rice.selector
Class SelectorManager

java.lang.Object
  java.lang.Thread
      rice.selector.SelectorManager

All Implemented Interfaces:

java.lang.Runnable, Destructable, Timer

Direct Known Subclasses:

ProfileSelector

public class SelectorManager
extends java.lang.Thread
implements Timer, Destructable

This class is the class which handles the selector, and listens for activity. When activity occurs, it figures out who is interested in what has happened, and hands off to that object.

Version:

$Id: SelectorManager.java 3524 2007-01-09 14:09:27Z jeffh $

Author:

Alan Mislove

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

protected java.util.HashSet	cancelledKeys
protected java.lang.String	instance
protected java.util.LinkedList	invocations
protected Logger	logger
protected java.util.HashSet	modifyKeys
protected boolean	running
protected boolean	select Can be disabled for the simulator to improve performance, only do this if you know you don't need to select on anything
protected java.nio.channels.Selector	selector
static int	TIMEOUT
protected java.util.Queue	timerQueue
protected TimeSource	timeSource
protected boolean	useLoopListeners LoopListeners is used in case you are worried that your process may not get scheduled for a while such as on an overloaded planetlab node, or if you hibernate your laptop, this is not needed for the simulator
protected long	wakeupTime

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

SelectorManager(java.lang.String instance, TimeSource timeSource, LogManager log)
Constructor, which is private since there is only one selector per JVM.

Method Summary

void	addLoopObserver(LoopObserver lo)
void	cancel(java.nio.channels.SelectionKey key) Method which asks the Selector Manager to add the given key to the cancelled set.
void	destroy()
protected void	doInvocations() Method which invokes all pending invocations.
protected void	doSelections()
protected void	executeDueTasks() Internal method which finds all due tasks and executes them.
protected java.lang.Runnable	getInvocation() Method which synchroniously returns the first element off of the invocations list.
java.nio.channels.SelectionKey	getKey(java.nio.channels.SelectableChannel channel) Utility method which returns the SelectionKey attached to the given channel, if one exists
protected java.nio.channels.SelectionKey	getModifyKey() Method which synchroniously returns on element off of the modifyKeys list
long	getNextTaskExecutionTime()
int	getNumInvocations() Debug method which returns the number of pending invocations
java.nio.channels.Selector	getSelector()
Timer	getTimer() Returns the timer associated with this SelectorManager (in this case, it is this).
void	invoke(java.lang.Runnable d) This method schedules a runnable task to be done by the selector thread during the next select() call.
boolean	isSelectorThread() Returns whether or not this thread of execution is the selector thread
void	modifyKey(java.nio.channels.SelectionKey key) Adds a selectionkey handler into the list of handlers which wish to change their keys.
protected void	notifyLoopListeners()
protected void	onLoop() This method is to be implemented by a subclass to do some task each loop.
java.nio.channels.SelectionKey	register(java.nio.channels.SelectableChannel channel, SelectionKeyHandler handler, int ops) Registers a new channel with the selector, and attaches the given SelectionKeyHandler as the handler for the newly created key.
void	removeLoopObserver(LoopObserver lo)
void	run() This method starts the socket manager listening for events.
void	schedule(TimerTask task) Method which schedules a task to run after a specified number of millis.
void	schedule(TimerTask task, long delay)
void	schedule(TimerTask task, long delay, long period) Method which schedules a task to run repeatedly after a specified delay and period
void	scheduleAtFixedRate(TimerTask task, long delay, long period) Method which schedules a task to run repeatedly (at a fixed rate) after a specified delay and period
protected java.nio.channels.SelectionKey[]	selectedKeys() Selects all of the currenlty selected keys on the selector and returns the result as an array of keys.
void	setEnvironment(Environment env) Can only be called once.
void	setSelect(boolean b)
void	useLoopListeners(boolean val) Set this to false when using the simulator, because you don't need to notify loop observers.
void	wakeup() Note, should hold the selector's (this) lock to call this.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

TIMEOUT

public static int TIMEOUT

selector

protected java.nio.channels.Selector selector

invocations

protected java.util.LinkedList invocations

modifyKeys

protected java.util.HashSet modifyKeys

cancelledKeys

protected java.util.HashSet cancelledKeys

timerQueue

protected java.util.Queue timerQueue

wakeupTime

protected long wakeupTime

timeSource

protected TimeSource timeSource

logger

protected Logger logger

instance

protected java.lang.String instance

running

protected boolean running

select

protected boolean select

Can be disabled for the simulator to improve performance, only do this if you know you don't need to select on anything

useLoopListeners

protected boolean useLoopListeners

LoopListeners is used in case you are worried that your process may not get scheduled for a while such as on an overloaded planetlab node, or if you hibernate your laptop, this is not needed for the simulator

Constructor Detail

SelectorManager

public SelectorManager(java.lang.String instance,
                       TimeSource timeSource,
                       LogManager log)

Constructor, which is private since there is only one selector per JVM.

