com.sun.sgs.impl.service.nodemap.affinity.dlpa
Class LabelPropagationServer

java.lang.Object
  com.sun.sgs.impl.service.nodemap.affinity.BasicState
      com.sun.sgs.impl.service.nodemap.affinity.dlpa.LabelPropagationServer

All Implemented Interfaces:

AffinityGroupFinder, LPAServer, LPAAffinityGroupFinder, Remote

public class LabelPropagationServer
extends BasicState
implements LPAAffinityGroupFinder, LPAServer

The server portion of the distributed label propagation algorithm.

The server is known to each node participating in the algorithm. It is responsible for preparing the nodes for a run of the algorithm, coordinating the iterations of the algorithm, and collecting and merging results from each node when finished.

Nested Class Summary

Nested classes/interfaces inherited from class com.sun.sgs.impl.service.nodemap.affinity.BasicState

BasicState.State

Field Summary

(package private) static int	DEFAULT_MAX_IO_ATTEMPTS The default number of IO task retries.
(package private) static int	DEFAULT_RETRY_WAIT_TIME The default time interval to wait between IO task retries.
static int	DEFAULT_SERVER_PORT The default value of the server port.
static String	IO_TASK_PROPERTY_PREFIX Prefix for io task related properties.
static String	IO_TASK_RETRIES_PROPERTY An optional property that specifies the maximum number of retries for IO tasks in services.
static String	IO_TASK_WAIT_TIME_PROPERTY An optional property that specifies the wait time between successive IO task retries.
static String	SERVER_EXPORT_NAME The name we export ourselves under.
static String	SERVER_PORT_PROPERTY The property name for the server port.

Fields inherited from class com.sun.sgs.impl.service.nodemap.affinity.BasicState

state

Constructor Summary

LabelPropagationServer(ProfileCollector col, WatchdogService wdog, Properties properties)
Constructs a new label propagation server.

Method Summary

void	disable() Disables the finder.
void	enable() Enables the finder.
NavigableSet<RelocatingAffinityGroup>	findAffinityGroups() Finds affinity groups across all nodes in the Darkstar cluster.
void	finishedIteration(long nodeId, boolean converged, boolean failed, int iteration) Indicates that the given nodeId has completed an iteration of the label propagation algorithm.
LPAClient	getLPAClientProxy(long nodeId) Returns the LPAClient for the given nodeId.
void	readyToBegin(long nodeId, boolean failed) Indicates that the given nodeId is ready to begin the label propagation algorithm.
void	register(long nodeId, LPAClient client) Registers a proxy for the node.
(package private) static boolean	runIoTask(IoRunnable ioTask, WatchdogService wdog, long nodeId, int maxTries, int waitTime, String name) Executes the specified ioTask by invoking its run method.
void	shutdown() Shuts down the finder.

Methods inherited from class com.sun.sgs.impl.service.nodemap.affinity.BasicState

checkForDisabledOrShutdownState, checkForShutdownState, setDisabledState, setEnabledState, setShutdownState

Methods inherited from class java.lang.Object

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

Field Detail

SERVER_PORT_PROPERTY

public static final String SERVER_PORT_PROPERTY

The property name for the server port.

See Also:

Constant Field Values

DEFAULT_SERVER_PORT

public static final int DEFAULT_SERVER_PORT

The default value of the server port.

See Also:

Constant Field Values

SERVER_EXPORT_NAME

public static final String SERVER_EXPORT_NAME

The name we export ourselves under.

See Also:

Constant Field Values

IO_TASK_PROPERTY_PREFIX

public static final String IO_TASK_PROPERTY_PREFIX

Prefix for io task related properties.

See Also:

Constant Field Values

IO_TASK_RETRIES_PROPERTY

public static final String IO_TASK_RETRIES_PROPERTY

An optional property that specifies the maximum number of retries for IO tasks in services.

See Also:

Constant Field Values

IO_TASK_WAIT_TIME_PROPERTY

public static final String IO_TASK_WAIT_TIME_PROPERTY

An optional property that specifies the wait time between successive IO task retries.

