org.apache.hadoop.hdfs.server.namenode.ha

Class ConfiguredFailoverProxyProvider<T>

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider<T>

All Implemented Interfaces:

Closeable, AutoCloseable, FailoverProxyProvider<T>

public class ConfiguredFailoverProxyProvider<T>
extends Object
implements FailoverProxyProvider<T>

A FailoverProxyProvider implementation which allows one to configure two URIs to connect to during fail-over. The first configured address is tried first, and on a fail-over event the other address is tried.

Constructor Summary

Constructors

Constructor and Description
ConfiguredFailoverProxyProvider(Configuration conf, URI uri, Class<T> xface)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close all the proxy objects which have been opened over the lifetime of this proxy provider.
Class<T>	getInterface() Return a reference to the interface this provider's proxy objects actually implement.
T	getProxy() Lazily initialize the RPC proxy object.
void	performFailover(T currentProxy) Called whenever the associated RetryPolicy determines that an error warrants failing over.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConfiguredFailoverProxyProvider

public ConfiguredFailoverProxyProvider(Configuration conf,
                               URI uri,
                               Class<T> xface)

Method Detail

getInterface

public Class<T> getInterface()

Description copied from interface: FailoverProxyProvider

Return a reference to the interface this provider's proxy objects actually implement. If any of the methods on this interface are annotated as being Idempotent or AtMostOnce, then this fact will be passed to the RetryPolicy.shouldRetry(Exception, int, int, boolean) method on error, for use in determining whether or not failover should be attempted.

Specified by:

getInterface in interface FailoverProxyProvider<T>

Returns:

the interface implemented by the proxy objects returned by FailoverProxyProvider.getProxy()

getProxy

public T getProxy()

Lazily initialize the RPC proxy object.

Specified by:

getProxy in interface FailoverProxyProvider<T>

Returns:

the proxy object to invoke methods upon

performFailover

public void performFailover(T currentProxy)

Description copied from interface: FailoverProxyProvider

Called whenever the associated RetryPolicy determines that an error warrants failing over.

Specified by:

performFailover in interface FailoverProxyProvider<T>

Parameters:

currentProxy - the proxy object which was being used before this failover event

close

public void close()
           throws IOException

Close all the proxy objects which have been opened over the lifetime of this proxy provider.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException