001    /**
002     * Copyright 2005-2012 The Kuali Foundation
003     *
004     * Licensed under the Educational Community License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.opensource.org/licenses/ecl2.php
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.kuali.rice.krms.impl.provider.repository;
017    
018    import org.kuali.rice.krms.api.engine.ExecutionEnvironment;
019    import org.kuali.rice.krms.api.repository.agenda.AgendaDefinition;
020    import org.kuali.rice.krms.framework.engine.AgendaTree;
021    
022    /**
023     * TODO... 
024     * 
025     * @author Kuali Rice Team (rice.collab@kuali.org)
026     *
027     */
028    public final class LazyAgendaTree implements AgendaTree {
029    
030            private final Object mutex = new Object();
031            private final AgendaDefinition agendaDefinition;
032            private final RepositoryToEngineTranslator translator;
033            
034            private AgendaTree agendaTree;
035            
036            public LazyAgendaTree(AgendaDefinition agendaDefinition, RepositoryToEngineTranslator translator) {
037                    this.agendaDefinition = agendaDefinition;
038                    this.translator = translator;
039            }
040    
041            public void execute(ExecutionEnvironment environment) {
042                    initialize();
043                    agendaTree.execute(environment);
044            }
045            
046            public void initialize() {
047                    // could use double-checked locking here for max efficiency
048                    synchronized (mutex) {
049                            if (agendaTree == null) {
050                                    agendaTree = translator.translateAgendaDefinitionToAgendaTree(agendaDefinition);
051                            }
052                    }
053            }
054    
055    }