org.adroitlogic.x.clustering

Class CuratorClusterManager

java.lang.Object

org.adroitlogic.x.clustering.CuratorClusterManager

All Implemented Interfaces:

XClusterManager, Initializable, Startable

@AutoInitialize
 @AutoStart
public class CuratorClusterManager
extends Object
implements XClusterManager

Cluster manager written on top of Apache Curator. This cluster manager currently support the following features.

• Distributed locks
• Distributed sequence numbers
• Distributed command framework
  
  • Command publishing/republishing
  • Command processing
• Failover processing
  
  • Node wise failover processing through NodeWiseFailoverStrategy
  • Group failover strategy through GroupFailoverStrategy

When it comes to failover processing, group failover strategy has to be plugged to the cluster manager bean when configuring for the failover processing to work. Otherwise, all the above mentioned functions will be provide except failover processing.

nodeName is kept in this class as it is required for command processing

Logger codes:

• 1-10 : startup/stop errors
• 10-20 : startup /stop errors of sub components
• 50-60 : Errors related to command publishing and so on

Since:

17.01

Author:

Imesha Sudasingha

Field Summary

Fields

Modifier and Type	Field and Description
protected XEnvironment	environment

Constructor Summary

Constructors

Constructor and Description
CuratorClusterManager()

Method Summary

Modifier and Type	Method and Description
void	archiveCommand(int commandVersion) This will archive the command in the form
void	destroy()
org.apache.curator.framework.CuratorFramework	getClient()
XClusterLock	getClusterLock(String path) This will use the ClusterPaths.locksZNodeRoot + lockPath as the lockPath to create the lock.
ClusterPaths	getClusterPaths()
String	getCommandSpace() Name of the command space to which this cluster manager is listening to.
int	getCurrentCommandVersion() Get's the current command version, which is the version of the last executed(by the command processor) command.
String	getDomain()
FailoverStrategy	getFailoverStrategy()
String	getNamespace()
Optional<Integer>	getNextSequenceNumber(String path) This method uses the ClusterPaths.sequencesZNodeRoot + path to keep tract of the distributed sequence number.
String	getNodeName()
CommandView	getPublishedCommandView(int commandVersion) Returns the CommandView corresponding to a given command version.
Map<Integer,CommandView>	getPublishedCommandViews(int from, int to) Gets the published commands between given two command versions (inclusive).
org.apache.curator.RetryPolicy	getRetryPolicy()
Status	getStatus() Get the cluster manager's current Status.
void	init(org.springframework.context.ApplicationContext context)
String	publishControlCommand(String command) This method is to be used over the REST API.
String	publishControlCommand(XControlCommand command) Publishes a command to the cluster.
String	republishControlCommand(int commandVersion) Republish a control command which was once published.
void	retryCommand(int commandVersion) Retries a given command.
void	setCommandSpace(String commandSpace)
void	setConnectionTimeoutMs(int connectionTimeoutMs)
void	setConnectString(String connectString)
void	setDomain(String domain)
void	setFailoverStrategy(FailoverStrategy failoverStrategy)
void	setRetryPolicy(org.apache.curator.RetryPolicy retryPolicy)
void	setSessionTimeoutMs(int sessionTimeoutMs)
void	setStartupTimeOutMs(int startupTimeOutMs)
void	setZkPassword(String zkPassword)
void	setZkUsername(String zkUsername)
void	start() Starts the cluster manager.
void	stop()

Methods inherited from class java.lang.Object

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

Field Detail

environment

@Autowired
protected XEnvironment environment

Constructor Detail

CuratorClusterManager

public CuratorClusterManager()

Method Detail

init

public void init(org.springframework.context.ApplicationContext context)

Specified by:

init in interface Initializable

start

public void start()

Starts the cluster manager. This will cause the CuratorFramework client to wait till connecting to the zookeeper cluster or till the connection timeout.

Specified by:

start in interface Startable

getClusterLock

public XClusterLock getClusterLock(String path)

This will use the ClusterPaths.locksZNodeRoot + lockPath as the lockPath to create the lock. Returns a distributed lock unique to the given path. The returned XClusterLock can be used to acquire a lock which will guarantee a critical section between different instances of the cluster manager (project x/ultraESB)

Specified by:

getClusterLock in interface XClusterManager

Parameters:

path - lock path

Returns:

XClusterLock

getNextSequenceNumber

public Optional<Integer> getNextSequenceNumber(String path)

This method uses the ClusterPaths.sequencesZNodeRoot + path to keep tract of the distributed sequence number. Generates a distributed sequence number which is the next in line of a distributed sequence. this will return an Optional as the result. Users have to check whether the value is available.

