this.registerSaveable(widget, saveable);
+            }
+        }
+        this.shell.onDidAddWidget(e => {
+            const saveable = Saveable.get(e);
+            if (saveable) {
+                this.registerSaveable(e, saveable);
+            }
+        });
+        this.shell.onDidChangeCurrentWidget(e => {
+            if (this.saveMode === 'onFocusChange') {
+                const widget = e.oldValue;
+                const saveable = Saveable.get(widget);
+                if (saveable && widget && this.shouldAutoSave(widget, saveable)) {
+                    saveable.save({
+                        saveReason: SaveReason.FocusChange
+                    });
+                }
+            }
+        });
+        this.shell.onDidRemoveWidget(e => {
+            const saveable = Saveable.get(e);
+            if (saveable) {
+                this.saveThrottles.get(saveable)?.dispose();
+                this.saveThrottles.delete(saveable);
+            }
+        });
+    }
+
+    protected updateAutoSaveMode(mode: AutoSaveMode): void {
+        this.saveMode = mode;
+        for (const saveThrottle of this.saveThrottles.values()) {
+            saveThrottle.autoSave = mode;
+        }
+        if (mode === 'onFocusChange') {
+            // If the new mode is onFocusChange, we need to save all dirty documents that are not focused
+            const widgets = this.shell.widgets;
+            for (const widget of widgets) {
+                const saveable = Saveable.get(widget);
+                if (saveable && widget !== this.shell.currentWidget && this.shouldAutoSave(widget, saveable)) {
+                    saveable.save({
+                        saveReason: SaveReason.FocusChange
+                    });
+                }
+            }
+        }
+    }
+
+    protected updateAutoSaveDelay(delay: number): void {
+        this.saveDelay = delay;
+        for (const saveThrottle of this.saveThrottles.values()) {
+            saveThrottle.autoSaveDelay = delay;
+        }
+    }
+
+    registerSaveable(widget: Widget, saveable: Saveable): Disposable {
+        const saveThrottle = new AutoSaveThrottle(
+            saveable,
+            () => {
+                if (this.saveMode === 'afterDelay' && this.shouldAutoSave(widget, saveable)) {
+                    saveable.save({
+                        saveReason: SaveReason.AfterDelay
+                    });
+                }
+            },
+            this.addBlurListener(widget, saveable)
+        );
+        saveThrottle.autoSave = this.saveMode;
+        saveThrottle.autoSaveDelay = this.saveDelay;
+        this.saveThrottles.set(saveable, saveThrottle);
+        return saveThrottle;
+    }
+
+    protected addBlurListener(widget: Widget, saveable: Saveable): Disposable {
+        const document = widget.node.ownerDocument;
+        const listener = (() => {
+            if (this.saveMode === 'onWindowChange' && !this.windowHasFocus(document) && this.shouldAutoSave(widget, saveable)) {
+                saveable.save({
+                    saveReason: SaveReason.FocusChange
+                });
+            }
+        }).bind(this);
+        document.addEventListener('blur', listener);
+        return Disposable.create(() => {
+            document.removeEventListener('blur', listener);
+        });
+    }
+
+    protected windowHasFocus(document: Document): boolean {
+        if (document.visibilityState === 'hidden') {
+            return false;
+        } else if (document.hasFocus()) {
+            return true;
+        }
+        // TODO: Add support for iframes
+        return false;
+    }
+
+    protected shouldAutoSave(widget: Widget, saveable: Saveable): boolean {
+        const uri = NavigatableWidget.getUri(widget);
+        if (uri?.scheme === UNTITLED_SCHEME) {
+            // Never auto-save untitled documents
+            return false;
+        } else {
+            return saveable.dirty;
+        }
+    }
 
     /**
      * Indicate if the document can be saved ('Save' command should be disable if not).
@@ -58,3 +196,66 @@ export class SaveResourceService {
         return Promise.reject('Unsupported: The base SaveResourceService does not support saveAs action.');
     }
 }
+
+export class AutoSaveThrottle implements Disposable {
+
+    private _saveable: Saveable;
+    private _cb: () => void;
+    private _disposable: DisposableCollection;
+    private _throttle?: ReturnType<typeof throttle>;
+    private _mode: AutoSaveMode = 'off';
+    private _autoSaveDelay = 1000;
+
+    get autoSave(): AutoSaveMode {
+        return this._mode;
+    }
+
+    set autoSave(value: AutoSaveMode) {
+        this._mode = value;
+        this.throttledSave();
+    }
+
+    get autoSaveDelay(): number {
+        return this._autoSaveDelay;
+    }
+
+    set autoSaveDelay(value: number) {
+        this._autoSaveDelay = value;
+        // Explicitly delete the throttle to recreate it with the new delay
+        this._throttle?.cancel();
+        this._throttle = undefined;
+        this.throttledSave();
+    }
+
+    constructor(saveable: Saveable, cb: () => void, ...disposables: Disposable[]) {
+        this._cb = cb;
+        this._saveable = saveable;
+        this._disposable = new DisposableCollection(
+            ...disposables,
+            saveable.onContentChanged(() => {
+                this.throttledSave();
+            }),
+            saveable.onDirtyChanged(() => {
+                this.throttledSave();
+            })
+        );
+    }
+
+    protected throttledSave(): void {
+        this._throttle?.cancel();
+        if (this._mode === 'afterDelay' && this._saveable.dirty) {
+            if (!this._throttle) {
+                this._throttle = throttle(() => this._cb(), this._autoSaveDelay, {
+                    leading: false,
+                    trailing: true
+                });
+            }
+            this._throttle();
+        }
+    }
+
+    dispose(): void {
+        this._disposable.dispose();
+    }
+
+}

