001/*
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019package org.apache.hadoop.hbase.regionserver.handler;
020
021import java.io.IOException;
022import org.apache.hadoop.hbase.HConstants;
023import org.apache.hadoop.hbase.Server;
024import org.apache.hadoop.hbase.ServerName;
025import org.apache.hadoop.hbase.client.RegionInfo;
026import org.apache.hadoop.hbase.executor.EventHandler;
027import org.apache.hadoop.hbase.executor.EventType;
028import org.apache.hadoop.hbase.procedure2.Procedure;
029import org.apache.hadoop.hbase.regionserver.HRegion;
030import org.apache.hadoop.hbase.regionserver.RegionServerServices;
031import org.apache.hadoop.hbase.regionserver.RegionServerServices.RegionStateTransitionContext;
032import org.apache.yetus.audience.InterfaceAudience;
033import org.slf4j.Logger;
034import org.slf4j.LoggerFactory;
035import org.apache.hadoop.hbase.shaded.protobuf.generated.RegionServerStatusProtos.RegionStateTransition.TransitionCode;
036
037/**
038 * Handles closing of a region on a region server.
039 * <p/>
040 * In normal operation, we use {@link UnassignRegionHandler} closing Regions but when shutting down
041 * the region server and closing out Regions, we use this handler instead; it does not expect to
042 * be able to communicate the close back to the Master.
043 * <p>Expects that the close *has* been registered in the hosting RegionServer before
044 * submitting this Handler; i.e. <code>rss.getRegionsInTransitionInRS().putIfAbsent(
045 * this.regionInfo.getEncodedNameAsBytes(), Boolean.FALSE);</code> has been called first.
046 * In here when done, we do the deregister.</p>
047 * @see UnassignRegionHandler
048 */
049@InterfaceAudience.Private
050public class CloseRegionHandler extends EventHandler {
051  // NOTE on priorities shutting down.  There are none for close. There are some
052  // for open.  I think that is right.  On shutdown, we want the meta to close
053  // after the user regions have closed.  What
054  // about the case where master tells us to shutdown a catalog region and we
055  // have a running queue of user regions to close?
056  private static final Logger LOG = LoggerFactory.getLogger(CloseRegionHandler.class);
057
058  private final RegionServerServices rsServices;
059  private final RegionInfo regionInfo;
060
061  // If true, the hosting server is aborting.  Region close process is different
062  // when we are aborting.
063  private final boolean abort;
064  private ServerName destination;
065
066  /**
067   * This method used internally by the RegionServer to close out regions.
068   * @param abort If the regionserver is aborting.
069   */
070  public CloseRegionHandler(final Server server,
071      final RegionServerServices rsServices,
072      final RegionInfo regionInfo, final boolean abort,
073      ServerName destination) {
074    this(server, rsServices, regionInfo, abort,
075      EventType.M_RS_CLOSE_REGION, destination);
076  }
077
078  protected CloseRegionHandler(final Server server,
079      final RegionServerServices rsServices, RegionInfo regionInfo,
080      boolean abort, EventType eventType, ServerName destination) {
081    super(server, eventType);
082    this.server = server;
083    this.rsServices = rsServices;
084    this.regionInfo = regionInfo;
085    this.abort = abort;
086    this.destination = destination;
087  }
088
089  public RegionInfo getRegionInfo() {
090    return regionInfo;
091  }
092
093  @Override
094  public void process() throws IOException {
095    String name = regionInfo.getEncodedName();
096    LOG.trace("Processing close of {}", name);
097    String encodedRegionName = regionInfo.getEncodedName();
098    // Check that this region is being served here
099    HRegion region = (HRegion)rsServices.getRegion(encodedRegionName);
100    try {
101      if (region == null) {
102        LOG.warn("Received CLOSE for region {} but currently not serving - ignoring", name);
103        // TODO: do better than a simple warning
104        return;
105      }
106
107      // Close the region
108      if (region.close(abort) == null) {
109        // This region has already been closed. Should not happen (A unit test makes this
110        // happen as a side effect, TestRegionObserverInterface.testPreWALAppendNotCalledOnMetaEdit)
111        LOG.warn("Can't close {}; already closed", name);
112        return;
113      }
114
115      this.rsServices.removeRegion(region, destination);
116      rsServices.reportRegionStateTransition(new RegionStateTransitionContext(TransitionCode.CLOSED,
117        HConstants.NO_SEQNUM, Procedure.NO_PROC_ID, -1, regionInfo));
118
119      // Done!  Region is closed on this RS
120      this.rsServices.getRegionsInTransitionInRS().
121        remove(this.regionInfo.getEncodedNameAsBytes(), Boolean.FALSE);
122      LOG.debug("Closed {}" + region.getRegionInfo().getRegionNameAsString());
123    } finally {
124      // Clear any reference in getServer().getRegionsInTransitionInRS() on success or failure,
125      // since a reference was added before this CRH was invoked. If we don't clear it, it can
126      // hold up regionserver abort on cluster shutdown. HBASE-23984.
127      this.rsServices.getRegionsInTransitionInRS().remove(regionInfo.getEncodedNameAsBytes());
128    }
129  }
130
131  @Override protected void handleException(Throwable t) {
132    server.abort("Unrecoverable exception while closing " +
133      this.regionInfo.getRegionNameAsString(), t);
134  }
135}