[jboss-jira] [JBoss JIRA] (JGRP-2184) (7.0.z) Sticky site masters

[Bartosz Spyrko-Śmietanko (JIRA)]

Bartosz Spyrko-Śmietanko created JGRP-2184:
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             Summary: (7.0.z) Sticky site masters
                 Key: JGRP-2184
                 URL: https://issues.jboss.org/browse/JGRP-2184
             Project: JGroups
          Issue Type: Feature Request
            Reporter: Bartosz Spyrko-Śmietanko
            Assignee: Bela Ban
             Fix For: 3.6.12, 4.0


If members in one site send messages to site masters of other sites, if we have multiple site masters, then reordering can occur.

Example:
* Member C in site LON sends messages C1 and C2 to site NYC
* C1 picks SM1 and C2 picks SM2
* Although site masters process messages in delivery order, because C1 and C2 travel through different site masters, C2 could pass C1, leading to ordering issues

h4. Design
* When sending a message to the one of the site masters of the current site, or from a site master to a remote site master, we invoke a callback to pick the site master based on the original caller
* Note that this only applies when we have more than one site master.
* The callback passes the address of the original caller and the list of available site masters, and needs to return a site master

h5. Transactions
* Transactions by different originators with overlapping key sets cannot be reliably ordered
* Transactional support therefore requires single site masters
* This should not be an issue as transactions bundle multiple updates, so the number of messages sent is less than non-transactional updates




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