org.jgroups.stack
Class Retransmitter

java.lang.Object
  org.jgroups.stack.Retransmitter

Direct Known Subclasses:

DefaultRetransmitter, RangeBasedRetransmitter

public abstract class Retransmitter
extends java.lang.Object

Abstract class of a retransmitter. Maintains a pool of sequence numbers of messages that need to be retransmitted. Messages are aged and retransmission requests sent according to age (configurable backoff). If a TimeScheduler instance is given to the constructor, it will be used, otherwise Reransmitter will create its own. The retransmit timeouts have to be set first thing after creating an instance. The add() method adds the sequence numbers of messages to be retransmitted. The remove() method removes a sequence number again, cancelling retransmission requests for it. Whenever a message needs to be retransmitted, the RetransmitCommand.retransmit() method is called. It can be used e.g. by an ack-based scheme (e.g. AckSenderWindow) to retransmit a message to the receiver, or by a nak-based scheme to send a retransmission request to the sender of the missing message.

Author:

Bela Ban

Nested Class Summary

static interface	Retransmitter.RetransmitCommand Retransmit command (see Gamma et al.) used to retrieve missing messages
protected class	Retransmitter.Task

Field Summary

protected Retransmitter.RetransmitCommand	cmd
protected static Log	log
protected Interval	retransmit_timeouts Default retransmit intervals (ms) - exponential approx.
protected Address	sender
protected TimeScheduler	timer
protected long	xmit_stagger_timeout

Constructor Summary

Retransmitter(Address sender, Retransmitter.RetransmitCommand cmd, TimeScheduler sched)
Create a new Retransmitter associated with the given sender address

Method Summary

abstract void	add(long first_seqno, long last_seqno) Add messages from first_seqno to last_seqno for retransmission
long	getXmitStaggerTimeout()
abstract void	remove(long seqno) Remove the given sequence number from retransmission
abstract void	reset() Reset the retransmitter: clear all msgs and cancel all the respective tasks
void	setRetransmitTimeouts(Interval interval)
void	setXmitStaggerTimeout(long xmit_stagger_timeout)
abstract int	size()

Methods inherited from class java.lang.Object

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

Field Detail

retransmit_timeouts

protected Interval retransmit_timeouts

Default retransmit intervals (ms) - exponential approx.

sender

protected final Address sender

cmd

protected final Retransmitter.RetransmitCommand cmd

timer

protected final TimeScheduler timer

xmit_stagger_timeout

protected long xmit_stagger_timeout

log

protected static final Log log

Constructor Detail

Retransmitter

public Retransmitter(Address sender,
                     Retransmitter.RetransmitCommand cmd,
                     TimeScheduler sched)

Create a new Retransmitter associated with the given sender address

Parameters:

sender - the address from which retransmissions are expected or to which retransmissions are sent

cmd - the retransmission callback reference

sched - retransmissions scheduler

Method Detail

setRetransmitTimeouts

public void setRetransmitTimeouts(Interval interval)

getXmitStaggerTimeout

public long getXmitStaggerTimeout()

setXmitStaggerTimeout

public void setXmitStaggerTimeout(long xmit_stagger_timeout)

add

public abstract void add(long first_seqno,
                         long last_seqno)

Add messages from first_seqno to last_seqno for retransmission

remove

public abstract void remove(long seqno)

Remove the given sequence number from retransmission

reset

public abstract void reset()

Reset the retransmitter: clear all msgs and cancel all the respective tasks

size

public abstract int size()