initial state is now sent again when the websocket connection is

established.
Also throttling based on user input. When browser sends multiple
messages per second the user will still only get one notification per
second at most.

pkg/server/ui/websessions.go

@@ -3,6 +3,7 @@ package ui
 import (
 	"context"
 	"git.wamblee.org/converge/pkg/models"
+	"git.wamblee.org/converge/pkg/support/throttling"
 	"log"
 	"net"
 	"net/http"
@@ -25,6 +26,7 @@ type WebSession struct {
 func NewWebSessions(notifications chan *models.State) *WebSessions {
 	websessions := &WebSessions{
 		sessions:         make(map[*WebSession]bool),
+		lastNotification: models.NewState(),
 	}
 
 	go func() {
@@ -76,7 +78,16 @@ func (sessions *WebSessions) NewSession(wsConnection net.Conn, ctx context.Conte
 		conn:          wsConnection,
 		ctx:           ctx,
 	}
+
+	// initial notification as soon as client connects.
 	go func() {
+		session.notifications <- sessions.lastNotification
+	}()
+
+	go func() {
+		throttler := throttling.NewAsyncThrottler(func(state *models.State) {
+			session.notifications <- state
+		}, time.Second, time.Second)
 		for {
 			// the web app opens one websocket connection and sends a hello
 			// message asking for the latest state when a page is loaded that requires this.
@@ -84,7 +95,7 @@ func (sessions *WebSessions) NewSession(wsConnection net.Conn, ctx context.Conte
 			p := make([]byte, 1024)
 			_, err := wsConnection.Read(p)
 			if err == nil {
-				session.notifications <- sessions.lastNotification
+				throttler.Notify(sessions.lastNotification)
 			} else {
 				log.Printf("Got error reading %v", err)
 				cancel()