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