chanfitness: unify requests to store in single chan info struct

We currently query the store for uptime and lifespan individually. As
we add more fields, we will need to add more queries with this design.
This change combines requests into a single channel infor request so
that we do not need to add unnecessary boilerplate going forward.

rpcserver.go

@@ -3536,42 +3536,28 @@ func createRPCOpenChannel(r *rpcServer, graph *channeldb.ChannelGraph,
 		return channel, nil
 	}
 
-	// Get the lifespan observed by the channel event store. If the channel is
-	// not known to the channel event store, return early because we cannot
-	// calculate any further uptime information.
+	// Query the event store for additional information about the channel.
+	// Do not fail if it is not available, because there is a potential
+	// race between a channel being added to our node and the event store
+	// being notified of it.
 	outpoint := dbChannel.FundingOutpoint
-	startTime, endTime, err := r.server.chanEventStore.GetLifespan(outpoint)
+	info, err := r.server.chanEventStore.GetChanInfo(outpoint)
 	switch err {
+	// If the store does not know about the channel, we just log it.
 	case chanfitness.ErrChannelNotFound:
 		rpcsLog.Infof("channel: %v not found by channel event store",
 			outpoint)
 
-		return channel, nil
+	// If we got our channel info, we further populate the channel.
 	case nil:
-		// If there is no error getting lifespan, continue to uptime
-		// calculation.
+		channel.Uptime = int64(info.Uptime.Seconds())
+		channel.Lifetime = int64(info.Lifetime.Seconds())
+
+	// If we get an unexpected error, we return it.
 	default:
 		return nil, err
 	}
 
-	// If endTime is zero, the channel is still open, progress endTime to
-	// the present so we can calculate lifetime.
-	if endTime.IsZero() {
-		endTime = time.Now()
-	}
-	channel.Lifetime = int64(endTime.Sub(startTime).Seconds())
-
-	// Once we have successfully obtained channel lifespan, we know that the
-	// channel is known to the event store, so we can return any non-nil error
-	// that occurs.
-	uptime, err := r.server.chanEventStore.GetUptime(
-		outpoint, startTime, endTime,
-	)
-	if err != nil {
-		return nil, err
-	}
-	channel.Uptime = int64(uptime.Seconds())
-
 	return channel, nil
 }