/**
    * 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 org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.errorhandling.ForeignException;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.procedure.Procedure;
  import org.apache.hadoop.hbase.procedure.ProcedureCoordinator;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
  import org.apache.hadoop.hbase.snapshot.HBaseSnapshotException;
  import org.apache.hadoop.hbase.util.Pair;
  
  import com.google.common.collect.Lists;
  
  /**
   * Handle the master side of taking a snapshot of an online table, regardless of snapshot type.
   * Uses a {@link Procedure} to run the snapshot across all the involved region servers.
   * @see ProcedureCoordinator
   */
  @InterfaceAudience.Private
  public class EnabledTableSnapshotHandler extends TakeSnapshotHandler {
  
    private static final Log LOG = LogFactory.getLog(EnabledTableSnapshotHandler.class);
    private final ProcedureCoordinator coordinator;
  
    public EnabledTableSnapshotHandler(SnapshotDescription snapshot, MasterServices master,
        final SnapshotManager manager) {
      super(snapshot, master);
      this.coordinator = manager.getCoordinator();
    }
  
    @Override
    public EnabledTableSnapshotHandler prepare() throws Exception {
      return (EnabledTableSnapshotHandler) super.prepare();
    }
  
    // TODO consider switching over to using regionnames, rather than server names. This would allow
    // regions to migrate during a snapshot, and then be involved when they are ready. Still want to
    // enforce a snapshot time constraints, but lets us be potentially a bit more robust.
  
    /**
     * This method kicks off a snapshot procedure.  Other than that it hangs around for various
     * phases to complete.
     */
    @Override
    protected void snapshotRegions(List<Pair<HRegionInfo, ServerName>> regions)
        throws HBaseSnapshotException, IOException {
      Set<String> regionServers = new HashSet<String>(regions.size());
      for (Pair<HRegionInfo, ServerName> region : regions) {
        if (region != null && region.getFirst() != null && region.getSecond() != null) {
          HRegionInfo hri = region.getFirst();
          if (hri.isOffline() && (hri.isSplit() || hri.isSplitParent())) continue;
          regionServers.add(region.getSecond().toString());
        }
      }
  
      // start the snapshot on the RS
      Procedure proc = coordinator.startProcedure(this.monitor, this.snapshot.getName(),
        this.snapshot.toByteArray(), Lists.newArrayList(regionServers));
      if (proc == null) {
        String msg = "Failed to submit distributed procedure for snapshot '"
            + snapshot.getName() + "'";
        LOG.error(msg);
        throw new HBaseSnapshotException(msg);
      }
  
      try {
        // wait for the snapshot to complete.  A timer thread is kicked off that should cancel this
        // if it takes too long.
        proc.waitForCompleted();
        LOG.info("Done waiting - online snapshot for " + this.snapshot.getName());
  
        // Take the offline regions as disabled
        for (Pair<HRegionInfo, ServerName> region : regions) {
         HRegionInfo regionInfo = region.getFirst();
         if (regionInfo.isOffline() && (regionInfo.isSplit() || regionInfo.isSplitParent())) {
           LOG.info("Take disabled snapshot of offline region=" + regionInfo);
           snapshotDisabledRegion(regionInfo);
         }
       }
     } catch (InterruptedException e) {
       ForeignException ee =
           new ForeignException("Interrupted while waiting for snapshot to finish", e);
       monitor.receive(ee);
       Thread.currentThread().interrupt();
     } catch (ForeignException e) {
       monitor.receive(e);
     }
   }
 }