Package kilim.nio

Class EndPoint

java.lang.Object

kilim.nio.EndPoint

public class EndPoint
extends Object

The EndPoint represents an open socket connection. It is a wrapper over a non-blocking socket (channel) and belongs to a SessionTask. It serves as the bridge between the SessionTask and the NioSelectorScheduler, using a pair of mailboxes for exchanging socket registration and socket ready events.

The other purpose of this class is to provide convenience methods that read from a socket into a bytebuffer, or write from a bytebuffer to the socket. If the socket is not ready for business, the endpoint (and hence the task) simply yields, without registering with the NioSelectorScheduler. The idea is to give the other runnable tasks a chance to run before retrying the operation (on resumption); this avoids waking up the selector -- an expensive operation -- as much as possible, and introduces a delay between retries. If, after a fixed number of times (YIELD_COUNT), the operation still hasn't succeeded, the endpoint registers itself with the NioSelectorScheduler, and waits for a socket-ready event from the selector. This scheme is adaptive to load, in that the delay between retries is proportional to the number of runnable tasks. Busy sockets tend to get serviced more often as the socket is always ready.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	EndPoint.Sched

Field Summary

Fields

Modifier and Type	Field	Description
private Mailbox<SockEvent>	box
private NioSelectorScheduler	sched
AbstractSelectableChannel	sockch	The socket channel wrapped by the EndPoint.
(package private) static final int	YIELD_COUNT

Constructor Summary

Constructors

Constructor	Description
EndPoint(NioSelectorScheduler nio, AbstractSelectableChannel ch)

Method Summary

Modifier and Type	Method	Description
IOException	close()	Deprecated. in a future version, this method will no longer print the stack trace
(package private) IOException	close2()	Close the endpoint
SocketChannel	dataChannel()
ByteBuffer	fill(ByteBuffer buf, int atleastN)	Read atleastN bytes more into the buffer if there's space.
ByteBuffer	fillMessage(ByteBuffer bb, int lengthLength, boolean lengthIncludesItself)	Reads a length-prefixed message in its entirety.
void	pauseUntilAcceptable()
void	pauseUntilReadable()
void	pauseUntilWritable()
void	write(ByteBuffer buf)	Write buf.remaining() bytes to dataChannel().
void	write(FileChannel fc, long start, long length)	Write a file to the endpoint using FileChannel.transferTo(long, long, java.nio.channels.WritableByteChannel)

Methods inherited from class java.lang.Object

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

Field Details

YIELD_COUNT

static final int YIELD_COUNT

sockch

public AbstractSelectableChannel sockch

The socket channel wrapped by the EndPoint. See #dataChannel()

box

private Mailbox<SockEvent> box

sched

private NioSelectorScheduler sched

Constructor Details

EndPoint

public EndPoint(NioSelectorScheduler nio,
 AbstractSelectableChannel ch)

Method Details

dataChannel

public SocketChannel dataChannel()

write

public void write(ByteBuffer buf)
           throws IOException,
Pausable

Write buf.remaining() bytes to dataChannel().

Throws:

IOException

Pausable

fill

public ByteBuffer fill(ByteBuffer buf,
 int atleastN)
                throws IOException,
Pausable

Read atleastN bytes more into the buffer if there's space. Otherwise, allocate a bigger buffer that'll accomodate the earlier contents and atleastN more bytes.

Parameters:

buf - ByteBuffer to be filled

atleastN - At least this many bytes to be read.

Throws:

IOException

Pausable

fillMessage

public ByteBuffer fillMessage(ByteBuffer bb,
 int lengthLength,
 boolean lengthIncludesItself)
                       throws IOException,
Pausable

Reads a length-prefixed message in its entirety.

Parameters:

bb - The bytebuffer to fill, assuming there is sufficient space (including the bytes for the length). Otherwise, the contents are copied into a sufficiently big buffer, and the new buffer is returned.

lengthLength - The number of bytes occupied by the length. Must be 1, 2 or 4, assumed to be in big-endian order.

lengthIncludesItself - true if the packet length includes lengthLength

Returns:

the buffer bb passed in if the message fits or a new buffer. Either way, the buffer returned has the entire message including the initial length prefix.

Throws:

IOException

Pausable

pauseUntilReadable

public void pauseUntilReadable()
                        throws Pausable,
IOException

Throws:

Pausable

IOException

pauseUntilWritable

public void pauseUntilWritable()
                        throws Pausable,
IOException

Throws:

Pausable

IOException

pauseUntilAcceptable

public void pauseUntilAcceptable()
                          throws Pausable,
IOException

Throws:

Pausable

IOException

write

public void write(FileChannel fc,
 long start,
 long length)
           throws IOException,
Pausable

Write a file to the endpoint using FileChannel.transferTo(long, long, java.nio.channels.WritableByteChannel)

Parameters:

fc - FileChannel to copy to endpoint

start - Start offset

length - Number of bytes to be written

Throws:

IOException

Pausable

close2

IOException close2()

Close the endpoint

close

@Deprecated
public IOException close()

Deprecated.

in a future version, this method will no longer print the stack trace

Close the endpoint, printing and returning and any IOException