audio: Bug fix: Seek might cause dead lock after Close

audio/audio.go

@@ -36,6 +36,7 @@ package audio
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"runtime"
 	"sync"
@@ -331,7 +332,8 @@ type Player struct {
 	volume float64
 
 	closeCh         chan struct{}
-	closedCh    chan error
+	closedCh        chan struct{}
+	readLoopEndedCh chan struct{}
 	seekCh          chan seekArgs
 	seekedCh        chan error
 	proceedCh       chan []int16
@@ -371,7 +373,8 @@ func NewPlayer(context *Context, src ReadSeekCloser) (*Player, error) {
 		buf:             []byte{},
 		volume:          1,
 		closeCh:         make(chan struct{}),
-		closedCh:    make(chan error),
+		closedCh:        make(chan struct{}),
+		readLoopEndedCh: make(chan struct{}),
 		seekCh:          make(chan seekArgs),
 		seekedCh:        make(chan error),
 		proceedCh:       make(chan []int16),
@@ -419,14 +422,23 @@ func (p *Player) Close() error {
 	runtime.SetFinalizer(p, nil)
 	p.players.removePlayer(p)
 
-	p.closeCh <- struct{}{}
-	return <-p.closedCh
+	select {
+	case p.closeCh <- struct{}{}:
+		<-p.closedCh
+		return nil
+	case <-p.readLoopEndedCh:
+		return fmt.Errorf("audio: the player is already closed")
+	}
 }
 
 func (p *Player) bufferToInt16(lengthInBytes int) ([]int16, error) {
-	p.proceedCh <- make([]int16, lengthInBytes/2)
+	select {
+	case p.proceedCh <- make([]int16, lengthInBytes/2):
 		r := <-p.proceededCh
 		return r.buf, r.err
+	case <-p.readLoopEndedCh:
+		return nil, fmt.Errorf("audio: the player is already closed")
+	}
 }
 
 // Play plays the stream.
@@ -438,12 +450,18 @@ func (p *Player) Play() error {
 }
 
 func (p *Player) readLoop() {
+	defer func() {
+		// Note: the error is ignored
+		p.src.Close()
+		close(p.readLoopEndedCh)
+	}()
+
 	t := time.After(0)
 	var readErr error
 	for {
 		select {
 		case <-p.closeCh:
-			p.closedCh <- p.src.Close()
+			p.closedCh <- struct{}{}
 			return
 
 		case s := <-p.seekCh:
@@ -549,8 +567,12 @@ func (p *Player) Rewind() error {
 func (p *Player) Seek(offset time.Duration) error {
 	o := int64(offset) * bytesPerSample * channelNum * int64(p.sampleRate) / int64(time.Second)
 	o &= mask
-	p.seekCh <- seekArgs{o, io.SeekStart}
+	select {
+	case p.seekCh <- seekArgs{o, io.SeekStart}:
 		return <-p.seekedCh
+	case <-p.readLoopEndedCh:
+		return fmt.Errorf("audio: the player is already closed")
+	}
 }
 
 // Pause pauses the playing.