Add ShutdownHandler for Main and Renderer

1 files changed, 92 insertions, 0 deletions

diff --git a/app/shutdown-handler.js b/app/shutdown-handler.js
new file mode 100644
index 0000000000..afd10f61b2
--- /dev/null
+++ b/app/shutdown-handler.js
@@ -0,0 +1,92 @@
+// @flow
+import { app, ipcMain, ipcRenderer } from 'electron';
+import { log } from './lib/platform';
+import type { WebContents } from 'electron';
+
+// The timeout before the shutdown is enforced
+const SHUTDOWN_TIMEOUT = 3000;
+
+/**
+ * Shutdown coordinator postpones the application shutdown until ShutdownHandler finished the
+ * shutdown sequence.
+ *
+ * ShutdownCoordinator can only be created from main process.
+ */
+class ShutdownCoordinator {
+  _canQuit = false;
+  _isQuitting = false;
+  _webContents: WebContents;
+  _shutdownTimeout: ?TimeoutID;
+
+  constructor(webContents: WebContents) {
+    this._webContents = webContents;
+
+    app.on('before-quit', this._onBeforeQuit);
+    ipcMain.on('app-shutdown-reply', this._onShutdownReply);
+  }
+
+  dispose() {
+    app
+      .removeListener('before-quit', this._onBeforeQuit)
+      .removeListener('app-shutdown-reply', this._onShutdownReply);
+  }
+
+  _onBeforeQuit = (event) => {
+    if (!this._canQuit) {
+      // make sure we don't call the shutdown handler twice
+      if (!this._isQuitting) {
+        this._isQuitting = true;
+
+        // start timer to force shutdown if the renderer process is not able to handle shutdown in
+        // a timely manner.
+        this._shutdownTimeout = setTimeout(this._onShutdownTimeout, SHUTDOWN_TIMEOUT);
+
+        this._webContents.send('app-shutdown');
+      }
+
+      event.preventDefault();
+    }
+  };
+
+  _onShutdownReply = () => {
+    const shutdownTimeout = this._shutdownTimeout;
+    if (shutdownTimeout) {
+      clearTimeout(shutdownTimeout);
+    }
+    this._grantShutdown();
+  };
+
+  _onShutdownTimeout = () => {
+    log.warn('It took longer than expected to shutdown. Forcing shutdown now.');
+    this._grantShutdown();
+  };
+
+  _grantShutdown() {
+    this._canQuit = true;
+    app.quit();
+  }
+}
+
+/**
+ * Executes the provided closure when application is about to quit.
+ * It works in tandem with ShutdownCoordinator and can only be used in renderer process.
+ * The shutdown will be postponed until the Promise returned from closure is resolved.
+ * ShutdownCoordinator will force the shutdown if the returned Promise is not resolved within
+ * the allocated time (see SHUTDOWN_TIMEOUT).
+ */
+function setShutdownHandler(handler: () => Promise<void>) {
+  ipcRenderer.once('app-shutdown', async (event) => {
+    try {
+      await handler();
+    } catch (error) {
+      log.warn(`An error occurred in shutdown handler: ${error.message}`);
+    }
+    event.sender.send('app-shutdown-reply');
+  });
+}
+
+if (ipcMain) {
+  module.exports = { ShutdownCoordinator };
+} else {
+  module.exports = { setShutdownHandler };
+}