1 package org.apache.onami.persist;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import javax.inject.Inject;
23 import javax.inject.Singleton;
24 import javax.persistence.EntityManagerFactory;
25
26 import static org.apache.onami.persist.Preconditions.checkNotNull;
27
28 /**
29 * Implementation of {@link PersistenceService} and {@link EntityManagerFactoryProvider} for
30 * container managed persistence units.
31 */
32 @Singleton
33 class ContainerManagedEntityManagerFactoryProvider
34 implements EntityManagerFactoryProvider, PersistenceService
35 {
36
37 /**
38 * The source for retrieving the entity manager factory instance.
39 */
40 private final EntityManagerFactorySource emfSource;
41
42 /**
43 * Currently active entity manager factory.
44 * Is {@code null} when the persistence service is not running.
45 */
46 private EntityManagerFactory emf;
47
48 /**
49 * Constructor.
50 *
51 * @param emfSource the source for the {@link EntityManagerFactory}. Must not be {@code null}.
52 */
53 @Inject
54 ContainerManagedEntityManagerFactoryProvider( EntityManagerFactorySource emfSource )
55 {
56 this.emfSource = checkNotNull( emfSource, "emfSource is mandatory!" );
57 }
58
59 /**
60 * {@inheritDoc}
61 */
62 // @Override
63 public EntityManagerFactory get()
64 {
65 if ( isRunning() )
66 {
67 return emf;
68 }
69
70 throw new IllegalStateException( "PersistenceService is not running." );
71 }
72
73 /**
74 * {@inheritDoc}
75 */
76 // @Override
77 public void start()
78 {
79 if ( isRunning() )
80 {
81 throw new IllegalStateException( "PersistenceService is already running." );
82 }
83
84 emf = emfSource.getEntityManagerFactory();
85 }
86
87 /**
88 * {@inheritDoc}
89 */
90 // @Override
91 public boolean isRunning()
92 {
93 return null != emf;
94 }
95
96 /**
97 * {@inheritDoc}
98 */
99 // @Override
100 public void stop()
101 {
102 emf = null;
103 // the entity manager factory must NOT be closed:
104 // - it was created by the container and it is therefore the responsibility of the container to close it
105 // - we cannot know if another part of the application has obtained the same instance
106 }
107
108 }