rpc: support subscriptions under custom namespaces

Author: bas-vk

rpc/client.go

@@ -27,6 +27,7 @@ import (
 	"net/url"
 	"reflect"
 	"strconv"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -373,14 +374,14 @@ func (c *Client) EthSubscribe(ctx context.Context, channel interface{}, args ...
 		return nil, ErrNotificationsUnsupported
 	}
 
-	msg, err := c.newMessage(subscribeMethod, args...)
+	msg, err := c.newMessage("eth"+subscribeMethodSuffix, args...)
 	if err != nil {
 		return nil, err
 	}
 	op := &requestOp{
 		ids:  []json.RawMessage{msg.ID},
 		resp: make(chan *jsonrpcMessage),
-		sub:  newClientSubscription(c, chanVal),
+		sub:  newClientSubscription(c, "eth", chanVal),
 	}
 
 	// Send the subscription request.
@@ -575,7 +576,7 @@ func (c *Client) closeRequestOps(err error) {
 }
 
 func (c *Client) handleNotification(msg *jsonrpcMessage) {
-	if msg.Method != notificationMethod {
+	if !strings.HasSuffix(msg.Method, notificationMethodSuffix) {
 		log.Debug(fmt.Sprint("dropping non-subscription message: ", msg))
 		return
 	}
@@ -653,26 +654,28 @@ func (c *Client) read(conn net.Conn) error {
 
 // A ClientSubscription represents a subscription established through EthSubscribe.
 type ClientSubscription struct {
-	client  *Client
-	etype   reflect.Type
-	channel reflect.Value
-	subid   string
-	in      chan json.RawMessage
+	client    *Client
+	etype     reflect.Type
+	channel   reflect.Value
+	namespace string
+	subid     string
+	in        chan json.RawMessage
 
 	quitOnce sync.Once     // ensures quit is closed once
 	quit     chan struct{} // quit is closed when the subscription exits
 	errOnce  sync.Once     // ensures err is closed once
 	err      chan error
 }
 
-func newClientSubscription(c *Client, channel reflect.Value) *ClientSubscription {
+func newClientSubscription(c *Client, namespace string, channel reflect.Value) *ClientSubscription {
 	sub := &ClientSubscription{
-		client:  c,
-		etype:   channel.Type().Elem(),
-		channel: channel,
-		quit:    make(chan struct{}),
-		err:     make(chan error, 1),
-		in:      make(chan json.RawMessage),
+		client:    c,
+		namespace: namespace,
+		etype:     channel.Type().Elem(),
+		channel:   channel,
+		quit:      make(chan struct{}),
+		err:       make(chan error, 1),
+		in:        make(chan json.RawMessage),
 	}
 	return sub
 }
@@ -774,5 +777,5 @@ func (sub *ClientSubscription) unmarshal(result json.RawMessage) (interface{}, e
 
 func (sub *ClientSubscription) requestUnsubscribe() error {
 	var result interface{}
-	return sub.client.Call(&result, unsubscribeMethod, sub.subid)
+	return sub.client.Call(&result, sub.namespace+unsubscribeMethodSuffix, sub.subid)
 }

rpc/json.go

@@ -30,11 +30,11 @@ import (
 )
 
 const (
-	jsonrpcVersion         = "2.0"
-	serviceMethodSeparator = "_"
-	subscribeMethod        = "eth_subscribe"
-	unsubscribeMethod      = "eth_unsubscribe"
-	notificationMethod     = "eth_subscription"
+	jsonrpcVersion           = "2.0"
+	serviceMethodSeparator   = "_"
+	subscribeMethodSuffix    = "_subscribe"
+	unsubscribeMethodSuffix  = "_unsubscribe"
+	notificationMethodSuffix = "_subscription"
 )
 
 type jsonRequest struct {
@@ -164,7 +164,7 @@ func parseRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error) {
 	}
 
 	// subscribe are special, they will always use `subscribeMethod` as first param in the payload
-	if in.Method == subscribeMethod {
+	if strings.HasSuffix(in.Method, subscribeMethodSuffix) {
 		reqs := []rpcRequest{{id: &in.Id, isPubSub: true}}
 		if len(in.Payload) > 0 {
 			// first param must be subscription name
@@ -174,17 +174,16 @@ func parseRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error) {
 				return nil, false, &invalidRequestError{"Unable to parse subscription request"}
 			}
 
-			// all subscriptions are made on the eth service
-			reqs[0].service, reqs[0].method = "eth", subscribeMethod[0]
+			reqs[0].service, reqs[0].method = strings.TrimSuffix(in.Method, subscribeMethodSuffix), subscribeMethod[0]
 			reqs[0].params = in.Payload
 			return reqs, false, nil
 		}
 		return nil, false, &invalidRequestError{"Unable to parse subscription request"}
 	}
 
