1 /**
2 *
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19 package org.apache.hadoop.hbase.ipc;
20
21 import java.io.IOException;
22
23 import org.apache.hadoop.hbase.classification.InterfaceAudience;
24
25 /**
26 * A call whose response can be delayed by the server.
27 */
28 @InterfaceAudience.Private
29 public interface Delayable {
30 /**
31 * Signal that the call response should be delayed, thus freeing the RPC
32 * server to handle different requests.
33 *
34 * @param delayReturnValue Controls whether the return value of the call
35 * should be set when ending the delay or right away. There are cases when
36 * the return value can be set right away, even if the call is delayed.
37 */
38 void startDelay(boolean delayReturnValue);
39
40 /**
41 * @return is the call delayed?
42 */
43 boolean isDelayed();
44
45 /**
46 * @return is the return value delayed?
47 */
48 boolean isReturnValueDelayed();
49
50 /**
51 * Signal that the RPC server is now allowed to send the response.
52 * @param result The value to return to the caller. If the corresponding
53 * delay response specified that the return value should
54 * not be delayed, this parameter must be null.
55 * @throws IOException
56 */
57 void endDelay(Object result) throws IOException;
58
59 /**
60 * Signal the end of a delayed RPC, without specifying the return value. Use
61 * this only if the return value was not delayed
62 * @throws IOException
63 */
64 void endDelay() throws IOException;
65
66 /**
67 * End the call, throwing and exception to the caller. This works regardless
68 * of the return value being delayed.
69 * @param t Object to throw to the client.
70 * @throws IOException
71 */
72 void endDelayThrowing(Throwable t) throws IOException;
73 }