Pending
- persistent failed inserts should be handled properly
- hwm vs complete pointers
- monitoring and debugging
- loss/throughput/buffers are related / network parameters (X3)
- ftop
- /~https://github.com/newtools/zsocket
- http://stomp.github.io/stomp-specification-1.2.html
- https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html
- https://en.wikipedia.org/wiki/Advanced_Message_Queuing_Protocol
- https://blog.iron.io/fastest-messaging-queue/
- https://cromwell-intl.com/open-source/performance-tuning/tcp.html
- Pull out serialisation into api.PersistentStream, MmapStream should only deal with []byte
- Simplify replicator storage data