fix: skip aware semerrgroup (#1176)

* fix: skip aware semerrgroup

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

* fix: skip aware semerrgroup

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

internal/semerrgroup/sem.go

@@ -2,7 +2,12 @@
 // size, so you can control the number of tasks being executed simultaneously.
 package semerrgroup
 
-import "golang.org/x/sync/errgroup"
+import (
+	"sync"
+
+	"github.com/goreleaser/goreleaser/internal/pipe"
+	"golang.org/x/sync/errgroup"
+)
 
 // Group is the Semphore ErrorGroup itself
 type Group interface {
@@ -47,18 +52,61 @@ func (s *parallelGroup) Wait() error {
 var _ Group = &serialGroup{}
 
 type serialGroup struct {
-	err error
+	err     error
+	errOnce sync.Once
 }
 
 // Go execs runs `fn` and saves the result if no error has been encountered.
 func (s *serialGroup) Go(fn func() error) {
 	if s.err != nil {
 		return
 	}
-	s.err = fn()
+	if err := fn(); err != nil {
+		s.errOnce.Do(func() {
+			s.err = err
+		})
+	}
 }
 
 // Wait waits for Go to complete and returns the first error encountered.
 func (s *serialGroup) Wait() error {
 	return s.err
 }
+
+var _ Group = &skipAwareGroup{}
+
+// NewSkipAware returns a new Group of a given size and aware of pipe skips.
+func NewSkipAware(g Group) Group {
+	return &skipAwareGroup{g: g}
+}
+
+type skipAwareGroup struct {
+	g        Group
+	skipErr  error
+	skipOnce sync.Once
+}
+
+// Go execs runs `fn` and saves the result if no error has been encountered.
+func (s *skipAwareGroup) Go(fn func() error) {
+	s.g.Go(func() error {
+		var err = fn()
+		// if the err is a skip, set it for later, but return nil for now so the
+		// the group proceeds.
+		if pipe.IsSkip(err) {
+			s.skipOnce.Do(func() {
+				s.skipErr = err
+			})
+			return nil
+		}
+		return err
+	})
+}
+
+// Wait waits for Go to complete and returns the first error encountered.
+func (s *skipAwareGroup) Wait() error {
+	// if we got a "real error", return it, otherwise return skipErr or nil.
+	if err := s.g.Wait(); err != nil {
+		return err
+	}
+	return s.skipErr
+}

internal/semerrgroup/sem_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/goreleaser/goreleaser/internal/pipe"
 	"github.com/stretchr/testify/require"
 )
 
@@ -54,3 +55,35 @@ func TestSemaphoreOrderError(t *testing.T) {
 	require.EqualError(t, g.Wait(), "fake err")
 	require.Equal(t, []int{0}, output)
 }
+
+func TestSemaphoreSkipAware(t *testing.T) {
+	var g = NewSkipAware(New(1))
+	var lock sync.Mutex
+	var counter int
+	for i := 0; i < 10; i++ {
+		g.Go(func() error {
+			time.Sleep(10 * time.Millisecond)
+			lock.Lock()
+			counter++
+			lock.Unlock()
+			return pipe.Skip("fake skip")
+		})
+	}
+	require.EqualError(t, g.Wait(), "fake skip")
+	require.Equal(t, counter, 10)
+}
+
+func TestSemaphoreSkipAndRealError(t *testing.T) {
+	var g = NewSkipAware(New(10))
+	for i := 0; i < 100; i++ {
+		g.Go(func() error {
+			time.Sleep(10 * time.Millisecond)
+			return pipe.Skip("fake skip")
+		})
+	}
+	g.Go(func() error {
+		time.Sleep(10 * time.Millisecond)
+		return fmt.Errorf("errrrrr")
+	})
+	require.EqualError(t, g.Wait(), "errrrrr")
+}