585cb83ed0
Backend published auf signage/screen/{slug}/playlist-changed nach
Playlist-Mutationen (2s Debounce). Agent subscribed und fetcht
Playlist sofort (3s Debounce). 60s-Polling bleibt als Fallback.
Neue Packages: mqttnotifier (Backend), mqttsubscriber (Agent)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
106 lines
2.9 KiB
Go
106 lines
2.9 KiB
Go
// Package mqttnotifier publishes playlist-changed notifications to MQTT.
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// It is safe for concurrent use and applies per-screen debouncing so that
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// rapid edits within a 2-second window produce at most one MQTT message.
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package mqttnotifier
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import (
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"fmt"
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"sync"
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"time"
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mqtt "github.com/eclipse/paho.mqtt.golang"
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)
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const (
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// debounceDuration is the minimum time between two publish calls for the
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// same screen. Any change arriving within this window resets the timer.
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debounceDuration = 2 * time.Second
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)
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// Notifier publishes "playlist-changed" MQTT messages with per-screen debounce.
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// If no broker URL is configured it behaves as a no-op (all methods are safe
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// to call and do nothing).
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type Notifier struct {
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client mqtt.Client // nil when disabled
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mu sync.Mutex
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timers map[string]*time.Timer // keyed by screenSlug
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}
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// New creates a Notifier connected to broker (e.g. "tcp://mosquitto:1883").
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// username/password may be empty. Returns a no-op Notifier when broker == "".
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func New(broker, username, password string) *Notifier {
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n := &Notifier{timers: make(map[string]*time.Timer)}
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if broker == "" {
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return n
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}
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opts := mqtt.NewClientOptions().
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AddBroker(broker).
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SetClientID("morz-backend").
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SetCleanSession(true).
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SetAutoReconnect(true).
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SetConnectRetry(true).
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SetConnectRetryInterval(10 * time.Second)
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if username != "" {
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opts.SetUsername(username)
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opts.SetPassword(password)
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}
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n.client = mqtt.NewClient(opts)
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n.client.Connect() // non-blocking; paho retries in background
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return n
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}
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// Topic returns the MQTT topic for a screen's playlist-changed notification.
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func Topic(screenSlug string) string {
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return fmt.Sprintf("signage/screen/%s/playlist-changed", screenSlug)
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}
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// NotifyChanged schedules a publish for screenSlug. If another call for the
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// same screen arrives within debounceDuration, the timer is reset (debounce).
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// The method returns immediately; the actual publish happens in a goroutine.
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func (n *Notifier) NotifyChanged(screenSlug string) {
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if n.client == nil {
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return
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}
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n.mu.Lock()
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defer n.mu.Unlock()
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// Reset existing timer if present (debounce).
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if t, ok := n.timers[screenSlug]; ok {
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t.Stop()
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}
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n.timers[screenSlug] = time.AfterFunc(debounceDuration, func() {
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n.mu.Lock()
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delete(n.timers, screenSlug)
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n.mu.Unlock()
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n.publish(screenSlug)
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})
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}
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func (n *Notifier) publish(screenSlug string) {
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topic := Topic(screenSlug)
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payload := []byte(fmt.Sprintf(`{"ts":%d}`, time.Now().UnixMilli()))
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token := n.client.Publish(topic, 0, false, payload)
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token.WaitTimeout(3 * time.Second)
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// Errors are silently dropped — the 60 s polling in the agent is the fallback.
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}
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// Close disconnects the MQTT client gracefully.
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func (n *Notifier) Close() {
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if n.client == nil {
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return
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}
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n.mu.Lock()
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for _, t := range n.timers {
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t.Stop()
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}
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n.timers = make(map[string]*time.Timer)
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n.mu.Unlock()
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n.client.Disconnect(250)
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}
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