1 /* 2 * Copyright 2010 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 21 package org.apache.hadoop.hbase.coprocessor; 22 23 import org.apache.hadoop.hbase.Coprocessor; 24 import org.apache.hadoop.hbase.HRegionInfo; 25 import org.apache.hadoop.hbase.regionserver.wal.HLogKey; 26 import org.apache.hadoop.hbase.regionserver.wal.WALEdit; 27 28 import java.io.IOException; 29 30 /** 31 * It's provided to have a way for coprocessors to observe, rewrite, 32 * or skip WALEdits as they are being written to the WAL. 33 * 34 * {@link org.apache.hadoop.hbase.coprocessor.RegionObserver} provides 35 * hooks for adding logic for WALEdits in the region context during reconstruction, 36 * 37 * Defines coprocessor hooks for interacting with operations on the 38 * {@link org.apache.hadoop.hbase.regionserver.wal.HLog}. 39 */ 40 public interface WALObserver extends Coprocessor { 41 42 /** 43 * Called before a {@link org.apache.hadoop.hbase.regionserver.wal.WALEdit} 44 * is writen to WAL. 45 * 46 * @param ctx 47 * @param info 48 * @param logKey 49 * @param logEdit 50 * @return true if default behavior should be bypassed, false otherwise 51 * @throws IOException 52 */ 53 boolean preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, 54 HRegionInfo info, HLogKey logKey, WALEdit logEdit) throws IOException; 55 56 /** 57 * Called after a {@link org.apache.hadoop.hbase.regionserver.wal.WALEdit} 58 * is writen to WAL. 59 * 60 * @param ctx 61 * @param info 62 * @param logKey 63 * @param logEdit 64 * @throws IOException 65 */ 66 void postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, 67 HRegionInfo info, HLogKey logKey, WALEdit logEdit) throws IOException; 68 }