bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/wrapper/DeepSingleOrErrorProcedure.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 import java.util.concurrent.atomic.AtomicInteger;
  16
  17 import org.simantics.db.AsyncReadGraph;
  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 DeepSingleOrErrorProcedure<Result> {
  23
  24         private Result result = null;
  25         final AsyncProcedure<Result> procedure;
  26     final AtomicBoolean done = new AtomicBoolean(false);
  27     final AtomicBoolean found = new AtomicBoolean(false);
  28     final AtomicInteger ready = new AtomicInteger(1);
  29
  30     public DeepSingleOrErrorProcedure(AsyncProcedure<Result> procedure) {
  31
  32         this.procedure = procedure;
  33
  34     }
  35
  36     public void inc() {
  37
  38         ready.incrementAndGet();
  39
  40     }
  41
  42     public void dec(AsyncReadGraph graph) {
  43
  44         if(ready.decrementAndGet() == 0) {
  45                         // Shall fire exactly once!
  46             if(done.compareAndSet(false, true)) {
  47                 try {
  48                         if(found.compareAndSet(false, true)) {
  49                                         procedure.exception(graph, new NoSingleResultException("No results."));
  50                         } else {
  51                                         procedure.execute(graph, result);
  52                         }
  53                 } catch (Throwable t) {
  54                         Logger.defaultLogError(t);
  55                 }
  56             }
  57         }
  58
  59     }
  60
  61     public void offer(AsyncReadGraph graph, Result result) {
  62
  63                 if(found.compareAndSet(false, true)) {
  64                         this.result = result;
  65                 } else {
  66                         // Shall fire exactly once!
  67                         if(done.compareAndSet(false, true)) {
  68                                 try {
  69                                         procedure.exception(graph, new NoSingleResultException(this.result + " and " + result));
  70                                 } catch (Throwable t) {
  71                                 Logger.defaultLogError(t);
  72                                 }
  73                         }
  74                 }
  75
  76     }
  77
  78     public void exception(AsyncReadGraph graph, Throwable t) {
  79                 // Shall fire exactly once!
  80                 if(done.compareAndSet(false, true)) {
  81                         try {
  82                                 procedure.exception(graph, t);
  83                         } catch (Throwable t2) {
  84                         Logger.defaultLogError(t2);
  85                         }
  86                 }
  87     }
  88
  89 }