scrape/manager.go
func NewManager(logger log.Logger, app Appendable) *Manager {
	if logger == nil {
		logger = log.NewNopLogger()
	}
	return &Manager{
		append:        app,
		logger:        logger,
		scrapeConfigs: make(map[string]*config.ScrapeConfig),
		scrapePools:   make(map[string]*scrapePool),
		graceShut:     make(chan struct{}),
		triggerReload: make(chan struct{}, 1),
	}
}
func NewManager(logger log.Logger, app Appendable) *Manager {
	if logger == nil {
		logger = log.NewNopLogger()
	}
	return &Manager{
		append:        app,
		logger:        logger,
		scrapeConfigs: make(map[string]*config.ScrapeConfig),
		scrapePools:   make(map[string]*scrapePool),
		graceShut:     make(chan struct{}),
		triggerReload: make(chan struct{}, 1),
	}
}
// NewManager is the Manager constructor