bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/SingleSetSyncListener.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 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  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.common.procedure.single;
  13
  14 import java.util.Collection;
  15 import java.util.HashSet;
  16
  17 import org.simantics.db.AsyncReadGraph;
  18 import org.simantics.db.ReadGraph;
  19 import org.simantics.db.common.request.ReadRequest;
  20 import org.simantics.db.common.utils.Logger;
  21 import org.simantics.db.exception.DatabaseException;
  22 import org.simantics.db.procedure.AsyncListener;
  23 import org.simantics.db.procedure.AsyncProcedure;
  24
  25 abstract public class SingleSetSyncListener<T> implements AsyncListener<Collection<T>>{
  26
  27     private Collection<T> previous = null;
  28
  29     /**
  30      * @param graph
  31      * @return <code>true</code> to continue, <code>false</code> to end processing here
  32      * @throws DatabaseException
  33      */
  34     public boolean start(ReadGraph graph) throws DatabaseException { return true; }
  35     public void add(ReadGraph graph, T item) throws DatabaseException {}
  36     public void remove(ReadGraph graph,T item) throws DatabaseException {}
  37     public void finished(ReadGraph graph) throws DatabaseException {}
  38
  39     public void exception(ReadGraph graph, Throwable t) throws DatabaseException {
  40                 Logger.defaultLogError(t);
  41     }
  42
  43     @Override
  44     final public void execute(AsyncReadGraph graph, final Collection<T> result) {
  45
  46         if(result == null) {
  47                 Logger.defaultLogError("SingleSetSyncListener does not accept null result.");
  48                 return;
  49         }
  50
  51         graph.asyncRequest(new ReadRequest() {
  52
  53                         @Override
  54                         public void run(ReadGraph graph) throws DatabaseException {
  55
  56                                 if (!start(graph))
  57                                         return;
  58
  59                                 if(previous == null) {
  60
  61                                         for(T t : result) add(graph, t);
  62
  63                                 } else {
  64
  65                                         HashSet<T> added = new HashSet<T>(result);
  66                                         added.removeAll(previous);
  67                                         HashSet<T> removed = new HashSet<T>(previous);
  68                                         removed.removeAll(result);
  69
  70                                         for(T t : added) add(graph, t);
  71                                         for(T t : removed) remove(graph, t);
  72
  73                                 }
  74
  75                                 finished(graph);
  76
  77                                 previous = result;
  78
  79                         }
  80
  81         }, new AsyncProcedure<Object>() {
  82
  83                         @Override
  84                         public void exception(AsyncReadGraph graph, Throwable t) {
  85                         Logger.defaultLogError(t);
  86                         }
  87
  88             @Override
  89             public void execute(AsyncReadGraph graph, Object result) {
  90             }
  91
  92         });
  93
  94     }
  95
  96     @Override
  97     final public void exception(AsyncReadGraph graph, final Throwable throwable) {
  98         graph.asyncRequest(new ReadRequest() {
  99
 100             @Override
 101             public void run(ReadGraph graph) throws DatabaseException {
 102                 exception((ReadGraph)graph, throwable);
 103             }
 104
 105         });
 106     }
 107
 108 }