Fixed buffered race condition (#136)

* Fixed buffered race condition

* Fix go 1.18 compatibility

* Bump go.uber.org/atomic to v1.10.0

* Use unsafe atomic pointer

Author: echistyakov

core/framing/buffered.go

@@ -4,91 +4,112 @@ import (
 	"encoding/binary"
 	"io"
 	"sync/atomic"
+	"unsafe"
 
 	"github.com/rsocket/rsocket-go/core"
 	"github.com/rsocket/rsocket-go/internal/common"
 	"github.com/rsocket/rsocket-go/internal/u24"
+	uberatomic "go.uber.org/atomic"
 )
 
 // bufferedFrame is basic frame implementation.
 type bufferedFrame struct {
-	inner *common.ByteBuff
-	refs  int32
+	innerPtr unsafe.Pointer
+	refs     uberatomic.Int32
 }
 
 func newBufferedFrame(inner *common.ByteBuff) *bufferedFrame {
-	return &bufferedFrame{
-		inner: inner,
-		refs:  1,
-	}
+	frame := &bufferedFrame{}
+	atomic.StorePointer(&frame.innerPtr, unsafe.Pointer(inner))
+	frame.refs.Store(1)
+	return frame
 }
 
 func (f *bufferedFrame) IncRef() int32 {
-	return atomic.AddInt32(&f.refs, 1)
+	return f.refs.Add(1)
 }
 
 func (f *bufferedFrame) RefCnt() int32 {
-	return atomic.LoadInt32(&f.refs)
+	return f.refs.Load()
 }
 
 func (f *bufferedFrame) Header() core.FrameHeader {
-	if f.inner == nil {
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		panic("frame has been released!")
 	}
-	b := f.inner.Bytes()
+	b := inner.Bytes()
 	_ = b[core.FrameHeaderLen-1]
 	var h core.FrameHeader
 	copy(h[:], b)
 	return h
 }
 
 func (f *bufferedFrame) HasFlag(flag core.FrameFlag) bool {
-	if f.inner == nil {
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		panic("frame has been released!")
 	}
-	n := binary.BigEndian.Uint16(f.inner.Bytes()[4:6])
+	n := binary.BigEndian.Uint16(inner.Bytes()[4:6])
 	return core.FrameFlag(n&0x03FF)&flag == flag
 }
 
 func (f *bufferedFrame) StreamID() uint32 {
-	if f.inner == nil {
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		panic("frame has been released!")
 	}
-	return binary.BigEndian.Uint32(f.inner.Bytes()[:4])
+	return binary.BigEndian.Uint32(inner.Bytes()[:4])
 }
 
 // Release releases resource.
 func (f *bufferedFrame) Release() {
-	if f != nil && f.inner != nil && atomic.AddInt32(&f.refs, -1) == 0 {
-		common.ReturnByteBuff(f.inner)
-		f.inner = nil
+	if f == nil {
+		return
+	}
+	refs := f.refs.Add(-1)
+	if refs > 0 {
+		return
+	}
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner != nil {
+		swapped := atomic.CompareAndSwapPointer(&f.innerPtr, unsafe.Pointer(inner), unsafe.Pointer(nil))
+		if swapped {
+			common.ReturnByteBuff(inner)
+		}
 	}
 }
 
 // Body returns frame body.
 func (f *bufferedFrame) Body() []byte {
-	if f.inner == nil {
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		return nil
 	}
-	b := f.inner.Bytes()
+	b := inner.Bytes()
 	_ = b[core.FrameHeaderLen-1]
 	return b[core.FrameHeaderLen:]
 }
 
 // Len returns length of frame.
 func (f *bufferedFrame) Len() int {
-	if f.inner == nil {
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		return 0
 	}
-	return f.inner.Len()
+	return inner.Len()
 }
 
 // WriteTo write frame to writer.
 func (f *bufferedFrame) WriteTo(w io.Writer) (n int64, err error) {
-	if f == nil || f.inner == nil {
+	if f == nil {
+		return
+	}
+	inner := (*common.ByteBuff)(atomic.LoadPointer(&f.innerPtr))
+	if inner == nil {
 		return
 	}
-	n, err = f.inner.WriteTo(w)
+	n, err = inner.WriteTo(w)
 	return
 }