licenser / ecrdt Goto Github PK

So we at basho have been looking at your work (yay, CRDTs). We have a quickcheck suite for testing CRDTs, which we've been having success with (it's here, if you're interested: https://github.com/basho/riak_dt/blob/multi_crdt/test/crdt_statem_eqc.erl ).

Firstly, there are obvious bugs in your program. You treat the pairs in the values section at times as {Element, ID}, and at other times as {ID, Element}.

Secondly, your merge function does not commute. We wrapped your implementation in the same interface as we had, and it was failing our tests for equality, which have to be based on the fact that merge/2 commutes.

I rewrote the module into one with a deterministic, commutative merge function, but I'm not sure if it's the same algorithm as specified in the accompanying paper, so it may not be "optimised". My function also relies on the ordering of timestamps, which may be problematic.

My alterations to the module are here: https://gist.github.com/lenary/5755145 (I did quite a bit of a rewrite, to use ord{dict,sets} everywhere, to remove bugs, and to make merge/2 commute.