Only close affected connections on Engine change

[Nielswps]

When the user saves changes to the engines through the EngineOptionsDialog, all engines are re-instantiated and their connections are closed. It would be more efficient to only close the connections that are no longer in the active port range of the affected engines.

Ecdar-GUI/src/main/java/ecdar/backend/BackendHelper.java

Lines 121 to 126 in a25b099

	public static void updateEngineInstances(ArrayList<Engine> updatedEngines) {
	BackendHelper.engines = FXCollections.observableList(updatedEngines);
	for (Runnable runnable : BackendHelper.enginesUpdatedListeners) {
	runnable.run();
	}
	}

Ecdar-GUI/src/main/java/ecdar/controllers/EngineOptionsDialogController.java

Lines 73 to 76 in a25b099

	// Close all engine connections to avoid dangling engine connections when port range is changed
	try {
	Ecdar.getBackendDriver().closeAllEngineConnections();
	} catch (IOException e) {

⚠️ This change might seem fairly easy, but it should include a refactor of the way engines are referenced and handled in the EngineOptionsDialogController.

This also becomes an issue if long-running queries are started and then the port range is changed for the associated engine in order to run other queries. This case would result in the long-running query being canceled. (Thanks to @Brandhoej for this example of the issue)

Suggested approach

I suggest that the EngineInstance (the visual representation of the engine within the EngineOptionsDialog) does not operate on the engines, but instead takes an Engine as a constructor parameter for populating the input fields and then has a method for constructing an engine based on the values of these fields.