com.sun.sgs.impl.nio
Class ReactiveChannelGroup

java.lang.Object
  com.sun.sgs.nio.channels.AsynchronousChannelGroup
      com.sun.sgs.impl.nio.AsyncGroupImpl
          com.sun.sgs.impl.nio.ReactiveChannelGroup

 class ReactiveChannelGroup
extends AsyncGroupImpl

A select-based AsynchronousChannelGroup.

This class is a container for a set of Reactors which do the actual work of registering and dispatching asynchronous operations on channels. It provides:

• Lifecycle support: creating and configuring the Reactor set, supporting graceful and immediate shutdown, and awaiting termination.
• Channel registration and load balancing across multiple Reactors: channels are assigned to one of the reactors in the set. Since reactors are single-threaded, the reactor set allows multiple CPUs to be utilized by having multiple separate reactors.

The default number of Reactors is set as the number of available processors, but it can be changed by setting the requested number in the system property "com.sun.sgs.nio.async.reactive.reactors".

Nested Class Summary

(package private) class	ReactiveChannelGroup.HashingReactorAssignmentStrategy A Reactor load balancing strategy that chooses a reactor based on the hash of the channel.
(package private) static interface	ReactiveChannelGroup.ReactorAssignmentStrategy Interface for Reactor load balancing strategies.
(package private) class	ReactiveChannelGroup.Worker Worker to run a reactor and check termination when a reactor completes.

Field Summary

static int	DEFAULT_REACTORS The default number of reactors to be used by channel groups: Runtime.getRuntime().availableProcessors()
protected static int	DONE State: terminated
protected int	lifecycleState The lifecycle state of this group.
(package private) static Logger	log The logger for this class.
(package private) ReactiveChannelGroup.ReactorAssignmentStrategy	reactorAssignmentStrategy The reactor load-balance strategy.
(package private) List<Reactor>	reactors The active reactors in this group.
static String	REACTORS_PROPERTY The property to specify the number of reactors to be used by channel groups: "com.sun.sgs.nio.async.reactive.reactors"
protected static int	RUNNING State: open and running
protected static int	SHUTDOWN State: graceful shutdown in progress
protected static int	SHUTDOWN_NOW State: forced shutdown in progress
(package private) Object	stateLock Lock held on updates to lifecycleState and reactors list, and the condition variable for awaiting group termination.

Fields inherited from class com.sun.sgs.impl.nio.AsyncGroupImpl

executor, uncaughtHandler

Constructor Summary

ReactiveChannelGroup(ReactiveAsyncChannelProvider provider, ExecutorService executor)
Creates a new group with the default number of reactors.

ReactiveChannelGroup(ReactiveAsyncChannelProvider provider, ExecutorService executor, int requestedReactors)
Creates a new group with the requested number of reactors.

Method Summary

boolean	awaitTermination(long timeout, TimeUnit unit) Awaits termination of the group.
boolean	isShutdown() Tells whether or not this asynchronous channel group is shutdown.
boolean	isTerminated() Tells whether or not this asynchronous channel group is terminated.
(package private) AsyncKey	register(SelectableChannel ch) Registers the given channel with this group, returning an AsyncKey that can be used to invoke asynchronous IO operations.
ReactiveChannelGroup	shutdown() Initiates an orderly shutdown of the group.
ReactiveChannelGroup	shutdownNow() Shuts down the group and closes all open channels in the group.

Methods inherited from class com.sun.sgs.impl.nio.AsyncGroupImpl

completionRunner, executor, finalize, selectorProvider

Methods inherited from class com.sun.sgs.nio.channels.AsynchronousChannelGroup

getDefaultUncaughtExceptionHandler, open, provider, setDefaultUncaughtExceptionHandler

Methods inherited from class java.lang.Object

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

Field Detail

log

static final Logger log

The logger for this class.

stateLock

final Object stateLock

Lock held on updates to lifecycleState and reactors list, and the condition variable for awaiting group termination.

lifecycleState

protected int lifecycleState

The lifecycle state of this group. Increases monotonically. It may only be accessed with stateLock held.

