bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/wrapper/SingleFunctionalOrNullProcedure.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.wrapper;
  13
  14 import java.util.concurrent.atomic.AtomicBoolean;
  15
  16 import org.simantics.db.AsyncReadGraph;
  17 import org.simantics.db.common.procedure.adapter.AsyncMultiProcedureAdapter;
  18 import org.simantics.db.exception.ManyObjectsForFunctionalRelationException;
  19 import org.simantics.db.procedure.AsyncProcedure;
  20
  21 final public class SingleFunctionalOrNullProcedure<Result> extends AsyncMultiProcedureAdapter<Result> {
  22
  23         final String location;
  24         final AsyncProcedure<Result> procedure;
  25     final AtomicBoolean found = new AtomicBoolean(false);
  26     final AtomicBoolean guard = new AtomicBoolean(false);
  27     final AtomicBoolean exception = new AtomicBoolean(false);
  28
  29     public SingleFunctionalOrNullProcedure(String location, AsyncProcedure<Result> procedure) {
  30
  31         this.location = location;
  32         this.procedure = procedure;
  33
  34     }
  35
  36     @Override
  37     public void execute(AsyncReadGraph graph, Result result) {
  38
  39         assert(!guard.get());
  40
  41         if(found.compareAndSet(false, true)) {
  42             procedure.execute(graph, result);
  43         } else {
  44             if(exception.compareAndSet(false, true)) {
  45                 procedure.exception(graph, new ManyObjectsForFunctionalRelationException(location + " -> " + procedure));
  46             }
  47         }
  48
  49     }
  50
  51     @Override
  52     public void finished(AsyncReadGraph graph) {
  53
  54         assert(!guard.get());
  55
  56         guard.set(true);
  57
  58         if(found.compareAndSet(false, true)) {
  59             procedure.execute(graph, null);
  60         }
  61
  62     }
  63
  64     @Override
  65     public void exception(AsyncReadGraph graph, Throwable t) {
  66
  67         procedure.exception(graph, t);
  68
  69     }
  70
  71     @Override
  72     public String toString() {
  73         return "SingleFunctionalOrNullProcedure -> " + procedure;
  74     }
  75
  76 }