Package org.apache.hadoop.hdfs.server.federation.resolver.order

Class AvailableSpaceResolver

java.lang.Object

org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace>

org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver

All Implemented Interfaces:

OrderedResolver

public class AvailableSpaceResolver
extends RouterResolver<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace>

Order the destinations based on available space. This resolver uses a higher probability (instead of "always") to choose the cluster with higher available space.

Field Summary

Fields

Modifier and Type	Field	Description
static final float	BALANCER_PREFERENCE_DEFAULT
static final String	BALANCER_PREFERENCE_KEY	Increases chance of files on subcluster with more available space.

Fields inherited from class org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver

MIN_UPDATE_PERIOD_KEY

Constructor Summary

Constructors

Constructor	Description
AvailableSpaceResolver(org.apache.hadoop.conf.Configuration conf, Router routerService)

Method Summary

Modifier and Type	Method	Description
protected String	chooseFirstNamespace(String path, PathLocation loc)	Choose the first namespace from queried subcluster mapping info.
protected Map<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace>	getSubclusterInfo(MembershipStore membershipStore)	Get the mapping from NamespaceId to subcluster space info.

Methods inherited from class org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver

getFirstNamespace, getMembershipStore, getRpcServer, getSubclusterMapping

Methods inherited from class java.lang.Object

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

Field Details

BALANCER_PREFERENCE_KEY

public static final String BALANCER_PREFERENCE_KEY

Increases chance of files on subcluster with more available space.

See Also:

• Constant Field Values

BALANCER_PREFERENCE_DEFAULT

public static final float BALANCER_PREFERENCE_DEFAULT

See Also:

• Constant Field Values

Constructor Details

AvailableSpaceResolver

public AvailableSpaceResolver(org.apache.hadoop.conf.Configuration conf,
 Router routerService)

Method Details

getSubclusterInfo

protected Map<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace> getSubclusterInfo(MembershipStore membershipStore)

Get the mapping from NamespaceId to subcluster space info. It gets this mapping from the subclusters through expensive calls (e.g., RPC) and uses caching to avoid too many calls. The cache might be updated asynchronously to reduce latency.

Specified by:

getSubclusterInfo in class RouterResolver<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace>

Parameters:

membershipStore - Membership store the resolver queried from.

Returns:

NamespaceId to AvailableSpaceResolver.SubclusterAvailableSpace.

chooseFirstNamespace

protected String chooseFirstNamespace(String path,
 PathLocation loc)

Description copied from class: RouterResolver

Choose the first namespace from queried subcluster mapping info.

Specified by:

chooseFirstNamespace in class RouterResolver<String,org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace>

Parameters:

path - Path to check.

loc - Federated location with multiple destinations.

Returns:

First namespace out of the locations.