de.aristaflow.adept2.core.registry.cluster

Class ClusterNodeState

java.lang.Object

de.aristaflow.adept2.core.registry.cluster.ClusterNodeState

public class ClusterNodeState
extends java.lang.Object

This class encapsulates the state of a cluster node in memory. It also provides control data like restarting or shutting down. Package-scoped methods are only called from the corresponding ClusterNode. Both classes interact closely with respect to field access and locking.

Field Summary

Fields

Modifier and Type	Field and Description
protected AbortServiceException	aseBlocker An AbortServiceException that occurred and blocks the cluster node from continuing.
protected java.lang.String	clusterName The cluster name of the node.
protected java.util.concurrent.locks.Lock	controlLock The lock required to control the cluster node.
protected java.util.concurrent.locks.Condition	controlSignal The condition for the node control to wait for external signals, e. g.
protected java.util.Set<java.lang.Thread>	currentStatusChangeWaiters The threads that await statusChange which has been signalled.
protected java.lang.Error	errBlocker An Error that occurred and blocks the cluster node from continuing.
protected boolean	isServer Whether the cluster node is a server node.
protected long	lastStatusUpdate The time the status has been updated the last time.
protected java.lang.String	name The name of the cluster node.
protected java.util.Set<java.lang.Thread>	nextStatusChangeWaiters The threads that await statusChange and have arrived after its last signalling.
protected java.lang.Thread	nodeControl The thread controlling the cluster node, that is it handles the complete node lifecycle including restarting and thus changing roles.
protected boolean	restarting Whether the control thread has accepted a restarting request and is currently restarting.
protected boolean	restartRequested Whether a restart has been requested from the outside or becomes necessary due to internal problems.
protected long	runningSince The time since the cluster node is running (value stems from the database).
protected boolean	shutdown Whether a shutdown has been requested from the outside or becomes necessary due to internal problems.
protected Status	status The current status of the cluster node.
protected java.util.concurrent.locks.Condition	statusChange The condition of the control lock for threads that wait for a specific status, awaitStatus(long, Status...).
protected java.util.concurrent.locks.Condition	statusChangeWaitersLeft The condition of the control lock to let node control wait for all threads currently waiting for statusChange.

Method Summary

Modifier and Type	Method and Description
Status	awaitStatus(long timeout, Status... statuses) Waits until the cluster node reaches one of the designated statuses or until the designated timeout elapsed.
java.lang.String	getClusterName() Gets the name of the cluster of this node if available.
java.lang.String	getClusterNodeName() Gets the complete name of this cluster node, that is the name of the cluster (if available) and the node name.
protected java.lang.String	getLogName() Gets the name of the cluster together with whether it is a server or client cluster node.
java.lang.String	getName() Gets the name of the cluster node.
Status	getStatus() Gets the current status of the cluster node without waiting.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected final java.lang.String name

The name of the cluster node. If none is provided via the configuration, a random default value is chosen automatically.

clusterName

protected java.lang.String clusterName

The cluster name of the node. This is only be available while a cluster platform exists.

isServer

protected volatile boolean isServer

Whether the cluster node is a server node.

shutdown

protected volatile boolean shutdown

Whether a shutdown has been requested from the outside or becomes necessary due to internal problems.

restartRequested

protected volatile boolean restartRequested

Whether a restart has been requested from the outside or becomes necessary due to internal problems.

restarting

protected volatile boolean restarting

Whether the control thread has accepted a restarting request and is currently restarting. While restarting further restart requests have to be ignored.

status

protected volatile Status status

The current status of the cluster node. This corresponds to the value in the corresponding table – usually a bit delayed.

lastStatusUpdate

protected volatile long lastStatusUpdate

The time the status has been updated the last time. Asynchronous requests needs this to detect whether the node control has responded to the request.

runningSince

protected volatile long runningSince

The time since the cluster node is running (value stems from the database).

aseBlocker

protected AbortServiceException aseBlocker

An AbortServiceException that occurred and blocks the cluster node from continuing.

errBlocker

protected java.lang.Error errBlocker

An Error that occurred and blocks the cluster node from continuing.

nodeControl

protected final java.lang.Thread nodeControl

The thread controlling the cluster node, that is it handles the complete node lifecycle including restarting and thus changing roles. When changing the node state the name of this thread will be adapted appropriately to reflect the current status.

controlLock

protected final java.util.concurrent.locks.Lock controlLock

The lock required to control the cluster node. This includes control operations like starting, terminating and restarting but also status changes.

controlSignal

protected final java.util.concurrent.locks.Condition controlSignal

The condition for the node control to wait for external signals, e. g. restart(long).

statusChange

protected final java.util.concurrent.locks.Condition statusChange

The condition of the control lock for threads that wait for a specific status, awaitStatus(long, Status...).

nextStatusChangeWaiters

protected volatile java.util.Set<java.lang.Thread> nextStatusChangeWaiters

The threads that await statusChange and have arrived after its last signalling.

currentStatusChangeWaiters

protected volatile java.util.Set<java.lang.Thread> currentStatusChangeWaiters

The threads that await statusChange which has been signalled. This threads have to leave (if their condition is right). This prevents threads waiting for statusChange to miss signals.

statusChangeWaitersLeft

protected final java.util.concurrent.locks.Condition statusChangeWaitersLeft

The condition of the control lock to let node control wait for all threads currently waiting for statusChange. This is signalled as soon as currentStatusChangeWaiters is empty.

Method Detail

getName

public java.lang.String getName()

Gets the name of the cluster node. This is independent from the status and created once for the complete lifetime of a ClusterNode.

Returns:

The name of the cluster node.

getClusterName

public java.lang.String getClusterName()

Gets the name of the cluster of this node if available. null if there is currently no platform.

Returns:

The name of the cluster of this node or null if there is no current platform.

getClusterNodeName

public java.lang.String getClusterNodeName()

Gets the complete name of this cluster node, that is the name of the cluster (if available) and the node name.

Returns:

The complete name of this cluster node, that is the name of the cluster (if available) and the node name.

getLogName

protected java.lang.String getLogName()

Gets the name of the cluster together with whether it is a server or client cluster node. Use this in log messages.

Returns:

The name of the cluster together with whether it is a server or client cluster node for usage in log messages.

getStatus

public Status getStatus()
                 throws AbortServiceException

Gets the current status of the cluster node without waiting.

Returns:

The current status of this cluster node.

Throws:

AbortServiceException - If there are non-recoverable problems with the cluster especially when bootstrapping, an AbortServiceException will be thrown. This exception indicates that the status is Status.TERMINATED.

awaitStatus

public Status awaitStatus(long timeout,
                          Status... statuses)
                   throws java.lang.InterruptedException,
                          AbortServiceException

Waits until the cluster node reaches one of the designated statuses or until the designated timeout elapsed. The reached status will be returned or null in case the timeout elapsed before one of these statuses has been reached.
If the node control is not running any more, Status.TERMINATED will remain the status and no waiting will take place.

Parameters:

timeout - The time in milliseconds to wait for the cluster node to reach one of the designated statuses. Use 0 to not wait at all or a negative value to wait without time limit. The time required for the lock will count to this timeout.

statuses - The statuses which should be reached by this cluster node.

Returns:

The current status of the cluster node if it is one of the awaited statuses, null otherwise.

Throws:

java.lang.InterruptedException - If the current thread is interrupted while waiting for one of the designated statuses, an InterruptedException will be thrown.

AbortServiceException - If there are non-recoverable problems with the cluster especially when bootstrapping, an AbortServiceException will be thrown.