audio: Error on duplicated source

Fixes #853

audio/audio.go

@@ -33,7 +33,6 @@ package audio
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"runtime"
@@ -149,7 +148,9 @@ func (c *Context) loop() {
 			<-resumeCh
 		default:
 			if _, err := io.CopyN(p, c.mux, 2048); err != nil {
+				c.m.Lock()
 				c.err = err
+				c.m.Unlock()
 				return
 			}
 			c.m.Lock()
@@ -270,9 +271,9 @@ type proceededValues struct {
 //
 // NewPlayer takes the ownership of src. Player's Close calls src's Close.
 func NewPlayer(context *Context, src io.ReadCloser) (*Player, error) {
-	if context.mux.hasSource(src) {
-		return nil, errors.New("audio: src cannot be shared with another Player")
-	}
+	//if context.mux.hasSource(src) {
+	//	return nil, errors.New("audio: src cannot be shared with another Player")
+	//}
 	p := &Player{
 		&playerImpl{
 			mux:         context.mux,

audio/audio_test.go

@@ -64,3 +64,31 @@ func TestGC(t *testing.T) {
 	}
 	t.Errorf("time out")
 }
+
+// Issue #853
+func TestSameSourcePlayers(t *testing.T) {
+	src := BytesReadSeekCloser(make([]byte, 4))
+	p0, err := NewPlayer(context, src)
+	if err != nil {
+		t.Error(err)
+	}
+	p1, err := NewPlayer(context, src)
+	if err != nil {
+		t.Error(err)
+	}
+
+	// As the player does not play yet, error doesn't happen.
+	if err := UpdateForTesting(); err != nil {
+		t.Error(err)
+	}
+
+	p0.Play()
+	p1.Play()
+
+	// 200[ms] should be enough all the bytes are consumed.
+	// TODO: This is a darty hack. Would it be possible to use virtual time?
+	time.Sleep(200 * time.Millisecond)
+	if err := UpdateForTesting(); err == nil {
+		t.Errorf("got: nil, want: an error")
+	}
+}

audio/mux.go

@@ -15,6 +15,7 @@
 package audio
 
 import (
+	"errors"
 	"io"
 	"runtime"
 	"sync"
@@ -43,6 +44,15 @@ func (m *mux) Read(b []byte) (int, error) {
 	m.m.Lock()
 	defer m.m.Unlock()
 
+	// Check the source duplication
+	srcs := map[io.ReadCloser]struct{}{}
+	for p := range m.ps {
+		if _, ok := srcs[p.src]; ok {
+			return 0, errors.New("audio: a same source is used by multiple Player")
+		}
+		srcs[p.src] = struct{}{}
+	}
+
 	if len(m.ps) == 0 {
 		l := len(b)
 		l &= mask
@@ -137,14 +147,3 @@ func (m *mux) hasPlayer(player *playerImpl) bool {
 	m.m.RUnlock()
 	return ok
 }
-
-func (m *mux) hasSource(src io.ReadCloser) bool {
-	m.m.RLock()
-	defer m.m.RUnlock()
-	for p := range m.ps {
-		if p.src == src {
-			return true
-		}
-	}
-	return false
-}