🐛 Fix reader slow than decoder

.github/workflows/ci.yaml

@@ -11,10 +11,10 @@ on:
 jobs:
   builder:
     name: builder
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
-        go: ["1.16", "1.15"]
+        go: ["1.20", "1.19", "1.18", "1.17", "1.16", "1.15"]
     steps:
       - name: Checkout branch
         uses: actions/checkout@v2

decode.go

@@ -44,6 +44,8 @@ type Decoder struct {
 	Channels      int
 	Kbps          int
 	Layer         int
+
+	originalEof bool // if the original reader is EOF, set this to true
 }
 
 // BufferSize Decoded data buffer size.
@@ -80,9 +82,11 @@ func NewDecoder(reader io.Reader) (dec *Decoder, err error) {
 			dec.data = append(dec.data, data[:n]...)
 			dec.readerLocker.Unlock()
 			if err == io.EOF {
+				dec.originalEof = true
 				break
 			}
 			if err != nil {
+				dec.originalEof = true
 				break
 			}
 		}
@@ -152,12 +156,23 @@ func (dec *Decoder) Started() (channel chan bool) {
 
 // Read read the raw stream
 func (dec *Decoder) Read(data []byte) (n int, err error) {
+	for {
+		select {
+		case <-dec.context.Done(): // if the decoder is stopped, then here should return EOF
+			err = io.EOF
+			return
+		default:
+		}
+		if len(dec.data) == 0 && len(dec.decodedData) == 0 && dec.originalEof {
+			err = io.EOF
+			return
+		} else if len(dec.decodedData) > 0 {
+			break
+		}
+		<-time.After(WaitForDataDuration)
+	}
 	dec.decoderLocker.Lock()
 	defer dec.decoderLocker.Unlock()
-	if len(dec.decodedData) == 0 {
-		err = io.EOF
-		return
-	}
 	n = copy(data, dec.decodedData[:])
 	dec.decodedData = dec.decodedData[n:]
 	return

decode_issue18_test.go

@@ -0,0 +1,60 @@
+package minimp3
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"testing"
+	"time"
+)
+
+// TestIssue18DelayPutData ...
+func TestIssue18DelayPutData(t *testing.T) {
+	reader, writer := io.Pipe()
+	dec, err := NewDecoder(reader)
+	if err != nil {
+		t.Errorf("NewDecoder failed: %v", err)
+	}
+	go func() {
+		time.Sleep(3 * time.Second)
+		file, err := os.ReadFile("test.mp3")
+		if err != nil {
+			t.Errorf("open file failed: %v", err)
+		}
+		_, err = io.Copy(writer, bytes.NewReader(file))
+		if err != nil {
+			t.Errorf("copy mp3 data to pipe failed: %v", err)
+		}
+		writer.Close() // nolint: errcheck
+	}()
+	// seems like the 'dec.Started' is unnecessary here
+	data, err := io.ReadAll(dec)
+	if err != nil {
+		t.Errorf("read the whole decoded data failed: %v", err)
+	}
+	if len(data) != 44928 {
+		t.Errorf("decode mp3 file failed, real is 44928, but got %d", len(data))
+	}
+}
+
+// TestIssue18GracefulExit ...
+func TestIssue18GracefulExit(t *testing.T) {
+	reader, writer := io.Pipe()
+	dec, err := NewDecoder(reader)
+	if err != nil {
+		t.Errorf("NewDecoder failed: %v", err)
+	}
+	go func() {
+		time.Sleep(3 * time.Second)
+		writer.Close() // nolint: errcheck
+	}()
+	// seems like the 'dec.Started' is necessary here
+	// if the Decoder input reader is closed, then the Decoder.Read will be returned
+	data, err := io.ReadAll(dec)
+	if err != nil {
+		t.Errorf("read the whole decoded data failed: %v", err)
+	}
+	if len(data) != 0 {
+		t.Errorf("graceful exit read something data")
+	}
+}