See Also:

Constant Field Values

DEFAULT_MAX_IO_ATTEMPTS

static final int DEFAULT_MAX_IO_ATTEMPTS

The default number of IO task retries.

See Also:

Constant Field Values

DEFAULT_RETRY_WAIT_TIME

static final int DEFAULT_RETRY_WAIT_TIME

The default time interval to wait between IO task retries.

See Also:

Constant Field Values

Constructor Detail

LabelPropagationServer

public LabelPropagationServer(ProfileCollector col,
                              WatchdogService wdog,
                              Properties properties)
                       throws IOException

Constructs a new label propagation server. Only one should exist within a Darkstar cluster.

Parameters:

col - the profile collector

wdog - the watchdog service, used for error reporting

properties - the application properties

Throws:

IOException - if an error occurs

Method Detail

findAffinityGroups

public NavigableSet<RelocatingAffinityGroup> findAffinityGroups()
                                                         throws AffinityGroupFinderFailedException

Finds affinity groups across all nodes in the Darkstar cluster. If no groups are found, an empty set is returned. If an error is encountered during a run, an AffinityGroupFinderFailedException is thrown. Errors include nodes not responding to server requests.

Specified by:

findAffinityGroups in interface LPAAffinityGroupFinder

Returns:

the affinity groups, or an empty set if none are found

Throws:

AffinityGroupFinderFailedException - if there is an error

disable

public void disable()

Disables the finder.

Specified by:

disable in interface AffinityGroupFinder

enable

public void enable()

Enables the finder.

Specified by:

enable in interface AffinityGroupFinder

shutdown

public void shutdown()

Shuts down the finder.

Specified by:

shutdown in interface AffinityGroupFinder

readyToBegin

public void readyToBegin(long nodeId,
                         boolean failed)
                  throws IOException

Indicates that the given nodeId is ready to begin the label propagation algorithm.

Specified by:

readyToBegin in interface LPAServer

Parameters:

nodeId - the node that is ready to begin

failed - true if there was a problem while setting up

Throws:

IOException - if there is a communication problem

finishedIteration

public void finishedIteration(long nodeId,
                              boolean converged,
                              boolean failed,
                              int iteration)
                       throws IOException

Indicates that the given nodeId has completed an iteration of the label propagation algorithm.

Specified by:

finishedIteration in interface LPAServer

Parameters:

nodeId - the node that has finished an iteration

converged - true if the node believes the algorithm has converged and can be stopped

failed - true if there was a problem while running

iteration - the iteration that has finished

Throws:

IOException - if there is a communication problem

getLPAClientProxy

public LPAClient getLPAClientProxy(long nodeId)
                            throws IOException

Returns the LPAClient for the given nodeId. If null is returned, the node should be considered failed.

Specified by:

getLPAClientProxy in interface LPAServer

Parameters:

nodeId - the node we need the proxy for

Returns:

the LPA client proxy for the given node, or null if the node has failed

Throws:

IOException - if there is a communication problem

register

public void register(long nodeId,
                     LPAClient client)
              throws IOException

Registers a proxy for the node. If a client has already been registered for the node, it is replaced.

Specified by:

register in interface LPAServer

Parameters:

nodeId - the node the proxy represents

client - the client proxy, which this server and other nodes can call

Throws:

IOException - if there is a communication problem

runIoTask

static boolean runIoTask(IoRunnable ioTask,
                         WatchdogService wdog,
                         long nodeId,
                         int maxTries,
                         int waitTime,
                         String name)

Executes the specified ioTask by invoking its run method. If the specified task throws an IOException, this method will retry the task for a fixed number of times. The number of retries and the wait time between retries are configurable properties.

This is much the same as the like method in AbstractService, except we don't bother to check for a transactional context (we won't be in one).

Parameters:

ioTask - a task with IO-related operations

wdog - the watchdog service for the local node, in case of failure

nodeId - the node that should be shut down in case of failure

maxTries - the number of times to attempt the retry

waitTime - the amount of time to wait before retry

name - name of caller, in case of failure

Returns:

true if the ioTask ran successfully