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.client;
019
020import static org.apache.hadoop.hbase.trace.HBaseSemanticAttributes.REGION_NAMES_KEY;
021
022import io.opentelemetry.api.trace.Span;
023import io.opentelemetry.api.trace.StatusCode;
024import io.opentelemetry.context.Scope;
025import java.io.IOException;
026import java.util.ArrayList;
027import java.util.Arrays;
028import java.util.Collections;
029import java.util.List;
030import java.util.Objects;
031import java.util.function.Function;
032import java.util.function.Supplier;
033import java.util.stream.Collectors;
034import org.apache.hadoop.hbase.CatalogReplicaMode;
035import org.apache.hadoop.hbase.HConstants;
036import org.apache.hadoop.hbase.HRegionLocation;
037import org.apache.hadoop.hbase.MetaTableAccessor;
038import org.apache.hadoop.hbase.RegionLocations;
039import org.apache.hadoop.hbase.TableName;
040import org.apache.hadoop.hbase.client.trace.TableSpanBuilder;
041import org.apache.hadoop.hbase.trace.TraceUtil;
042import org.apache.yetus.audience.InterfaceAudience;
043
044import org.apache.hbase.thirdparty.org.apache.commons.collections4.CollectionUtils;
045
046/**
047 * An implementation of {@link RegionLocator}. Used to view region location information for a single
048 * HBase table. Lightweight. Get as needed and just close when done. Instances of this class SHOULD
049 * NOT be constructed directly. Obtain an instance via {@link Connection}. See
050 * {@link ConnectionFactory} class comment for an example of how.
051 * <p/>
052 * This class is thread safe
053 */
054@InterfaceAudience.Private
055public class HRegionLocator implements RegionLocator {
056
057  private final TableName tableName;
058  private final ConnectionImplementation connection;
059
060  public HRegionLocator(TableName tableName, ConnectionImplementation connection) {
061    this.connection = connection;
062    this.tableName = tableName;
063  }
064
065  /**
066   * {@inheritDoc}
067   */
068  @Override
069  public void close() throws IOException {
070    // This method is required by the RegionLocator interface. This implementation does not have any
071    // persistent state, so there is no need to do anything here.
072  }
073
074  @Override
075  public HRegionLocation getRegionLocation(byte[] row, int replicaId, boolean reload)
076    throws IOException {
077    final Supplier<Span> supplier = new TableSpanBuilder(connection)
078      .setName("HRegionLocator.getRegionLocation").setTableName(tableName);
079    return tracedLocationFuture(() -> connection
080      .locateRegion(tableName, row, !reload, true, replicaId).getRegionLocation(replicaId),
081      AsyncRegionLocator::getRegionNames, supplier);
082  }
083
084  @Override
085  public List<HRegionLocation> getRegionLocations(byte[] row, boolean reload) throws IOException {
086    final Supplier<Span> supplier = new TableSpanBuilder(connection)
087      .setName("HRegionLocator.getRegionLocations").setTableName(tableName);
088    final RegionLocations locs = tracedLocationFuture(
089      () -> connection.locateRegion(tableName, row, !reload, true, RegionInfo.DEFAULT_REPLICA_ID),
090      AsyncRegionLocator::getRegionNames, supplier);
091    return Arrays.asList(locs.getRegionLocations());
092  }
093
094  @Override
095  public List<HRegionLocation> getAllRegionLocations() throws IOException {
096    final Supplier<Span> supplier = new TableSpanBuilder(connection)
097      .setName("HRegionLocator.getAllRegionLocations").setTableName(tableName);
098    return tracedLocationFuture(() -> {
099      ArrayList<HRegionLocation> regions = new ArrayList<>();
100      for (RegionLocations locations : listRegionLocations()) {
101        for (HRegionLocation location : locations.getRegionLocations()) {
102          regions.add(location);
103        }
104        RegionLocations cleaned = locations.removeElementsWithNullLocation();
105        // above can return null if all locations had null location
106        if (cleaned != null) {
107          connection.cacheLocation(tableName, cleaned);
108        }
109      }
110      return regions;
111    }, HRegionLocator::getRegionNames, supplier);
112  }
113
114  private static List<String> getRegionNames(List<HRegionLocation> locations) {
115    if (CollectionUtils.isEmpty(locations)) {
116      return Collections.emptyList();
117    }
118    return locations.stream().filter(Objects::nonNull).map(AsyncRegionLocator::getRegionNames)
119      .filter(Objects::nonNull).flatMap(List::stream).collect(Collectors.toList());
120  }
121
122  @Override
123  public void clearRegionLocationCache() {
124    final Supplier<Span> supplier = new TableSpanBuilder(connection)
125      .setName("HRegionLocator.clearRegionLocationCache").setTableName(tableName);
126    TraceUtil.trace(() -> connection.clearRegionCache(tableName), supplier);
127  }
128
129  @Override
130  public TableName getName() {
131    return this.tableName;
132  }
133
134  @SuppressWarnings("MixedMutabilityReturnType")
135  private List<RegionLocations> listRegionLocations() throws IOException {
136    if (TableName.isMetaTableName(tableName)) {
137      return Collections
138        .singletonList(connection.locateRegion(tableName, HConstants.EMPTY_START_ROW, false, true));
139    }
140    final List<RegionLocations> regions = new ArrayList<>();
141    MetaTableAccessor.Visitor visitor = new MetaTableAccessor.TableVisitorBase(tableName) {
142      @Override
143      public boolean visitInternal(Result result) throws IOException {
144        RegionLocations locations = MetaTableAccessor.getRegionLocations(result);
145        if (locations == null) {
146          return true;
147        }
148        regions.add(locations);
149        return true;
150      }
151    };
152    CatalogReplicaMode metaReplicaMode = CatalogReplicaMode.fromString(connection.getConfiguration()
153      .get(LOCATOR_META_REPLICAS_MODE, CatalogReplicaMode.NONE.toString()));
154    MetaTableAccessor.scanMetaForTableRegions(connection, visitor, tableName, metaReplicaMode);
155    return regions;
156  }
157
158  private <R, T extends Throwable> R tracedLocationFuture(TraceUtil.ThrowingCallable<R, T> action,
159    Function<R, List<String>> getRegionNames, Supplier<Span> spanSupplier) throws T {
160    final Span span = spanSupplier.get();
161    try (Scope ignored = span.makeCurrent()) {
162      final R result = action.call();
163      final List<String> regionNames = getRegionNames.apply(result);
164      if (!CollectionUtils.isEmpty(regionNames)) {
165        span.setAttribute(REGION_NAMES_KEY, regionNames);
166      }
167      span.setStatus(StatusCode.OK);
168      span.end();
169      return result;
170    } catch (Throwable e) {
171      TraceUtil.setError(span, e);
172      span.end();
173      throw e;
174    }
175  }
176}