Modify the runtime to use time-based timeouts rather than retry based. Fixes #2556

This allows for slow vs. fast connection failures (e.g. an active rejection vs. no response).

docs/en_US/desktop_deployment.rst

@@ -57,7 +57,7 @@ In order to configure the Python code, follow these steps:
 
        $ python setup.py
 
-Alternatively, you can simply run ``pgAdmin4.py`` at this point or aat a later time,
+Alternatively, you can simply run ``pgAdmin4.py`` at this point or at a later time,
 and ``pgadmin4.db`` will be created automatically at first run.
     
 Runtime
@@ -73,6 +73,25 @@ semi-colon character, for example:
 
      /Users/dpage/.virtualenvs/pgadmin4/lib/python2.7/site-packages/;/Users/dpage/python-libs/
     
-The configuration settings are stored using the QSettings class in Qt, which 
+The configuration settings are stored using the QSettings class in Qt, which
-will use an INI file on Unix systems, a plist file on Mac OS X, and the registry
+will use an INI file on Unix systems (~/.config/pgadmin/pgadmin4.conf),
-on Windows. The Python Path setting is stored in the ``PythonPath`` key.
+a plist file on Mac OS X (~/Library/Preferences/org.pgadmin.pgadmin4.plist),
+and the registry on Windows (HKEY_CURRENT_USER\\Software\\pgadmin\\pgadmin4).
+
+The configuration settings:
+
++--------------------------+--------------------+---------------------------------------------------------------+
+| Key                      | Type               | Purpose                                                       |
++==========================+====================+===============================================================+
+| ApplicationPath          | String             | The directory containing pgAdmin4.py                          |
++--------------------------+--------------------+---------------------------------------------------------------+
+| ConnectionTimeout        | Integer            | The number of seconds to wait for application server startup. |
++--------------------------+--------------------+---------------------------------------------------------------+
+| PythonPath               | String             | The Python module search path                                 |
++--------------------------+--------------------+---------------------------------------------------------------+
+| Browser/Geometry         | Binary             | The runtime window's size/shape                               |
++--------------------------+--------------------+---------------------------------------------------------------+
+| Browser/WindowState      | Binary             | The runtime window's state                                    |
++--------------------------+--------------------+---------------------------------------------------------------+
+| Browser/Zoom             | String             | The runtime window's zoom level (zoom % / 100)                |
++--------------------------+--------------------+---------------------------------------------------------------+

runtime/pgAdmin4.cpp

@@ -340,30 +340,38 @@ int main(int argc, char * argv[])
     // Generate the app server URL
     QString appServerUrl = QString("http://127.0.0.1:%1/?key=%2").arg(port).arg(key);
 
+    // Read the server connection timeout from the registry or set the default timeout.
+    QSettings settings;
+    int timeout = settings.value("ConnectionTimeout", 30).toInt();
+
     // Now the server should be up, we'll attempt to connect and get a response.
     // We'll retry in a loop a few time before aborting if necessary.
-    int attempt = 0;
+
-    while (attempt++ < 50)
+    QTime endTime = QTime::currentTime().addSecs(timeout);
+    bool alive = false;
+
+    while(QTime::currentTime() <= endTime)
     {
-        bool alive = PingServer(QUrl(appServerUrl));
+        alive = PingServer(QUrl(appServerUrl));
 
         if (alive)
         {
             break;
         }
 
-        if (attempt == 50)
-        {
-            splash->finish(NULL);
-            QString error(QWidget::tr("The application server could not be contacted."));
-            QMessageBox::critical(NULL, QString(QWidget::tr("Fatal Error")), error);
-
-            exit(1);
-        }
-
         delay(200);
     }
 
+    // Attempt to connect one more time in case of a long network timeout while looping
+    if(!alive && !PingServer(QUrl(appServerUrl)))
+    {
+        splash->finish(NULL);
+        QString error(QWidget::tr("The application server could not be contacted."));
+        QMessageBox::critical(NULL, QString(QWidget::tr("Fatal Error")), error);
+
+        exit(1);
+    }
+
     // Create & show the main window
     BrowserWindow browserWindow(appServerUrl);
     browserWindow.setWindowTitle(PGA_APP_NAME);
@@ -394,7 +402,7 @@ bool PingServer(QUrl url)
     QNetworkReply *reply;
     QVariant redirectUrl;
 
-    url.setPath("/misc/ping");
+    url.setPath("/misc/pingx");
 
     do
     {