bundles/org.simantics.db.common/src/org/simantics/db/common/procedure/single/wrapper/NullSingleOrNullProcedure.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 org.simantics.db.AsyncReadGraph;
  15 import org.simantics.db.common.utils.Logger;
  16 import org.simantics.db.procedure.AsyncProcedure;
  17
  18 final public class NullSingleOrNullProcedure<Result> {
  19
  20         private Result result = null;
  21         final AsyncProcedure<Result> procedure;
  22
  23         boolean done = false;
  24         boolean found = false;
  25         int ready = 1;
  26
  27 //      final AtomicBoolean done = new AtomicBoolean(false);
  28 //      final AtomicBoolean found = new AtomicBoolean(false);
  29 //      final AtomicInteger ready = new AtomicInteger(1);
  30
  31         public NullSingleOrNullProcedure(AsyncProcedure<Result> procedure) {
  32
  33                 this.procedure = procedure;
  34
  35         }
  36
  37         public void inc() {
  38                 ready++;
  39 //              ready.incrementAndGet();
  40         }
  41
  42         public void dec(AsyncReadGraph graph) {
  43
  44                 if((--ready) == 0) {
  45                         // Shall fire exactly once!
  46                         if(!done) {
  47                                 done = true;
  48                                 try {
  49                                         procedure.execute(graph, result);
  50                                 } catch (Throwable t) {
  51                                 Logger.defaultLogError(t);
  52                                 }
  53                         }
  54                 }
  55
  56         }
  57
  58         public void offer(AsyncReadGraph graph, Result result) {
  59
  60                 if(!found) {
  61                         found = true;
  62                         this.result = result;
  63                 } else {
  64                         // Shall fire exactly once!
  65                         if(!done) {
  66                                 done = true;
  67                                 try {
  68                                         procedure.execute(graph, null);
  69                                 } catch (Throwable t) {
  70                                 Logger.defaultLogError(t);
  71                                 }
  72                         }
  73                 }
  74
  75         }
  76
  77         public void exception(AsyncReadGraph graph, Throwable t) {
  78                 // Shall fire exactly once!
  79                 if(!done) {
  80                         done = true;
  81                         try {
  82                                 procedure.exception(graph, t);
  83                         } catch (Throwable t2) {
  84                         Logger.defaultLogError(t2);
  85                         }
  86                 }
  87         }
  88
  89 }