org.jgroups.stack
Class RangeBasedRetransmitter

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

public class RangeBasedRetransmitter
extends Retransmitter

This retransmitter is specialized in maintaining ranges of seqnos, e.g. [3-20], [89-89], [100-120]. The ranges are stored in a sorted hashmap and the Comparable.compareTo(Object) method compares both ranges again ranges, and ranges against seqnos. The latter helps to find a range given a seqno, e.g. seqno 105 will find range [100-120].

Each range is implemented by SeqnoRange, which has a bitset of all missing seqnos. When a seqno is received, that bit set is updated; the bit corresponding to the seqno is set to 1. A task linked to the range periodically retransmits missing messages.

When all bits are 1 (= all messages have been received), the range is removed from the hashmap and the retransmission task is cancelled.

RangeBasedRetransmitter requires sequence numbers and sequence number ranges to be added in ascending and non-overlapping order: e.g. 1 4 [10-21] 22 [50-60] is ok, while [3-7] [5-8] 20 18 is not !

Author:

Bela Ban

Nested Class Summary

protected class

RangeBasedRetransmitter.RangeTask

Nested classes/interfaces inherited from class org.jgroups.stack.Retransmitter

Retransmitter.RetransmitCommand, Retransmitter.Task

Field Summary

Fields inherited from class org.jgroups.stack.Retransmitter

cmd, log, retransmit_timeouts, sender, timer, xmit_stagger_timeout

Constructor Summary

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

Method Summary

void	add(long first_seqno, long last_seqno) Add the given range [first_seqno, last_seqno] in the list of entries eligible for retransmission.
java.lang.String	printStats()
void	remove(long seqno) Remove the given sequence number from the list of seqnos eligible for retransmission.
void	reset() Reset the retransmitter: clear all msgs and cancel all the respective tasks
int	size()
java.lang.String	toString()

Methods inherited from class org.jgroups.stack.Retransmitter

getXmitStaggerTimeout, setRetransmitTimeouts, setXmitStaggerTimeout

Methods inherited from class java.lang.Object

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

Constructor Detail

RangeBasedRetransmitter

public RangeBasedRetransmitter(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

add

public void add(long first_seqno,
                long last_seqno)

Add the given range [first_seqno, last_seqno] in the list of entries eligible for retransmission. If first_seqno > last_seqno, then the range [last_seqno, first_seqno] is added instead

Specified by:

add in class Retransmitter

remove

public void remove(long seqno)

Remove the given sequence number from the list of seqnos eligible for retransmission. If there are no more seqno intervals in the respective entry, cancel the entry from the retransmission scheduler and remove it from the pending entries

Specified by:

remove in class Retransmitter

reset

public void reset()

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

Specified by:

reset in class Retransmitter

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

size

public int size()

Specified by:

size in class Retransmitter

printStats

public java.lang.String printStats()