/*
    *
    * 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.replication.master;
  
  import com.google.common.base.Preconditions;
  import java.util.Map;
  import org.apache.commons.collections.MapUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.master.cleaner.BaseLogCleanerDelegate;
  import org.apache.hadoop.hbase.replication.ReplicationException;
  import org.apache.hadoop.hbase.replication.ReplicationFactory;
  import org.apache.hadoop.hbase.replication.ReplicationQueuesClient;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import java.io.IOException;
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  
  import com.google.common.base.Predicate;
  import com.google.common.collect.ImmutableSet;
  import com.google.common.collect.Iterables;
  import com.google.common.collect.Sets;
  import org.apache.zookeeper.KeeperException;
  
  /**
   * Implementation of a log cleaner that checks if a log is still scheduled for
   * replication before deleting it when its TTL is over.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
  public class ReplicationLogCleaner extends BaseLogCleanerDelegate {
    private static final Log LOG = LogFactory.getLog(ReplicationLogCleaner.class);
    private ZooKeeperWatcher zkw = null;
    private ReplicationQueuesClient replicationQueues;
    private boolean stopped = false;
    private MasterServices master;
    private boolean shareZK = false;
  
    @Override
    public Iterable<FileStatus> getDeletableFiles(Iterable<FileStatus> files) {
     // all members of this class are null if replication is disabled,
     // so we cannot filter the files
      if (this.getConf() == null) {
        return files;
      }
  
      final Set<String> wals;
      try {
        // The concurrently created new WALs may not be included in the return list,
        // but they won't be deleted because they're not in the checking set.
        wals = loadWALsFromQueues();
      } catch (KeeperException e) {
        LOG.warn("Failed to read zookeeper, skipping checking deletable files", e);
        return Collections.emptyList();
      }
      return Iterables.filter(files, new Predicate<FileStatus>() {
        @Override
        public boolean apply(FileStatus file) {
          String wal = file.getPath().getName();
          boolean logInReplicationQueue = wals.contains(wal);
          if (LOG.isDebugEnabled()) {
            if (logInReplicationQueue) {
              LOG.debug("Found log in ZK, keeping: " + wal);
            } else {
              LOG.debug("Didn't find this log in ZK, deleting: " + wal);
            }
          }
         return !logInReplicationQueue;
        }});
    }
  
    /**
     * Load all wals in all replication queues from ZK. This method guarantees to return a
     * snapshot which contains all WALs in the zookeeper at the start of this call even there
     * is concurrent queue failover. However, some newly created WALs during the call may
     * not be included.
    */
   private Set<String> loadWALsFromQueues() throws KeeperException {
     for (int retry = 0; ; retry++) {
       int v0 = replicationQueues.getQueuesZNodeCversion();
       List<String> rss = replicationQueues.getListOfReplicators();
       if (rss == null || rss.isEmpty()) {
         LOG.debug("Didn't find any region server that replicates, won't prevent any deletions.");
         return ImmutableSet.of();
       }
       Set<String> wals = Sets.newHashSet();
       for (String rs : rss) {
         List<String> listOfPeers = replicationQueues.getAllQueues(rs);
         // if rs just died, this will be null
         if (listOfPeers == null) {
           continue;
         }
         for (String id : listOfPeers) {
           List<String> peersWals = replicationQueues.getLogsInQueue(rs, id);
           if (peersWals != null) {
             wals.addAll(peersWals);
           }
         }
       }
       int v1 = replicationQueues.getQueuesZNodeCversion();
       if (v0 == v1) {
         return wals;
       }
       LOG.info(String.format("Replication queue node cversion changed from %d to %d, retry = %d",
           v0, v1, retry));
     }
   }
 
   @Override
   public void setConf(Configuration config) {
     // If replication is disabled, keep all members null
     if (!config.getBoolean(HConstants.REPLICATION_ENABLE_KEY,
         HConstants.REPLICATION_ENABLE_DEFAULT)) {
       LOG.warn("Not configured - allowing all wals to be deleted");
       return;
     }
     super.setConf(config);
   }
 
   @Override
   public void init(Map<String, Object> params) {
     if (getConf() == null) {
       // Replication is disabled so do nothing.
       return;
     }
 
     if (MapUtils.isNotEmpty(params)) {
       Object master = params.get(HMaster.MASTER);
       if (master != null && master instanceof HMaster) {
         this.master = (HMaster)master;
         zkw = ((HMaster) master).getZooKeeper();
         shareZK = true;
       }
     }
     init(getConf(), this.zkw, null);
   }
 
   @InterfaceAudience.Private
   public void init(Configuration conf, ZooKeeperWatcher zk,
       ReplicationQueuesClient replicationQueuesClient) {
     super.setConf(conf);
     try {
       if (zk != null) {
         this.zkw = zk;
       } else {
         this.zkw = new ZooKeeperWatcher(getConf(), "replicationLogCleaner", null);
       }
       Preconditions.checkNotNull(this.zkw, "Zookeeper watcher cannot be null");
       if (replicationQueuesClient != null) {
         this.replicationQueues = replicationQueuesClient;
       } else {
         this.replicationQueues =
           ReplicationFactory.getReplicationQueuesClient(zkw, getConf(), master);
         this.replicationQueues.init();
       }
       Preconditions.checkNotNull(this.replicationQueues,
         "ReplicationQueues cannot be null");
     } catch (IOException | ReplicationException e) {
       LOG.error("Error while configuring " + this.getClass().getName(), e);
     }
   }
 
   @Override
   public void stop(String why) {
     if (this.stopped) return;
     this.stopped = true;
     if (!shareZK && this.zkw != null) {
       LOG.info("Stopping " + this.zkw);
       this.zkw.close();
     }
   }
 
   @Override
   public boolean isStopped() {
     return this.stopped;
   }
 }