Java Doc for RequestProcessor.java in  » IDE-Netbeans » openide » org » openide » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

There are several use cases for RequestProcessor:

• Having something done asynchronously in some other thread, not insisting on any kind of serialization of the requests: Use RequestProcessor. RequestProcessor.getDefault . RequestProcessor.post(java.lang.Runnable) post(runnable) for this purpose.
• Having something done later in some other thread: Use RequestProcessor. RequestProcessor.getDefault . RequestProcessor.post(java.lang.Runnable,int) post(runnable, delay)
• Having something done periodically in any thread: Use the RequestProcessor.Task 's ability to RequestProcessor.Task.schedule schedule() , like

   static RequestProcessor.Task CLEANER = RequestProcessor.getDefault().post(runnable,DELAY);
   public void run() {
   doTheWork();
   CLEANER.schedule(DELAY);
   }
   

  Note: Please think twice before implementing some periodic background activity. It is generally considered evil if it will run regardless of user actions and the application state, even while the application is minimized / not currently used.
• Having something done in some other thread but properly ordered: Create a private instance of the RequestProcessor.RequestProcessor(java.lang.String) RequestProcessor(name) and use it from all places you'd like to have serialized. It works like a simple Mutex.
• Having some entity that will do processing in a limited number of threads paralelly: Create a private instance of the RequestProcessor.RequestProcessor(java.lang.Stringint) RequestProcessor(name,throughput) set proper throughput and use it to schedule the work. It works like a queue of requests passing through a semafore with predefined number of DOWN()s.

Since version 6.3 there is a conditional support for interruption of long running tasks. There always was a way how to cancel not yet running task using RequestProcessor.Task.cancel but if the task was already running, one was out of luck. Since version 6.3 the thread running the task is interrupted and the Runnable can check for that and terminate its execution sooner. In the runnable one shall check for thread interruption (done from RequestProcessor.Task.cancel ) and if true, return immediatelly as in this example:

 public void run () {
 while (veryLongTimeLook) {
 doAPieceOfIt ();
 if (Thread.interrupted ()) return;
 }
 }
 

 public void run () {
 while (veryLongTimeLook) {
 doAPieceOfIt ();
 if (Thread.interrupted ()) return;
 }
 }
 

For request relaying please consider:

 post(run, timeToWait, Thread.currentThread().getPriority());