org.modeshape.jcr.clustering

Class ClusteringService

java.lang.Object

org.modeshape.jcr.clustering.ClusteringService

@ThreadSafe
public abstract class ClusteringService
extends Object

ModeShape service which handles sending/receiving messages in a cluster via JGroups

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	ClusteringService.Listener
protected class	ClusteringService.Receiver

Field Summary

Fields

Modifier and Type	Field and Description
protected org.jgroups.JChannel	channel The JGroups channel which will be used to send/receive event across the cluster
protected String	clusterName The name of the cluster (in standalone mode) or the ID of the fork stack (in forked mode)
protected ClusteringService.Listener	listener The listener for channel changes.
protected org.jgroups.blocks.locking.LockService	lockService The service used for cluster-wide locking
protected static Logger	LOGGER
protected ClusteringService.Receiver	receiver The component that will receive the JGroups messages.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ClusteringService(String clusterName)

Method Summary

Methods

Modifier and Type	Method and Description
void	addConsumer(MessageConsumer<? extends Serializable> consumer) Adds a new message consumer to this service.
String	clusterName() Returns the name of the cluster which has been configured for this service.
protected Serializable	fromByteArray(byte[] data, ClassLoader classLoader)
protected org.jgroups.JChannel	getChannel()
long	getMaxAllowedClockDelayMillis() Returns the maximum accepted delay in clock time between cluster members.
protected abstract void	init()
boolean	isOpen() Checks if this instance is open or not (open means the JGroups channel has been connected).
int	membersInCluster() Returns the number of members in the cluster.
boolean	multipleMembersInCluster() Checks if the cluster has multiple members.
void	restart() Performs a shutdown/startup sequence.
boolean	sendMessage(Serializable payload) Sends a message of a given type across a cluster.
boolean	shutdown() Shuts down and clears resources held by this service.
static ClusteringService	startForked(String forkStackId, org.jgroups.Channel mainChannel) Starts a new clustering service by forking a channel of an existing JGroups channel.
static ClusteringService	startStandalone(String clusterName, String jgroupsConfig) Starts a standalone clustering service which in turn will start & connect its own JGroup channel.
boolean	tryLock(long time, TimeUnit unit) Acquires a cluster-wide lock, waiting a maximum amount of time for it.
void	unlock() Unlocks a previously acquired cluster-wide lock.

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

protected static final Logger LOGGER

listener

protected final ClusteringService.Listener listener

The listener for channel changes.

receiver

protected final ClusteringService.Receiver receiver

The component that will receive the JGroups messages.

clusterName

protected final String clusterName

The name of the cluster (in standalone mode) or the ID of the fork stack (in forked mode)

channel

protected org.jgroups.JChannel channel

The JGroups channel which will be used to send/receive event across the cluster

lockService

protected org.jgroups.blocks.locking.LockService lockService

The service used for cluster-wide locking

Constructor Detail

ClusteringService

protected ClusteringService(String clusterName)

Method Detail

restart

public void restart()
             throws Exception

Performs a shutdown/startup sequence.

Throws:

Exception - if anything unexpected fails

addConsumer

public void addConsumer(MessageConsumer<? extends Serializable> consumer)

Adds a new message consumer to this service.

Parameters:

consumer - a MessageConsumer instance.

shutdown

public boolean shutdown()

Shuts down and clears resources held by this service.

Returns:

true if the service has been shutdown or false if it had already been shut down.

tryLock

public boolean tryLock(long time,
              TimeUnit unit)

Acquires a cluster-wide lock, waiting a maximum amount of time for it.

Parameters:

time - an amount of time

unit - a TimeUnit; may not be null

Returns:

true if the lock was successfully acquired, false otherwise

See Also:

Lock.tryLock(long, java.util.concurrent.TimeUnit)

unlock

public void unlock()

Unlocks a previously acquired cluster-wide lock.

See Also:

Lock.unlock()

isOpen

public boolean isOpen()

Checks if this instance is open or not (open means the JGroups channel has been connected).

Returns:

true if the service is open, false otherwise.

multipleMembersInCluster

public boolean multipleMembersInCluster()

Checks if the cluster has multiple members.

Returns:

true if the cluster has multiple members, false otherwise.

membersInCluster

public int membersInCluster()

Returns the number of members in the cluster.

Returns:

the number of active members

clusterName

public String clusterName()

Returns the name of the cluster which has been configured for this service.

Returns:

a String the name of the cluster; never null

getMaxAllowedClockDelayMillis

public long getMaxAllowedClockDelayMillis()

Returns the maximum accepted delay in clock time between cluster members.

Returns:

the number of milliseconds representing the maximum accepted delay.

sendMessage

public boolean sendMessage(Serializable payload)

Sends a message of a given type across a cluster.

Parameters:

payload - the main body of the message; must not be null

Returns:

true if the send operation was successful, false otherwise

startStandalone

public static ClusteringService startStandalone(String clusterName,
                                String jgroupsConfig)

Starts a standalone clustering service which in turn will start & connect its own JGroup channel.

Parameters:

clusterName - the name of the cluster to which the JGroups channel should connect; may not be null

jgroupsConfig - either the path or the XML content of a JGroups configuration file; may not be null

Returns:

a ClusteringService instance, never null

startForked

public static ClusteringService startForked(String forkStackId,
                            org.jgroups.Channel mainChannel)

Starts a new clustering service by forking a channel of an existing JGroups channel.

Parameters:

forkStackId - a String representing the JGroups stack ID of the fork stack. Services which are supposed to communicate with each other should use the same stack id; may not be null

mainChannel - a Channel instance; may not be null.

Returns:

a ClusteringService instance, never null

fromByteArray

protected Serializable fromByteArray(byte[] data,
                         ClassLoader classLoader)
                              throws IOException,
                                     ClassNotFoundException

Throws:

IOException

ClassNotFoundException

getChannel

protected org.jgroups.JChannel getChannel()

init

protected abstract void init()