/** * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.hadoop.hbase.coprocessor; import java.io.IOException; import org.apache.hadoop.hbase.HBaseInterfaceAudience; import org.apache.hadoop.hbase.replication.ReplicationEndpoint; import org.apache.yetus.audience.InterfaceAudience; import org.apache.yetus.audience.InterfaceStability; /** * Defines coprocessor hooks for interacting with operations on the * {@link org.apache.hadoop.hbase.regionserver.HRegionServer} process. * * Since most implementations will be interested in only a subset of hooks, this class uses * 'default' functions to avoid having to add unnecessary overrides. When the functions are * non-empty, it's simply to satisfy the compiler by returning value of expected (non-void) type. * It is done in a way that these default definitions act as no-op. So our suggestion to * implementation would be to not call these 'default' methods from overrides. * <br><br> * * <h3>Exception Handling</h3> * For all functions, exception handling is done as follows: * <ul> * <li>Exceptions of type {@link IOException} are reported back to client.</li> * <li>For any other kind of exception: * <ul> * <li>If the configuration {@link CoprocessorHost#ABORT_ON_ERROR_KEY} is set to true, then * the server aborts.</li> * <li>Otherwise, coprocessor is removed from the server and * {@link org.apache.hadoop.hbase.DoNotRetryIOException} is returned to the client.</li> * </ul> * </li> * </ul> */ @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC) @InterfaceStability.Evolving public interface RegionServerObserver { /** * Called before stopping region server. * @param ctx the environment to interact with the framework and region server. */ default void preStopRegionServer( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called before executing user request to roll a region server WAL. * @param ctx the environment to interact with the framework and region server. */ default void preRollWALWriterRequest( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called after executing user request to roll a region server WAL. * @param ctx the environment to interact with the framework and region server. */ default void postRollWALWriterRequest( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called after the replication endpoint is instantiated. * @param ctx the environment to interact with the framework and region server. * @param endpoint - the base endpoint for replication * @return the endpoint to use during replication. */ default ReplicationEndpoint postCreateReplicationEndPoint( ObserverContext<RegionServerCoprocessorEnvironment> ctx, ReplicationEndpoint endpoint) { return endpoint; } // TODO remove below 2 hooks when we implement AC as a core impl than a CP impl. /** * This will be called before executing replication request to shipping log entries. * @param ctx the environment to interact with the framework and region server. * @deprecated As of release 2.0.0 with out any replacement. This is maintained for internal * usage by AccessController. Do not use these hooks in custom co-processors. */ @Deprecated default void preReplicateLogEntries(final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException { } /** * This will be called after executing replication request to shipping log entries. * @param ctx the environment to interact with the framework and region server. * @deprecated As of release 2.0.0 with out any replacement. This is maintained for internal * usage by AccessController. Do not use these hooks in custom co-processors. */ @Deprecated default void postReplicateLogEntries( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException { } /** * This will be called before clearing compaction queues * @param ctx the environment to interact with the framework and region server. */ default void preClearCompactionQueues( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called after clearing compaction queues * @param ctx the environment to interact with the framework and region server. */ default void postClearCompactionQueues( final ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called before executing procedures * @param ctx the environment to interact with the framework and region server. */ default void preExecuteProcedures(ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} /** * This will be called after executing procedures * @param ctx the environment to interact with the framework and region server. */ default void postExecuteProcedures(ObserverContext<RegionServerCoprocessorEnvironment> ctx) throws IOException {} }