all: sync with master; upd chlog

internal/next/agh/agh.go

@@ -0,0 +1,63 @@
+// Package agh contains common entities and interfaces of AdGuard Home.
+package agh
+
+import "context"
+
+// Service is the interface for API servers.
+//
+// TODO(a.garipov): Consider adding a context to Start.
+//
+// TODO(a.garipov): Consider adding a Wait method or making an extension
+// interface for that.
+type Service interface {
+	// Start starts the service.  It does not block.
+	Start() (err error)
+
+	// Shutdown gracefully stops the service.  ctx is used to determine
+	// a timeout before trying to stop the service less gracefully.
+	Shutdown(ctx context.Context) (err error)
+}
+
+// type check
+var _ Service = EmptyService{}
+
+// EmptyService is a [Service] that does nothing.
+//
+// TODO(a.garipov): Remove if unnecessary.
+type EmptyService struct{}
+
+// Start implements the [Service] interface for EmptyService.
+func (EmptyService) Start() (err error) { return nil }
+
+// Shutdown implements the [Service] interface for EmptyService.
+func (EmptyService) Shutdown(_ context.Context) (err error) { return nil }
+
+// ServiceWithConfig is an extension of the [Service] interface for services
+// that can return their configuration.
+//
+// TODO(a.garipov): Consider removing this generic interface if we figure out
+// how to make it testable in a better way.
+type ServiceWithConfig[ConfigType any] interface {
+	Service
+
+	Config() (c ConfigType)
+}
+
+// type check
+var _ ServiceWithConfig[struct{}] = (*EmptyServiceWithConfig[struct{}])(nil)
+
+// EmptyServiceWithConfig is a ServiceWithConfig that does nothing.  Its Config
+// method returns Conf.
+//
+// TODO(a.garipov): Remove if unnecessary.
+type EmptyServiceWithConfig[ConfigType any] struct {
+	EmptyService
+
+	Conf ConfigType
+}
+
+// Config implements the [ServiceWithConfig] interface for
+// *EmptyServiceWithConfig.
+func (s *EmptyServiceWithConfig[ConfigType]) Config() (conf ConfigType) {
+	return s.Conf
+}