fix comments

stats/stats.go

@@ -32,7 +32,7 @@
  */
 
 // Package stats is for collecting and reporting various network and RPC stats.
-// This package is for monitoring purpose only.
+// This package is for monitoring purpose only. All fields are read-only.
 // All APIs are experimental.
 package stats // import "google.golang.org/grpc/stats"
 
@@ -72,7 +72,7 @@ type InPayload struct {
 	Client bool
 	// Payload is the payload with original type.
 	Payload interface{}
-	// Data is the unencrypted message payload.
+	// Data is the serialized message payload.
 	Data []byte
 	// Length is the length of uncompressed data.
 	Length int
@@ -99,7 +99,7 @@ type InHeader struct {
 	RemoteAddr net.Addr
 	// LocalAddr is the local address of the corresponding connection.
 	LocalAddr net.Addr
-	// Encryption is encrypt method used in the RPC.
+	// Encryption is the encryption algorithm used for the RPC.
 	Encryption string
 }
 
@@ -123,7 +123,7 @@ type OutPayload struct {
 	Client bool
 	// Payload is the payload with original type.
 	Payload interface{}
-	// Data is the unencrypted message payload.
+	// Data is the serialized message payload.
 	Data []byte
 	// Length is the length of uncompressed data.
 	Length int
@@ -150,7 +150,7 @@ type OutHeader struct {
 	RemoteAddr net.Addr
 	// LocalAddr is the local address of the corresponding connection.
 	LocalAddr net.Addr
-	// Encryption is encrypt method used in the RPC.
+	// Encryption is the encryption algorithm used for the RPC.
 	Encryption string
 }
 

stream.go

@@ -214,7 +214,7 @@ func newClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, meth
 		tracing: EnableTracing,
 		trInfo:  trInfo,
 
-		userCtx: ctx,
+		statsCtx: ctx,
 	}
 	if cc.dopts.cp != nil {
 		cs.cbuf = new(bytes.Buffer)
@@ -268,9 +268,10 @@ type clientStream struct {
 	// and is set to nil when the clientStream's finish method is called.
 	trInfo traceInfo
 
-	// Keep the user context for stats handling.
-	// All stats handling should use the user context instead of the stream context.
-	userCtx context.Context
+	// statsCtx keeps the user context for stats handling.
+	// All stats collection should use the statsCtx (instead of the stream context)
+	// so that all the generated stats for a particular RPC can be associated in the processing phase.
+	statsCtx context.Context
 }
 
 func (cs *clientStream) Context() context.Context {
@@ -286,7 +287,7 @@ func (cs *clientStream) Header() (_ metadata.MD, err error) {
 				EndTime: time.Now(),
 				Error:   err,
 			}
-			stats.Handle(cs.userCtx, end)
+			stats.Handle(cs.statsCtx, end)
 		}
 	}()
 	m, err := cs.s.Header()
@@ -318,7 +319,7 @@ func (cs *clientStream) SendMsg(m interface{}) (err error) {
 				Client: true,
 				Error:  err,
 			}
-			stats.Handle(cs.userCtx, end)
+			stats.Handle(cs.statsCtx, end)
 		}
 	}()
 	defer func() {
@@ -361,7 +362,7 @@ func (cs *clientStream) SendMsg(m interface{}) (err error) {
 	err = cs.t.Write(cs.s, out, &transport.Options{Last: false})
 	if err == nil && outPayload != nil {
 		outPayload.SentTime = time.Now()
-		stats.Handle(cs.userCtx, outPayload)
+		stats.Handle(cs.statsCtx, outPayload)
 	}
 	return err
 }
@@ -378,7 +379,7 @@ func (cs *clientStream) RecvMsg(m interface{}) (err error) {
 				EndTime: time.Now(),
 				Error:   e,
 			}
-			stats.Handle(cs.userCtx, end)
+			stats.Handle(cs.statsCtx, end)
 		}
 	}()
 	var inPayload *stats.InPayload
@@ -403,7 +404,7 @@ func (cs *clientStream) RecvMsg(m interface{}) (err error) {
 			cs.mu.Unlock()
 		}
 		if inPayload != nil {
-			stats.Handle(cs.userCtx, inPayload)
+			stats.Handle(cs.statsCtx, inPayload)
 		}
 		if !cs.desc.ClientStreams || cs.desc.ServerStreams {
 			return

transport/http2_client.go

@@ -349,7 +349,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 		return nil, ErrConnClosing
 	}
 	s := t.newStream(ctx, callHdr)
-	s.userCtx = userCtx
+	s.clientStatsCtx = userCtx
 	t.activeStreams[s.id] = s
 
 	// This stream is not counted when applySetings(...) initialize t.streamsQuota.
@@ -460,7 +460,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 			LocalAddr:  t.conn.LocalAddr(),
 			Encryption: callHdr.SendCompress,
 		}
-		stats.Handle(s.userCtx, outHeader)
+		stats.Handle(s.clientStatsCtx, outHeader)
 	}
 	t.writableChan <- 0
 	return s, nil
@@ -897,13 +897,13 @@ func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
 					Client:     true,
 					WireLength: int(frame.Header().Length),
 				}
-				stats.Handle(s.userCtx, inHeader)
+				stats.Handle(s.clientStatsCtx, inHeader)
 			} else {
 				inTrailer := &stats.InTrailer{
 					Client:     true,
 					WireLength: int(frame.Header().Length),
 				}
-				stats.Handle(s.userCtx, inTrailer)
+				stats.Handle(s.clientStatsCtx, inTrailer)
 			}
 		}
 	}()

transport/transport.go

@@ -168,9 +168,11 @@ type Stream struct {
 	id uint32
 	// nil for client side Stream.
 	st ServerTransport
-	// Keep the user context for stats handling.
-	// All stats handling should use the user context instead of the stream context.
-	userCtx context.Context
+	// userStatsCtx keeps the user context for stats handling.
+	// It's only valid on client side. Server side stats context is same as s.ctx.
+	// All stats collection should use the statsCtx (instead of the stream context)
+	// so that all the generated stats for a particular RPC can be associated in the processing phase.
+	clientStatsCtx context.Context
 	// ctx is the associated context of the stream.
 	ctx context.Context
 	// cancel is always nil for client side Stream.