RUNNING

protected static final int RUNNING

State: open and running

See Also:

Constant Field Values

SHUTDOWN

protected static final int SHUTDOWN

State: graceful shutdown in progress

See Also:

Constant Field Values

SHUTDOWN_NOW

protected static final int SHUTDOWN_NOW

State: forced shutdown in progress

See Also:

Constant Field Values

DONE

protected static final int DONE

State: terminated

See Also:

Constant Field Values

reactors

final List<Reactor> reactors

The active reactors in this group. It may only be accessed with stateLock held.

REACTORS_PROPERTY

public static final String REACTORS_PROPERTY

The property to specify the number of reactors to be used by channel groups: "com.sun.sgs.nio.async.reactive.reactors"

See Also:

Constant Field Values

DEFAULT_REACTORS

public static final int DEFAULT_REACTORS

The default number of reactors to be used by channel groups: Runtime.getRuntime().availableProcessors()

reactorAssignmentStrategy

final ReactiveChannelGroup.ReactorAssignmentStrategy reactorAssignmentStrategy

The reactor load-balance strategy.

Constructor Detail

ReactiveChannelGroup

ReactiveChannelGroup(ReactiveAsyncChannelProvider provider,
                     ExecutorService executor)
               throws IOException

Creates a new group with the default number of reactors.

Parameters:

provider - the provider that created this group

executor - the executor for this group

Throws:

IOException - if an I/O error occurs

ReactiveChannelGroup

ReactiveChannelGroup(ReactiveAsyncChannelProvider provider,
                     ExecutorService executor,
                     int requestedReactors)
               throws IOException

Creates a new group with the requested number of reactors. If {code 0} reactors are requested, a default is chosen as the number of available processors.

Parameters:

provider - the provider that created this group

executor - the executor for this group

requestedReactors - the number of reactors to create in this group, or 0 to use the default

Throws:

IllegalArgumentException - if a negative number of reactors is requested

IOException - if an I/O error occurs

Method Detail

register

AsyncKey register(SelectableChannel ch)
            throws IOException

Registers the given channel with this group, returning an AsyncKey that can be used to invoke asynchronous IO operations. If this group is shutdown, this method will throw ShutdownChannelGroupException and close the channel.

Specified by:

register in class AsyncGroupImpl

Parameters:

ch - the underlying channel for IO operations

Returns:

an AsyncKey that supports asynchronous operations on the underlying channel

Throws:

IOException - if an I/O error occurs

awaitTermination

public boolean awaitTermination(long timeout,
                                TimeUnit unit)
                         throws InterruptedException

Awaits termination of the group.

This method blocks until all channels in the group have been closed and all resources associated with the group have been released.

Specified by:

awaitTermination in class AsynchronousChannelGroup

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

true if the group has terminated; false if the timeout elapsed before termination

Throws:

InterruptedException - if interrupted while waiting

isShutdown

public boolean isShutdown()

Tells whether or not this asynchronous channel group is shutdown.

Specified by:

isShutdown in class AsynchronousChannelGroup

Returns:

true if this asynchronous channel group is shutdown

isTerminated

public boolean isTerminated()

Tells whether or not this asynchronous channel group is terminated.

Specified by:

isTerminated in class AsynchronousChannelGroup

Returns:

true if this asynchronous channel group is terminated

shutdown

public ReactiveChannelGroup shutdown()

Initiates an orderly shutdown of the group.

This method marks the group as shutdown. Further attempts to construct a channel that binds to this group will throw ShutdownChannelGroupException. The group terminates when all asynchronous channels in the group are closed and all resources have been released. This method has no effect if the group is already shutdown.

Specified by:

shutdown in class AsynchronousChannelGroup

Returns:

this group

shutdownNow

public ReactiveChannelGroup shutdownNow()
                                 throws IOException

Shuts down the group and closes all open channels in the group.

In addition to the actions performed by the AsynchronousChannelGroup.shutdown() method, this method invokes the close method on all open channels in the group. This method does not attempt to stop actively executing completion handlers.

The group is likely to terminate quickly after invoking this method but there is no guarantee that the group has terminated on completion of this method.

Specified by:

shutdownNow in class AsynchronousChannelGroup

Returns:

this group

Throws:

IOException - if an I/O error occurs