[
https://issues.apache.org/jira/browse/CASSANDRA-5062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13593250#comment-13593250
]
Cristian Opris commented on CASSANDRA-5062:
-------------------------------------------
[~slebresne] I see you intend to separate it but I'm not sure the separation is
correct.
In receive(PROPOSE) you have:
{code}
if (P_max != null && P <= P_max)
{
// We've already seen a more recent proposal
send(REJECT);
}
{code}
If this doesn't hold you have the tm > tn thing I was talking about and then:
{code}
// Read the most recent *accepted* proposal we have for round R (simple slice
query).
P', CAS(u', v') = read_max(paxos_state, C, R, 'accepted')
{code}
If I read that correctly as read_max(R) this could be a stale accept from a
previously unfinished round that the acceptor never committed.
> Support CAS
> -----------
>
> Key: CASSANDRA-5062
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5062
> Project: Cassandra
> Issue Type: New Feature
> Components: API, Core
> Reporter: Jonathan Ellis
> Fix For: 2.0
>
> Attachments: half-baked commit 1.jpg, half-baked commit 2.jpg,
> half-baked commit 3.jpg
>
>
> "Strong" consistency is not enough to prevent race conditions. The classic
> example is user account creation: we want to ensure usernames are unique, so
> we only want to signal account creation success if nobody else has created
> the account yet. But naive read-then-write allows clients to race and both
> think they have a green light to create.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
