[WIP] Hemlock

Distributed transactional kv store. Mutant baby whose parents are Ceph, Calvin, Kafka and Mesos. Oh baby!

eventual architecture:

• high throughput distributed transactions
• serializable snapshot isolation for external consistency
• homogeneous services that compete for tunable quorum responsibilities
• load-based automatic resharding
• metadata (CRUSH map) distribution via gossip + polling hybrid
• backed by rocksdb instances with configurable replication factor
• implemented as a c++ mesos framework

ideas based on

• Calvin
• Ceph (CRUSH)
• SWIM
• Spanner