/**
    * 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.util;
  
  import java.io.IOException;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.client.RegionReplicaUtil;
  import org.apache.hadoop.hbase.client.replication.ReplicationAdmin;
  import org.apache.hadoop.hbase.io.HFileLink;
  import org.apache.hadoop.hbase.io.Reference;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  import org.apache.hadoop.hbase.regionserver.StoreFileInfo;
  import org.apache.hadoop.hbase.replication.ReplicationException;
  import org.apache.hadoop.hbase.replication.ReplicationPeerConfig;
  import org.apache.hadoop.hbase.replication.regionserver.RegionReplicaReplicationEndpoint;
  import org.apache.hadoop.hbase.zookeeper.ZKConfig;
  
  /**
   * Similar to {@link RegionReplicaUtil} but for the server side
   */
  public class ServerRegionReplicaUtil extends RegionReplicaUtil {
  
    /**
     * Whether asynchronous WAL replication to the secondary region replicas is enabled or not.
     * If this is enabled, a replication peer named "region_replica_replication" will be created
     * which will tail the logs and replicate the mutatations to region replicas for tables that
     * have region replication > 1. If this is enabled once, disabling this replication also
     * requires disabling the replication peer using shell or ReplicationAdmin java class.
     * Replication to secondary region replicas works over standard inter-cluster replication.·
     * So replication, if disabled explicitly, also has to be enabled by setting "hbase.replication"·
     * to true for this feature to work.
     */
    public static final String REGION_REPLICA_REPLICATION_CONF_KEY
      = "hbase.region.replica.replication.enabled";
    private static final boolean DEFAULT_REGION_REPLICA_REPLICATION = false;
    private static final String REGION_REPLICA_REPLICATION_PEER = "region_replica_replication";
  
    /**
     * Enables or disables refreshing store files of secondary region replicas when the memory is
     * above the global memstore lower limit. Refreshing the store files means that we will do a file
     * list of the primary regions store files, and pick up new files. Also depending on the store
     * files, we can drop some memstore contents which will free up memory.
     */
    public static final String REGION_REPLICA_STORE_FILE_REFRESH
      = "hbase.region.replica.storefile.refresh";
    private static final boolean DEFAULT_REGION_REPLICA_STORE_FILE_REFRESH = true;
  
    /**
     * The multiplier to use when we want to refresh a secondary region instead of flushing a primary
     * region. Default value assumes that for doing the file refresh, the biggest secondary should be
     * 4 times bigger than the biggest primary.
     */
    public static final String REGION_REPLICA_STORE_FILE_REFRESH_MEMSTORE_MULTIPLIER
      = "hbase.region.replica.storefile.refresh.memstore.multiplier";
    private static final double DEFAULT_REGION_REPLICA_STORE_FILE_REFRESH_MEMSTORE_MULTIPLIER = 4;
  
    /**
     * Returns the regionInfo object to use for interacting with the file system.
     * @return An HRegionInfo object to interact with the filesystem
     */
    public static HRegionInfo getRegionInfoForFs(HRegionInfo regionInfo) {
      if (regionInfo == null) {
        return null;
      }
      return RegionReplicaUtil.getRegionInfoForDefaultReplica(regionInfo);
    }
  
    /**
     * Returns whether this region replica can accept writes.
     * @param region the HRegion object
     * @return whether the replica is read only
     */
    public static boolean isReadOnly(HRegion region) {
      return region.getTableDesc().isReadOnly()
        || !isDefaultReplica(region.getRegionInfo());
    }
  
    /**
     * Returns whether to replay the recovered edits to flush the results.
    * Currently secondary region replicas do not replay the edits, since it would
    * cause flushes which might affect the primary region. Primary regions even opened
    * in read only mode should replay the edits.
    * @param region the HRegion object
    * @return whether recovered edits should be replayed.
    */
   public static boolean shouldReplayRecoveredEdits(HRegion region) {
     return isDefaultReplica(region.getRegionInfo());
   }
 
