Whenever handleResponse calls the delegate function "func" my GUI crashes with no exception. The delegate function appends text to a RichTextBox on the GUI.
If I call this.func in "connect" it works just fine.
private void handleResponse(IAsyncResult result)
{
try
{
this.func.Invoke("test");
}
catch (Exception e)
{
throw e;
}
}
public void connect(string ip, int port, delegateFunction func) {
try
{
connection.Connect(ip, port);
socket = connection.Client;
this.func = func;
socket.BeginReceive(incomingBuffer, 0, incomingBuffer.Length, SocketFlags.None, handleResponse, null);
}
catch (Exception e)
{
throw e;
}
}
Could be a threading issue. Your GUI probably has to be updated on a specific GUI thread. How switching to that thread is achieved is specific to the GUI framework you use.
Related
My test method looks like this:
private static System.Timers.Timer _myTimer;
static void Main(string[] args)
{
using (_myTimer = new System.Timers.Timer(1000))
{
_myTimer.Elapsed += (o, e) => Console.WriteLine($"timer elapsed");
_myTimer.AutoReset = true;
_myTimer.Enabled = true;
Thread.Sleep(4000); // let the timer fire a couple of times
} // dispose timer?
Thread.Sleep(2000); // timer won't fire here
try
{
Console.WriteLine($"no problem accessing _myTimer: {_myTimer.Interval}"); // this won't throw an ObjectDisposedException on _myTimer
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex}");
}
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
try
{
Console.WriteLine($"no problem accessing _myTimer: {_myTimer.Interval}"); // still no ObjectDisposedException
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex}");
}
try
{
//_myTimer.Start(); // throws the ObjectDisposedException
_myTimer.Dispose(); // does not throw the ObjectDisposedException
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex}");
}
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
try
{
Console.WriteLine($"no problem accessing _myTimer: {_myTimer.Interval}"); // still no ObjectDisposedException
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex}");
}
Console.WriteLine("Press any key to continue...");
Console.ReadLine();
}
I would expect to get the ObjectDisposedException after leaving the using block.
Accessing the _myTimer.Interval works all the way to the end of the program. Also, I can call _myTimer.Dispose() anytime. Even waiting for the GarbageCollector does not help to get the ObjectDisposedException.
However, I do get the ObjectDisposedException if I call _myTimer.Start() after leaving the using block.
How can _myTimer be around for the entire lifetime of my program?
Calling Dispose doesn't remove the object or references to it. It will not be GCed as long as there are references to it. Dispose releases unmanaged resources within the object, which is likely but by no means guaranteed to cause at least some of its methods to stop working and start throwing ObjectDisposedException.
I'm trying to call SearchFactory optimize to run a scheduled index maintenance job (compacting segments - the application is a write intensive). But it does not seem to invoke immediately until I shutdown the Tomcat. My code is calling simply like this.
public synchronized void optimizeIndexes() {
getFullTextEntityManager().flushToIndexes(); //apply any changes before optimizing
getFullTextEntityManager().getSearchFactory().optimize();
logger.info("[Lucene] optimization has performed on all the indexes...");
}
I got it to work around by loaning IndexWriter from HSearch backend.
private synchronized void optimizeBareMetal() {
try {
LuceneBackendQueueProcessor backend = (LuceneBackendQueueProcessor) getIndexManager().getBackendQueueProcessor();
LuceneBackendResources resources = backend.getIndexResources();
AbstractWorkspaceImpl workspace = resources.getWorkspace();
IndexWriter indexWriter = workspace.getIndexWriter();
indexWriter.forceMerge(1, true);
indexWriter.commit();
} catch (LockObtainFailedException e) {
e.printStackTrace();
} catch (CorruptIndexException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private synchronized DirectoryBasedIndexManager getIndexManager() {
SearchFactoryImplementor searchFactory = (SearchFactoryImplementor) getFullTextEntityManager().getSearchFactory();
IndexManagerHolder indexManagerHolder = searchFactory.getIndexManagerHolder();
return (DirectoryBasedIndexManager) indexManagerHolder.getIndexManager(getEntityClass().getName());
}
I want to use java nio in java ee.
But I don't know how to do it right.
I need to after server has deploy java.nio.selector always listens the port and processing socket connection.
I try do it there:
#Singleton
#Lock(LockType.READ)
public class TaskManager {
private static final int LISTENINGPORT;
static {
LISTENINGPORT = ConfigurationSettings.getConfigureSettings().getListeningPort();
}
private ArrayList<ServerCalculationInfo> serverList;
public TaskManager() {
serverList = new ArrayList<ServerCalculationInfo>();
select();
}
#Asynchronous
public void select() {
try {
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
Selector selector = Selector.open();
serverSocketChannel.configureBlocking(false);
serverSocketChannel.socket().bind(new InetSocketAddress(LISTENINGPORT));
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
while (true) {
try {
selector.select();
} catch (IOException ex) {
Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, ex);
break;
}
Iterator it = selector.selectedKeys().iterator();
while (it.hasNext()) {
SelectionKey selKey = (SelectionKey) it.next();
it.remove();
try {
processSelectionKey(serverSocketChannel, selKey);
} catch (IOException e) {
serverList.remove(serverCalculationInfo);
}
}
}
} catch (IOException e) {
Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, e);
} catch (Exception e) {
Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, e);
}
}
}
It don't work correctly. The process hangs during deploy and redeploy application possible only after restart Glassfish.
