org.apache.hadoop.hdfs.server.datanode.fsdataset
Class RoundRobinVolumeChoosingPolicy<V extends FsVolumeSpi>

java.lang.Object
  org.apache.hadoop.hdfs.server.datanode.fsdataset.RoundRobinVolumeChoosingPolicy<V>

All Implemented Interfaces:

org.apache.hadoop.hdfs.server.datanode.fsdataset.VolumeChoosingPolicy<V>

public class RoundRobinVolumeChoosingPolicy<V extends FsVolumeSpi>
extends Object
implements org.apache.hadoop.hdfs.server.datanode.fsdataset.VolumeChoosingPolicy<V>

Choose volumes in round-robin order.

Field Summary

static org.apache.commons.logging.Log

LOG

Constructor Summary

RoundRobinVolumeChoosingPolicy()

Method Summary

V	chooseVolume(List<V> volumes, long blockSize) Choose a volume to place a replica, given a list of volumes and the replica size sought for storage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

public static final org.apache.commons.logging.Log LOG

Constructor Detail

RoundRobinVolumeChoosingPolicy

public RoundRobinVolumeChoosingPolicy()

Method Detail

chooseVolume

public V chooseVolume(List<V> volumes,
                      long blockSize)
                                   throws IOException

Description copied from interface: org.apache.hadoop.hdfs.server.datanode.fsdataset.VolumeChoosingPolicy

Choose a volume to place a replica, given a list of volumes and the replica size sought for storage. The implementations of this interface must be thread-safe.

Specified by:

chooseVolume in interface org.apache.hadoop.hdfs.server.datanode.fsdataset.VolumeChoosingPolicy<V extends FsVolumeSpi>

Parameters:

volumes - - a list of available volumes.

blockSize - - the size of the replica for which a volume is sought.

Returns:

the chosen volume.

Throws:

IOException - when disks are unavailable or are full.