ServiceSerializationHelper


1   // Copyright 2005 The Apache Software Foundation
2   //
3   // Licensed under the Apache License, Version 2.0 (the "License");
4   // you may not use this file except in compliance with the License.
5   // You may obtain a copy of the License at
6   //
7   //     http://www.apache.org/licenses/LICENSE-2.0
8   //
9   // Unless required by applicable law or agreed to in writing, software
10  // distributed under the License is distributed on an "AS IS" BASIS,
11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  
15  package org.apache.hivemind.internal.ser;
16  
17  import java.lang.ref.WeakReference  ;
18  
19  import org.apache.hivemind.ApplicationRuntimeException;
20  
21  /**
22   * Class used to hold a <em>global</em> instance of
23   * {@link org.apache.hivemind.internal.ser.ServiceSerializationSupport}, so that
24   * {@link org.apache.hivemind.internal.ser.ServiceToken}s may locate them.
25   * 
26   * @author Howard M. Lewis Ship
27   * @since 1.1
28   */
29  public class ServiceSerializationHelper
30  {
31      private static final ThreadLocal   _threadLocal = new ThreadLocal  ();
32  
33      /**
34       * Returns the previously stored SSS.
35       * 
36       * @throws ApplicationRuntimeException
37       *             if no SSS has been stored.
38       */
39      public static ServiceSerializationSupport getServiceSerializationSupport()
40      {
41          ServiceSerializationSupport result = null;
42  
43          WeakReference   reference = (WeakReference  ) _threadLocal.get();
44          if (reference != null)
45              result = (ServiceSerializationSupport) reference.get();
46  
47          if (result == null)
48              throw new ApplicationRuntimeException(SerMessages.noSupportSet());
49  
50          return result;
51      }
52  
53      /**
54       * Stores the SSS instance for later access; if an existing SSS is already stored, then an error
55       * is logged (should be just one SSS per class loader).
56       */
57  
58      public static void setServiceSerializationSupport(
59              ServiceSerializationSupport serviceSerializationSupport)
60      {
61          WeakReference   reference = new WeakReference  (serviceSerializationSupport);
62  
63          _threadLocal.set(reference);
64      }
65  }
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