change comment for tagRPC and stats fields

stats/handlers.go

@@ -48,18 +48,19 @@ type ConnTagInfo struct {
 }
 
 // RPCTagInfo defines the relevant information needed by RPC context tagger.
-// FailFast is only valid on client side, it's always false on server side.
 type RPCTagInfo struct {
 	// FullMethodName is the RPC method in the format of /package.service/method.
 	FullMethodName string
 	// FailFast indicates if this RPC is failfast.
+	// This field is only valid on client side, it's always false on server side.
 	FailFast bool
 }
 
 // Handler defines the interface for the related stats handling (e.g., RPCs, connections).
 type Handler interface {
 	// TagRPC can attach some information to the given context.
-	// The returned context is used in the rest lifetime of the RPC.
+	// The context used for the rest lifetime of the RPC will be derived from
+	// the returned context.
 	TagRPC(context.Context, *RPCTagInfo) context.Context
 	// HandleRPC processes the RPC stats.
 	HandleRPC(context.Context, RPCStats)

stats/stats.go

@@ -86,13 +86,13 @@ func (s *InPayload) IsClient() bool { return s.Client }
 func (s *InPayload) isRPCStats() {}
 
 // InHeader contains stats when a header is received.
-// FullMethod, addresses and Compression are only valid if Client is false.
 type InHeader struct {
 	// Client is true if this InHeader is from client side.
 	Client bool
 	// WireLength is the wire length of header.
 	WireLength int
 
+	// The following fields are valid only if Client is false.
 	// FullMethod is the full RPC method string, i.e., /package.service/method.
 	FullMethod string
 	// RemoteAddr is the remote address of the corresponding connection.
@@ -143,13 +143,13 @@ func (s *OutPayload) IsClient() bool { return s.Client }
 func (s *OutPayload) isRPCStats() {}
 
 // OutHeader contains stats when a header is sent.
-// FullMethod, addresses and Compression are only valid if Client is true.
 type OutHeader struct {
 	// Client is true if this OutHeader is from client side.
 	Client bool
 	// WireLength is the wire length of header.
 	WireLength int
 
+	// The following fields are valid only if Client is true.
 	// FullMethod is the full RPC method string, i.e., /package.service/method.
 	FullMethod string
 	// RemoteAddr is the remote address of the corresponding connection.