fix #2: implement safe.Job

safe/background.go

@@ -2,31 +2,34 @@ package safe
 
 import "sync"
 
-type Job interface {
-	Do(func() error, func(error))
-	Wait()
-}
-
-func Background() Job {
-	return &background{}
-}
-
-type background sync.WaitGroup
+// A Job provides a top level API above the sync.WaitGroup.
+//
+//  job := new(safe.Job)
+//  for _, action := range jobs {
+//  	job.Do(action, logger)
+//  }
+//  job.Wait()
+//
+// It looks a little bit similar to the golang.org/x/sync/errgroup.
+type Job sync.WaitGroup
 
-func (bg *background) Do(action func() error, handler func(error)) {
-	(*sync.WaitGroup)(bg).Add(1)
+// Do calls the given function in a new goroutine.
+// If an error is not nil, it passes it to the handler.
+func (job *Job) Do(action func() error, handler func(error)) {
+	(*sync.WaitGroup)(job).Add(1)
 	go Do(func() error {
 		if err := action(); err != nil {
 			return err
 		}
-		(*sync.WaitGroup)(bg).Done()
+		(*sync.WaitGroup)(job).Done()
 		return nil
 	}, func(err error) {
 		handler(err)
-		(*sync.WaitGroup)(bg).Done()
+		(*sync.WaitGroup)(job).Done()
 	})
 }
 
-func (bg *background) Wait() {
-	(*sync.WaitGroup)(bg).Wait()
+// Wait blocks until the sync.WaitGroup counter is zero.
+func (job *Job) Wait() {
+	(*sync.WaitGroup)(job).Wait()
 }

safe/background_test.go

@@ -11,10 +11,10 @@ import (
 	. "go.octolab.org/safe"
 )
 
-func TestBackground(t *testing.T) {
+func TestJob(t *testing.T) {
 	var spy uint32
 
-	job := Background()
+	job := new(Job)
 	for range make([]struct{}, 10) {
 		job.Do(func() error {
 			atomic.AddUint32(&spy, 1)
@@ -43,23 +43,23 @@ func BenchmarkBackground(b *testing.B) {
 	b.Run("without error", func(b *testing.B) {
 		b.ReportAllocs()
 		for i := 0; i < b.N; i++ {
-			job := Background()
+			job := new(Job)
 			job.Do(func() error { return nil }, nil)
 			job.Wait()
 		}
 	})
 	b.Run("with error", func(b *testing.B) {
 		b.ReportAllocs()
 		for i := 0; i < b.N; i++ {
-			job := Background()
+			job := new(Job)
 			job.Do(func() error { return errors.New("test") }, func(error) {})
 			job.Wait()
 		}
 	})
 	b.Run("with panic", func(b *testing.B) {
 		b.ReportAllocs()
 		for i := 0; i < b.N; i++ {
-			job := Background()
+			job := new(Job)
 			job.Do(func() error { panic(errors.New("at the Disco")) }, func(error) {})
 			job.Wait()
 		}