packages/core/src/browser/saveable.ts

@@ -22,12 +22,22 @@ import { Key } from './keyboard/keys';
 import { AbstractDialog } from './dialogs';
 import { waitForClosed } from './widgets';
 import { nls } from '../common/nls';
-import { Disposable, isObject } from '../common';
+import { DisposableCollection, isObject } from '../common';
+
+export type AutoSaveMode = 'off' | 'afterDelay' | 'onFocusChange' | 'onWindowChange';
 
 export interface Saveable {
     readonly dirty: boolean;
+    /**
+     * This event is fired when the content of the `dirty` variable changes.
+     */
     readonly onDirtyChanged: Event<void>;
-    readonly autoSave: 'off' | 'afterDelay' | 'onFocusChange' | 'onWindowChange';
+    /**
+     * This event is fired when the content of the saveable changes.
+     * While `onDirtyChanged` is fired to notify the UI that the widget is dirty,
+     * `onContentChanged` is used for the auto save throttling.
+     */
+    readonly onContentChanged: Event<void>;
     /**
      * Saves dirty changes.
      */
@@ -53,11 +63,15 @@ export interface SaveableSource {
 export class DelegatingSaveable implements Saveable {
     dirty = false;
     protected readonly onDirtyChangedEmitter = new Emitter<void>();
+    protected readonly onContentChangedEmitter = new Emitter<void>();
 
     get onDirtyChanged(): Event<void> {
         return this.onDirtyChangedEmitter.event;
     }
-    autoSave: 'off' | 'afterDelay' | 'onFocusChange' | 'onWindowChange' = 'off';
+
+    get onContentChanged(): Event<void> {
+        return this.onContentChangedEmitter.event;
+    }
 
     async save(options?: SaveOptions): Promise<void> {
         await this._delegate?.save(options);
@@ -68,16 +82,19 @@ export class DelegatingSaveable implements Saveable {
     applySnapshot?(snapshot: object): void;
 
     protected _delegate?: Saveable;
-    protected toDispose?: Disposable;
+    protected toDispose = new DisposableCollection();
 
     set delegate(delegate: Saveable) {
-        this.toDispose?.dispose();
+        this.toDispose.dispose();
+        this.toDispose = new DisposableCollection();
         this._delegate = delegate;
-        this.toDispose = delegate.onDirtyChanged(() => {
+        this.toDispose.push(delegate.onDirtyChanged(() => {
             this.dirty = delegate.dirty;
             this.onDirtyChangedEmitter.fire();
-        });
-        this.autoSave = delegate.autoSave;
+        }));
+        this.toDispose.push(delegate.onContentChanged(() => {
+            this.onContentChangedEmitter.fire();
+        }));
         if (this.dirty !== delegate.dirty) {
             this.dirty = delegate.dirty;
             this.onDirtyChangedEmitter.fire();
@@ -142,6 +159,7 @@ export namespace Saveable {
 
     function createCloseWithSaving(
         getOtherSaveables?: () => Array<Widget | SaveableWidget>,
+        isAutoSaveEnabled?: () => boolean,
         doSave?: (widget: Widget, options?: SaveOptions) => Promise<void>
     ): (this: SaveableWidget, options?: SaveableWidget.CloseOptions) => Promise<void> {
         let closing = false;
@@ -152,6 +170,9 @@ export namespace Saveable {
             closing = true;
             try {
                 const result = await shouldSave(saveable, () => {
+                    if (isAutoSaveEnabled?.()) {
+                        return true;
+                    }
                     const notLastWithDocument = !closingWidgetWouldLoseSaveable(this, getOtherSaveables?.() ?? []);
                     if (notLastWithDocument) {
                         return this.closeWithoutSaving(false).then(() => undefined);
@@ -209,6 +230,7 @@ export namespace Saveable {
 
     export function apply(
         widget: Widget,
+        isAutoSaveEnabled?: () => boolean,
         getOtherSaveables?: () => Array<Widget | SaveableWidget>,
         doSave?: (widget: Widget, options?: SaveOptions) => Promise<void>,
     ): SaveableWidget | undefined {
@@ -222,7 +244,7 @@ export namespace Saveable {
         const saveableWidget = widget as SaveableWidget;
         setDirty(saveableWidget, saveable.dirty);
         saveable.onDirtyChanged(() => setDirty(saveableWidget, saveable.dirty));
-        const closeWithSaving = createCloseWithSaving(getOtherSaveables, doSave);
+        const closeWithSaving = createCloseWithSaving(getOtherSaveables, isAutoSaveEnabled, doSave);
         return Object.assign(saveableWidget, {
             closeWithoutSaving,
             closeWithSaving,
@@ -235,10 +257,6 @@ export namespace Saveable {
             return false;
         }
 
-        if (saveable.autoSave !== 'off') {
-            return true;
-        }
-
         return cb();
     }
 }
@@ -302,11 +320,28 @@ export const enum FormatType {
     DIRTY
 };
 
+export namespace SaveReason {
+
+    export const Manual = 1;
+    export const AfterDelay = 2;
+    export const FocusChange = 3;
+
+    export function isManual(reason?: number): reason is typeof Manual {
+        return reason === Manual;
+    }
+}
+
+export type SaveReason = 1 | 2 | 3;
+
 export interface SaveOptions {
     /**
      * Formatting type to apply when saving.
      */
     readonly formatType?: FormatType;
+    /**
+     * The reason for saving the resource.
+     */
+    readonly saveReason?: SaveReason;
 }
 
 /**