Rework the API to use flatbuffers or CapNP depending on which is faster.

[cholcombe973]

They both seem to satisfy the basic requirements of API versioning, backwards compatibility and fast throughput. With small IO operations it's critical that the API serialize and deserialize quickly so as not to introduce to much latency. Generally 4K writes in Ceph and Gluster are pretty terrible and there's a variety of reasons why but RPC overhead is a big part of it. The other big part is just physics of moving packets to replicas and waiting for the last writer to respond before responding to the client with success.

[cgmcintyr]

Which of these turned out to be better for use in a DFS?

[cholcombe973]

I think flatbuffers ended up being the best in terms of serialization speed and network packet size.