com.sun.sgs.impl.service.watchdog
Class WatchdogServerImpl

java.lang.Object
  com.sun.sgs.impl.util.AbstractService
      com.sun.sgs.impl.service.watchdog.WatchdogServerImpl

All Implemented Interfaces:

WatchdogServer, Service, Remote

public final class WatchdogServerImpl
extends AbstractService
implements WatchdogServer

The WatchdogServer implementation.

The constructor supports the following properties:

Property: com.sun.sgs.impl.service.watchdog.server.port
Default: 44533

Specifies the network port for the server. This value must be greater than or equal to 0 and no greater than 65535. If the value specified is 0, then an anonymous port will be chosen. The value chosen will be logged, and can also be accessed with the getPort method.

Property: com.sun.sgs.impl.service.watchdog.server.renew.interval
Default: 1000 (one second)

Specifies the renew interval which is returned by the renewNode method). The interval must be greater than or equal to 5 milliseconds and less than or equal to 10000 milliseconds (10 seconds).

Property: com.sun.sgs.impl.service.watchdog.server.timeflush.interval
Default: 5000 (five seconds)

Represents the amount of time in milliseconds that the server will wait between updates to the global application time stored in the data store. A larger value will take less system resources but will allow the possibility of the global application clock to drift by at least the given value if the system crashes. The interval must be greater than or equal to 100 milliseconds and less than or equal to 300000 milliseconds.

Note that this server caches NodeImpls outside the data service to maintain state.

Nested Class Summary

Nested classes/interfaces inherited from class com.sun.sgs.impl.util.AbstractService

AbstractService.State, AbstractService.Version

Field Summary

(package private) static int	DEFAULT_PORT The default value of the server port.
(package private) SortedSet<NodeImpl>	expirationSet The set of alive nodes, sorted by renew expiration time.
(package private) long	localNodeId The node ID for this server.
(package private) Object	notifyClientsLock The lock for notifying the NotifyClientsThread.
(package private) static String	PORT_PROPERTY The property name for the server port.
(package private) long	renewInterval The renew interval.
(package private) Queue<NodeImpl>	statusChangedNodes The queue of nodes whose status has changed.
(package private) long	timeflushInterval The timeflush interval.
(package private) static String	WATCHDOG_SERVER_NAME The server name in the registry.

Fields inherited from class com.sun.sgs.impl.util.AbstractService

appName, dataService, IO_TASK_PROPERTY_PREFIX, IO_TASK_RETRIES_PROPERTY, IO_TASK_WAIT_TIME_PROPERTY, maxIoAttempts, retryWaitTime, taskOwner, taskScheduler, transactionScheduler, txnProxy

Constructor Summary

WatchdogServerImpl(Properties properties, ComponentRegistry systemRegistry, TransactionProxy txnProxy, String host, WatchdogClient client, boolean fullStack)
Constructs an instance of this class with the specified properties.

Method Summary

long	currentAppTimeMillis() Returns the global application time in milliseconds as it is maintained by the central node.
protected void	doReady() Performs ready operations.
protected void	doShutdown() Performs shutdown operations.
int	getPort() Returns the port being used for this server.
(package private) long	getTimeOffset() Returns the offset being used by this server to report global application time with the currentAppTimeMillis() method.
protected void	handleServiceVersionMismatch(AbstractService.Version oldVersion, AbstractService.Version currentVersion) Handles conversion from the oldVersion to the currentVersion.
(package private) Collection<NodeImpl>	processNodeFailures(Collection<NodeImpl> nodesToFail) Processes the nodes which have failed by calling the failure methods for each node in the collection.
void	recoveredNode(long nodeId, long backupId) Notifies this watchdog that the node with the specified nodeId has been recovered by the node with the specified backupId.
long	registerNode(long nodeId, String host, WatchdogClient client, int jmxPort) Registers a node with the corresponding nodeId, host, and client, and returns the interval (in milliseconds) that this watchdog must be notified, via the renewNode method, in order for the specified node to be considered alive.
boolean	renewNode(long nodeId) Notifies this watchdog that the node with the specified nodeId is alive.
void	setNodeHealth(long nodeId, boolean isLocal, Node.Health health, String component, int maxNumberOfAttempts) Notifies the node with the given ID that its health has been set.

Methods inherited from class com.sun.sgs.impl.util.AbstractService

callFinished, callStarted, checkNonTransactionalContext, checkServiceVersion, createTaskQueue, getDataService, getName, getState, isAlive, isInInitializedState, isRetryableException, ready, runIoTask, shutdown, shuttingDown

Methods inherited from class java.lang.Object

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

Field Detail

WATCHDOG_SERVER_NAME

static final String WATCHDOG_SERVER_NAME

The server name in the registry.

See Also:

Constant Field Values

PORT_PROPERTY

static final String PORT_PROPERTY

The property name for the server port.

See Also:

Constant Field Values

DEFAULT_PORT

static final int DEFAULT_PORT

The default value of the server port.

See Also:

Constant Field Values

renewInterval

final long renewInterval

The renew interval.

timeflushInterval

final long timeflushInterval

The timeflush interval.

localNodeId

final long localNodeId

The node ID for this server.

notifyClientsLock

final Object notifyClientsLock

The lock for notifying the NotifyClientsThread.

statusChangedNodes

final Queue<NodeImpl> statusChangedNodes

The queue of nodes whose status has changed.

expirationSet

final SortedSet<NodeImpl> expirationSet

The set of alive nodes, sorted by renew expiration time.

