com.hp.nbio

Class IOLoop<M extends Message,B extends MessageBuffer<M>>

java.lang.Object

com.hp.nbio.SelectLoop

com.hp.nbio.IOLoop<M,B>

Type Parameters:

M - message type

B - message buffer type

All Implemented Interfaces:

Runnable

public abstract class IOLoop<M extends Message,B extends MessageBuffer<M>>
extends SelectLoop

Abstraction of an I/O loop for driving buffered message transfer across network socket connections.

Loosely based on I/O loop algorithm authored by David Erickson.

Author:

Thomas Vachuska, Simon Hunt

Field Summary

Fields inherited from class com.hp.nbio.SelectLoop

DEFAULT_TIMEOUT, log, selector, stopped, timeout

Constructor Summary

Constructors

Constructor and Description
IOLoop() Creates an IO loop with default timeout.
IOLoop(long timeout) Creates an IO loop with the specified timeout.

Method Summary

Modifier and Type	Method and Description
protected void	connect(SelectionKey key) Processes a connection request represented by the supplied select key.
protected abstract B	createBuffer(ByteChannel ch, SSLContext sslContext) Creates a new message buffer backed by the given socket channel and driven by the specified loop.
protected void	discardBuffer(MessageBuffer<M> b) Discards the specified message buffer from the list of registered buffers.
protected void	handleMessageProcessingException(B b, RuntimeException e) Invoked if a runtime exception is thrown from processMessages(com.hp.nbio.MessageBuffer<M>, java.util.List<M>).
protected void	loop() I/O event loop.
protected void	processIO(SelectionKey key) Processes a single IO request represented by the supplied select key.
protected abstract void	processMessages(MessageBuffer<M> b, List<M> messages) Processes the list of messages received from the specified message buffer.
void	prune() Prunes the registered buffers by discarding any stale ones.
void	registerAccept(SocketChannel ch, SSLContext sslContext) Registers a new socket channel by creating a new message buffer backed by the socket channel and driven by this loop.
void	registerConnect(SocketChannel ch, SSLContext sslContext) Registers a new client-side socket channel by creating a new message buffer backed by the socket channel and driven by this loop.

Methods inherited from class com.hp.nbio.SelectLoop

cease, getError, openSelector, run, signalStart, waitForFinish, waitForStart

Methods inherited from class java.lang.Object

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

Constructor Detail

IOLoop

public IOLoop()
       throws IOException

Creates an IO loop with default timeout.

Throws:

IOException - if unable to open selector

IOLoop

public IOLoop(long timeout)
       throws IOException

Creates an IO loop with the specified timeout.

Parameters:

timeout - select timeout in milliseconds

Throws:

IOException - if unable to open selector

Method Detail

createBuffer

protected abstract B createBuffer(ByteChannel ch,
                                  SSLContext sslContext)

Creates a new message buffer backed by the given socket channel and driven by the specified loop. If an SSL context is specified, the IOLoop is expected to provide a secure MessageBuffer.

Parameters:

ch - backing byte channel

sslContext - optional SSL context

Returns:

newly created message buffer

discardBuffer

protected void discardBuffer(MessageBuffer<M> b)

Discards the specified message buffer from the list of registered buffers.

One should not invoke this method directly as this is merely a hook invoked by the default implementation of MessageBuffer.discard() method, which is what should be used directly instead.

Parameters:

b - message buffer

processMessages

protected abstract void processMessages(MessageBuffer<M> b,
                                        List<M> messages)

Processes the list of messages received from the specified message buffer.

Parameters:

b - source message buffer

messages - list of received messages; guaranteed not to be null and not empty

connect

protected void connect(SelectionKey key)

Processes a connection request represented by the supplied select key. Default implementation sets the key's interestedOps to SelectionKey.OP_READ and then attempts to finish the connection on the key socket channel.

Parameters:

key - selection key holding the pending connect operation.

processIO

protected void processIO(SelectionKey key)

Processes a single IO request represented by the supplied select key.

Parameters:

key - selection key holding the pending I/O operation.

handleMessageProcessingException

protected void handleMessageProcessingException(B b,
                                                RuntimeException e)

Invoked if a runtime exception is thrown from processMessages(com.hp.nbio.MessageBuffer<M>, java.util.List<M>).

This default implementation simply rethrows the exception.

Parameters:

b - the buffer that was being processed

e - the runtime exception that was thrown

prune

public void prune()

Prunes the registered buffers by discarding any stale ones.

registerAccept

public void registerAccept(SocketChannel ch,
                           SSLContext sslContext)

Registers a new socket channel by creating a new message buffer backed by the socket channel and driven by this loop. If an SSL context is specified, the IOLoop is expected to provide a secure MessageBuffer.

Parameters:

ch - socket channel

sslContext - optional SSL context

registerConnect

public void registerConnect(SocketChannel ch,
                            SSLContext sslContext)

Registers a new client-side socket channel by creating a new message buffer backed by the socket channel and driven by this loop. If an SSL context is specified, the IOLoop is expected to provide a secure MessageBuffer.

Parameters:

ch - socket channel

sslContext - optional SSL context

loop

protected void loop()
             throws IOException

Description copied from class: SelectLoop

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

Specified by:

loop in class SelectLoop

Throws:

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