WIP mrpc/jstreamrpc trying to make the types work with jstreamrpc

mrpc/jstreamrpc/jstreamrpc.go

@@ -5,7 +5,6 @@ package jstreamrpc
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"io"
 
@@ -13,19 +12,12 @@ import (
 	"github.com/mediocregopher/mediocre-go-lib/mrpc"
 )
 
-// TODO Debug
-// 	- ReqHead
-//		- client encodes into context
-//		- handler decodes from context
-// 	- ResTail
-//		- handler ?
-//		- client ?
-
 // TODO Error?
 // TODO SizeHints
+// TODO it'd be nice if the types here played nice with mrpc.ReflectClient
 
 type debug struct {
-	Debug map[string]map[string]json.RawMessage `json:"debug,omitempty"`
+	Debug mrpc.Debug `json:"debug,omitempty"`
 }
 
 type reqHead struct {
@@ -35,7 +27,7 @@ type reqHead struct {
 
 type resTail struct {
 	debug
-	Error interface{} `json:"err,omitempty"`
+	Error error `json:"err,omitempty"`
 }
 
 type ctxVal int
@@ -86,6 +78,9 @@ func HandleCall(
 	w *jstream.StreamWriter,
 	h mrpc.Handler,
 ) error {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
 	var head reqHead
 	if err := r.Next().Value(&head); err != nil {
 		return err
@@ -96,28 +91,32 @@ func HandleCall(
 	var didReadBody bool
 	ctx = context.WithValue(ctx, ctxValR, r)
 	ctx = context.WithValue(ctx, ctxValW, w)
-	ret, err := h.ServeRPC(mrpc.Call{
+
+	rw := new(mrpc.ResponseWriter)
+	h.ServeRPC(mrpc.Request{
 		Context: ctx,
 		Method:  head.Method,
-		UnmarshalArgs: func(i interface{}) error {
+		Unmarshal: func(i interface{}) error {
 			didReadBody = true
 			return unmarshalBody(i, r.Next())
 		},
-	})
-	// TODO that error is ignored, need a way to differentiate a recoverable
-	// error from a non-recoverable one
+		Debug: head.debug.Debug,
+	}, rw)
 
-	// TODO the writing and reading of the next section could be done in
-	// parallel?
+	// TODO unmarshaling request and marshaling response should be in
+	// their own go-routines, just in case they are streams/bytes which depend
+	// on each other
 
-	// TODO if ret is a byte blob or stream there may be user-spawned
-	// go-routines waiting to write to it, but if this errors out before
-	// marshalBody is called they will block forever. Probably need to cancel
-	// the context to let them know?
-
-	if err := marshalBody(w, ret); err != nil {
+	resErr, resErrOk := rw.Response.(error)
+	if resErrOk {
+		if err := w.EncodeValue(nil); err != nil {
 			return err
 		}
+	} else {
+		if err := marshalBody(w, rw.Response); err != nil {
+			return err
+		}
+	}
 
 	// TODO to reduce chance of user error maybe Discard should discard any
 	// remaining data on the Element, not on Elements which haven't been read
@@ -127,11 +126,49 @@ func HandleCall(
 	// Reading the tail (and maybe discarding the body) should only be done once
 	// marshalBody has finished
 	if !didReadBody {
-		// TODO what if this errors?
-		r.Next().Discard()
+		if err := r.Next().Discard(); err != nil {
+			return err
+		}
 	}
 
-	// TODO write response tail
+	if err := w.EncodeValue(resTail{
+		debug: debug{Debug: rw.Debug},
+		Error: resErr,
+	}); err != nil {
+		return err
+	}
 
 	return nil
 }
+
+/*
+func sqr(r mrpc.Request, rw *mrpc.ResponseWriter) {
+	ch := make(chan int)
+	rw.Response = func(w *jstream.StreamWriter) error {
+		for i := range ch {
+			if err := w.EncodeValue(i * i); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	go func() {
+		defer close(ch)
+		err := r.Unmarshal(func(r *jstream.StreamReader) error {
+			for {
+				var i int
+				if err := r.Next().Value(&i); err == jstream.ErrStreamEnded {
+					return nil
+				} else if err != nil {
+					return err
+				}
+				ch <- i
+			}
+		})
+		if err != nil {
+			panic("TODO")
+		}
+	}()
+}
+*/

mrpc/mrpc.go

@@ -15,14 +15,8 @@ import (
 	"reflect"
 )
 
-// TODO Request is making things difficult. It wants to be split into two types,
-// like the Response is, but naming them is annoying. ClientRequest and
-// HandlerRequest? RequestReader? Maybe 4 arguments to Client isn't that much...
-
 // Request describes an RPC request being processed by a Handler
 type Request struct {
-	// Depending on the implementation of Client, Context may be canceled to
-	// indicate the Client has canceled the request.
 	Context context.Context
 
 	// The name of the RPC method being called.
@@ -34,7 +28,7 @@ type Request struct {
 	Unmarshal func(interface{}) error
 
 	// Debugging information being carried with the Request. See Debug's docs
-	// for more on how it is intended to be used
+	// for more on how it is intended to be used.
 	Debug Debug
 }
 
@@ -68,6 +62,9 @@ type Response struct {
 // Handler is a type which serves RPC calls. For each incoming Requests the
 // ServeRPC method is called with a ResponseWriter which will write the call's
 // response back to the client.
+//
+// Any go-routines spawned by ServeRPC should expect to terminate if the
+// Request's Context is canceled
 type Handler interface {
 	ServeRPC(Request, *ResponseWriter)
 }
@@ -84,16 +81,23 @@ func (hf HandlerFunc) ServeRPC(r Request, rw *ResponseWriter) {
 
 // Client is an entity which can perform RPC calls against a remote endpoint.
 type Client interface {
-	CallRPC(Request) Response
+	CallRPC(ctx context.Context, method string, args interface{}, debug Debug) Response
 }
 
 // ClientFunc can be used to wrap an individual function which fits the CallRPC
 // signature, and use that function as a Client
-type ClientFunc func(Request) Response
+type ClientFunc func(context.Context, string, interface{}, Debug) Response
 
 // CallRPC implements the method for the Client interface by calling the
 // underlying function
-func (cf ClientFunc) CallRPC(r Request) { return cf(r) }
+func (cf ClientFunc) CallRPC(
+	ctx context.Context,
+	method string,
+	args interface{},
+	debug Debug,
+) Response {
+	return cf(ctx, method, args, debug)
+}
 
 // ReflectClient returns a Client whose CallRPC method will use reflection to
 // call the given Handler's ServeRPC method directly, using reflect.Value's Set
@@ -115,11 +119,13 @@ func ReflectClient(h Handler) Client {
 		ctx context.Context,
 		method string,
 		args interface{},
+		debug Debug,
 	) Response {
 		req := Request{
 			Context:   ctx,
 			Method:    method,
 			Unmarshal: func(i interface{}) error { return into(i, args) },
+			Debug:     debug,
 		}
 		rw := ResponseWriter{}
 		h.ServeRPC(req, &rw)