bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/wrapper/SingleOrErrorProcedure.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.common.utils.Logger;
  19 import org.simantics.db.exception.NoSingleResultException;
  20 import org.simantics.db.procedure.AsyncProcedure;
  21
  22 final public class SingleOrErrorProcedure<Result> extends AsyncMultiProcedureAdapter<Result> {
  23
  24         private Result result = null;
  25         final AsyncProcedure<Result> procedure;
  26     final AtomicBoolean found = new AtomicBoolean(false);
  27     final AtomicBoolean done = new AtomicBoolean(false);
  28
  29     public SingleOrErrorProcedure(AsyncProcedure<Result> procedure) {
  30         this.procedure = procedure;
  31     }
  32
  33     @Override
  34     public void finished(AsyncReadGraph graph) {
  35
  36         // Shall fire exactly once!
  37         if(done.compareAndSet(false, true)) {
  38                 try {
  39                         if(result == null) {
  40                                         procedure.exception(graph, new NoSingleResultException("No items " + procedure, 0));
  41                         } else {
  42                                 procedure.execute(graph, result);
  43                         }
  44                 } catch (Throwable t) {
  45                         Logger.defaultLogError(t);
  46                 }
  47         }
  48
  49     }
  50
  51         public void execute(AsyncReadGraph graph, Result result) {
  52
  53                 if(found.compareAndSet(false, true)) {
  54                         this.result = result;
  55                 } else {
  56                         // Shall fire exactly once!
  57                         if(done.compareAndSet(false, true)) {
  58                                 try {
  59                                         procedure.exception(graph, new NoSingleResultException("Multiple items " + this.result + " and " + result, -1));
  60                                 } catch (Throwable t) {
  61                                 Logger.defaultLogError(t);
  62                                 }
  63                         }
  64                 }
  65
  66         }
  67
  68         public void exception(AsyncReadGraph graph, Throwable t) {
  69                 // Shall fire exactly once!
  70                 if(done.compareAndSet(false, true)) {
  71                         try {
  72                                 procedure.exception(graph, t);
  73                         } catch (Throwable t2) {
  74                         Logger.defaultLogError(t2);
  75                         }
  76                 }
  77         }
  78
  79
  80     @Override
  81     public String toString() {
  82         return "SingleOrErrorProcedure -> " + procedure;
  83     }
  84
  85 }