Method Detail

setEnvironment

public void setEnvironment(Environment env)

Can only be called once. The rest of the time the argument is rejected. This is needed so that when the NodeFactory clones the Environment, it doesn't get restarted/have multiple different environments etc...

Parameters:

env -

cancel

public void cancel(java.nio.channels.SelectionKey key)

Method which asks the Selector Manager to add the given key to the cancelled set. If noone calls register on this key during the rest of this select() operation, the key will be cancelled. Otherwise, it will be returned as a result of the register operation.

Parameters:

key - The key to cancel

getKey

public java.nio.channels.SelectionKey getKey(java.nio.channels.SelectableChannel channel)

Utility method which returns the SelectionKey attached to the given channel, if one exists

Parameters:

channel - The channel to return the key for

Returns:

The key

register

public java.nio.channels.SelectionKey register(java.nio.channels.SelectableChannel channel,
                                               SelectionKeyHandler handler,
                                               int ops)
                                        throws java.io.IOException

Registers a new channel with the selector, and attaches the given SelectionKeyHandler as the handler for the newly created key. Operations which the hanlder is interested in will be called as available.

Parameters:

channel - The channel to regster with the selector

handler - The handler to use for the callbacks

ops - The initial interest operations

Returns:

The SelectionKey which uniquely identifies this channel

Throws:

java.io.IOException

invoke

public void invoke(java.lang.Runnable d)

This method schedules a runnable task to be done by the selector thread during the next select() call. All operations which modify the selector should be done using this method, as they must be done in the selector thread.

Parameters:

d - The runnable task to invoke

getNumInvocations

public int getNumInvocations()

Debug method which returns the number of pending invocations

Returns:

The number of pending invocations

modifyKey

public void modifyKey(java.nio.channels.SelectionKey key)

Adds a selectionkey handler into the list of handlers which wish to change their keys. Thus, modifyKeys() will be called on the next selection operation

Parameters:

key - The key which is to be chanegd

onLoop

protected void onLoop()

This method is to be implemented by a subclass to do some task each loop.

run

public void run()

This method starts the socket manager listening for events. It is designed to be started when this thread's start() method is invoked.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

destroy

public void destroy()

Specified by:

destroy in interface Destructable

Overrides:

destroy in class java.lang.Thread

useLoopListeners

public void useLoopListeners(boolean val)

Set this to false when using the simulator, because you don't need to notify loop observers.

Parameters:

val -

notifyLoopListeners

protected void notifyLoopListeners()

addLoopObserver

public void addLoopObserver(LoopObserver lo)

removeLoopObserver

public void removeLoopObserver(LoopObserver lo)

doSelections

protected void doSelections()
                     throws java.io.IOException

Throws:

java.io.IOException

doInvocations

protected void doInvocations()

Method which invokes all pending invocations. This method should *only* be called by the selector thread.

getInvocation

protected java.lang.Runnable getInvocation()

Method which synchroniously returns the first element off of the invocations list.

Returns:

An item from the invocations list

getModifyKey

protected java.nio.channels.SelectionKey getModifyKey()

Method which synchroniously returns on element off of the modifyKeys list

Returns:

An item from the invocations list

selectedKeys

protected java.nio.channels.SelectionKey[] selectedKeys()
                                                 throws java.io.IOException

Selects all of the currenlty selected keys on the selector and returns the result as an array of keys.

Returns:

The array of keys

Throws:

java.io.IOException - DESCRIBE THE EXCEPTION

isSelectorThread

public boolean isSelectorThread()

Returns whether or not this thread of execution is the selector thread

Returns:

Whether or not this is the selector thread

schedule

public void schedule(TimerTask task)

Method which schedules a task to run after a specified number of millis. The task must have a proper nextExecutionTime set

Specified by:

schedule in interface Timer

Parameters:

task - The task to run

schedule

public void schedule(TimerTask task,
                     long delay)

Specified by:

schedule in interface Timer

schedule

public void schedule(TimerTask task,
                     long delay,
                     long period)

Method which schedules a task to run repeatedly after a specified delay and period

Specified by:

schedule in interface Timer

Parameters:

task - The task to run

delay - The delay before first running, in milliseconds

period - The period with which to run in milliseconds

scheduleAtFixedRate

public void scheduleAtFixedRate(TimerTask task,
                                long delay,
                                long period)

Method which schedules a task to run repeatedly (at a fixed rate) after a specified delay and period

Specified by:

scheduleAtFixedRate in interface Timer

Parameters:

task - The task to run

delay - The delay before first running in milliseconds

period - The period with which to run in milliseconds

wakeup

public void wakeup()

Note, should hold the selector's (this) lock to call this.

getNextTaskExecutionTime

public long getNextTaskExecutionTime()

executeDueTasks

protected void executeDueTasks()

Internal method which finds all due tasks and executes them.

getTimer

public Timer getTimer()

Returns the timer associated with this SelectorManager (in this case, it is this).

Returns:

The associated timer

getSelector

public java.nio.channels.Selector getSelector()

setSelect

public void setSelect(boolean b)