/**
* Copyright 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.client;
import static org.apache.hadoop.hbase.client.ConnectionUtils.createCloseRowBefore;
import static org.apache.hadoop.hbase.client.ConnectionUtils.incRPCRetriesMetrics;
import static org.apache.hadoop.hbase.client.ConnectionUtils.isEmptyStartRow;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.hbase.DoNotRetryIOException;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.RegionLocations;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
import org.apache.hadoop.hbase.util.Bytes;
/**
* A reversed ScannerCallable which supports backward scanning.
*/
@InterfaceAudience.Private
public class ReversedScannerCallable extends ScannerCallable {
/**
* @param connection
* @param tableName
* @param scan
* @param scanMetrics
* @param rpcFactory to create an {@link com.google.protobuf.RpcController} to talk to the
* regionserver
*/
public ReversedScannerCallable(ClusterConnection connection, TableName tableName, Scan scan,
ScanMetrics scanMetrics, RpcControllerFactory rpcFactory) {
super(connection, tableName, scan, scanMetrics, rpcFactory);
}
/**
* @param connection
* @param tableName
* @param scan
* @param scanMetrics
* @param rpcFactory to create an {@link com.google.protobuf.RpcController} to talk to the
* regionserver
* @param replicaId the replica id
*/
public ReversedScannerCallable(ClusterConnection connection, TableName tableName, Scan scan,
ScanMetrics scanMetrics, RpcControllerFactory rpcFactory, int replicaId) {
super(connection, tableName, scan, scanMetrics, rpcFactory, replicaId);
}
/**
* @param reload force reload of server location
* @throws IOException
*/
@Override
public void prepare(boolean reload) throws IOException {
if (Thread.interrupted()) {
throw new InterruptedIOException();
}
if (!instantiated || reload) {
// we should use range locate if
// 1. we do not want the start row
// 2. the start row is empty which means we need to locate to the last region.
if (scan.includeStartRow() && !isEmptyStartRow(getRow())) {
// Just locate the region with the row
RegionLocations rl = RpcRetryingCallerWithReadReplicas.getRegionLocations(reload, id,
getConnection(), getTableName(), getRow());
this.location = id < rl.size() ? rl.getRegionLocation(id) : null;
if (location == null || location.getServerName() == null) {
throw new IOException("Failed to find location, tableName="
+ getTableName() + ", row=" + Bytes.toStringBinary(getRow()) + ", reload="
+ reload);
}
} else {
// Need to locate the regions with the range, and the target location is
// the last one which is the previous region of last region scanner
byte[] locateStartRow = createCloseRowBefore(getRow());
List<HRegionLocation> locatedRegions = locateRegionsInRange(
locateStartRow, getRow(), reload);
if (locatedRegions.isEmpty()) {
throw new DoNotRetryIOException(
"Does hbase:meta exist hole? Couldn't get regions for the range from "
+ Bytes.toStringBinary(locateStartRow) + " to "
+ Bytes.toStringBinary(getRow()));
}
this.location = locatedRegions.get(locatedRegions.size() - 1);
}
setStub(getConnection().getClient(getLocation().getServerName()));
checkIfRegionServerIsRemote();
instantiated = true;
}
// check how often we retry.
if (reload) {
incRPCRetriesMetrics(scanMetrics, isRegionServerRemote);
}
}
/**
* Get the corresponding regions for an arbitrary range of keys.
* @param startKey Starting row in range, inclusive
* @param endKey Ending row in range, exclusive
* @param reload force reload of server location
* @return A list of HRegionLocation corresponding to the regions that contain
* the specified range
* @throws IOException
*/
private List<HRegionLocation> locateRegionsInRange(byte[] startKey,
byte[] endKey, boolean reload) throws IOException {
final boolean endKeyIsEndOfTable = Bytes.equals(endKey,
HConstants.EMPTY_END_ROW);
if ((Bytes.compareTo(startKey, endKey) > 0) && !endKeyIsEndOfTable) {
throw new IllegalArgumentException("Invalid range: "
+ Bytes.toStringBinary(startKey) + " > "
+ Bytes.toStringBinary(endKey));
}
List<HRegionLocation> regionList = new ArrayList<>();
byte[] currentKey = startKey;
do {
RegionLocations rl = RpcRetryingCallerWithReadReplicas.getRegionLocations(reload, id,
getConnection(), getTableName(), currentKey);
HRegionLocation regionLocation = id < rl.size() ? rl.getRegionLocation(id) : null;
if (regionLocation != null && regionLocation.getRegionInfo().containsRow(currentKey)) {
regionList.add(regionLocation);
} else {
throw new DoNotRetryIOException("Does hbase:meta exist hole? Locating row "
+ Bytes.toStringBinary(currentKey) + " returns incorrect region "
+ (regionLocation == null ? null : regionLocation.getRegionInfo()));
}
currentKey = regionLocation.getRegionInfo().getEndKey();
} while (!Bytes.equals(currentKey, HConstants.EMPTY_END_ROW)
&& (endKeyIsEndOfTable || Bytes.compareTo(currentKey, endKey) < 0));
return regionList;
}
@Override
public ScannerCallable getScannerCallableForReplica(int id) {
ReversedScannerCallable r = new ReversedScannerCallable(getConnection(), getTableName(),
this.getScan(), this.scanMetrics, rpcControllerFactory, id);
r.setCaching(this.getCaching());
return r;
}
}