/// <summary>
/// Get an instance of the configured Block Placement Policy based on the
/// the configuration property
/// <see cref="Org.Apache.Hadoop.Hdfs.DFSConfigKeys.DfsBlockReplicatorClassnameKey"/>
/// .
/// </summary>
/// <param name="conf">the configuration to be used</param>
/// <param name="stats">an object that is used to retrieve the load on the cluster</param>
/// <param name="clusterMap">the network topology of the cluster</param>
/// <returns>an instance of BlockPlacementPolicy</returns>
public static BlockPlacementPolicy GetInstance(Configuration conf, FSClusterStats
stats, NetworkTopology clusterMap, Host2NodesMap host2datanodeMap)
{
Type replicatorClass = conf.GetClass <BlockPlacementPolicy>(DFSConfigKeys.DfsBlockReplicatorClassnameKey
, DFSConfigKeys.DfsBlockReplicatorClassnameDefault);
BlockPlacementPolicy replicator = ReflectionUtils.NewInstance(replicatorClass, conf
);
replicator.Initialize(conf, stats, clusterMap, host2datanodeMap);
return(replicator);
}
protected internal override void Initialize(Configuration conf, FSClusterStats stats
, NetworkTopology clusterMap, Host2NodesMap host2datanodeMap)
{
base.Initialize(conf, stats, clusterMap, host2datanodeMap);
}
protected internal BlockPlacementPolicyWithNodeGroup(Configuration conf, FSClusterStats
stats, NetworkTopology clusterMap, DatanodeManager datanodeManager)
{
Initialize(conf, stats, clusterMap, host2datanodeMap);
}
/// <summary>Used to setup a BlockPlacementPolicy object.</summary>
/// <remarks>
/// Used to setup a BlockPlacementPolicy object. This should be defined by
/// all implementations of a BlockPlacementPolicy.
/// </remarks>
/// <param name="conf">the configuration object</param>
/// <param name="stats">retrieve cluster status from here</param>
/// <param name="clusterMap">cluster topology</param>
protected internal abstract void Initialize(Configuration conf, FSClusterStats stats
, NetworkTopology clusterMap, Host2NodesMap host2datanodeMap);