cdmlib-persistence/src/main/java/eu/etaxonomy/cdm/persistence/validation/EntityValidationTaskQueue.java

   1 /**
   2 * Copyright (C) 2009 EDIT
   3 * European Distributed Institute of Taxonomy
   4 * http://www.e-taxonomy.eu
   5 *
   6 * The contents of this file are subject to the Mozilla Public License Version 1.1
   7 * See LICENSE.TXT at the top of this package for the full license terms.
   8 */
   9 package eu.etaxonomy.cdm.persistence.validation;
  10
  11 import java.util.Collection;
  12 import java.util.Iterator;
  13 import java.util.concurrent.ArrayBlockingQueue;
  14 import java.util.concurrent.TimeUnit;
  15
  16 /**
  17  * A job queue catering to the needs of the entity validation process. If an entity validation
  18  * task is submitted to the queue, and the queue already contains tasks validating the exact
  19  * same entity, those tasks should be removed first, because they are validating a state of the
  20  * entity that is no longer actual. Note that it is not fatal to validate the entity in those
  21  * intermediary states, because in the end the final state of the entity does get validated as
  22  * well. It's just useless and may lead to unnecessary contention of the queue.
  23  *
  24  * @author ayco holleman
  25  *
  26  */
  27 @SuppressWarnings("serial")
  28 class EntityValidationTaskQueue extends ArrayBlockingQueue<Runnable> {
  29
  30         public EntityValidationTaskQueue(int capacity)
  31         {
  32                 super(capacity);
  33         }
  34
  35
  36         @Override
  37         public boolean add(Runnable r)
  38         {
  39                 cleanup(r);
  40                 return super.add(r);
  41         }
  42
  43
  44         @Override
  45         public boolean offer(Runnable r, long timeout, TimeUnit unit) throws InterruptedException
  46         {
  47                 cleanup(r);
  48                 return super.offer(r, timeout, unit);
  49         }
  50
  51
  52         @Override
  53         public boolean offer(Runnable r)
  54         {
  55                 cleanup(r);
  56                 return super.offer(r);
  57         }
  58
  59
  60         @Override
  61         public void put(Runnable r) throws InterruptedException
  62         {
  63                 cleanup(r);
  64                 super.put(r);
  65         }
  66
  67
  68         @Override
  69         public boolean addAll(Collection<? extends Runnable> c)
  70         {
  71                 throw new RuntimeException("Submitting multiple validation tasks at once not supported");
  72         }
  73
  74
  75         private void cleanup(Runnable runnable)
  76         {
  77                 EntityValidationTaskBase newTask = (EntityValidationTaskBase) runnable;
  78                 Iterator<Runnable> iterator = this.iterator();
  79                 while (iterator.hasNext()) {
  80                         EntityValidationTaskBase oldTask = (EntityValidationTaskBase) iterator.next();
  81                         if (oldTask.getEntity().equals(newTask.getEntity())) {
  82                                 iterator.remove();
  83                         }
  84                 }
  85         }
  86
  87 }