package nats import ( "errors" "time" "github.com/nats-io/nats.go/jetstream" ) var ( timerStore jetstream.KeyValue ticker *time.Ticker ) func TimerStoreConnect() error { if client.JS == nil { return errors.New("jetstream must be connected first") } logger.Debug("Looking for KV store") listener := client.JS.KeyValueStoreNames(ctx) found := false for name := range listener.Name() { if name == "KV_hats_timers" { found = true } } var err error if found { logger.Debug("Connecting to Timers KV store") timerStore, err = client.JS.KeyValue(ctx, "hats_timers") } else { logger.Debug("Creating Timers KV store") timerStore, err = client.JS.CreateKeyValue(ctx, jetstream.KeyValueConfig{ Bucket: "hats_timers", }) } return err } type HatsTimer struct { Name string Duration time.Duration NextActivation time.Time } func NewTimerWithDuration(name, duration string) *HatsTimer { t := &HatsTimer{ Name: name, } d, err := time.ParseDuration(duration) if err != nil { d = 5 * time.Minute } t.Duration = d return t.CalculateNext() } func NewTimerWithActivation(name string, activation []byte) (*HatsTimer, error) { t := &HatsTimer{ Name: name, Duration: 5 * time.Minute, } a, err := time.Parse(time.RFC3339, string(activation)) if err != nil { return t.CalculateNext(), err } t.NextActivation = a return t, nil } func GetTimer(name string) (*HatsTimer, error) { value, err := timerStore.Get(ctx, name) if err != nil { return nil, err } return NewTimerWithActivation(name, value.Value()) } func (t *HatsTimer) CalculateNext() *HatsTimer { t.NextActivation = time.Now().Add(t.Duration) return t } func (t *HatsTimer) Marshall() []byte { timestamp, _ := t.NextActivation.MarshalText() return timestamp } func (t *HatsTimer) Activate() { timerStore.Put(ctx, t.Name, t.Marshall()) } func (t *HatsTimer) ActivateIfNotAlready() { timerStore.Create(ctx, t.Name, t.Marshall()) } func (t *HatsTimer) Cancel() { timerStore.Purge(ctx, t.Name) } func (t *HatsTimer) End() { t.Cancel() PublishString("timers."+t.Name, "done") } func WatchTimers() { ticker = time.NewTicker(time.Second) for { t := <-ticker.C timers, _ := timerStore.Keys(ctx, jetstream.IgnoreDeletes()) for _, timerName := range timers { timer, err := GetTimer(timerName) if err != nil { logger.Error("Error retrieving timer", "timer", timerName, "error", err) continue } if t.After(timer.NextActivation) { timer.End() } } } } func StopTimers() { if ticker != nil { ticker.Stop() } }