Specified by:

getNextSequenceNumber in interface XClusterManager

Parameters:

path - path to be used to generate the sequence number

Returns:

next sequence number as an optional

publishControlCommand

public String publishControlCommand(XControlCommand command)

Publishes a command to the cluster. An XControlCommand instance should be provided as the command. The command will be marshaled and sent to the zookeeper for publishing the command.

Specified by:

publishControlCommand in interface XClusterManager

Parameters:

command - the command to be published

Returns:

the path of the newly created command ZNode | null if failed

publishControlCommand

public String publishControlCommand(String command)

This method is to be used over the REST API. The command will be received as an marshaled command.

Specified by:

publishControlCommand in interface XClusterManager

Parameters:

command - Marshaled XControlCommand

Returns:

the path of the newly created command ZNode | null if failed

See Also:

XClusterManager.publishControlCommand(XControlCommand)

republishControlCommand

public String republishControlCommand(int commandVersion)

Republish a control command which was once published. The command to be republished will be identified through the version number of the command.

Specified by:

republishControlCommand in interface XClusterManager

Parameters:

commandVersion - Version of the command to be republished

Returns:

Name of the published command's ZNode | null

archiveCommand

public void archiveCommand(int commandVersion)

This will archive the command in the form

ControlCommand_00..00{commandVersion}

. Therefore, please note that the command version is always 1 unit below the CVersion of the

commands/current

ZNode. Archives a given command. The command is identified by its version number which is appended to the ZNode name when a sequential node is being created

Specified by:

archiveCommand in interface XClusterManager

Parameters:

commandVersion - sequence number of the command which is to be archived

retryCommand

public void retryCommand(int commandVersion)

Description copied from interface: XClusterManager

Retries a given command. Command is obtained by the command version number

Specified by:

retryCommand in interface XClusterManager

Parameters:

commandVersion - command version number to be retried

See Also:

{@inheritDoc}

getCurrentCommandVersion

public int getCurrentCommandVersion()

Get's the current command version, which is the version of the last executed(by the command processor) command.

Specified by:

getCurrentCommandVersion in interface XClusterManager

Returns:

current command version

getPublishedCommandViews

public Map<Integer,CommandView> getPublishedCommandViews(int from,
                                                         int to)

Gets the published commands between given two command versions (inclusive).

Specified by:

getPublishedCommandViews in interface XClusterManager

Parameters:

from - starting version from which the commands to be fetched

to - ending version up to which commands has to be fetched

Returns:

A map of published commands between those two versions with version number as the key and and the published command as the value.

getPublishedCommandView

public CommandView getPublishedCommandView(int commandVersion)
                                    throws Exception

Returns the CommandView corresponding to a given command version. Please note that, the

commandVersion

is expected to be 1-based (starting from 1). This method will do the proper conversions in order to address the command version difference among the API and the implementation.

Specified by:

getPublishedCommandView in interface XClusterManager

Parameters:

commandVersion - command version

Returns:

the command view for the matching command version

Throws:

Exception - zookeeper errors

getStatus

public Status getStatus()

Get the cluster manager's current Status.

Specified by:

getStatus in interface XClusterManager

Returns:

state of the cluster manager

stop

public void stop()

Specified by:

stop in interface Startable

destroy

public void destroy()

Specified by:

destroy in interface Initializable

setConnectString

public void setConnectString(String connectString)

setSessionTimeoutMs

public void setSessionTimeoutMs(int sessionTimeoutMs)

setConnectionTimeoutMs

public void setConnectionTimeoutMs(int connectionTimeoutMs)

setZkUsername

public void setZkUsername(String zkUsername)

setZkPassword

public void setZkPassword(String zkPassword)

setStartupTimeOutMs

public void setStartupTimeOutMs(int startupTimeOutMs)

getNamespace

public String getNamespace()

getClusterPaths

public ClusterPaths getClusterPaths()

setFailoverStrategy

public void setFailoverStrategy(FailoverStrategy failoverStrategy)

getCommandSpace

public String getCommandSpace()

Description copied from interface: XClusterManager

Name of the command space to which this cluster manager is listening to. The nodes in the same command space will receive the same cluster commands

Specified by:

getCommandSpace in interface XClusterManager

Returns:

command space name

setCommandSpace

public void setCommandSpace(String commandSpace)

getFailoverStrategy

public FailoverStrategy getFailoverStrategy()

getClient

public org.apache.curator.framework.CuratorFramework getClient()

getDomain

public String getDomain()

Specified by:

getDomain in interface XClusterManager

setDomain

public void setDomain(String domain)

getNodeName

public String getNodeName()

Specified by:

getNodeName in interface XClusterManager

getRetryPolicy

public org.apache.curator.RetryPolicy getRetryPolicy()

setRetryPolicy

public void setRetryPolicy(org.apache.curator.RetryPolicy retryPolicy)