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 volatile int maxQueueLength;
  19     private ArrayDeque<Runnable> disposerQueue;
  20     private TObjectLongHashMap<Runnable> disposeTime;
  21     private Runnable currentlyScheduled = null;
  22
  23     private Runnable disposeOne = () -> {
  24         if(!disposerQueue.isEmpty()) {
  25             Runnable runnable = disposerQueue.removeFirst();
  26             disposeTime.remove(runnable);
  27             currentlyScheduled = null;
  28             runnable.run();
  29             if(DEBUG)
  30                 System.out.println("Executed disposer " + runnable);
  31             if(!disposerQueue.isEmpty())
  32                 scheduleDispose();
  33         }
  34     };
  35
  36     public DisposingPolicy() {
  37         this(MAX_QUEUE_LENGTH);
  38     }
  39
  40     public DisposingPolicy(int maxQueueLength) {
  41         this.maxQueueLength = maxQueueLength;
  42         this.disposerQueue = new ArrayDeque<>(maxQueueLength);
  43         this.disposeTime = new TObjectLongHashMap<>(maxQueueLength);
  44     }
  45
  46     public void setMaxQueueLength(int maxQueueLength) {
  47         this.maxQueueLength = maxQueueLength;
  48     }
  49
  50     private void scheduleDispose() {
  51         currentlyScheduled = disposerQueue.peekFirst();
  52         long delay = Math.max(
  53                 disposeTime.get(currentlyScheduled) - System.currentTimeMillis(),
  54                 MIN_DELAY);
  55         Display.getCurrent().timerExec((int)delay, disposeOne);
  56         if(DEBUG)
  57             System.out.println("Scheduled disposer " + currentlyScheduled + " in " + delay + " ms");
  58     }
  59
  60     /**
  61      * Runs the disposer either after DISPOSE_TIME or when there are
  62      * more than {@link #maxQueueLength} disposers active and this is first
  63      * of them (by activation order). This method must be called from
  64      * UI thread.
  65      */
  66     public void addDisposer(Runnable disposer) {
  67         if(DEBUG)
  68             System.out.println("Added disposer " + disposer);
  69         if(disposeTime.contains(disposer))
  70             return;
  71         if(disposerQueue.size() >= maxQueueLength)
  72             disposeOne.run();
  73         disposerQueue.addLast(disposer);
  74         disposeTime.put(disposer, System.currentTimeMillis()+DISPOSE_TIME);
  75         if(disposerQueue.size() == 1)
  76             scheduleDispose();
  77     }
  78
  79     /**
  80      * Cancels a disposer added before. This method must be called from
  81      * UI thread.
  82      */
  83     public void removeDisposer(Runnable disposer) {
  84         if(DEBUG)
  85             System.out.println("Removed disposer " + disposer);
  86         disposerQueue.remove(disposer);
  87         disposeTime.remove(disposer);
  88         if(disposer == currentlyScheduled) {
  89             currentlyScheduled = null;
  90             if(!disposerQueue.isEmpty())
  91                 scheduleDispose();
  92         }
  93     }
  94
  95 }