HTTP Server: Statuses can be collected in the background (#203)

* Fixed collection of statuses.

* AutoConnect also supports periodic update.

* Refresh.

* Convurrent.

* More logging.

application/application.go

@@ -393,7 +393,7 @@ func (a *Application) Update() error {
 		if err == nil {
 			break
 		}
-		a.log("error getting receiever status: %v", err)
+		a.log("error getting receiver status: %v", err)
 		a.log("unable to get status from device; attempt %d/5, retrying...", i+1)
 		time.Sleep(time.Second * 2)
 	}

cast/payload.go

@@ -165,4 +165,5 @@ type DeviceInfo struct {
 	Ssid       string  `json:"ssid"`
 	Timezone   string  `json:"timezone"`
 	UptimeSec  float64 `json:"uptime"`
+	SsdpUdn    string  `json:"ssdp_udn"`
 }

http/handlers.go

@@ -4,14 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"golang.org/x/sync/errgroup"
 	"net"
 	"net/http"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
-	"golang.org/x/sync/errgroup"
-
 	log "github.com/sirupsen/logrus"
 	"github.com/vishen/go-chromecast/application"
 	"github.com/vishen/go-chromecast/dns"
@@ -22,28 +22,73 @@ type Handler struct {
 	apps map[string]application.App
 	mux  *http.ServeMux
 
-	verbose     bool
-	autoconnect bool
+	verbose bool
+
+	autoconnectPeriod time.Duration
+	autoconnectTicker *time.Ticker
+
+	// autoupdatePeriodSec defines how frequently app.Update method is called in the background.
+	autoupdatePeriod time.Duration
+	autoupdateTicker *time.Ticker
 }
 
 func NewHandler(verbose bool) *Handler {
 	handler := &Handler{
-		verbose:     verbose,
-		apps:        map[string]application.App{},
-		mux:         http.NewServeMux(),
-		mu:          sync.Mutex{},
-		autoconnect: false,
+		verbose: verbose,
+		apps:    map[string]application.App{},
+		mux:     http.NewServeMux(),
+		mu:      sync.Mutex{},
+
+		autoconnectPeriod: time.Duration(-1),
+		autoconnectTicker: nil,
+
+		autoupdatePeriod: time.Duration(-1),
+		autoupdateTicker: nil,
 	}
 	handler.registerHandlers()
 	return handler
 }
 
-// Autoconnect configures the handler to perform auto-discovery of all the cast devices & groups.
+// AutoConnect configures the handler to perform periodic auto-discovery of all the cast devices & groups.
+// It's intended to be called just after `NewHandler()`, before the handler is registered in the server.
+func (h *Handler) AutoConnect(period time.Duration) error {
+	// Setting the autoconnect property - to allow (in future) periodic refresh of the connections.
+	h.autoconnectPeriod = period
+	if err := h.connectAllInternal("", "3"); err != nil {
+		return err
+	}
+	if h.autoconnectPeriod > 0 {
+		h.autoconnectTicker = time.NewTicker(period)
+		go func() {
+			for {
+				<-h.autoconnectTicker.C
+				if err := h.connectAllInternal("", "3"); err != nil {
+					log.Printf("AutoConnect issued connectAllInternal failed: %v", err)
+				}
+			}
+		}()
+	}
+	return nil
+}
+
+// AutoUpdate configures the handler to perform auto-update of all the cast devices & groups.
 // It's intended to be called just after `NewHandler()`, before the handler is registered in the server.
-func (h *Handler) Autoconnect() error {
+// Thanks to AutoUpdate, /status and /statuses returns relatively recent status 'instantly'.
+func (h *Handler) AutoUpdate(period time.Duration) error {
 	// Setting the autoconnect property - to allow (in future) periodic refresh of the connections.
-	h.autoconnect = true
-	return h.connectAllInternal("", "3")
+	h.autoupdatePeriod = period
+	if h.autoupdatePeriod > 0 {
+		h.autoupdateTicker = time.NewTicker(period)
+		go func() {
+			for {
+				<-h.autoupdateTicker.C
+				if err := h.UpdateAll(); err != nil {
+					log.Printf("AutoUpdate issued UpdateAll failed: %v", err)
+				}
+			}
+		}()
+	}
+	return nil
 }
 
