All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.hadoop.hbase.coprocessor.WALObserver Maven / Gradle / Ivy

There is a newer version: 3.0.0-beta-1
Show newest version
/*
 *
 * 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.fs.Path;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.wal.WALEdit;
import org.apache.hadoop.hbase.wal.WALKey;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.yetus.audience.InterfaceStability;

/**
 * It's provided to have a way for coprocessors to observe, rewrite,
 * or skip WALEdits as they are being written to the WAL.
 *
 * Note that implementers of WALObserver will not see WALEdits that report themselves
 * as empty via {@link WALEdit#isEmpty()}.
 *
 * {@link org.apache.hadoop.hbase.coprocessor.RegionObserver} provides
 * hooks for adding logic for WALEdits in the region context during reconstruction.
 *
 * Defines coprocessor hooks for interacting with operations on the
 * {@link org.apache.hadoop.hbase.wal.WAL}.
 *
 * 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.
 * 

* *

Exception Handling

* For all functions, exception handling is done as follows: *
    *
  • Exceptions of type {@link IOException} are reported back to client.
  • *
  • For any other kind of exception: *
      *
    • If the configuration {@link CoprocessorHost#ABORT_ON_ERROR_KEY} is set to true, then * the server aborts.
    • *
    • Otherwise, coprocessor is removed from the server and * {@link org.apache.hadoop.hbase.DoNotRetryIOException} is returned to the client.
    • *
    *
  • *
*/ @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC) @InterfaceStability.Evolving public interface WALObserver { /** * Called before a {@link WALEdit} * is writen to WAL. * Do not amend the WALKey. It is InterfaceAudience.Private. Changing the WALKey will cause * damage. * @deprecated Since hbase-2.0.0. To be replaced with an alternative that does not expose * InterfaceAudience classes such as WALKey and WALEdit. Will be removed in hbase-3.0.0. */ @Deprecated default void preWALWrite(ObserverContext ctx, RegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {} /** * Called after a {@link WALEdit} * is writen to WAL. * Do not amend the WALKey. It is InterfaceAudience.Private. Changing the WALKey will cause * damage. * @deprecated Since hbase-2.0.0. To be replaced with an alternative that does not expose * InterfaceAudience classes such as WALKey and WALEdit. Will be removed in hbase-3.0.0. */ @Deprecated default void postWALWrite(ObserverContext ctx, RegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {} /** * Called before rolling the current WAL * @param oldPath the path of the current wal that we are replacing * @param newPath the path of the wal we are going to create */ default void preWALRoll(ObserverContext ctx, Path oldPath, Path newPath) throws IOException {} /** * Called after rolling the current WAL * @param oldPath the path of the wal that we replaced * @param newPath the path of the wal we have created and now is the current */ default void postWALRoll(ObserverContext ctx, Path oldPath, Path newPath) throws IOException {} }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy