View Javadoc

1   /*
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  
16  package org.apache.hadoop.hbase.coprocessor;
17  
18  import java.io.IOException;
19  
20  import org.apache.hadoop.hbase.classification.InterfaceAudience;
21  import org.apache.hadoop.hbase.classification.InterfaceStability;
22  import org.apache.hadoop.hbase.Coprocessor;
23  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
24  
25  import com.google.protobuf.Message;
26  import com.google.protobuf.Service;
27  
28  /**
29   * Coprocessors implement this interface to observe and mediate endpoint invocations
30   * on a region.
31   */
32  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
33  @InterfaceStability.Evolving
34  public interface EndpointObserver extends Coprocessor {
35  
36    /**
37     * Called before an Endpoint service method is invoked.
38     * The request message can be altered by returning a new instance. Throwing an
39     * exception will abort the invocation.
40     * Calling {@link org.apache.hadoop.hbase.coprocessor.ObserverContext#bypass()} has no
41     * effect in this hook.
42     * @param ctx the environment provided by the region server
43     * @param service the endpoint service
44     * @param methodName the invoked service method
45     * @param request the request message
46     * @return the possibly modified message
47     * @throws IOException
48     */
49    Message preEndpointInvocation(ObserverContext<RegionCoprocessorEnvironment> ctx, Service service,
50        String methodName, Message request) throws IOException;
51  
52    /**
53     * Called after an Endpoint service method is invoked. The response message can be
54     * altered using the builder.
55     * @param ctx the environment provided by the region server
56     * @param service the endpoint service
57     * @param methodName the invoked service method
58     * @param request the request message
59     * @param responseBuilder the response message builder
60     * @throws IOException
61     */
62    void postEndpointInvocation(ObserverContext<RegionCoprocessorEnvironment> ctx, Service service,
63        String methodName, Message request, Message.Builder responseBuilder) throws IOException;
64  
65  }