How can I do right it?
It works correctly if invoke #Asynchronous method from the #PostConstructor:
#PostConstruct
public void postTaskManager() {
serverList = new ArrayList<ServerCalculationInfo>();
select();
}
instead of invoke it from constructor.
But class must be without #Startup annotation.
I had an rcp application which runs for only first run, when a user attempts to re-execute the application, second instance behaves as a client which encodes and sends its arguments over the socket to the first instance which acts as a server and then exits silently. The first instance receives and decodes that message, then behaves as if it had been invoked with those arguments.
so far so good i made internal protocol specification for passing arguments between two instances.
I could not bring the first instance(RCP application) to front. It is in minimized state only,
this is in continuation to my previous question
the change i made to previous post is start method of application class
public Object start(IApplicationContext context) throws Exception {
if (!ApplicationInstanceManager.registerInstance()) {
return IApplication.EXIT_OK;
}
ApplicationInstanceManager
.setApplicationInstanceListener(new ApplicationInstanceListener() {
public void newInstanceCreated() {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
System.out.println("New instance detected...");
//Display.getCurrent().getActiveShell()
.forceActive();// this gives null
// pointer exception
// hence commented
}
});
}
});
Display display = PlatformUI.createDisplay();
try {
int returnCode = PlatformUI.createAndRunWorkbench(display,
new ApplicationWorkbenchAdvisor());
if (returnCode == PlatformUI.RETURN_RESTART)
return IApplication.EXIT_RESTART;
else
return IApplication.EXIT_OK;
} finally {
display.dispose();
}
}
below line is stopping me to bring Application to front
Display.getCurrent().getActiveShell().forceActive();
generates null pointer exception at getActiveShell()
how can i maximize the previous instance or bring it to front
I wrote an instance manager to restrict my RCP to a single instance.
Here's the code that goes in Application.java, in the start method:
if (!ApplicationInstanceManager.registerInstance()) {
return IApplication.EXIT_OK;
}
ApplicationInstanceManager
.setApplicationInstanceListener(new ApplicationInstanceListener() {
public void newInstanceCreated() {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
if (DEBUG)
System.out.println("New instance detected...");
Display.getCurrent().getActiveShell().forceActive();
}
});
}
});
Here's the listener interface:
public interface ApplicationInstanceListener {
public void newInstanceCreated();
}
And here's the Manager class:
public class ApplicationInstanceManager {
private static final boolean DEBUG = true;
private static ApplicationInstanceListener subListener;
/** Randomly chosen, but static, high socket number */
public static final int SINGLE_INSTANCE_NETWORK_SOCKET = 44331;
/** Must end with newline */
public static final String SINGLE_INSTANCE_SHARED_KEY = "$$RabidNewInstance$$\n";
/**
* Registers this instance of the application.
*
* #return true if first instance, false if not.
*/
public static boolean registerInstance() {
// returnValueOnError should be true if lenient (allows app to run on
// network error) or false if strict.
boolean returnValueOnError = true;
// try to open network socket
// if success, listen to socket for new instance message, return true
// if unable to open, connect to existing and send new instance message,
// return false
try {
final ServerSocket socket = new ServerSocket(
SINGLE_INSTANCE_NETWORK_SOCKET, 10, InetAddress
.getLocalHost());
if (DEBUG)
System.out
.println("Listening for application instances on socket "
+ SINGLE_INSTANCE_NETWORK_SOCKET);
Thread instanceListenerThread = new InstanceListenerThread(socket);
instanceListenerThread.start();
// listen
} catch (UnknownHostException e) {
EclipseLogging.logError(RabidPlugin.getDefault(),
RabidPlugin.PLUGIN_ID, e);
return returnValueOnError;
} catch (IOException e) {
return portTaken(returnValueOnError, e);
}
return true;
}
private static boolean portTaken(boolean returnValueOnError, IOException e) {
if (DEBUG)
System.out.println("Port is already taken. "
+ "Notifying first instance.");
try {
Socket clientSocket = new Socket(InetAddress.getLocalHost(),
SINGLE_INSTANCE_NETWORK_SOCKET);
OutputStream out = clientSocket.getOutputStream();
out.write(SINGLE_INSTANCE_SHARED_KEY.getBytes());
out.close();
clientSocket.close();
System.out.println("Successfully notified first instance.");
return false;
} catch (UnknownHostException e1) {
EclipseLogging.logError(RabidPlugin.getDefault(),
RabidPlugin.PLUGIN_ID, e);
return returnValueOnError;
} catch (IOException e1) {
EclipseLogging
.logError(
RabidPlugin.getDefault(),
RabidPlugin.PLUGIN_ID,
"Error connecting to local port for single instance notification",
e);
return returnValueOnError;
}
}
public static void setApplicationInstanceListener(
ApplicationInstanceListener listener) {
subListener = listener;
}
private static void fireNewInstance() {
if (subListener != null) {
subListener.newInstanceCreated();
}
}
public static void main(String[] args) {
if (!ApplicationInstanceManager.registerInstance()) {
// instance already running.
