Create separate read/write errors.

streaming.go

@@ -79,20 +79,37 @@ type StreamEncoder interface {
 
 // StreamReadError is returned when a read error is encountered
 // that relates to a supplied stream. This will allow you to
-// find out which reader/writer has failed.
-type StreamError struct {
-	Err    error  // The error
-	Stream int    // The stream number on which the error occurred
-	Op     string // Will be "read" or "write".
+// find out which reader has failed.
+type StreamReadError struct {
+	Err    error // The error
+	Stream int   // The stream number on which the error occurred
 }
 
 // Error returns the error as a string
-func (s StreamError) Error() string {
-	return fmt.Sprintf("error on %s stream #%d: %s", s.Op, s.Stream, s.Err)
+func (s StreamReadError) Error() string {
+	return fmt.Sprintf("error reading stream %d: %s", s.Stream, s.Err)
 }
 
 // String returns the error as a string
-func (s StreamError) String() string {
+func (s StreamReadError) String() string {
+	return s.Error()
+}
+
+// StreamWriteError is returned when a write error is encountered
+// that relates to a supplied stream. This will allow you to
+// find out which reader has failed.
+type StreamWriteError struct {
+	Err    error // The error
+	Stream int   // The stream number on which the error occurred
+}
+
+// Error returns the error as a string
+func (s StreamWriteError) Error() string {
+	return fmt.Sprintf("error writing stream %d: %s", s.Stream, s.Err)
+}
+
+// String returns the error as a string
+func (s StreamWriteError) String() string {
 	return s.Error()
 }
 
@@ -241,7 +258,7 @@ func readShards(dst [][]byte, in []io.Reader) error {
 		case nil:
 			continue
 		default:
-			return StreamError{Err: err, Op: "read", Stream: i}
+			return StreamReadError{Err: err, Stream: i}
 		}
 	}
 	if size == 0 {
@@ -260,11 +277,11 @@ func writeShards(out []io.Writer, in [][]byte) error {
 		}
 		n, err := out[i].Write(in[i])
 		if err != nil {
-			return StreamError{Err: err, Op: "write", Stream: i}
+			return StreamWriteError{Err: err, Stream: i}
 		}
 		//
 		if n != len(in[i]) {
-			return StreamError{Err: io.ErrShortWrite, Op: "write", Stream: i}
+			return StreamWriteError{Err: io.ErrShortWrite, Stream: i}
 		}
 	}
 	return nil
@@ -315,7 +332,7 @@ func cReadShards(dst [][]byte, in []io.Reader) error {
 			dst[r.n] = dst[r.n][0:r.size]
 		case nil:
 		default:
-			return StreamError{Err: r.err, Op: "read", Stream: r.n}
+			return StreamReadError{Err: r.err, Stream: r.n}
 		}
 	}
 	if size == 0 {
@@ -341,11 +358,11 @@ func cWriteShards(out []io.Writer, in [][]byte) error {
 			}
 			n, err := out[i].Write(in[i])
 			if err != nil {
-				errs <- StreamError{Err: err, Op: "write", Stream: i}
+				errs <- StreamWriteError{Err: err, Stream: i}
 				return
 			}
 			if n != len(in[i]) {
-				errs <- StreamError{Err: io.ErrShortWrite, Op: "write", Stream: i}
+				errs <- StreamWriteError{Err: io.ErrShortWrite, Stream: i}
 			}
 		}(i)
 	}
@@ -464,7 +481,7 @@ func (r rsStream) Join(dst io.Writer, shards []io.Reader, outSize int64) error {
 	shards = shards[:r.r.DataShards]
 	for i := range shards {
 		if shards[i] == nil {
-			return StreamError{Err: ErrShardNoData, Op: "read", Stream: i}
+			return StreamReadError{Err: ErrShardNoData, Stream: i}
 		}
 	}
 	// Join all shards
@@ -504,7 +521,7 @@ func (r rsStream) Split(data io.Reader, dst []io.Writer, size int64) error {
 
 	for i := range dst {
 		if dst[i] == nil {
-			return StreamError{Err: ErrShardNoData, Op: "write", Stream: i}
+			return StreamWriteError{Err: ErrShardNoData, Stream: i}
 		}
 	}
 
@@ -519,7 +536,7 @@ func (r rsStream) Split(data io.Reader, dst []io.Writer, size int64) error {
 	for i := range dst {
 		n, err := io.CopyN(dst[i], data, perShard)
 		if err != io.EOF && err != nil {
-			return StreamError{Err: err, Op: "write", Stream: i}
+			return err
 		}
 		if n != perShard {
 			return ErrShortData

streaming_test.go

@@ -599,12 +599,15 @@ func TestStreamSplitJoin(t *testing.T) {
 	bufs := toReaders(emptyBuffers(5))
 	bufs[2] = nil
 	err = enc.Join(buf, bufs, 0)
-	if se, ok := err.(StreamError); ok {
+	if se, ok := err.(StreamReadError); ok {
 		if se.Err != ErrShardNoData {
 			t.Errorf("expected %v, got %v", ErrShardNoData, se.Err)
 		}
+		if se.Stream != 2 {
+			t.Errorf("Expected error on stream 2, got %d", se.Stream)
+		}
 	} else {
-		t.Errorf("expected error type %T, got %T", StreamError{}, err)
+		t.Errorf("expected error type %T, got %T", StreamReadError{}, err)
 	}
 
 	err = enc.Join(buf, toReaders(toBuffers(splits)), int64(len(data)+1))