com.hp.nbio

Class SelectLoop

java.lang.Object

com.hp.nbio.SelectLoop

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

AcceptLoop, IOLoop

public abstract class SelectLoop
extends Object
implements Runnable

Base abstraction of an I/O loop.

Author:

Thomas Vachuska

Field Summary

Fields

Modifier and Type	Field and Description
static long	DEFAULT_TIMEOUT Default select timeout of 500L milliseconds.
protected org.slf4j.Logger	log Shared logger.
protected Selector	selector Shared selector used to drive the loop operation.
protected boolean	stopped When true, implementations are expected to break their loop.
protected long	timeout Select timeout in milliseconds.

Constructor Summary

Constructors

Constructor and Description
SelectLoop() Creates a select loop with default timeout.
SelectLoop(long timeout) Creates a select loop with the specified timeout.

Method Summary

Methods

Modifier and Type	Method and Description
void	cease() Gracefully stops the loop.
Throwable	getError() Gets the prior I/O error, if one occurred.
protected abstract void	loop() I/O event loop.
protected Selector	openSelector() Opens a new selector for the use by the loop.
void	run()
protected void	signalStart() Signals all observers that loop has started.
boolean	waitForFinish(long timeout) Waits for the loop execution to stop.
boolean	waitForStart(long timeout) Waits for the loop execution to start.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected org.slf4j.Logger log

Shared logger.

DEFAULT_TIMEOUT

public static final long DEFAULT_TIMEOUT

Default select timeout of 500L milliseconds.

See Also:

Constant Field Values

selector

protected Selector selector

Shared selector used to drive the loop operation.

stopped

protected volatile boolean stopped

When true, implementations are expected to break their loop.

timeout

protected long timeout

Select timeout in milliseconds.

Constructor Detail

SelectLoop

public SelectLoop()
           throws IOException

Creates a select loop with default timeout.

Throws:

IOException - if unable to open selector

SelectLoop

public SelectLoop(long timeout)
           throws IOException

Creates a select loop with the specified timeout.

Parameters:

timeout - select timeout in milliseconds

Throws:

IOException - if unable to open selector

Method Detail

openSelector

protected Selector openSelector()
                         throws IOException

Opens a new selector for the use by the loop.

Returns:

newly open selector

Throws:

IOException - if unable to open selector

cease

public void cease()

Gracefully stops the loop.

loop

protected abstract void loop()
                      throws IOException

I/O event loop. Implementations are expected to break when stopped becomes true via cease() invocation. Also, implementations are expected to signalStart() when ready.

Throws:

IOException - if unable to properly select channels or an I/O error is propagated by an event handler.

run

public void run()

This implementation first resets the stopped state to false, then allocates the selector and finally invokes the loop() method.

Specified by:

run in interface Runnable

signalStart

protected void signalStart()

Signals all observers that loop has started.

Implementations are expected to invoke this method from their loop() method when ready to start processing requests.

waitForStart

public final boolean waitForStart(long timeout)

Waits for the loop execution to start.

Parameters:

timeout - number of milliseconds to wait

Returns:

true if loop started in time

waitForFinish

public final boolean waitForFinish(long timeout)

Waits for the loop execution to stop.

Parameters:

timeout - number of milliseconds to wait

Returns:

true if loop finished in time

getError

public Throwable getError()

Gets the prior I/O error, if one occurred.

Returns:

flush error; null if none occurred