Fixes#865.
This makes the necessary changes so that consensu is selected on "init" with a
flag set, by default, to "crdt". This generates only a "crdt" or a "raft"
section, not both.
If the configuration file has a "raft" section, "raft" will be used to start
the daemon. If it has a "crdt" section, "crdt" will be used. If it has none or
both sections, an error will happen.
This also affects "state *" commands, which will now autoselect how to work
from the existing configuration.
It has a few implications to launch a raft peer when you wanted to do crdt and vice-versa.
Same when exporting and exporting states.
Users starting cluster peers should be explicit about their consensus choice.
Also, if we ever want to make `crdt` the default, we can't do that before
making `raft` non-default first. I don't like to break things but otherwise
the experience for new users wanting to try crdts might be aweful.
This adds a new "crdt" consensus component using go-ds-crdt.
This implies several refactors to fully make cluster consensus-component
independent:
* Delete mapstate and fully adopt dsstate (after people have migrated).
* Return errors from state methods rather than ignoring them.
* Add a new "datastore" modules so that we can configure datastores in the
main configuration like other components.
* Let the consensus components fully define the "state.State". Thus, they do
not receive the state, they receive the storage where we put the state (a
go-datastore).
* Allow to customize how the monitor component obtains Peers() (the current
peerset), including avoiding using the current peerset. At the moment the
crdt consensus uses the monitoring component to define the current peerset.
Therefore the monitor component cannot rely on the consensus component to
produce a peerset.
* Re-factor/re-implementation of "ipfs-cluster-service state"
operations. Includes the dissapearance of the "migrate" one.
The CRDT consensus component defines creates a crdt-datastore (with ipfs-lite)
and uses it to intitialize a dssate. Thus the crdt-store is elegantly
wrapped. Any modifications to the state get automatically replicated to other
peers. We store all the CRDT DAG blocks in the local datastore.
The consensus components only expose a ReadOnly state, as any modifications to
the shared state should happen through them.
DHT and PubSub facilities must now be created outside of Cluster and passed in
so they can be re-used by different components.
Better error messages in test-lib init functions and ipfshttp
Cleanup functions are now called after every test file
License: MIT
Signed-off-by: Wyatt Daviau <wdaviau@cs.stanford.edu>
