Struct BasicService

services/basic_service.go:52–73

BasicService implements contract of Service interface, using three supplied functions: StartingFn, RunningFn and StoppingFn. When service is started, these three functions are called as service transitions to Starting, Running and Stopping state. Since they are called sequentially, they don't need

// * 1. StartingFn, 2. RunningFn, 3. StoppingFn -- this is most common, when StartingFn doesn't return error,
// service is not stopped and context isn't stopped externally while running StartingFn.
type BasicService struct {
	// functions only run, if they are not nil. If functions are nil, service will effectively do nothing
	// in given state, and go to the next one without any error.
	startFn    StartingFn
	runningFn  RunningFn
	stoppingFn StoppingFn

	// everything below is protected by this mutex
	stateMu     sync.RWMutex
	state       State
	failureCase error
	listeners   []chan func(l Listener)
	serviceName string

	// closed when state reaches Running, Terminated or Failed state
	runningWaitersCh chan struct{}
	// closed when state reaches Terminated or Failed state
	terminatedWaitersCh chan struct{}

	serviceContext context.Context
	serviceCancel  context.CancelFunc
}

func invalidServiceStateError(state, expected State) error {
	return fmt.Errorf("invalid service state: %v, expected: %v", state, expected)