Nodes would stabilize on different encoding formats for the values,
some having the pre-migration format and some having the post-migration
format. This would be reflected in the Merkle trees never converging
and thus having an infinite resync loop.
- change the terminology: the network configuration becomes the role
table, the configuration of a nodes becomes a node's role
- the modification of the role table takes place in two steps: first,
changes are staged in a CRDT data structure. Then, once the user is
happy with the changes, they can commit them all at once (or revert
them).
- update documentation
- fix tests
- implement smarter partition assignation algorithm
This patch breaks the format of the network configuration: when
migrating, the cluster will be in a state where no roles are assigned.
All roles must be re-assigned and commited at once. This migration
should not pose an issue.
- Explicit "replication_mode" configuration parameters that takes
either "none", "2" or "3" as values, instead of letting user configure
replication factor themselves. These are presets whose corresponding
replication/quorum values can be found in replication/mode.rs
- Explicit support for single-node and two-node deployments
(number of nodes must be at least "replication_mode", with "none"
we can have only one node)
- Ring is now stored much more compactly with 256*8 + n*32 bytes,
instead of 256*32 bytes
- Support for gateway-only nodes that do not store data
(these nodes still need a metadata_directory to store the list
of bucket and keys since those are stored on all nodes; it also
technically needs a data_directory to start but it will stay
empty unless we have bugs)
