bundles/org.simantics.modeling.ui/src/org/simantics/modeling/ui/diagramEditor/DisposingPolicy.java

   1 package org.simantics.modeling.ui.diagramEditor;
   2
   3 import gnu.trove.map.hash.TObjectLongHashMap;
   4
   5 import java.util.ArrayDeque;
   6
   7 import org.eclipse.swt.widgets.Display;
   8
   9
  10 public class DisposingPolicy {
  11
  12     public static final boolean DEBUG = false;
  13
  14     public static final int MAX_QUEUE_LENGTH = 8;
  15     public static final long DISPOSE_TIME = 30000L; // ms
  16     public static final long MIN_DELAY = 200L; // ms
  17
  18     private final int maxQueueLength;
  19     private ArrayDeque<Runnable> disposerQueue = new ArrayDeque<Runnable>(MAX_QUEUE_LENGTH);
  20     private TObjectLongHashMap<Runnable> disposeTime =
  21             new TObjectLongHashMap<Runnable>(MAX_QUEUE_LENGTH);
  22     private Runnable currentlyScheduled = null;
  23
  24     private Runnable disposeOne = () -> {
  25         if(!disposerQueue.isEmpty()) {
  26             Runnable runnable = disposerQueue.removeFirst();
  27             disposeTime.remove(runnable);
  28             currentlyScheduled = null;
  29             runnable.run();
  30             if(DEBUG)
  31                 System.out.println("Executed disposer " + runnable);
  32             if(!disposerQueue.isEmpty())
  33                 scheduleDispose();
  34         }
  35     };
  36
  37     public DisposingPolicy() {
  38         this(MAX_QUEUE_LENGTH);
  39     }
  40
  41     public DisposingPolicy(int maxQueueLength) {
  42         this.maxQueueLength = maxQueueLength;
  43     }
  44
  45     private void scheduleDispose() {
  46         currentlyScheduled = disposerQueue.peekFirst();
  47         long delay = Math.max(
  48                 disposeTime.get(currentlyScheduled) - System.currentTimeMillis(),
  49                 MIN_DELAY);
  50         Display.getCurrent().timerExec((int)delay, disposeOne);
  51         if(DEBUG)
  52             System.out.println("Scheduled disposer " + currentlyScheduled + " in " + delay + " ms");
  53     }
  54
  55     /**
  56      * Runs the disposer either after DISPOSE_TIME or when there are
  57      * more than {@link #maxQueueLength} disposers active and this is first
  58      * of them (by activation order). This method must be called from
  59      * UI thread.
  60      */
  61     public void addDisposer(Runnable disposer) {
  62         if(DEBUG)
  63             System.out.println("Added disposer " + disposer);
  64         if(disposeTime.contains(disposer))
  65             return;
  66         if(disposerQueue.size() >= maxQueueLength)
  67             disposeOne.run();
  68         disposerQueue.addLast(disposer);
  69         disposeTime.put(disposer, System.currentTimeMillis()+DISPOSE_TIME);
  70         if(disposerQueue.size() == 1)
  71             scheduleDispose();
  72     }
  73
  74     /**
  75      * Cancels a disposer added before. This method must be called from
  76      * UI thread.
  77      */
  78     public void removeDisposer(Runnable disposer) {
  79         if(DEBUG)
  80             System.out.println("Removed disposer " + disposer);
  81         disposerQueue.remove(disposer);
  82         disposeTime.remove(disposer);
  83         if(disposer == currentlyScheduled) {
  84             currentlyScheduled = null;
  85             if(!disposerQueue.isEmpty())
  86                 scheduleDispose();
  87         }
  88     }
  89
  90 }