Package 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.conf.Configurable, VolumeChoosingPolicy<V>

public class RoundRobinVolumeChoosingPolicy<V extends FsVolumeSpi>
extends Object
implements VolumeChoosingPolicy<V>, org.apache.hadoop.conf.Configurable

Choose volumes with the same storage type in round-robin order. Use fine-grained locks to synchronize volume choosing.

Field Summary

Fields

Modifier and Type	Field	Description
static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor	Description
RoundRobinVolumeChoosingPolicy()

Method Summary

Modifier and Type	Method	Description
V	chooseVolume(List<V> volumes, long blockSize, String storageId)	Choose a volume to place a replica, given a list of volumes and the replica size sought for storage.
org.apache.hadoop.conf.Configuration	getConf()
void	setConf(org.apache.hadoop.conf.Configuration conf)

Methods inherited from class java.lang.Object

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

Field Details

LOG

public static final org.slf4j.Logger LOG

Constructor Details

RoundRobinVolumeChoosingPolicy

public RoundRobinVolumeChoosingPolicy()

Method Details

setConf

public void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:

setConf in interface org.apache.hadoop.conf.Configurable

getConf

public org.apache.hadoop.conf.Configuration getConf()

Specified by:

getConf in interface org.apache.hadoop.conf.Configurable

chooseVolume

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

Description copied from interface: VolumeChoosingPolicy

Choose a volume to place a replica, given a list of volumes and the replica size sought for storage. The caller should synchronize access to the list of volumes.

Specified by:

chooseVolume in interface VolumeChoosingPolicy<V extends FsVolumeSpi>

Parameters:

volumes - - a list of available volumes.

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

storageId - - the storage id of the Volume nominated by the namenode. This can usually be ignored by the VolumeChoosingPolicy.

Returns:

the chosen volume.

Throws:

IOException - when disks are unavailable or are full.