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## 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 3519 2007-01-08 17:57:39Z 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)

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