Constructor Detail

WatchdogServerImpl

public WatchdogServerImpl(Properties properties,
                          ComponentRegistry systemRegistry,
                          TransactionProxy txnProxy,
                          String host,
                          WatchdogClient client,
                          boolean fullStack)
                   throws Exception

Constructs an instance of this class with the specified properties. See the class documentation for a list of supported properties.

Parameters:

properties - server properties

systemRegistry - the system registry

txnProxy - the transaction proxy

host - the local host name

client - the local watchdog client

fullStack - true if this server is running on a full stack

Throws:

Exception - if there is a problem starting the server

Method Detail

handleServiceVersionMismatch

protected void handleServiceVersionMismatch(AbstractService.Version oldVersion,
                                            AbstractService.Version currentVersion)

Handles conversion from the oldVersion to the currentVersion. This method is invoked by checkServiceVersion if a version mismatch is detected and is invoked from within a transaction.

Specified by:

handleServiceVersionMismatch in class AbstractService

Parameters:

oldVersion - the old version

currentVersion - the current version

doReady

protected void doReady()
                throws Exception

Performs ready operations. This method is invoked by the ready method only once so that the subclass can perform any operations necessary during the "ready" phase.

Specified by:

doReady in class AbstractService

Throws:

Exception - if a problem occurs

doShutdown

protected void doShutdown()

Performs shutdown operations. This method is invoked by the shutdown method only once so that the subclass can perform any operations necessary to shutdown the service.

Specified by:

doShutdown in class AbstractService

registerNode

public long registerNode(long nodeId,
                         String host,
                         WatchdogClient client,
                         int jmxPort)
                  throws NodeRegistrationFailedException

Registers a node with the corresponding nodeId, host, and client, and returns the interval (in milliseconds) that this watchdog must be notified, via the renewNode method, in order for the specified node to be considered alive.

If this method throws NodeRegistrationFailedException, the caller should not retry as this indicates a fatal error.

When a node fails or a new node starts, the given client will be notified of these status changes via its nodeStatusChanges method.

Specified by:

registerNode in interface WatchdogServer

Parameters:

nodeId - the node ID of the node

host - a host name

client - a watchdog client

jmxPort - the port JMX is listening on, or -1 if JMX is not enabled for remote listening on the node

Returns:

the renew interval (in milliseconds)

Throws:

NodeRegistrationFailedException - if there is a problem registering the node

renewNode

public boolean renewNode(long nodeId)

Notifies this watchdog that the node with the specified nodeId is alive. This method returns true if this watchdog still considers the node alive, and returns false otherwise. This watchdog considers the node to have failed if a renew request is not received from the node before the assigned interval, returned from registerNode, expires. If this method returns false for a given nodeId, the caller should not retry this method because the node is considered to have failed.

Specified by:

renewNode in interface WatchdogServer

Parameters:

nodeId - a node ID

Returns:

true if the node is considered alive, false otherwise

recoveredNode

public void recoveredNode(long nodeId,
                          long backupId)

Notifies this watchdog that the node with the specified nodeId has been recovered by the node with the specified backupId.

Specified by:

recoveredNode in interface WatchdogServer

Parameters:

nodeId - the recovered node's ID

backupId - the backup node's ID

setNodeHealth

public void setNodeHealth(long nodeId,
                          boolean isLocal,
                          Node.Health health,
                          String component,
                          int maxNumberOfAttempts)

Notifies the node with the given ID that its health has been set. If the health is RED it indicates that the node has failed and should be shutdown. In this case, if the given node is a remote node, this notification is a result of a server running into difficulty communicating with a remote node, so the server's watchdog service is responsible for notifying the watchdog service in order to issue the shutdown. The component parameter may be any identifying string, but is typically the class name of the component that reported the specified health.

Specified by:

setNodeHealth in interface WatchdogServer

Parameters:

nodeId - the node's ID

isLocal - specifies if the node is reporting health on itself or a remote node

health - the node's health

component - the component reported the specified health

maxNumberOfAttempts - the maximum number of attempts to try and resolve an IOException

currentAppTimeMillis

public long currentAppTimeMillis()

Returns the global application time in milliseconds as it is maintained by the central node. This method returns the amount of time in milliseconds that the current application has been running since the initialize method was called on the application's AppListener object.

Note: Since this method is typically called as part of a Remote interface, appropriate measures should be taken to account for possible network latency.

Specified by:

currentAppTimeMillis in interface WatchdogServer

Returns:

the global application time in milliseconds according to the central time server

getTimeOffset

long getTimeOffset()

Returns the offset being used by this server to report global application time with the currentAppTimeMillis() method.

Returns:

the time offset

processNodeFailures

Collection<NodeImpl> processNodeFailures(Collection<NodeImpl> nodesToFail)

Processes the nodes which have failed by calling the failure methods for each node in the collection. The processes are separated into two for-loops so that a failed node is not mistakenly chosen as a backup while this operation is occurring.

Parameters:

nodesToFail - the collection of failed nodes

Returns:

a subset of nodesToFail that were marked as failed from this method

getPort

public int getPort()

Returns the port being used for this server.

Returns:

the server port