Gracefully shut down database operations before app exit

main.js

@@ -329,27 +329,43 @@ function createWindow() {
   captureClicks(mainWindow);
 
   // Emitted when the window is about to be closed.
-  mainWindow.on('close', e => {
+  // Note: We do most of our shutdown logic here because all windows are closed by
+  //   Electron before the app quits.
+  mainWindow.on('close', async e => {
+    console.log('close event', {
+      readyForShutdown: mainWindow ? mainWindow.readyForShutdown : null,
+      shouldQuit: windowState.shouldQuit(),
+    });
     // If the application is terminating, just do the default
     if (
-      windowState.shouldQuit() ||
       config.environment === 'test' ||
-      config.environment === 'test-lib'
+      config.environment === 'test-lib' ||
+      (mainWindow.readyForShutdown && windowState.shouldQuit())
     ) {
       return;
     }
 
+    // Prevent the shutdown
+    e.preventDefault();
+    mainWindow.hide();
+
     // On Mac, or on other platforms when the tray icon is in use, the window
     // should be only hidden, not closed, when the user clicks the close button
-    if (usingTrayIcon || process.platform === 'darwin') {
-      e.preventDefault();
-      mainWindow.hide();
-
+    if (
+      !windowState.shouldQuit() &&
+      (usingTrayIcon || process.platform === 'darwin')
+    ) {
       // toggle the visibility of the show/hide tray icon menu entries
       if (tray) {
         tray.updateContextMenu();
       }
+
+      return;
     }
+
+    await requestShutdown();
+    mainWindow.readyForShutdown = true;
+    app.quit();
   });
 
   // Emitted when the window is closed.
@@ -691,7 +707,51 @@ function setupMenu(options) {
   Menu.setApplicationMenu(menu);
 }
 
+async function requestShutdown() {
+  if (!mainWindow || !mainWindow.webContents) {
+    return;
+  }
+
+  console.log('requestShutdown: Requesting close of mainWindow...');
+  const request = new Promise((resolve, reject) => {
+    ipc.once('now-ready-for-shutdown', (_event, error) => {
+      console.log('requestShutdown: Response received');
+
+      if (error) {
+        return reject(error);
+      }
+
+      return resolve();
+    });
+    mainWindow.webContents.send('get-ready-for-shutdown');
+
+    // We'll wait two minutes, then force the app to go down. This can happen if someone
+    //   exits the app before we've set everything up in preload() (so the browser isn't
+    //   yet listening for these events), or if there are a whole lot of stacked-up tasks.
+    // Note: two minutes is also our timeout for SQL tasks in data.js in the browser.
+    setTimeout(() => {
+      console.log(
+        'requestShutdown: Response never received; forcing shutdown.'
+      );
+      resolve();
+    }, 2 * 60 * 1000);
+  });
+
+  try {
+    await request;
+  } catch (error) {
+    console.log(
+      'requestShutdown error:',
+      error && error.stack ? error.stack : error
+    );
+  }
+}
+
 app.on('before-quit', () => {
+  console.log('before-quit event', {
+    readyForShutdown: mainWindow ? mainWindow.readyForShutdown : null,
+    shouldQuit: windowState.shouldQuit(),
+  });
   windowState.markShouldQuit();
 });