org.jgroups.stack

Class AckSenderWindow

java.lang.Object

org.jgroups.stack.AckSenderWindow

All Implemented Interfaces:

Retransmitter.RetransmitCommand

public class AckSenderWindow
extends java.lang.Object
implements Retransmitter.RetransmitCommand

ACK-based sliding window for a sender. Messages are added to the window keyed by seqno When an ACK is received, the corresponding message is removed. The Retransmitter continously iterates over the entries in the hashmap, retransmitting messages based on their creation time and an (increasing) timeout. When there are no more messages in the retransmission table left, the thread terminates. It will be re-activated when a new entry is added to the retransmission table.

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AckSenderWindow.RetransmitCommand

Constructor Summary

Constructors

Constructor and Description
AckSenderWindow(AckSenderWindow.RetransmitCommand com) Creates a new instance.
AckSenderWindow(AckSenderWindow.RetransmitCommand com, long[] interval)
AckSenderWindow(AckSenderWindow.RetransmitCommand com, long[] interval, TimeScheduler sched)
AckSenderWindow(AckSenderWindow.RetransmitCommand com, long[] interval, TimeScheduler sched, Address sender)

Method Summary

Methods

Modifier and Type	Method and Description
void	ack(long seqno) Removes the message from msgs, removing them also from retransmission.
void	add(long seqno, Message msg) Adds a new message to the retransmission table.
static void	main(java.lang.String[] args)
java.lang.String	printDetails()
void	reset()
void	retransmit(long first_seqno, long last_seqno, Address sender) Get the missing messages between sequence numbers first_seqno and last_seqno.
int	size()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

AckSenderWindow

public AckSenderWindow(AckSenderWindow.RetransmitCommand com)

Creates a new instance. Thre retransmission thread has to be started separately with start().

Parameters:

com - If not null, its method retransmit() will be called when a message needs to be retransmitted (called by the Retransmitter).

AckSenderWindow

public AckSenderWindow(AckSenderWindow.RetransmitCommand com,
               long[] interval)

AckSenderWindow

public AckSenderWindow(AckSenderWindow.RetransmitCommand com,
               long[] interval,
               TimeScheduler sched)

AckSenderWindow

public AckSenderWindow(AckSenderWindow.RetransmitCommand com,
               long[] interval,
               TimeScheduler sched,
               Address sender)

Method Detail

reset

public void reset()

add

public void add(long seqno,
       Message msg)

Adds a new message to the retransmission table. If the message won't have received an ack within a certain time frame, the retransmission thread will retransmit the message to the receiver. If a sliding window protocol is used, we only add up to window_size messages. If the table is full, we add all new messages to a queue. Those will only be added once the table drains below a certain threshold (min_threshold)

ack

public void ack(long seqno)

Removes the message from msgs, removing them also from retransmission. If sliding window protocol is used, and was queueing, check whether we can resume adding elements. Add all elements. If this goes above window_size, stop adding and back to queueing. Else set queueing to false.

size

public int size()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

printDetails

public java.lang.String printDetails()

retransmit

public void retransmit(long first_seqno,
              long last_seqno,
              Address sender)

Description copied from interface: Retransmitter.RetransmitCommand

Get the missing messages between sequence numbers first_seqno and last_seqno. This can either be done by sending a retransmit message to destination sender (nak-based scheme), or by retransmitting the missing message(s) to sender (ack-based scheme).

Specified by:

retransmit in interface Retransmitter.RetransmitCommand

Parameters:

first_seqno - The sequence number of the first missing message

last_seqno - The sequence number of the last missing message

sender - The destination of the member to which the retransmit request will be sent (nak-based scheme), or to which the message will be retransmitted (ack-based scheme).

main

public static void main(java.lang.String[] args)