001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.coprocessor;
019
020import java.io.IOException;
021import org.apache.hadoop.hbase.HBaseInterfaceAudience;
022import org.apache.hadoop.hbase.client.Mutation;
023import org.apache.hadoop.hbase.replication.ReplicationEndpoint;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.yetus.audience.InterfaceStability;
026
027import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos;
028
029/**
030 * Defines coprocessor hooks for interacting with operations on the
031 * {@link org.apache.hadoop.hbase.regionserver.HRegionServer} process. Since most implementations
032 * will be interested in only a subset of hooks, this class uses 'default' functions to avoid having
033 * to add unnecessary overrides. When the functions are non-empty, it's simply to satisfy the
034 * compiler by returning value of expected (non-void) type. It is done in a way that these default
035 * definitions act as no-op. So our suggestion to implementation would be to not call these
036 * 'default' methods from overrides. <br>
037 * <br>
038 * <h3>Exception Handling</h3> For all functions, exception handling is done as follows:
039 * <ul>
040 * <li>Exceptions of type {@link IOException} are reported back to client.</li>
041 * <li>For any other kind of exception:
042 * <ul>
043 * <li>If the configuration {@link CoprocessorHost#ABORT_ON_ERROR_KEY} is set to true, then the
044 * server aborts.</li>
045 * <li>Otherwise, coprocessor is removed from the server and
046 * {@link org.apache.hadoop.hbase.DoNotRetryIOException} is returned to the client.</li>
047 * </ul>
048 * </li>
049 * </ul>
050 */
051@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
052@InterfaceStability.Evolving
053public interface RegionServerObserver {
054  /**
055   * Called before stopping region server.
056   * @param ctx the environment to interact with the framework and region server.
057   */
058  default void preStopRegionServer(final ObserverContext<RegionServerCoprocessorEnvironment> ctx)
059    throws IOException {
060  }
061
062  /**
063   * This will be called before executing user request to roll a region server WAL.
064   * @param ctx the environment to interact with the framework and region server.
065   */
066  default void preRollWALWriterRequest(
067    final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {
068  }
069
070  /**
071   * This will be called after executing user request to roll a region server WAL.
072   * @param ctx the environment to interact with the framework and region server.
073   */
074  default void postRollWALWriterRequest(
075    final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {
076  }
077
078  /**
079   * This will be called after the replication endpoint is instantiated.
080   * @param ctx      the environment to interact with the framework and region server.
081   * @param endpoint - the base endpoint for replication
082   * @return the endpoint to use during replication.
083   */
084  default ReplicationEndpoint postCreateReplicationEndPoint(
085    ObserverContext<RegionServerCoprocessorEnvironment> ctx, ReplicationEndpoint endpoint) {
086    return endpoint;
087  }
088
089  // TODO remove below 2 hooks when we implement AC as a core impl than a CP impl.
090  /**
091   * This will be called before executing replication request to shipping log entries.
092   * @param ctx the environment to interact with the framework and region server.
093   * @deprecated As of release 2.0.0 with out any replacement. This is maintained for internal usage
094   *             by AccessController. Do not use these hooks in custom co-processors.
095   */
096  @Deprecated
097  default void preReplicateLogEntries(final ObserverContext<RegionServerCoprocessorEnvironment> ctx)
098    throws IOException {
099  }
100
101  /**
102   * This will be called after executing replication request to shipping log entries.
103   * @param ctx the environment to interact with the framework and region server.
104   * @deprecated As of release 2.0.0 with out any replacement. This is maintained for internal usage
105   *             by AccessController. Do not use these hooks in custom co-processors.
106   */
107  @Deprecated
108  default void postReplicateLogEntries(
109    final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {
110  }
111
112  /**
113   * This will be called before clearing compaction queues
114   * @param ctx the environment to interact with the framework and region server.
115   */
116  default void preClearCompactionQueues(
117    final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {
118  }
119
120  /**
121   * This will be called after clearing compaction queues
122   * @param ctx the environment to interact with the framework and region server.
123   */
124  default void postClearCompactionQueues(
125    final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {
126  }
127
128  /**
129   * This will be called before executing procedures
130   * @param ctx the environment to interact with the framework and region server.
131   */
132  default void preExecuteProcedures(ObserverContext<RegionServerCoprocessorEnvironment> ctx)
133    throws IOException {
134  }
135
136  /**
137   * This will be called after executing procedures
138   * @param ctx the environment to interact with the framework and region server.
139   */
140  default void postExecuteProcedures(ObserverContext<RegionServerCoprocessorEnvironment> ctx)
141    throws IOException {
142  }
143
144  /**
145   * This will be called before replication sink mutations are executed on the sink table as part of
146   * batch call.
147   * @param ctx      the environment to interact with the framework and region server.
148   * @param walEntry wal entry from which mutation is formed.
149   * @param mutation mutation to be applied at sink cluster.
150   * @throws IOException if something goes wrong.
151   */
152  default void preReplicationSinkBatchMutate(
153    ObserverContext<RegionServerCoprocessorEnvironment> ctx, AdminProtos.WALEntry walEntry,
154    Mutation mutation) throws IOException {
155
156  }
157
158  /**
159   * This will be called after replication sink mutations are executed on the sink table as part of
160   * batch call.
161   * @param ctx      the environment to interact with the framework and region server.
162   * @param walEntry wal entry from which mutation is formed.
163   * @param mutation mutation to be applied at sink cluster.
164   * @throws IOException if something goes wrong.
165   */
166  default void postReplicationSinkBatchMutate(
167    ObserverContext<RegionServerCoprocessorEnvironment> ctx, AdminProtos.WALEntry walEntry,
168    Mutation mutation) throws IOException {
169
170  }
171
172}