 func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -291,20 +336,42 @@ func (h *Handler) connectAll(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) connectAllInternal(iface string, waitSec string) error {
-	devices := h.discoverDnsEntries(context.Background(), iface, waitSec)
-	uuidMap := map[string]application.App{}
+	ctx := context.Background()
+	devices := h.discoverDnsEntries(ctx, iface, waitSec)
+	apps := make(chan *application.App, len(devices)+1)
+	g, ctx := errgroup.WithContext(ctx)
 	for _, device := range devices {
-		app, err := h.connectInternal(device.Addr, device.Port, device.DeviceName)
+		g.Go(func() error {
+			log.Printf("Connecting to %s:%d (%s)", device.Addr, device.Port, device.DeviceName)
+			app, err := h.connectInternal(device.Addr, device.Port, device.DeviceName)
+			if err != nil {
+				log.Printf("Connection to %s:%d (%s) failed: %v", device.Addr, device.Port, device.DeviceName, err)
+				return err
+			}
+			log.Printf("Connected to %s:%d (%s)", device.Addr, device.Port, device.DeviceName)
+			apps <- &app
+			return nil
+		})
+	}
+	err := g.Wait()
+	log.Printf("Post wait status: %v", err)
+	close(apps)
+
+	// Even if we cannot connect to some of the devices, we still update the map for remaining devices.
+	uuidMap := map[string]application.App{}
+	for app := range apps {
+		info, err := (*app).Info()
 		if err != nil {
-			return err
+			log.Printf("Skipping device %v", app)
+		} else {
+			uuidMap[strings.ReplaceAll(info.SsdpUdn, "-", "")] = *app
 		}
-		uuidMap[device.UUID] = app
 	}
 
 	h.mu.Lock()
 	h.apps = uuidMap
 	h.mu.Unlock()
-	return nil
+	return err
 }
 
 func (h *Handler) disconnect(w http.ResponseWriter, r *http.Request) {
@@ -353,7 +420,14 @@ func (h *Handler) status(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	h.log("status for device")
-
+	syncUpdate := r.URL.Query().Get("syncUpdate") == "true"
+	if syncUpdate {
+		if err := app.Update(); err != nil {
+			h.log("error updating  status: %v", err)
+			httpError(w, fmt.Errorf("error updating status: %w", err))
+			return
+		}
+	}
 	castApplication, castMedia, castVolume := app.Status()
 	info, err := app.Info()
 	if err != nil {
@@ -377,8 +451,21 @@ func (h *Handler) status(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func (h *Handler) UpdateAll() error {
+	uuids := h.ConnectedDeviceUUIDs()
+	g := new(errgroup.Group)
+	for _, deviceUUID := range uuids {
+		app, ok := h.app(deviceUUID)
+		if ok {
+			g.Go(func() error { return app.Update() })
+		}
+	}
+	return g.Wait()
+}
+
 func (h *Handler) statuses(w http.ResponseWriter, r *http.Request) {
 	h.log("statuses for devices")
+	syncUpdate := r.URL.Query().Get("syncUpdate") == "true"
 	uuids := h.ConnectedDeviceUUIDs()
 	mapUUID2Ch := map[string]chan statusResponse{}
 	g := new(errgroup.Group)
@@ -388,6 +475,11 @@ func (h *Handler) statuses(w http.ResponseWriter, r *http.Request) {
 			ch := make(chan statusResponse, 1)
 			mapUUID2Ch[deviceUUID] = ch
 			g.Go(func() error {
+				if syncUpdate {
+					if err := app.Update(); err != nil {
+						return err
+					}
+				}
 				castApplication, castMedia, castVolume := app.Status()
 				info, err := app.Info()
 				if err != nil {
@@ -404,8 +496,9 @@ func (h *Handler) statuses(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 	if err := g.Wait(); err != nil {
-		h.log("%v", err)
-		httpError(w, err)
+		h.log("collecting statuses failed: %v", err)
+		httpError(w, fmt.Errorf("collecting statuses failed: %w", err))
+		return
 	}
 
 	statusResponses := map[string]statusResponse{}
@@ -560,7 +653,7 @@ func (h *Handler) rewind(w http.ResponseWriter, r *http.Request) {
 	q := r.URL.Query()
 	seconds := q.Get("seconds")
 	if seconds == "" {
-		httpValidationError(w, "missing 'seconds' in query paramater")
+		httpValidationError(w, "missing 'seconds' in query parameter")
 		return
 	}
 
@@ -589,7 +682,7 @@ func (h *Handler) seek(w http.ResponseWriter, r *http.Request) {
 	q := r.URL.Query()
 	seconds := q.Get("seconds")
 	if seconds == "" {
-		httpValidationError(w, "missing 'seconds' in query paramater")
+		httpValidationError(w, "missing 'seconds' in query parameter")
 		return
 	}