This commit addresses a bug in the channel event store
where the opened time of a channel event log was not
set for peers that were offline on startup.
Previously, opened time was set to the time of the first
event in the event log. This worked for online peers,
because the eventlog was created with an initial online
event. However, offline peers had no inital event so had
no open time set.
This commit simplifies the creation of an event log by
removing the initial event and setting open time for all
event logs. This has the effect of potentially introducing
a gap between opened time for a log and the first peer
online event for peers with channels that exist at startup
if a peer takes time to reconnect. However, the cost of this
is less than the benefit of reducing the bug-prone custom
code path that was previously in place.
In this commit, the channelEventStore in the channel
fitness subsystem is changed to identify channels
by their outpoint rather than short channel id. This
change is made made becuase outpoints are the preferred
way to expose references over rpc, and easier to perform
queries within lnd.
This commit adds a channel event store to the channel fitness
package which is used to manage tracking of a node's channels.
It adds tracking for channel open/closed and peer online/offline
events for all channels that a node has open.
Events are consumed from channelNotifier and peerNotifier event
subscriptions. If either of these subscriptions is cancelled,
channel scoring stops, because both subscriptions are expected
to run until node shutdown.
Two functions are exposed to allow external callers to get uptime
information about a channel. GetLifespan returns the period over
which the channel has been monitored. GetUptime returns the channel's
uptime over a specified period. Callers can use these functions to
get the channel's remote peer uptime over its entire lifetime, or
a subset of that period.
