]
Bela Ban commented on JGRP-1875:
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Perhaps we should drop this altogether and only implement JGRP-1874, which reduces traffic
caused by {{GET-FIRST-SEQNO}} and sending of the missing messages...
UNICAST3/UNICAST2: sync receiver table with sender table
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Key: JGRP-1875
URL:
https://issues.jboss.org/browse/JGRP-1875
Project: JGroups
Issue Type: Enhancement
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.5.1, 3.6
If a receiver B closes its recv-table and the sender A doesn't, then (when receiving
msgs from the sender) the receiver engages in a protocol using {{GET-FIRST-SEQNO}} to sync
itself with the sender. This has several problems, detailed in JGRP-1873 and JGRP-1874.
(Note that the other way round (sender closing send-table), there is no issue, as the
sender will create a new connection with a new {{conn-id}}).
To prevent {{STABLE}} messages interfering with {{GET-FIRST-SEQNO}} messages (JGRP-1873),
we could run an additional {{SYNC}} protocol round, e.g.
* B needs to get the lowest and highest seqno sent from A
* B sends a {{SYNC}} message to A (instead of a {{GET-FIRST-SEQNO}} message)
* B sets a flag that discards all {{STABLE}} or {{ACK}} messages on reception of
{{SYNC}}
* B replies with a {{SYNC-OK}} containing the _lowest_ and _highest_ sent seqnos
* B creates an entry for A with the lowest and highest seqnos
* B sends a {{SYNC-ACK}} to A
* A resets the flag and starts accepting {{STABLE}} / {{ACK}} messages from B again
* A and B now use the usual protocols to retransmit missing messages