1 /*******************************************************************************
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2 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
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3 * in Industry THTH ry.
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4 * All rights reserved. This program and the accompanying materials
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5 * are made available under the terms of the Eclipse Public License v1.0
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6 * which accompanies this distribution, and is available at
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7 * http://www.eclipse.org/legal/epl-v10.html
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10 * VTT Technical Research Centre of Finland - initial API and implementation
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11 *******************************************************************************/
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12 package org.simantics.db.common.procedure.single.wrapper;
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14 import java.util.concurrent.atomic.AtomicBoolean;
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16 import org.simantics.db.AsyncReadGraph;
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17 import org.simantics.db.common.procedure.adapter.AsyncMultiProcedureAdapter;
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18 import org.simantics.db.common.utils.Logger;
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19 import org.simantics.db.procedure.AsyncProcedure;
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21 final public class SingleOrNullProcedure<Result> extends AsyncMultiProcedureAdapter<Result> {
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23 private Result result = null;
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24 final AsyncProcedure<Result> procedure;
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25 final AtomicBoolean found = new AtomicBoolean(false);
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26 final AtomicBoolean done = new AtomicBoolean(false);
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28 public SingleOrNullProcedure(AsyncProcedure<Result> procedure) {
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29 this.procedure = procedure;
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33 public void finished(AsyncReadGraph graph) {
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35 // Shall fire exactly once!
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36 if(done.compareAndSet(false, true)) {
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38 procedure.execute(graph, result);
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39 } catch (Throwable t) {
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40 Logger.defaultLogError(t);
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47 public void execute(AsyncReadGraph graph, Result result) {
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49 if(found.compareAndSet(false, true)) {
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50 this.result = result;
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52 // Shall fire exactly once!
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53 if(done.compareAndSet(false, true)) {
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55 procedure.execute(graph, null);
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56 } catch (Throwable t) {
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57 Logger.defaultLogError(t);
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66 public void exception(AsyncReadGraph graph, Throwable t) {
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67 // Shall fire exactly once!
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68 if(done.compareAndSet(false, true)) {
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70 procedure.exception(graph, t);
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71 } catch (Throwable t2) {
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72 Logger.defaultLogError(t2);
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78 public String toString() {
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79 return "SingleOrNullProcedure -> " + procedure;
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