rpc: properly discard values.

R=r, rsc, r2
CC=golang-dev
https://golang.org/cl/4171050

src/pkg/rpc/client.go

@@ -53,7 +53,9 @@ type Client struct {
 // The client calls WriteRequest to write a request to the connection
 // and calls ReadResponseHeader and ReadResponseBody in pairs
 // to read responses.  The client calls Close when finished with the
-// connection.
+// connection. ReadResponseBody may be called with a nil
+// argument to force the body of the response to be read and then
+// discarded.
 type ClientCodec interface {
 	WriteRequest(*Request, interface{}) os.Error
 	ReadResponseHeader(*Response) os.Error
@@ -89,7 +91,6 @@ func (client *Client) send(c *Call) {
 
 func (client *Client) input() {
 	var err os.Error
-	var marker struct{}
 	for err == nil {
 		response := new(Response)
 		err = client.codec.ReadResponseHeader(response)
@@ -115,7 +116,7 @@ func (client *Client) input() {
 			// any subsequent requests will get the ReadResponseBody
 			// error if there is one.
 			c.Error = ServerError(response.Error)
-			err = client.codec.ReadResponseBody(&marker)
+			err = client.codec.ReadResponseBody(nil)
 			if err != nil {
 				err = os.ErrorString("reading error body: " + err.String())
 			}

src/pkg/rpc/jsonrpc/client.go

@@ -98,6 +98,9 @@ func (c *clientCodec) ReadResponseHeader(r *rpc.Response) os.Error {
 }
 
 func (c *clientCodec) ReadResponseBody(x interface{}) os.Error {
+	if x == nil {
+		return nil
+	}
 	return json.Unmarshal(*c.resp.Result, x)
 }
 

src/pkg/rpc/jsonrpc/server.go

@@ -85,6 +85,9 @@ func (c *serverCodec) ReadRequestHeader(r *rpc.Request) os.Error {
 }
 
 func (c *serverCodec) ReadRequestBody(x interface{}) os.Error {
+	if x == nil {
+		return nil
+	}
 	// JSON params is array value.
 	// RPC params is struct.
 	// Unmarshal into array containing struct for now.

src/pkg/rpc/server.go

@@ -302,7 +302,7 @@ type InvalidRequest struct {
 	Marker int
 }
 
-var invalidRequest = InvalidRequest{1}
+var invalidRequest = InvalidRequest{}
 
 func _new(t *reflect.PtrType) *reflect.PtrValue {
 	v := reflect.MakeZero(t).(*reflect.PtrValue)
@@ -399,7 +399,7 @@ func (server *Server) ServeCodec(codec ServerCodec) {
 				break
 			}
 			// discard body
-			codec.ReadRequestBody(new(interface{}))
+			codec.ReadRequestBody(nil)
 
 			// send a response if we actually managed to read a header.
 			if req != nil {
@@ -486,7 +486,8 @@ func RegisterName(name string, rcvr interface{}) os.Error {
 // The server calls ReadRequestHeader and ReadRequestBody in pairs
 // to read requests from the connection, and it calls WriteResponse to
 // write a response back.  The server calls Close when finished with the
-// connection.
+// connection. ReadRequestBody may be called with a nil
+// argument to force the body of the request to be read and discarded.
 type ServerCodec interface {
 	ReadRequestHeader(*Request) os.Error
 	ReadRequestBody(interface{}) os.Error