Package org.apache.hadoop.hdfs

Class HAUtil

java.lang.Object

org.apache.hadoop.hdfs.HAUtil

@Private
public class HAUtil
extends java.lang.Object

Field Summary

Fields

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

Method Summary

Modifier and Type	Method	Description
static java.net.InetSocketAddress	getAddressOfActive(org.apache.hadoop.fs.FileSystem fs)	Get the internet address of the currently-active NN.
static java.util.List<org.apache.hadoop.conf.Configuration>	getConfForOtherNodes(org.apache.hadoop.conf.Configuration myConf)	Given the configuration for this node, return a list of configurations for the other nodes in an HA setup.
static java.lang.String	getNameNodeId(org.apache.hadoop.conf.Configuration conf, java.lang.String nsId)	Get the namenode Id by matching the addressKey with the the address of the local node.
static java.lang.String	getNameNodeIdFromAddress(org.apache.hadoop.conf.Configuration conf, java.net.InetSocketAddress address, java.lang.String... keys)	Similar to DFSUtil.getNameServiceIdFromAddress(Configuration, InetSocketAddress, String...)
static java.util.List<java.lang.String>	getNameNodeIdOfOtherNodes(org.apache.hadoop.conf.Configuration conf, java.lang.String nsId)	Get the NN ID of the other nodes in an HA setup.
static java.util.List<org.apache.hadoop.hdfs.protocol.ClientProtocol>	getProxiesForAllNameNodesInNameservice(org.apache.hadoop.conf.Configuration conf, java.lang.String nsId)	Get an RPC proxy for each NN in an HA nameservice.
static <T> java.util.List<org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo<T>>	getProxiesForAllNameNodesInNameservice(org.apache.hadoop.conf.Configuration conf, java.lang.String nsId, java.lang.Class<T> xface)	Get an RPC proxy for each NN in an HA nameservice.
static boolean	isAtLeastOneActive(java.util.List<org.apache.hadoop.hdfs.protocol.ClientProtocol> namenodes)	Used to ensure that at least one of the given HA NNs is currently in the active state..
static boolean	isHAEnabled(org.apache.hadoop.conf.Configuration conf, java.lang.String nsId)	Returns true if HA for namenode is configured for the given nameservice
static void	setAllowStandbyReads(org.apache.hadoop.conf.Configuration conf, boolean val)
static boolean	shouldAllowStandbyReads(org.apache.hadoop.conf.Configuration conf)	This is used only by tests at the moment.
static boolean	useLogicalUri(org.apache.hadoop.conf.Configuration conf, java.net.URI nameNodeUri)	Check whether logical URI is needed for the namenode and the corresponding failover proxy provider in the config.
static boolean	usesSharedEditsDir(org.apache.hadoop.conf.Configuration conf)	Returns true if HA is using a shared edits directory.

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

Method Detail

isHAEnabled

public static boolean isHAEnabled(org.apache.hadoop.conf.Configuration conf,
                                  java.lang.String nsId)

Returns true if HA for namenode is configured for the given nameservice

Parameters:

conf - Configuration

nsId - nameservice, or null if no federated NS is configured

Returns:

true if HA is configured in the configuration; else false.

usesSharedEditsDir

public static boolean usesSharedEditsDir(org.apache.hadoop.conf.Configuration conf)

Returns true if HA is using a shared edits directory.

Parameters:

conf - Configuration

Returns:

true if HA config is using a shared edits dir, false otherwise.

getNameNodeId

public static java.lang.String getNameNodeId(org.apache.hadoop.conf.Configuration conf,
                                             java.lang.String nsId)

Get the namenode Id by matching the addressKey with the the address of the local node. If DFSConfigKeys.DFS_HA_NAMENODE_ID_KEY is not specifically configured, this method determines the namenode Id by matching the local node's address with the configured addresses. When a match is found, it returns the namenode Id from the corresponding configuration key.

Parameters:

conf - Configuration

Returns:

namenode Id on success, null on failure.

