Ensure only one reload extension dialog can be shown at a time (#1473)

If `showReloadExtensionNotification` is in flight and being awaited then
return the promise being awaited instead of showing another dialog.

Also, debounce `showReloadExtensionNotification` with a 5 second window
because its possible for users to close the first dialog very fast and
have another one appear immediately if we update several settings at a
time that require an extension restart.

Issue: #1471

Author: plemarquand

src/ui/ReloadExtension.ts

@@ -14,23 +14,49 @@
 
 import * as vscode from "vscode";
 import { Workbench } from "../utilities/commands";
+// eslint-disable-next-line @typescript-eslint/no-require-imports
+import debounce = require("lodash.debounce");
 
 /**
  * Prompts the user to reload the extension in cases where we are unable to do
- * so automatically.
+ * so automatically. Only one of these prompts will be shown at a time.
  *
  * @param message the warning message to display to the user
  * @param items extra buttons to display
  * @returns the selected button or undefined if cancelled
  */
-export async function showReloadExtensionNotification<T extends string>(
-    message: string,
-    ...items: T[]
-): Promise<"Reload Extensions" | T | undefined> {
-    const buttons: ("Reload Extensions" | T)[] = ["Reload Extensions", ...items];
-    const selected = await vscode.window.showWarningMessage(message, ...buttons);
-    if (selected === "Reload Extensions") {
-        await vscode.commands.executeCommand(Workbench.ACTION_RELOADWINDOW);
-    }
-    return selected;
+export function showReloadExtensionNotificationInstance<T extends string>() {
+    let inFlight: Promise<"Reload Extensions" | T | undefined> | null = null;
+
+    return async function (
+        message: string,
+        ...items: T[]
+    ): Promise<"Reload Extensions" | T | undefined> {
+        if (inFlight) {
+            return inFlight;
+        }
+
+        const buttons: ("Reload Extensions" | T)[] = ["Reload Extensions", ...items];
+        inFlight = (async () => {
+            try {
+                const selected = await vscode.window.showWarningMessage(message, ...buttons);
+                if (selected === "Reload Extensions") {
+                    await vscode.commands.executeCommand(Workbench.ACTION_RELOADWINDOW);
+                }
+                return selected;
+            } finally {
+                inFlight = null;
+            }
+        })();
+
+        return inFlight;
+    };
 }
+
+// In case the user closes the dialog immediately we want to debounce showing it again
+// for 10 seconds to prevent another popup perhaps immediately appearing.
+export const showReloadExtensionNotification = debounce(
+    showReloadExtensionNotificationInstance(),
+    10_000,
+    { leading: true }
+);

test/unit-tests/ui/ReloadExtension.test.ts

@@ -11,15 +11,24 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 //===----------------------------------------------------------------------===//
+import { beforeEach } from "mocha";
 import { expect } from "chai";
 import { mockGlobalObject } from "../../MockUtils";
 import * as vscode from "vscode";
-import { showReloadExtensionNotification } from "../../../src/ui/ReloadExtension";
+import { showReloadExtensionNotificationInstance } from "../../../src/ui/ReloadExtension";
 import { Workbench } from "../../../src/utilities/commands";
 
 suite("showReloadExtensionNotification()", async function () {
     const mockedVSCodeWindow = mockGlobalObject(vscode, "window");
     const mockedVSCodeCommands = mockGlobalObject(vscode, "commands");
+    let showReloadExtensionNotification: (
+        message: string,
+        ...items: string[]
+    ) => Promise<string | undefined>;
+
+    beforeEach(() => {
+        showReloadExtensionNotification = showReloadExtensionNotificationInstance();
+    });
 
     test("displays a warning message asking the user if they would like to reload the window", async () => {
         mockedVSCodeWindow.showWarningMessage.resolves(undefined);
@@ -57,4 +66,18 @@ suite("showReloadExtensionNotification()", async function () {
         );
         expect(mockedVSCodeCommands.executeCommand).to.not.have.been.called;
     });
+
+    test("only shows one dialog at a time", async () => {
+        mockedVSCodeWindow.showWarningMessage.resolves(undefined);
+
+        await Promise.all([
+            showReloadExtensionNotification("Want to reload?"),
+            showReloadExtensionNotification("Want to reload?"),
+        ]);
+
+        expect(mockedVSCodeWindow.showWarningMessage).to.have.been.calledOnceWithExactly(
+            "Want to reload?",
+            "Reload Extensions"
+        );
+    });
 });