/**
    * 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.master.snapshot;
  
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.concurrent.ThreadPoolExecutor;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.client.RegionReplicaUtil;
  import org.apache.hadoop.hbase.errorhandling.ForeignException;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
  import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
  import org.apache.hadoop.hbase.snapshot.SnapshotManifest;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.util.ModifyRegionUtils;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.zookeeper.KeeperException;
  
  /**
   * Take a snapshot of a disabled table.
   * <p>
   * Table must exist when taking the snapshot, or results are undefined.
   */
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public class DisabledTableSnapshotHandler extends TakeSnapshotHandler {
    private static final Log LOG = LogFactory.getLog(DisabledTableSnapshotHandler.class);
  
    /**
     * @param snapshot descriptor of the snapshot to take
     * @param masterServices master services provider
     * @throws IOException if it cannot access the filesystem of the snapshot
     *         temporary directory
     */
    public DisabledTableSnapshotHandler(SnapshotDescription snapshot,
        final MasterServices masterServices, final SnapshotManager snapshotManager)
        throws IOException {
      super(snapshot, masterServices, snapshotManager);
    }
  
    @Override
    public DisabledTableSnapshotHandler prepare() throws Exception {
      return (DisabledTableSnapshotHandler) super.prepare();
    }
  
    // TODO consider parallelizing these operations since they are independent. Right now its just
    // easier to keep them serial though
    @Override
    public void snapshotRegions(List<Pair<HRegionInfo, ServerName>> regionsAndLocations)
        throws IOException, KeeperException {
      try {
        // 1. get all the regions hosting this table.
  
        // extract each pair to separate lists
        Set<HRegionInfo> regions = new HashSet<HRegionInfo>();
        for (Pair<HRegionInfo, ServerName> p : regionsAndLocations) {
          // Don't include non-default regions
          HRegionInfo hri = p.getFirst();
          if (RegionReplicaUtil.isDefaultReplica(hri)) {
            regions.add(hri);
          }
        }
  
        // 2. for each region, write all the info to disk
        String msg = "Starting to write region info and WALs for regions for offline snapshot:"
            + ClientSnapshotDescriptionUtils.toString(snapshot);
        LOG.info(msg);
        status.setStatus(msg);
  
        ThreadPoolExecutor exec = SnapshotManifest.createExecutor(conf, "DisabledTableSnapshot");
        try {
          ModifyRegionUtils.editRegions(exec, regions, new ModifyRegionUtils.RegionEditTask() {
            @Override
            public void editRegion(final HRegionInfo regionInfo) throws IOException {
              snapshotManifest.addRegion(FSUtils.getTableDir(rootDir, snapshotTable), regionInfo);
           }
         });
       } finally {
         exec.shutdown();
       }
     } catch (Exception e) {
       // make sure we capture the exception to propagate back to the client later
       String reason = "Failed snapshot " + ClientSnapshotDescriptionUtils.toString(snapshot)
           + " due to exception:" + e.getMessage();
       ForeignException ee = new ForeignException(reason, e);
       monitor.receive(ee);
       status.abort("Snapshot of table: "+ snapshotTable + " failed because " + e.getMessage());
     } finally {
       LOG.debug("Marking snapshot" + ClientSnapshotDescriptionUtils.toString(snapshot)
           + " as finished.");
     }
   }
 }