1 package org.apache.helix.controller.pipeline;
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 org.apache.helix.controller.stages.ClusterEvent;
23
24 /**
25 * Logically independent unit in processing callbacks for cluster changes
26 *
27 */
28 public interface Stage
29 {
30
31 /**
32 * Initialize a stage
33 * @param context
34 */
35 void init(StageContext context);
36
37 /**
38 * Called before process() on each callback
39 */
40 void preProcess();
41
42 /**
43 * Actual callback processing logic
44 * @param event
45 * @throws Exception
46 */
47 public void process(ClusterEvent event) throws Exception;
48
49 /**
50 * Called after process() on each callback
51 */
52 void postProcess();
53
54 /**
55 * Destruct a stage
56 */
57 void release();
58
59 /**
60 * Get the name of the stage
61 * @return
62 */
63 public String getStageName();
64 }