Hi all,

I hope this list is appropriate to place my question regarding one of the most 
recent papers on ZooKeeper's Zab protocol: 
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5958223&tag=1

When Phase II (Synchronization) of the protocol is described, in step f.2.1 
there are two actions performed "atomically": setting f.a to e' and accepting 
every transaction in the initial history given by the leader. My question is: 
what precisely does "atomically" mean? Does it mean that either none or both 
are executed? Then, do the core properties depend on the atomic execution of 
those actions? I've read the proofs in that paper and apparently the atomic 
execution of those actions is not mentioned. How does this relate to Zab 
protocol in the code? I haven't yet found a synchronization code that sets f.a 
(currentEpoch in the code) "atomically" together with the history (through 
TRUNC, DIFF, or SNAP messages).

Thanks for the attention,
Andre Medeiros

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