01 /*
02 * Licensed to the Apache Software Foundation (ASF) under one
03 * or more contributor license agreements. See the NOTICE file
04 * distributed with this work for additional information
05 * regarding copyright ownership. The ASF licenses this file
06 * to you under the Apache License, Version 2.0 (the
07 * "License"); you may not use this file except in compliance
08 * with the License. You may obtain a copy of the License at
09 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 *
20 */
21
22 package org.apache.qpid.client.failover;
23
24 import org.apache.qpid.client.AMQConnection;
25
26 /**
27 * FailoverNoopSupport is a {@link FailoverSupport} implementation that does not really provide any failover support
28 * at all. It wraps a {@link FailoverProtectedOperation} but should that operation throw {@link FailoverException} this
29 * support class simply re-raises that exception as an IllegalStateException. This support wrapper should only be
30 * used where the caller can be certain that the failover protected operation cannot acutally throw a failover exception,
31 * for example, because the caller already holds a lock preventing that condition from arising.
32 *
33 * <p><table id="crc"><caption>CRC Card</caption>
34 * <tr><th> Responsibilities <th> Collaborations
35 * <tr><td> Perform a fail-over protected operation raising providing no handling of fail-over conditions.
36 * </table>
37 */
38 public class FailoverNoopSupport<T, E extends Exception> implements FailoverSupport<T, E>
39 {
40 /** The protected operation that is to be retried in the event of fail-over. */
41 FailoverProtectedOperation<T, E> operation;
42
43 /** The connection on which the fail-over protected operation is to be performed. */
44 AMQConnection connection;
45
46 /**
47 * Creates an automatic retrying fail-over handler for the specified operation.
48 *
49 * @param operation The fail-over protected operation to wrap in this handler.
50 */
51 public FailoverNoopSupport(FailoverProtectedOperation<T, E> operation, AMQConnection con)
52 {
53 this.operation = operation;
54 this.connection = con;
55 }
56
57 /**
58 * Delegates to another continuation which is to be provided with fail-over handling.
59 *
60 * @return The return value from the delegated to continuation.
61 * @throws E Any exception that the delegated to continuation may raise.
62 */
63 public T execute() throws E
64 {
65 try
66 {
67 return operation.execute();
68 }
69 catch (FailoverException e)
70 {
71 throw new IllegalStateException("Fail-over interupted no-op failover support. "
72 + "No-op support should only be used where the caller is certain fail-over cannot occur.", e);
73 }
74 }
75 }
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