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1   /*
2    * Copyright 2006-2007 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.springframework.batch.repeat.support;
18  
19  import org.springframework.batch.repeat.RepeatCallback;
20  import org.springframework.batch.repeat.RepeatContext;
21  import org.springframework.batch.repeat.RepeatOperations;
22  
23  /**
24   * Global variable support for repeat clients. Normally it is not necessary for
25   * clients to be aware of the surrounding environment because a
26   * {@link RepeatCallback} can always use the context it is passed by the
27   * enclosing {@link RepeatOperations}. But occasionally it might be helpful to
28   * have lower level access to the ongoing {@link RepeatContext} so we provide a
29   * global accessor here. The mutator methods ({@link #clear()} and
30   * {@link #register(RepeatContext)} should not be used except internally by
31   * {@link RepeatOperations} implementations.
32   * 
33   * @author Dave Syer
34   * 
35   */
36  public final class RepeatSynchronizationManager {
37  
38  	private static final ThreadLocal<RepeatContext> contextHolder = new ThreadLocal<RepeatContext>();
39  
40  	private RepeatSynchronizationManager() {
41  	}
42  
43  	/**
44  	 * Getter for the current context. A context is shared by all items in the
45  	 * batch, so this method is intended to return the same context object
46  	 * independent of whether the callback is running synchronously or
47  	 * asynchronously with the surrounding {@link RepeatOperations}.
48  	 * 
49  	 * @return the current {@link RepeatContext} or null if there is none (if we
50  	 * are not in a batch).
51  	 */
52  	public static RepeatContext getContext() {
53  		return contextHolder.get();
54  	}
55  
56  	/**
57  	 * Convenience method to set the current repeat operation to complete if it
58  	 * exists.
59  	 */
60  	public static void setCompleteOnly() {
61  		RepeatContext context = getContext();
62  		if (context != null) {
63  			context.setCompleteOnly();
64  		}
65  	}
66  
67  	/**
68  	 * Method for registering a context - should only be used by
69  	 * {@link RepeatOperations} implementations to ensure that
70  	 * {@link #getContext()} always returns the correct value.
71  	 * 
72  	 * @param context a new context at the start of a batch.
73  	 * @return the old value if there was one.
74  	 */
75  	public static RepeatContext register(RepeatContext context) {
76  		RepeatContext oldSession = getContext();
77  		RepeatSynchronizationManager.contextHolder.set(context);
78  		return oldSession;
79  	}
80  
81  	/**
82  	 * Clear the current context at the end of a batch - should only be used by
83  	 * {@link RepeatOperations} implementations.
84  	 * 
85  	 * @return the old value if there was one.
86  	 */
87  	public static RepeatContext clear() {
88  		RepeatContext context = getContext();
89  		RepeatSynchronizationManager.contextHolder.set(null);
90  		return context;
91  	}
92  
93  	/**
94  	 * Set current session and all ancestors (via parent) to complete.,
95  	 */
96  	public static void setAncestorsCompleteOnly() {
97  		RepeatContext context = getContext();
98  		while (context != null) {
99  			context.setCompleteOnly();
100 			context = context.getParent();
101 		}
102 	}
103 
104 }