Please review: [Bug 570667] MMR: simultaneous total updates on the masters cause deadlock and data loss

[Noriko Hosoi]

Subject: MMR: simultaneous total updates on the masters cause deadlock and data loss

https://bugzilla.redhat.com/show_bug.cgi?id=570667

Description: In the MMR topology, if a master receives a total
update request to initialize the other master and being initialized
by the other master at the same time, the 2 replication threads hang
and the replicated backend instance could be wiped out.

To prevent the server running the total update supplier and the
consumer at the same time, REPLICA_TOTAL_EXCLUSIVE bit has
been introduced and set to the replica state flag by the either
operation.  Once the bit is detected, the other operation fails with
the error.

Files:
  ldap/servers/plugins/replication/repl5.h
  ldap/servers/plugins/replication/repl5_protocol.c
  ldap/servers/plugins/replication/repl_extop.c


[Fix proposal]
  -->  (https://bugzilla.redhat.com/attachment.cgi?id=397962)
git patch file

Please review (take 2): [Bug 570667] MMR: simultaneous total updates on the masters cause deadlock and data loss

[Noriko Hosoi]

Subject: MMR: simultaneous total updates on the masters cause deadlock and data loss

https://bugzilla.redhat.com/show_bug.cgi?id=570667

[Revised proposal]
  -->  (https://bugzilla.redhat.com/attachment.cgi?id=398089)
git patch file

I revised the previous patch to allow sending simultaneous total updates
against other replicas.  I think it's no need to disallow it.

Thank you!
--noriko

>  Description: In the MMR topology, if a master receives a total
>  update request to initialize the other master and being initialized
>  by the other master at the same time, the 2 replication threads hang
>  and the replicated backend instance could be wiped out.
>
>  To prevent the server running the total update supplier and the
>  consumer at the same time, REPLICA_TOTAL_EXCLUSIVE bit has
>  been introduced and set to the replica state flag by the either
>  operation.  Once the bit is detected, the other operation fails with
>  the error.
>
>  Files:
>   ldap/servers/plugins/replication/repl5.h
>   ldap/servers/plugins/replication/repl5_protocol.c
>   ldap/servers/plugins/replication/repl_extop.c
>
>
>  [Fix proposal]
>   -->  (https://bugzilla.redhat.com/attachment.cgi?id=397962)
>  git patch file
>
>
>
>  --
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