Isn't spec compliant due to the lack of a spec to be compliant too.
Slight deviation from the paper by using a unique list instead of a multiset.
Closes#186, progresses #277.
This probably should be done with n-long lived tasks, one per Tributary. While
this may not be suitably performant long-term (potential DoS vector), this at
least resolves the halting concerns.
When we receive messages, we're provided with a message ID we can use to
prevent handling an item multiple times. That doesn't prevent us from *sending*
an item multiple times though. Thanks to the UID system, we can now not send if
already present.
Alternatively, we can remove the ordered message ID for just the UID, allowing
duplicates to be sent without issue, and handled on the receiving end.
Reduces lock contention.
Additionally changes block_key to include the genesis. While not technically
needed, the lack of genesis introduced a side effect where any Tributary on the
the database could return the block of any other Tributary. While that wasn't a
security issue, returning it suggested it was on-chain when it wasn't. This may
have been usable to create issues.
We had a race condition where'd we be informed of blocks 1 .. 3, and
immediately add 1 .. 3. Because we immediately tried to add 2 after 1, it'd
fail since the tip was still the genesis, yet 2 needs the tip to be 1.
Adding a channel, while ugly, was the simplest way to accomplish this.
Also has any added block be broadcasted. Else there's a race condition where a
node which syncs up to the most recent block does so, yet fails to add the next
block when it's committed to.
This defines the tart of a very complex series of locks I'm really unhappy
with. At the same time, there's not immediately a better solution. This also
should work without issue.
add_active_tributary writes the spec to disk before it returns, so even if the
VecDeque it pushes to isn't popped, the tributary will still be loaded on boot.
Removes last_block as an argument from Tendermint. It now loads from the DB as
needed. While slightly less performant, it's easiest and should be fine.
