This commit replaces the simplistic rate limiting
technique added in 557cb6e2, to use the
golang.org/x/time's rate limiter. This has the
benefit of performing traffic shaping to meet a
target maximum rate, and yet tolerate bursts. Bursts
are expected during initial sync, though should become
more rare afterwards. Performing traffic shaping with
this mechanism should improve the ability of the gossip
syncer to detect sustained bursts from the remote peer,
and penalize them appropriately.
This commit also modifies the default parameters to
accept bursts of 10 queries, with a target rate of 1
reply every 5 seconds.
In this commit, we allow the gossiper syncer to store the chunk size for
its respective encoding type. We do this to prevent a race condition
that would arise within the unit tests by modifying the values of the
encodingTypeToChunkSize map to allow for easier testing.
In this commit, we extend the AuthenticatedGossiper to take advantage of
the new query features in the case that it gets a channel update w/o
first receiving the full channel announcement. If this happens, we'll
attempt to find a syncer that's fully synced, and request the channel
announcement from it.
This new method allows outside callers to sample the current state of
the gossipSyncer in a concurrent-safe manner. In order to achieve this,
we now only modify the g.state variable atomically.
In this commit, introduce a new struct, the gossipSyncer. The role of
this struct is to encapsulate the state machine required to implement
the new gossip query range feature recently added to the spec. With this
change, each peer that knows of this new feature will have a new
goroutine that will be managed by the gossiper.
Once created and started, the gossipSyncer will start to progress
through each possible state, finally ending at the chansSynced stage. In
this stage, it has synchronized state with the remote peer, and is
simply awaiting any new messages from the gossiper to send directly to
the peer. Each message will only be sent if the remote peer actually has
a set update horizon, and the message isn't before or after that
horizon.
A set of unit tests has been added to ensure that two state machines
properly terminate and synchronize channel state.
