Рыба проекта. Минимальная функциональность

pkg/adapters/scheduler/cron/cron.go

@@ -0,0 +1,66 @@
+package cron
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/robfig/cron/v3"
+
+	"git.tswf.io/infra/go-synapse-backupper/pkg/domain"
+)
+
+// cronScheduler wraps robfig/cron/v3 to implement domain.Scheduler.
+type cronScheduler struct {
+	cron       *cron.Cron
+	waitGroup  sync.WaitGroup
+	stopCancel context.CancelFunc
+	stoppedCtx context.Context
+}
+
+// NewCronScheduler creates a new cron-based scheduler.
+// The expr must be a valid cron expression. When WithSeconds is used
+// (as in this implementation) the expression should contain six fields.
+func NewCronScheduler(
+	expr string,
+	job func(),
+) (
+	domain.Scheduler,
+	error,
+) {
+	scheduler := &cronScheduler{
+		cron: cron.New(cron.WithSeconds()),
+	}
+
+	_, err := scheduler.cron.AddFunc(
+		expr,
+		func() {
+			scheduler.waitGroup.Add(1)
+			defer scheduler.waitGroup.Done()
+			job()
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("invalid cron expression %q: %w", expr, err)
+	}
+
+	scheduler.stoppedCtx, scheduler.stopCancel = context.WithCancel(context.Background())
+
+	return scheduler, nil
+}
+
+// Start begins executing the scheduled job.
+func (s *cronScheduler) Start() {
+	s.cron.Start()
+}
+
+// Stop halts the scheduler and returns a context that is cancelled
+// once all in-flight jobs have completed.
+func (s *cronScheduler) Stop() context.Context {
+	s.cron.Stop()
+	go func() {
+		s.waitGroup.Wait()
+		s.stopCancel()
+	}()
+	return s.stoppedCtx
+}