bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/wrapper/SingleFunctionalOrNullProcedure.java

   1 /*******************************************************************************\r
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
   3  * in Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  *\r
   9  * Contributors:\r
  10  *     VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 package org.simantics.db.common.procedure.single.wrapper;\r
  13 \r
  14 import java.util.concurrent.atomic.AtomicBoolean;\r
  15 \r
  16 import org.simantics.db.AsyncReadGraph;\r
  17 import org.simantics.db.common.procedure.adapter.AsyncMultiProcedureAdapter;\r
  18 import org.simantics.db.exception.ManyObjectsForFunctionalRelationException;\r
  19 import org.simantics.db.procedure.AsyncProcedure;\r
  20 \r
  21 final public class SingleFunctionalOrNullProcedure<Result> extends AsyncMultiProcedureAdapter<Result> {\r
  22     \r
  23         final String location;\r
  24         final AsyncProcedure<Result> procedure;\r
  25     final AtomicBoolean found = new AtomicBoolean(false);\r
  26     final AtomicBoolean guard = new AtomicBoolean(false);\r
  27     final AtomicBoolean exception = new AtomicBoolean(false);\r
  28     \r
  29     public SingleFunctionalOrNullProcedure(String location, AsyncProcedure<Result> procedure) {\r
  30         \r
  31         this.location = location;\r
  32         this.procedure = procedure;\r
  33         \r
  34     }\r
  35     \r
  36     @Override\r
  37     public void execute(AsyncReadGraph graph, Result result) {\r
  38         \r
  39         assert(!guard.get());\r
  40 \r
  41         if(found.compareAndSet(false, true)) {\r
  42             procedure.execute(graph, result);\r
  43         } else {\r
  44             if(exception.compareAndSet(false, true)) {\r
  45                 procedure.exception(graph, new ManyObjectsForFunctionalRelationException(location + " -> " + procedure));\r
  46             }\r
  47         }\r
  48         \r
  49     }\r
  50         \r
  51     @Override\r
  52     public void finished(AsyncReadGraph graph) {\r
  53 \r
  54         assert(!guard.get());\r
  55         \r
  56         guard.set(true);\r
  57         \r
  58         if(found.compareAndSet(false, true)) {\r
  59             procedure.execute(graph, null);\r
  60         }\r
  61         \r
  62     }\r
  63     \r
  64     @Override\r
  65     public void exception(AsyncReadGraph graph, Throwable t) {\r
  66         \r
  67         procedure.exception(graph, t);\r
  68         \r
  69     }\r
  70     \r
  71     @Override\r
  72     public String toString() {\r
  73         return "SingleFunctionalOrNullProcedure -> " + procedure;\r
  74     }\r
  75 \r
  76 }\r