/*
* Copyright 2010 The Apache Software Foundation
*
* 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.replication.regionserver;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Row;
import org.apache.hadoop.hbase.regionserver.wal.HLog;
import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.Stoppable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
/**
* This class is responsible for replicating the edits coming
* from another cluster.
* <p/>
* This replication process is currently waiting for the edits to be applied
* before the method can return. This means that the replication of edits
* is synchronized (after reading from HLogs in ReplicationSource) and that a
* single region server cannot receive edits from two sources at the same time
* <p/>
* This class uses the native HBase client in order to replicate entries.
* <p/>
*
* TODO make this class more like ReplicationSource wrt log handling
*/
public class ReplicationSink {
private static final Log LOG = LogFactory.getLog(ReplicationSink.class);
// Name of the HDFS directory that contains the temporary rep logs
public static final String REPLICATION_LOG_DIR = ".replogs";
private final Configuration conf;
// Pool used to replicated
private final HTablePool pool;
private final ReplicationSinkMetrics metrics;
/**
* Create a sink for replication
*
* @param conf conf object
* @param stopper boolean to tell this thread to stop
* @throws IOException thrown when HDFS goes bad or bad file name
*/
public ReplicationSink(Configuration conf, Stoppable stopper)
throws IOException {
this.conf = conf;
this.pool = new HTablePool(this.conf,
conf.getInt("replication.sink.htablepool.capacity", 10));
this.metrics = new ReplicationSinkMetrics();
}
/**
* Replicate this array of entries directly into the local cluster
* using the native client.
*
* @param entries
* @throws IOException
*/
public void replicateEntries(HLog.Entry[] entries)
throws IOException {
if (entries.length == 0) {
return;
}
// Very simple optimization where we batch sequences of rows going
// to the same table.
try {
long totalReplicated = 0;
// Map of table => list of Rows, we only want to flushCommits once per
// invocation of this method per table.
Map<byte[], List<Row>> rows = new TreeMap<byte[], List<Row>>(Bytes.BYTES_COMPARATOR);
for (HLog.Entry entry : entries) {
WALEdit edit = entry.getEdit();
byte[] table = entry.getKey().getTablename();
Put put = null;
Delete del = null;
KeyValue lastKV = null;
List<KeyValue> kvs = edit.getKeyValues();
for (KeyValue kv : kvs) {
if (lastKV == null || lastKV.getType() != kv.getType() || !lastKV.matchingRow(kv)) {
if (kv.isDelete()) {
del = new Delete(kv.getRow());
del.setClusterId(entry.getKey().getClusterId());
addToMultiMap(rows, table, del);
} else {
put = new Put(kv.getRow());
put.setClusterId(entry.getKey().getClusterId());
addToMultiMap(rows, table, put);
}
}
if (kv.isDelete()) {
del.addDeleteMarker(kv);
} else {
put.add(kv);
}
lastKV = kv;
}
totalReplicated++;
}
for(byte [] table : rows.keySet()) {
batch(table, rows.get(table));
}
this.metrics.setAgeOfLastAppliedOp(
entries[entries.length-1].getKey().getWriteTime());
this.metrics.appliedBatchesRate.inc(1);
LOG.info("Total replicated: " + totalReplicated);
} catch (IOException ex) {
LOG.error("Unable to accept edit because:", ex);
throw ex;
}
}
/**
* Simple helper to a map from key to (a list of) values
* TODO: Make a general utility method
* @param map
* @param key
* @param value
* @return
*/
private <K, V> List<V> addToMultiMap(Map<K, List<V>> map, K key, V value) {
List<V> values = map.get(key);
if (values == null) {
values = new ArrayList<V>();
map.put(key, values);
}
values.add(value);
return values;
}
/**
* Do the changes and handle the pool
* @param tableName table to insert into
* @param rows list of actions
* @throws IOException
*/
private void batch(byte[] tableName, List<Row> rows) throws IOException {
if (rows.isEmpty()) {
return;
}
HTableInterface table = null;
try {
table = this.pool.getTable(tableName);
table.batch(rows);
this.metrics.appliedOpsRate.inc(rows.size());
} catch (InterruptedException ix) {
throw new IOException(ix);
} finally {
if (table != null) {
table.close();
}
}
}
}