rice.pastry.socket
Class SocketChannelWriter

java.lang.Object
  rice.pastry.socket.SocketChannelWriter

public class SocketChannelWriter

extends java.lang.Object

Class which serves as an "writer" for all of the messages sent across the wire in Pastry. This class serializes and properly formats all messages, and then waits to be called with an available SocketChannel in order to write the message out. If the messagae could not be written in one go, subsequent calls to the write() method will finish writing out the message. This class also maintains an internal queue of messages waiting to be sent across the wire. Calling isEmpty() will tell clients if it is safe to mark the SelectionKey as not being interested in writing.

Version:

$Id: SocketChannelWriter.java,v 1.5 2004/03/08 19:53:57 amislove Exp $

Author:

Alan Mislove

Field Summary

static int	MAXIMUM_QUEUE_LENGTH DESCRIBE THE FIELD
protected SourceRoute	path DESCRIBE THE FIELD

Constructor Summary

SocketChannelWriter(PastryNode spn, SourceRoute path)
Constructor which creates this SocketChannelWriter with a pastry node and an object to write out.

Method Summary

boolean	enqueue(java.lang.Object o) Adds an object to this SocketChannelWriter's queue of pending objects to write.
java.util.LinkedList	getQueue() Returns the queue of writes for the remote address
boolean	isEmpty() Returns whether or not there are objects in the queue on in writing.
protected void	record(java.lang.String action, java.lang.Object obj, int size, SourceRoute path) DESCRIBE THE METHOD
void	reset() Returns the queue of writes for the remote address
static java.nio.ByteBuffer	serialize(java.lang.Object o) Method which serializes a given object into a ByteBuffer, in order to prepare it for writing.
protected void	setPath(SourceRoute path) Sets this writer's path
boolean	write(java.nio.channels.SocketChannel sc) Method which is designed to be called when this writer should write out its data.

Methods inherited from class java.lang.Object

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

Field Detail

path

protected SourceRoute path

DESCRIBE THE FIELD

MAXIMUM_QUEUE_LENGTH

public static int MAXIMUM_QUEUE_LENGTH

DESCRIBE THE FIELD

Constructor Detail

SocketChannelWriter

public SocketChannelWriter(PastryNode spn,
                           SourceRoute path)

Constructor which creates this SocketChannelWriter with a pastry node and an object to write out.

Parameters:

spn - The spn the SocketChannelWriter servers

path - DESCRIBE THE PARAMETER

Method Detail

isEmpty

public boolean isEmpty()

Returns whether or not there are objects in the queue on in writing. If the result is true, it the safe to mark the SelectionKey as not being interested in writing.

Returns:

Whether or not there are objects still to be written.

getQueue

public java.util.LinkedList getQueue()

Returns the queue of writes for the remote address

Returns:

the queue of writes for the remote address

setPath

protected void setPath(SourceRoute path)

Sets this writer's path

Parameters:

path - The path this writer is using

enqueue

public boolean enqueue(java.lang.Object o)

Adds an object to this SocketChannelWriter's queue of pending objects to write. This methos is synchronized and therefore safe for use by multiple threads.

Parameters:

o - The object to be written.

Returns:

DESCRIBE THE RETURN VALUE

reset

public void reset()

Returns the queue of writes for the remote address

record

protected void record(java.lang.String action,
                      java.lang.Object obj,
                      int size,
                      SourceRoute path)

DESCRIBE THE METHOD

Parameters:

action - DESCRIBE THE PARAMETER

obj - DESCRIBE THE PARAMETER

size - DESCRIBE THE PARAMETER

path - DESCRIBE THE PARAMETER

write

public boolean write(java.nio.channels.SocketChannel sc)
              throws java.io.IOException

Method which is designed to be called when this writer should write out its data. Returns whether or not the message was completely written. If false is returns, write() will need to be called again when the SocketChannel is ready for data to be written.

Parameters:

sc - The SocketChannel to write to

Returns:

true if this output stream is done, false otherwise

Throws:

java.io.IOException - DESCRIBE THE EXCEPTION

serialize

public static java.nio.ByteBuffer serialize(java.lang.Object o)
                                     throws java.io.IOException

Method which serializes a given object into a ByteBuffer, in order to prepare it for writing. This is necessary because the size of the object must be prepended to the to the front of the buffer in order to tell the reciever how long the object is.

Parameters:

o - The object to serialize

Returns:

A ByteBuffer containing the object prepended with its size.

Throws:

java.io.IOException - DESCRIBE THE EXCEPTION