don't block dasboard rendering for too long

updates #210

web/handlers/admin/dashboard.go

@@ -5,8 +5,11 @@ package admin
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	"go.mindeco.de/http/render"
+	"go.mindeco.de/log/level"
+	"go.mindeco.de/logging"
 	refs "go.mindeco.de/ssb-refs"
 
 	"github.com/ssb-ngi-pointer/go-ssb-room/internal/network"
@@ -25,36 +28,53 @@ type dashboardHandler struct {
 }
 
 func (h dashboardHandler) overview(w http.ResponseWriter, req *http.Request) (interface{}, error) {
-	roomRef := h.netInfo.RoomID.Ref()
+	var (
+		ctx     = req.Context()
+		roomRef = h.netInfo.RoomID.Ref()
 
-	onlineRefs := h.roomState.List()
+		onlineRefs   []refs.FeedRef
+		refsUpdateCh = make(chan []refs.FeedRef)
+		onlineCount  = -1
+	)
 
+	// this is an attempt to sidestep the _dashboard doesn't render_ bug (issue #210)
+	// first we retreive the member state via a goroutine in the background
+	go func() {
+		refsUpdateCh <- h.roomState.ListAsRefs()
+	}()
+
+	// if it doesn't complete in 10 seconds the slice stays empty and onlineCount remains -1 (to indicate a problem)
+	select {
+	case <-time.After(10 * time.Second):
+		logger := logging.FromContext(ctx)
+		level.Warn(logger).Log("event", "didnt retreive room state in time")
+
+	case onlineRefs = <-refsUpdateCh:
+		onlineCount = len(onlineRefs)
+	}
+
+	// in the timeout case, nothing will happen here since the onlineRefs slice is empty
 	onlineMembers := make([]roomdb.Member, len(onlineRefs))
-	for i := range onlineRefs {
-		ref, err := refs.ParseFeedRef(onlineRefs[i])
-		if err != nil {
-			return nil, fmt.Errorf("failed to parse online ref: %w", err)
-		}
-		onlineMembers[i], err = h.dbs.Members.GetByFeed(req.Context(), *ref)
+	for i, ref := range onlineRefs {
+		var err error
+		onlineMembers[i], err = h.dbs.Members.GetByFeed(ctx, ref)
 		if err != nil {
 			// TODO: do we want to show "external users" (non-members) on the dashboard?
 			return nil, fmt.Errorf("failed to lookup online member: %w", err)
 		}
 	}
 
-	onlineCount := len(onlineMembers)
-
-	memberCount, err := h.dbs.Members.Count(req.Context())
+	memberCount, err := h.dbs.Members.Count(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to count members: %w", err)
 	}
 
-	inviteCount, err := h.dbs.Invites.Count(req.Context())
+	inviteCount, err := h.dbs.Invites.Count(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to count invites: %w", err)
 	}
 
-	deniedCount, err := h.dbs.DeniedKeys.Count(req.Context())
+	deniedCount, err := h.dbs.DeniedKeys.Count(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to count denied keys: %w", err)
 	}