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.regionserver;
019
020import com.google.protobuf.Message;
021import java.io.IOException;
022import java.util.Collection;
023import java.util.List;
024import java.util.UUID;
025import org.apache.hadoop.hbase.HBaseInterfaceAudience;
026import org.apache.hadoop.hbase.client.Durability;
027import org.apache.hadoop.hbase.client.Mutation;
028import org.apache.hadoop.hbase.wal.WALEdit;
029import org.apache.yetus.audience.InterfaceAudience;
030import org.apache.yetus.audience.InterfaceStability;
031
032/**
033 * Defines the procedures to atomically perform multiple scans and mutations on a HRegion. This is
034 * invoked by {@link Region#processRowsWithLocks(RowProcessor)}. This class performs scans and
035 * generates mutations and WAL edits. The locks and MVCC will be handled by HRegion. The
036 * RowProcessor user code could have data that needs to be sent across for proper initialization at
037 * the server side. The generic type parameter S is the type of the request data sent to the server.
038 * The generic type parameter T is the return type of RowProcessor.getResult().
039 * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0. For customization, use
040 *             Coprocessors instead.
041 */
042@Deprecated
043@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
044@InterfaceStability.Evolving
045public interface RowProcessor<S extends Message, T extends Message> {
046
047  /**
048   * Rows to lock while operation. They have to be sorted with <code>RowProcessor</code> to avoid
049   * deadlock.
050   */
051  Collection<byte[]> getRowsToLock();
052
053  /**
054   * Obtain the processing result. All row processor implementations must implement this, even if
055   * the method is simply returning an empty Message.
056   */
057  T getResult();
058
059  /**
060   * Is this operation read only? If this is true, process() should not add any mutations or it
061   * throws IOException.
062   * @return ture if read only operation
063   */
064  boolean readOnly();
065
066  /**
067   * HRegion handles the locks and MVCC and invokes this method properly. You should override this
068   * to create your own RowProcessor. If you are doing read-modify-write here, you should consider
069   * using <code>IsolationLevel.READ_UNCOMMITTED</code> for scan because we advance MVCC after
070   * releasing the locks for optimization purpose.
071   * @param now       the current system millisecond
072   * @param region    the HRegion
073   * @param mutations the output mutations to apply to memstore
074   * @param walEdit   the output WAL edits to apply to write ahead log
075   */
076  void process(long now, HRegion region, List<Mutation> mutations, WALEdit walEdit)
077    throws IOException;
078
079  /**
080   * The hook to be executed before process().
081   * @param region  the HRegion
082   * @param walEdit the output WAL edits to apply to write ahead log
083   */
084  void preProcess(HRegion region, WALEdit walEdit) throws IOException;
085
086  /**
087   * The hook to be executed after the process() but before applying the Mutations to region. Also
088   * by the time this hook is called, mvcc transaction have started.
089   * @param walEdit the output WAL edits to apply to write ahead log
090   */
091  void preBatchMutate(HRegion region, WALEdit walEdit) throws IOException;
092
093  /**
094   * The hook to be executed after the process() and applying the Mutations to region. The
095   * difference of this one with {@link #postProcess(HRegion, WALEdit, boolean)} is this hook will
096   * be executed before the mvcc transaction completion.
097   */
098  void postBatchMutate(HRegion region) throws IOException;
099
100  /**
101   * The hook to be executed after process() and applying the Mutations to region.
102   * @param region  the HRegion
103   * @param walEdit the output WAL edits to apply to write ahead log
104   * @param success true if batch operation is successful otherwise false.
105   */
106  void postProcess(HRegion region, WALEdit walEdit, boolean success) throws IOException;
107
108  /** Returns The cluster ids that have the change. */
109  List<UUID> getClusterIds();
110
111  /**
112   * Human readable name of the processor
113   * @return The name of the processor
114   */
115  String getName();
116
117  /**
118   * This method should return any additional data that is needed on the server side to construct
119   * the RowProcessor. The server will pass this to the {@link #initialize(Message msg)} method. If
120   * there is no RowProcessor specific data then null should be returned.
121   * @return the PB message n
122   */
123  S getRequestData() throws IOException;
124
125  /**
126   * This method should initialize any field(s) of the RowProcessor with a parsing of the passed
127   * message bytes (used on the server side). nn
128   */
129  void initialize(S msg) throws IOException;
130
131  /** Returns The {@link Durability} to use */
132  Durability useDurability();
133}