System.out.println("Another instance of this application "
+ "is already running. Exiting.");
System.exit(0);
}
ApplicationInstanceManager
.setApplicationInstanceListener(new ApplicationInstanceListener() {
public void newInstanceCreated() {
System.out.println("New instance detected...");
// this is where your handler code goes...
}
});
}
public static class InstanceListenerThread extends Thread {
private ServerSocket socket;
public InstanceListenerThread(ServerSocket socket) {
this.socket = socket;
}
#Override
public void run() {
boolean socketClosed = false;
while (!socketClosed) {
if (socket.isClosed()) {
socketClosed = true;
} else {
try {
Socket client = socket.accept();
BufferedReader in = new BufferedReader(
new InputStreamReader(client.getInputStream()));
String message = in.readLine();
if (SINGLE_INSTANCE_SHARED_KEY.trim().equals(
message.trim())) {
if (DEBUG)
System.out.println("Shared key matched - "
+ "new application instance found");
fireNewInstance();
}
in.close();
client.close();
} catch (IOException e) {
socketClosed = true;
}
}
}
}
}
}
After your IApplication start up, you can also check and lock the OSGi instance location using org.eclipse.osgi.service.datalocation.Location.isSet() and org.eclipse.osgi.service.datalocation.Location.lock()
The location is usually retrieved from your Activator using code like:
public Location getInstanceLocation() {
if (locationTracker == null) {
Filter filter = null;
try {
filter = context.createFilter(Location.INSTANCE_FILTER);
} catch (InvalidSyntaxException e) {
// ignore this. It should never happen as we have tested the
// above format.
}
locationTracker = new ServiceTracker(context, filter, null);
locationTracker.open();
}
return (Location) locationTracker.getService();
}
I try to use get result from a api called j-calais, and then out put the result on a web page, i write all the code in client, but it cant compile right, dont know why??? please help. the source code like below:
there is no obvious error arise, but it cant be compile successfully..... thanks a lot:
public void onModuleLoad() {
// Create table for stock data.
stocksFlexTable.setText(0, 0, "Type");
stocksFlexTable.setText(0, 1, "Name");
// Assemble Add Stock panel.
addPanel.add(newSymbolTextBox);
addPanel.add(addStockButton);
// Assemble Main panel.
mainPanel.add(stocksFlexTable);
mainPanel.add(addPanel);
mainPanel.add(lastUpdatedLabel);
// Associate the Main panel with the HTML host page.
RootPanel.get("stockList").add(mainPanel);
// Move cursor focus to the input box.
newSymbolTextBox.setFocus(true);
// Listen for mouse events on the Add button.
addStockButton.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
try {
addStock();
} catch (Exception e) {
e.printStackTrace();
}
}
});
// Listen for keyboard events in the input box.
newSymbolTextBox.addKeyPressHandler(new KeyPressHandler() {
public void onKeyPress(KeyPressEvent event) {
if (event.getCharCode() == KeyCodes.KEY_ENTER) {
try {
addStock();
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
}
private void addStock() throws Exception {
final String url_s = newSymbolTextBox.getText().toUpperCase().trim();
newSymbolTextBox.setFocus(true);
newSymbolTextBox.setText("");
int row = stocksFlexTable.getRowCount();
CalaisClient client = new CalaisRestClient("ysw5rx69jkvdnzqf6sgjduqj");
System.out.print("read success...\n");
URL url = new URL(url_s);
CalaisResponse response = client.analyze(url);
for (CalaisObject entity : response.getEntities()) {
System.out.println(entity.getField("_type") + ":"
+ entity.getField("name"));
stocks.add(entity.getField("_type"));
stocksFlexTable.setText(row, 0, entity.getField("_type"));
stocksFlexTable.setText(row, 1, entity.getField("name"));
}
for (CalaisObject topic : response.getTopics()) {
System.out.println(topic.getField("categoryName"));
}
}
}
GWT only handles unchecked exceptions so you can throw Runtime Exceptions
or write your own Exception that extends from Runtime Exception then it will not cause any compile time problem
void f() throws NullPointerException // will not cause any problem because it is Runtime exception so unchecked
void f() throws IllegalAccessException // it is checked exception so there will be problem at compile time