Sporadically crashes on Windows when exit. Fixes #3177

1) Shutdown the python server properly.
  2) Disabled "Shutdown server" menu till server is not successfully started.

Initial patch sent by Maxim, modified by Akshay Joshi.

runtime/Server.cpp

@@ -328,3 +328,14 @@ void Server::run()
     fclose(cp);
 }
 
+void Server::shutdown(QUrl url)
+{
+    bool shotdown = shutdownServer(url);
+    if (!shotdown)
+        setError(tr("Failed to shutdown application server thread."));
+
+    QThread::quit();
+    QThread::wait();
+    while(!this->isFinished()){}
+}
+

runtime/Server.h

@@ -29,6 +29,9 @@ public:
     bool Init();
     QString getError() { return m_error; }
 
+public slots:
+    void shutdown(QUrl url);
+
 protected:
     void run();
 

runtime/TrayIcon.cpp

@@ -148,6 +148,7 @@ void TrayIcon::createActions()
     connect(m_logAction, SIGNAL(triggered()), this, SLOT(onLog()));
 
     m_quitAction = new QAction(tr("&Shutdown server"), this);
+    m_quitAction->setEnabled(false);
     connect(m_quitAction, SIGNAL(triggered()), this, SLOT(onQuit()));
 }
 
@@ -239,6 +240,16 @@ void TrayIcon::onQuit()
 {
     if (QMessageBox::Yes == QMessageBox::question(this, tr("Shutdown server?"), QString(tr("Are you sure you want to shutdown the %1 server?")).arg(PGA_APP_NAME), QMessageBox::Yes | QMessageBox::No))
     {
+        // Emit the signal to shutdown the python server.
+        emit shutdownSignal(m_appServerUrl);
         exit(0);
     }
 }
+
+void TrayIcon::enableShutdownMenu()
+{
+    if (m_quitAction != NULL)
+    {
+        m_quitAction->setEnabled(true);
+    }
+}

runtime/TrayIcon.h

@@ -31,6 +31,7 @@ public:
 
     bool Init();
     void setAppServerUrl(QString appServerUrl);
+    void enableShutdownMenu();
 
 private:
     void createTrayIcon();
@@ -56,6 +57,9 @@ private slots:
     void onConfig();
     void onLog();
     void onQuit();
+
+signals:
+    void shutdownSignal(QUrl);
 };
 
 #endif // TRAYICON_H

runtime/pgAdmin4.cpp

@@ -239,6 +239,7 @@ int main(int argc, char * argv[])
             exit(1);
         }
 
+        QObject::connect(server, SIGNAL(finished()), server, SLOT(deleteLater()));
         server->start();
 
         // This is a hack to give the server a chance to start and potentially fail. As
@@ -336,6 +337,8 @@ int main(int argc, char * argv[])
 
     // Go!
     trayicon->setAppServerUrl(appServerUrl);
+    // Enable the shutdown server menu as server started successfully.
+    trayicon->enableShutdownMenu();
 
     QString cmd = settings.value("BrowserCommand").toString();
 
@@ -355,6 +358,8 @@ int main(int argc, char * argv[])
         }
     }
 
+    QObject::connect(trayicon, SIGNAL(shutdownSignal(QUrl)), server, SLOT(shutdown(QUrl)));
+
     splash->finish(NULL);
 
     return app.exec();
@@ -435,3 +440,44 @@ unsigned long sdbm(unsigned char *str)
 
     return hash;
 }
+
+// Shutdown the application server
+bool shutdownServer(QUrl url)
+{
+    QNetworkAccessManager manager;
+    QEventLoop loop;
+    QNetworkReply *reply;
+    QVariant redirectUrl;
+
+    url.setPath("/misc/shutdown");
+
+    do
+    {
+        reply = manager.get(QNetworkRequest(url));
+
+        QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
+        loop.exec();
+
+        redirectUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
+        url = redirectUrl.toUrl();
+
+        if (!redirectUrl.isNull())
+            delete reply;
+
+    } while (!redirectUrl.isNull());
+
+    if (reply->error() != QNetworkReply::NoError)
+    {
+        return false;
+    }
+
+    QString response = reply->readAll();
+
+    if (response != "SHUTDOWN")
+    {
+        qDebug() << "Failed to connect, server response: " << response;
+        return false;
+    }
+
+    return true;
+}

runtime/pgAdmin4.h

@@ -39,5 +39,6 @@ bool PingServer(QUrl url);
 void delay(int milliseconds);
 void cleanup();
 unsigned long sdbm(unsigned char *str);
+bool shutdownServer(QUrl url);
 
 #endif // PGADMIN4_H

web/pgadmin/misc/__init__.py

@@ -10,7 +10,7 @@
 """A blueprint module providing utility functions for the application."""
 
 import pgadmin.utils.driver as driver
-from flask import url_for, render_template, Response
+from flask import url_for, render_template, Response, request
 from flask_babel import gettext
 from pgadmin.utils import PgAdminModule
 from pgadmin.utils.preferences import Preferences
@@ -116,3 +116,17 @@ def explain_js():
         status=200,
         mimetype="application/javascript"
     )
+
+##########################################################################
+# A special URL used to shutdown the server
+##########################################################################
+@blueprint.route("/shutdown", methods=('get', 'post'))
+def shutdown():
+    if config.SERVER_MODE is not True:
+        func = request.environ.get('werkzeug.server.shutdown')
+        if func is None:
+            raise RuntimeError('Not running with the Werkzeug Server')
+        func()
+        return 'SHUTDOWN'
+    else:
+        return ''