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; 019 020import org.apache.yetus.audience.InterfaceAudience; 021import org.apache.hadoop.hbase.HBaseInterfaceAudience; 022import org.apache.hadoop.hbase.wal.WAL.Entry; 023 024/** 025 * A Filter for WAL entries before being sent over to replication. Multiple 026 * filters might be chained together using {@link ChainWALEntryFilter}. 027 * Applied on the replication source side. 028 * <p>There is also a filter that can be installed on the sink end of a replication stream. 029 * See {@link org.apache.hadoop.hbase.replication.regionserver.WALEntrySinkFilter}. Certain 030 * use-cases may need such a facility but better to filter here on the source side rather 031 * than later, after the edit arrives at the sink.</p> 032 * @see org.apache.hadoop.hbase.replication.regionserver.WALEntrySinkFilter for filtering 033 * replication on the sink-side. 034 */ 035@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION) 036public interface WALEntryFilter { 037 038 /** 039 * <p> 040 * Applies the filter, possibly returning a different Entry instance. If null is returned, the 041 * entry will be skipped. 042 * </p> 043 * <p> 044 * Notice that you are free to modify the cell list of the give entry, but do not change the 045 * content of the cell, it may be used by others at the same time(and usually you can not modify a 046 * cell unless you cast it to the implementation class, which is not a good idea). 047 * </p> 048 * @param entry Entry to filter 049 * @return a (possibly modified) Entry to use. Returning null or an entry with no cells will cause 050 * the entry to be skipped for replication. 051 */ 052 public Entry filter(Entry entry); 053}