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

Class RequestHedgingProxyProvider<T>

java.lang.Object

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

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

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

All Implemented Interfaces:

Closeable, AutoCloseable, org.apache.hadoop.io.retry.FailoverProxyProvider<T>

public class RequestHedgingProxyProvider<T>
extends ConfiguredFailoverProxyProvider<T>

A FailoverProxyProvider implementation that technically does not "failover" per-se. It constructs a wrapper proxy that sends the request to ALL underlying proxies simultaneously. It assumes the in an HA setup, there will be only one Active, and the active should respond faster than any configured standbys. Once it recieve a response from any one of the configred proxies, outstanding requests to other proxies are immediately cancelled.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.io.retry.FailoverProxyProvider

org.apache.hadoop.io.retry.FailoverProxyProvider.ProxyInfo<T>

Field Summary

Fields

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

Fields inherited from class org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider

conf, proxies, xface

Constructor Summary

Constructors

Constructor and Description
RequestHedgingProxyProvider(org.apache.hadoop.conf.Configuration conf, URI uri, Class<T> xface)

Method Summary

Methods

Modifier and Type	Method and Description
org.apache.hadoop.io.retry.FailoverProxyProvider.ProxyInfo<T>	getProxy() Lazily initialize the RPC proxy object.
void	performFailover(T currentProxy)

Methods inherited from class org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider

close, getInterface, useLogicalURI

Methods inherited from class org.apache.hadoop.hdfs.server.namenode.ha.AbstractNNFailoverProxyProvider

getFallbackToSimpleAuth, setFallbackToSimpleAuth

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.slf4j.Logger LOG

Constructor Detail

RequestHedgingProxyProvider

public RequestHedgingProxyProvider(org.apache.hadoop.conf.Configuration conf,
                           URI uri,
                           Class<T> xface)

Method Detail

getProxy

public org.apache.hadoop.io.retry.FailoverProxyProvider.ProxyInfo<T> getProxy()

Description copied from class: ConfiguredFailoverProxyProvider

Lazily initialize the RPC proxy object.

Specified by:

getProxy in interface org.apache.hadoop.io.retry.FailoverProxyProvider<T>

Overrides:

getProxy in class ConfiguredFailoverProxyProvider<T>

performFailover

public void performFailover(T currentProxy)

Specified by:

performFailover in interface org.apache.hadoop.io.retry.FailoverProxyProvider<T>

Overrides:

performFailover in class ConfiguredFailoverProxyProvider<T>