life.go

package life

import (
	"sync"
)

// Life handles the creation of the background thread and shutdown management
type Life struct {
	wg    *sync.WaitGroup
	Done  chan struct{}
	run   func()
	once  *sync.Once
	close *sync.Once
}

// NewLife creates life with the expected defaults
func NewLife() *Life {
	return &Life{
		wg:    &sync.WaitGroup{},
		Done:  make(chan struct{}, 0),
		once:  &sync.Once{},
		close: &sync.Once{},
	}
}

// Start the background thread.
func (l Life) Start() {
	l.once.Do(func() {
		l.WGAdd(1)
		go l.runner()
	})
}

func (l Life) runner() {
	defer l.wg.Done()
	l.run()
}

// SetRun will set the run function that will be called by Start.
func (l *Life) SetRun(f func()) {
	l.run = f
}

// WGAdd will add to life's waitgroup.
func (l Life) WGAdd(i int) {
	l.wg.Add(i)
}

// WGDone will decrement life's waitgroup.
func (l Life) WGDone() {
	l.wg.Done()
}

// Close will wait for the background thread to finish and then exit
func (l Life) Close() error {
	l.close.Do(func() {
		close(l.Done)
	})
	l.wg.Wait()
	return nil
}