Add read-only mode support and enhance logging throughout the application

mk2core/core.go

@@ -2,8 +2,11 @@ package mk2core
 
 import (
 	"git.coadcorp.com/nathan/invertergui/mk2driver"
+	"github.com/sirupsen/logrus"
 )
 
+var log = logrus.WithField("ctx", "inverter-gui-core")
+
 type Core struct {
 	mk2driver.Mk2
 	plugins  map[*subscription]bool
@@ -16,6 +19,7 @@ func NewCore(m mk2driver.Mk2) *Core {
 		register: make(chan *subscription, 255),
 		plugins:  map[*subscription]bool{},
 	}
+	log.Info("Core initialized")
 	go core.run()
 	return core
 }
@@ -25,6 +29,7 @@ func (c *Core) NewSubscription() mk2driver.Mk2 {
 		send: make(chan *mk2driver.Mk2Info),
 	}
 	c.register <- sub
+	log.Debug("New plugin subscription registered")
 	return sub
 }
 
@@ -33,11 +38,13 @@ func (c *Core) run() {
 		select {
 		case r := <-c.register:
 			c.plugins[r] = true
+			log.WithField("subscribers", len(c.plugins)).Debug("Subscription added")
 		case e := <-c.C():
 			for plugin := range c.plugins {
 				select {
 				case plugin.send <- e:
 				default:
+					log.WithField("subscribers", len(c.plugins)).Warn("Dropping update for a slow subscriber")
 				}
 			}
 		}