Throws:

org.apache.hadoop.HadoopIllegalArgumentException - on error

getNameNodeIdFromAddress

public static java.lang.String getNameNodeIdFromAddress(org.apache.hadoop.conf.Configuration conf,
                                                        java.net.InetSocketAddress address,
                                                        java.lang.String... keys)

Similar to DFSUtil.getNameServiceIdFromAddress(Configuration, InetSocketAddress, String...)

getNameNodeIdOfOtherNodes

public static java.util.List<java.lang.String> getNameNodeIdOfOtherNodes(org.apache.hadoop.conf.Configuration conf,
                                                                         java.lang.String nsId)

Get the NN ID of the other nodes in an HA setup.

Parameters:

conf - the configuration of this node

Returns:

a list of NN IDs of other nodes in this nameservice

getConfForOtherNodes

public static java.util.List<org.apache.hadoop.conf.Configuration> getConfForOtherNodes(org.apache.hadoop.conf.Configuration myConf)

Given the configuration for this node, return a list of configurations for the other nodes in an HA setup.

Parameters:

myConf - the configuration of this node

Returns:

a list of configuration of other nodes in an HA setup

shouldAllowStandbyReads

public static boolean shouldAllowStandbyReads(org.apache.hadoop.conf.Configuration conf)

This is used only by tests at the moment.

Returns:

true if the NN should allow read operations while in standby mode.

setAllowStandbyReads

public static void setAllowStandbyReads(org.apache.hadoop.conf.Configuration conf,
                                        boolean val)

useLogicalUri

public static boolean useLogicalUri(org.apache.hadoop.conf.Configuration conf,
                                    java.net.URI nameNodeUri)
                             throws java.io.IOException

Check whether logical URI is needed for the namenode and the corresponding failover proxy provider in the config.

Parameters:

conf - Configuration

nameNodeUri - The URI of namenode

Returns:

true if logical URI is needed. false, if not needed.

Throws:

java.io.IOException - most likely due to misconfiguration.

getAddressOfActive

public static java.net.InetSocketAddress getAddressOfActive(org.apache.hadoop.fs.FileSystem fs)
                                                     throws java.io.IOException

Get the internet address of the currently-active NN. This should rarely be used, since callers of this method who connect directly to the NN using the resulting InetSocketAddress will not be able to connect to the active NN if a failover were to occur after this method has been called.

Parameters:

fs - the file system to get the active address of.

Returns:

the internet address of the currently-active NN.

Throws:

java.io.IOException - if an error occurs while resolving the active NN.

getProxiesForAllNameNodesInNameservice

public static java.util.List<org.apache.hadoop.hdfs.protocol.ClientProtocol> getProxiesForAllNameNodesInNameservice(org.apache.hadoop.conf.Configuration conf,
                                                                                                                    java.lang.String nsId)
                                                                                                             throws java.io.IOException

Get an RPC proxy for each NN in an HA nameservice. Used when a given RPC call should be made on every NN in an HA nameservice, not just the active.

Parameters:

conf - configuration

nsId - the nameservice to get all of the proxies for.

Returns:

a list of RPC proxies for each NN in the nameservice.

Throws:

java.io.IOException - in the event of error.

getProxiesForAllNameNodesInNameservice

public static <T> java.util.List<org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo<T>> getProxiesForAllNameNodesInNameservice(org.apache.hadoop.conf.Configuration conf,
                                                                                                                                      java.lang.String nsId,
                                                                                                                                      java.lang.Class<T> xface)
                                                                                                                               throws java.io.IOException

Get an RPC proxy for each NN in an HA nameservice. Used when a given RPC call should be made on every NN in an HA nameservice, not just the active.

Parameters:

conf - configuration

nsId - the nameservice to get all of the proxies for.

xface - the protocol class.

Returns:

a list of RPC proxies for each NN in the nameservice.

Throws:

java.io.IOException - in the event of error.

isAtLeastOneActive

public static boolean isAtLeastOneActive(java.util.List<org.apache.hadoop.hdfs.protocol.ClientProtocol> namenodes)
                                  throws java.io.IOException

Used to ensure that at least one of the given HA NNs is currently in the active state..

Parameters:

namenodes - list of RPC proxies for each NN to check.

Returns:

true if at least one NN is active, false if all are in the standby state.

Throws:

java.io.IOException - in the event of error.