   /**
    * Returns a StoreFileInfo from the given FileStatus. Secondary replicas refer to the
    * files of the primary region, so an HFileLink is used to construct the StoreFileInfo. This
    * way ensures that the secondary will be able to continue reading the store files even if
    * they are moved to archive after compaction
    * @throws IOException
    */
   public static StoreFileInfo getStoreFileInfo(Configuration conf, FileSystem fs,
       HRegionInfo regionInfo, HRegionInfo regionInfoForFs, String familyName, Path path)
       throws IOException {
 
     // if this is a primary region, just return the StoreFileInfo constructed from path
     if (regionInfo.equals(regionInfoForFs)) {
       return new StoreFileInfo(conf, fs, path);
     }
 
     // else create a store file link. The link file does not exists on filesystem though.
     if (HFileLink.isHFileLink(path) || StoreFileInfo.isHFile(path)) {
       HFileLink link = HFileLink
           .build(conf, regionInfoForFs.getTable(), regionInfoForFs.getEncodedName(), familyName,
               path.getName());
       return new StoreFileInfo(conf, fs, link.getFileStatus(fs), link);
     } else if (StoreFileInfo.isReference(path)) {
       Reference reference = Reference.read(fs, path);
       Path referencePath = StoreFileInfo.getReferredToFile(path);
       if (HFileLink.isHFileLink(referencePath)) {
         // HFileLink Reference
         HFileLink link = HFileLink.buildFromHFileLinkPattern(conf, referencePath);
         return new StoreFileInfo(conf, fs, link.getFileStatus(fs), reference, link);
       } else {
         // Reference
         HFileLink link = HFileLink
             .build(conf, regionInfoForFs.getTable(), regionInfoForFs.getEncodedName(), familyName,
                 path.getName());
         return new StoreFileInfo(conf, fs, link.getFileStatus(fs), reference);
       }
     } else {
       throw new IOException("path=" + path + " doesn't look like a valid StoreFile");
     }
   }
 
   /**
    * Create replication peer for replicating to region replicas if needed.
    * @param conf configuration to use
    * @throws IOException
    */
   public static void setupRegionReplicaReplication(Configuration conf) throws IOException {
     if (!isRegionReplicaReplicationEnabled(conf)) {
       return;
     }
     ReplicationAdmin repAdmin = new ReplicationAdmin(conf);
     try {
       if (repAdmin.getPeerConfig(REGION_REPLICA_REPLICATION_PEER) == null) {
         ReplicationPeerConfig peerConfig = new ReplicationPeerConfig();
         peerConfig.setClusterKey(ZKConfig.getZooKeeperClusterKey(conf));
         peerConfig.setReplicationEndpointImpl(RegionReplicaReplicationEndpoint.class.getName());
         repAdmin.addPeer(REGION_REPLICA_REPLICATION_PEER, peerConfig, null);
       }
     } catch (ReplicationException ex) {
       throw new IOException(ex);
     } finally {
       repAdmin.close();
     }
   }
 
   public static boolean isRegionReplicaReplicationEnabled(Configuration conf) {
     return conf.getBoolean(REGION_REPLICA_REPLICATION_CONF_KEY,
       DEFAULT_REGION_REPLICA_REPLICATION);
   }
 
   public static boolean isRegionReplicaWaitForPrimaryFlushEnabled(Configuration conf) {
     return conf.getBoolean(REGION_REPLICA_WAIT_FOR_PRIMARY_FLUSH_CONF_KEY,
       DEFAULT_REGION_REPLICA_WAIT_FOR_PRIMARY_FLUSH);
   }
 
   public static boolean isRegionReplicaStoreFileRefreshEnabled(Configuration conf) {
     return conf.getBoolean(REGION_REPLICA_STORE_FILE_REFRESH,
       DEFAULT_REGION_REPLICA_STORE_FILE_REFRESH);
   }
 
   public static double getRegionReplicaStoreFileRefreshMultiplier(Configuration conf) {
     return conf.getDouble(REGION_REPLICA_STORE_FILE_REFRESH_MEMSTORE_MULTIPLIER,
       DEFAULT_REGION_REPLICA_STORE_FILE_REFRESH_MEMSTORE_MULTIPLIER);
   }
 
   /**
    * Return the peer id used for replicating to secondary region replicas
    */
   public static String getReplicationPeerId() {
     return REGION_REPLICA_REPLICATION_PEER;
   }
 
 }