Package uk.ac.manchester.spinnaker.messages.scp

Class SCPRequestHeader

java.lang.Object

uk.ac.manchester.spinnaker.messages.scp.SCPRequestHeader

All Implemented Interfaces:

SerializableMessage

public final class SCPRequestHeader
extends Object
implements SerializableMessage

Represents the header of an SCP Request.

The sequence number, if zero, will be set by the message sending code to the actual sequence number when the message is sent on a connection.

Field Summary

Fields

Modifier and Type	Field	Description
CommandCode	command	The command of the SCP packet.

Method Summary

Modifier and Type	Method	Description
void	addToBuffer(ByteBuffer buffer)	Writes this message into the given buffer as a contiguous range of bytes.
int	getSequence()
int	issueSequenceNumber(Set<Integer> inFlight)	Set the sequence number of this request to the next available number.

Methods inherited from class java.lang.Object

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

Field Details

command

public final CommandCode command

The command of the SCP packet.

Method Details

addToBuffer

public void addToBuffer(ByteBuffer buffer)

Writes this message into the given buffer as a contiguous range of bytes. This is so that a message can be sent. Implementors may assume that the buffer has been configured to be little-endian and that its position is at the point where they should begin writing. Once it has finished, the position should be immediately after the last byte written by this method.

Calling this method should not update the internal state of the message. It should be possible to add the message to multiple buffers without special precautions by the caller.

This must not be called until after a sequence number is set.

Specified by:

addToBuffer in interface SerializableMessage

Parameters:

buffer - The buffer to write into.

issueSequenceNumber

public int issueSequenceNumber(Set<Integer> inFlight)

Set the sequence number of this request to the next available number. This can only ever be called once per request.

Parameters:

inFlight - What sequence numbers are current in use and shouldn't be used.

Returns:

The number that was issued.

Throws:

IllegalStateException - If an attempt is made to set a sequence number a second time

getSequence

public int getSequence()

Returns:

The message's sequence number.