The round was usable to build the current clock in an accumulated
fashion, relative to the previous round. The end time is the absolute
metric of it, which can be used to calculate the round number (with all
previous end times).
Substrate now builds off the best block, not genesis, using the end time
included in the justification to start its machine in a synchronized
state.
Knowing the end time of a round, or the round in which block was
committed to, is necessary for nodes to sync up with Tendermint.
Encoding it in the commit ensures it's long lasting and makes it readily
available, without the load of an entire transaction.
Substrate doesn't expect nor officially support children with less work
than their parents. It's a trick used here. Accordingly, ensure the
trick's validity.
By claiming File, they're not sent ovber the P2P network before they
have a justification, as desired. Unfortunately, they never were. This
works around that.
The BasicQueue returned obscures the TendermintImport struct.
Accordingly, a Future scoped with access is returned upwards, which when
awaited will create the machine. This makes creating the machine
optional while maintaining scope boundaries.
Is sufficient to create a 1-node net which produces and finalizes
blocks.