Method main

services/basic_service.go:156–228

This is the "main" method, that does most of the work of service. Service is in Starting state when this method runs. Entire lifecycle of the service happens here.

()

// Service is in Starting state when this method runs.
// Entire lifecycle of the service happens here.
func (b *BasicService) main() {
	var err error

	if b.startFn != nil {
		err = b.startFn(b.serviceContext)
	}

	if err != nil {
		b.mustSwitchState(Starting, Failed, func() {
			b.failureCase = err
			b.serviceCancel() // cancel the context, just in case if anything started in StartingFn is using it
			// we will not reach Running or Terminated, notify waiters
			close(b.runningWaitersCh)
			close(b.terminatedWaitersCh)
			b.notifyListeners(func(l Listener) { l.Failed(Starting, err) }, true)
		})
		return
	}

	stoppingFrom := Starting

	// Starting has succeeded. We should switch to Running now, but let's not do that
	// if our context has been canceled in the meantime.
	if err = b.serviceContext.Err(); err != nil {
		err = nil // don't report this as a failure, it is a normal "stop" signal.
		goto stop
	}

	// We have reached Running state
	b.mustSwitchState(Starting, Running, func() {
		// unblock waiters waiting for Running state
		close(b.runningWaitersCh)
		b.notifyListeners(func(l Listener) { l.Running() }, false)
	})

	stoppingFrom = Running
	if b.runningFn != nil {
		err = b.runningFn(b.serviceContext)
	}

stop:
	failure := err
	b.mustSwitchState(stoppingFrom, Stopping, func() {
		if stoppingFrom == Starting {
			// we will not reach Running state
			close(b.runningWaitersCh)
		}
		b.notifyListeners(func(l Listener) { l.Stopping(stoppingFrom) }, false)
	})

	// Make sure we cancel the context before running stoppingFn
	b.serviceCancel()

	if b.stoppingFn != nil {
		err = b.stoppingFn(failure)
		if failure == nil {
			failure = err
		}