move pipe option into dedicated struct

transport/pipe/impl.go

@@ -21,15 +21,23 @@ const (
 	errord
 )
 
+type pipeOption struct {
+	limit           int32 // maximum buffer size in bytes
+	discardOverflow bool
+}
+
+func (o *pipeOption) isFull(curSize int32) bool {
+	return o.limit >= 0 && curSize > o.limit
+}
+
 type pipe struct {
 	sync.Mutex
 	data        buf.MultiBuffer
 	readSignal  *signal.Notifier
 	writeSignal *signal.Notifier
 	done        *done.Instance
-	limit           int32
+	option      pipeOption
 	state       state
-	discardOverflow bool
 }
 
 var errBufferFull = errors.New("buffer full")
@@ -37,7 +45,7 @@ var errBufferFull = errors.New("buffer full")
 func (p *pipe) getState(forRead bool) error {
 	switch p.state {
 	case open:
-		if !forRead && p.limit >= 0 && p.data.Len() > p.limit {
+		if !forRead && p.option.isFull(p.data.Len()) {
 			return errBufferFull
 		}
 		return nil
@@ -130,7 +138,7 @@ func (p *pipe) WriteMultiBuffer(mb buf.MultiBuffer) error {
 			// Yield current goroutine. Hopefully the reading counterpart can pick up the payload.
 			runtime.Gosched()
 			return nil
-		case err == errBufferFull && p.discardOverflow:
+		case err == errBufferFull && p.option.discardOverflow:
 			mb.Release()
 			return nil
 		case err != errBufferFull:

transport/pipe/pipe.go

@@ -9,26 +9,26 @@ import (
 )
 
 // Option for creating new Pipes.
-type Option func(*pipe)
+type Option func(*pipeOption)
 
 // WithoutSizeLimit returns an Option for Pipe to have no size limit.
 func WithoutSizeLimit() Option {
-	return func(p *pipe) {
+	return func(opt *pipeOption) {
-		p.limit = -1
+		opt.limit = -1
 	}
 }
 
 // WithSizeLimit returns an Option for Pipe to have the given size limit.
 func WithSizeLimit(limit int32) Option {
-	return func(p *pipe) {
+	return func(opt *pipeOption) {
-		p.limit = limit
+		opt.limit = limit
 	}
 }
 
 // DiscardOverflow returns an Option for Pipe to discard writes if full.
 func DiscardOverflow() Option {
-	return func(p *pipe) {
+	return func(opt *pipeOption) {
-		p.discardOverflow = true
+		opt.discardOverflow = true
 	}
 }
 
@@ -49,14 +49,16 @@ func OptionsFromContext(ctx context.Context) []Option {
 // New creates a new Reader and Writer that connects to each other.
 func New(opts ...Option) (*Reader, *Writer) {
 	p := &pipe{
-		limit:       -1,
 		readSignal:  signal.NewNotifier(),
 		writeSignal: signal.NewNotifier(),
 		done:        done.New(),
+		option: pipeOption{
+			limit: -1,
+		},
 	}
 
 	for _, opt := range opts {
-		opt(p)
+		opt(&(p.option))
 	}
 
 	return &Reader{