bundles/org.simantics.browsing.ui.swt/src/org/simantics/browsing/ui/swt/ImageLoaderJob.java

   1 /*******************************************************************************
   2  * Copyright (c) 2013 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *     Semantum Oy - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.browsing.ui.swt;
  13
  14 import java.util.concurrent.atomic.AtomicBoolean;
  15
  16 import org.eclipse.core.runtime.IProgressMonitor;
  17 import org.eclipse.core.runtime.IStatus;
  18 import org.eclipse.core.runtime.Status;
  19 import org.eclipse.core.runtime.jobs.Job;
  20 import org.eclipse.ui.progress.IProgressConstants;
  21 import org.simantics.DatabaseJob;
  22
  23 /**
  24  * @author Tuukka Lehtonen
  25  */
  26 public class ImageLoaderJob extends DatabaseJob {
  27
  28         private GraphExplorerImplBase ge;
  29         private AtomicBoolean isScheduled = new AtomicBoolean();
  30
  31         public ImageLoaderJob(GraphExplorerImplBase ge) {
  32                 super("Image Loader");
  33                 this.ge = ge;
  34                 setSystem(true);
  35                 setUser(false);
  36                 setPriority(Job.DECORATE);
  37                 setProperty(IProgressConstants.NO_IMMEDIATE_ERROR_PROMPT_PROPERTY, Boolean.TRUE);
  38         }
  39
  40         /**
  41          * Schedules the job with {@link Job#schedule()} if necessary, i.e. if
  42          * not already scheduled. This method avoids some unnecessary overhead
  43          * caused by repeatedly invoking {@link Job#schedule()}.
  44          *
  45          * @return <code>true</code> if scheduled, <code>false</code> otherwise
  46          */
  47         public boolean scheduleIfNecessary(long delay) {
  48                 if (isScheduled.compareAndSet(false, true)) {
  49                         schedule(delay);
  50                         return true;
  51                 }
  52                 return false;
  53         }
  54
  55         @Override
  56         public boolean shouldRun() {
  57                 return ge != null;
  58         }
  59
  60         @Override
  61         public boolean shouldSchedule() {
  62                 return ge != null;
  63         }
  64
  65         @Override
  66         protected IStatus run(IProgressMonitor monitor) {
  67                 try {
  68                         isScheduled.set(false);
  69                         GraphExplorerImplBase ge = this.ge;
  70                         return (ge != null) ? ge.setPendingImages(monitor) : Status.CANCEL_STATUS;
  71                 } finally {
  72                         monitor.done();
  73                 }
  74         }
  75
  76         public void dispose() {
  77                 ge = null;
  78         }
  79 }