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.replication; 019import org.apache.hadoop.hbase.HBaseInterfaceAudience; 020import org.apache.hadoop.hbase.wal.WAL.Entry; 021import org.apache.yetus.audience.InterfaceAudience; 022 023/** 024 * A Filter for WAL entries before being sent over to replication. Multiple 025 * filters might be chained together using {@link ChainWALEntryFilter}. 026 * Applied on the replication source side. 027 * <p>There is also a filter that can be installed on the sink end of a replication stream. 028 * See {@link org.apache.hadoop.hbase.replication.regionserver.WALEntrySinkFilter}. Certain 029 * use-cases may need such a facility but better to filter here on the source side rather 030 * than later, after the edit arrives at the sink.</p> 031 * @see org.apache.hadoop.hbase.replication.regionserver.WALEntrySinkFilter for filtering 032 * replication on the sink-side. 033 */ 034@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION) 035public interface WALEntryFilter { 036 /** 037 * <p> 038 * Applies the filter, possibly returning a different Entry instance. If null is returned, the 039 * entry will be skipped. 040 * </p> 041 * <p> 042 * Notice that you are free to modify the cell list of the give entry, but do not change the 043 * content of the cell, it may be used by others at the same time(and usually you can not modify a 044 * cell unless you cast it to the implementation class, which is not a good idea). 045 * </p> 046 * @param entry Entry to filter 047 * @return a (possibly modified) Entry to use. Returning null or an entry with no cells will cause 048 * the entry to be skipped for replication. 049 */ 050 Entry filter(Entry entry); 051}