Assisign manual recovery from a complete persistent cluster crash.
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                 Key: QPID-2220
                 URL: https://issues.apache.org/jira/browse/QPID-2220
             Project: Qpid
          Issue Type: Improvement
          Components: C++ Broker
    Affects Versions: 0.5
            Reporter: Alan Conway
            Assignee: Alan Conway


If every member of a persistent cluster crashes then manual intervention is 
required to identify which store is most up-to-date, so it can be used to 
recover.
We need to provide tools to assist in this identification.

The cluster can save a config-change counter with each config change. In 
recovery, the broker with the highest config-change counter has the best store. 
However if the last brokers in the cluster crash so close together that none 
can record a config-change we need an additional decider.

The store at http://qpidcomponents.org/download.html#persistence maintains a 
global counter called the RecordIdentifier (RID) that is incremented for each 
enqueue and dequeue. If the cluster stores  (config-change,RID) pairs then in 
recovery we can use actual-RID - RID at config-change as a tiebreaker.

Is it reasonable to provide access to this counter in the generic MessageStore 
API? Stores that don't implement it can simply return 0, and the cluster must 
fall back to relying on config-change counts.

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