-	if in.Method == unsubscribeMethod {
+	if strings.HasSuffix(in.Method, unsubscribeMethodSuffix) {
 		return []rpcRequest{{id: &in.Id, isPubSub: true,
-			method: unsubscribeMethod, params: in.Payload}}, false, nil
+			method: in.Method, params: in.Payload}}, false, nil
 	}
 
 	elems := strings.Split(in.Method, serviceMethodSeparator)
@@ -216,8 +215,8 @@ func parseBatchRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error)
 
 		id := &in[i].Id
 
-		// subscribe are special, they will always use `subscribeMethod` as first param in the payload
-		if r.Method == subscribeMethod {
+		// subscribe are special, they will always use `subscriptionMethod` as first param in the payload
+		if strings.HasSuffix(r.Method, subscribeMethodSuffix) {
 			requests[i] = rpcRequest{id: id, isPubSub: true}
 			if len(r.Payload) > 0 {
 				// first param must be subscription name
@@ -227,17 +226,16 @@ func parseBatchRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error)
 					return nil, false, &invalidRequestError{"Unable to parse subscription request"}
 				}
 
-				// all subscriptions are made on the eth service
-				requests[i].service, requests[i].method = "eth", subscribeMethod[0]
+				requests[i].service, requests[i].method = strings.TrimSuffix(r.Method, subscribeMethodSuffix), subscribeMethod[0]
 				requests[i].params = r.Payload
 				continue
 			}
 
 			return nil, true, &invalidRequestError{"Unable to parse (un)subscribe request arguments"}
 		}
 
-		if r.Method == unsubscribeMethod {
-			requests[i] = rpcRequest{id: id, isPubSub: true, method: unsubscribeMethod, params: r.Payload}
+		if strings.HasSuffix(r.Method, unsubscribeMethodSuffix) {
+			requests[i] = rpcRequest{id: id, isPubSub: true, method: r.Method, params: r.Payload}
 			continue
 		}
 
@@ -325,13 +323,13 @@ func (c *jsonCodec) CreateErrorResponseWithInfo(id interface{}, err Error, info
 }
 
 // CreateNotification will create a JSON-RPC notification with the given subscription id and event as params.
-func (c *jsonCodec) CreateNotification(subid string, event interface{}) interface{} {
+func (c *jsonCodec) CreateNotification(subid, namespace string, event interface{}) interface{} {
 	if isHexNum(reflect.TypeOf(event)) {
-		return &jsonNotification{Version: jsonrpcVersion, Method: notificationMethod,
+		return &jsonNotification{Version: jsonrpcVersion, Method: namespace + notificationMethodSuffix,
 			Params: jsonSubscription{Subscription: subid, Result: fmt.Sprintf(`%#x`, event)}}
 	}
 
-	return &jsonNotification{Version: jsonrpcVersion, Method: notificationMethod,
+	return &jsonNotification{Version: jsonrpcVersion, Method: namespace + notificationMethodSuffix,
 		Params: jsonSubscription{Subscription: subid, Result: event}}
 }
 

rpc/server.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"reflect"
 	"runtime"
+	"strings"
 	"sync"
 	"sync/atomic"
 
@@ -96,32 +97,30 @@ func (s *Server) RegisterName(name string, rcvr interface{}) error {
 		return fmt.Errorf("%s is not exported", reflect.Indirect(rcvrVal).Type().Name())
 	}
 
+	methods, subscriptions := suitableCallbacks(rcvrVal, svc.typ)
+
 	// already a previous service register under given sname, merge methods/subscriptions
 	if regsvc, present := s.services[name]; present {
-		methods, subscriptions := suitableCallbacks(rcvrVal, svc.typ)
 		if len(methods) == 0 && len(subscriptions) == 0 {
 			return fmt.Errorf("Service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
 		}
-
 		for _, m := range methods {
 			regsvc.callbacks[formatName(m.method.Name)] = m
 		}
 		for _, s := range subscriptions {
 			regsvc.subscriptions[formatName(s.method.Name)] = s
 		}
-
 		return nil
 	}
 
 	svc.name = name
-	svc.callbacks, svc.subscriptions = suitableCallbacks(rcvrVal, svc.typ)
+	svc.callbacks, svc.subscriptions = methods, subscriptions
 
 	if len(svc.callbacks) == 0 && len(svc.subscriptions) == 0 {
 		return fmt.Errorf("Service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
 	}
 
 	s.services[svc.name] = svc
-
 	return nil
 }
 
@@ -303,7 +302,7 @@ func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverReque
 		// active the subscription after the sub id was successfully sent to the client
 		activateSub := func() {
 			notifier, _ := NotifierFromContext(ctx)
-			notifier.activate(subid)
+			notifier.activate(subid, req.svcname)
 		}
 
 		return codec.CreateResponse(req.id, subid), activateSub
@@ -383,7 +382,7 @@ func (s *Server) execBatch(ctx context.Context, codec ServerCodec, requests []*s
 		codec.Close()
 	}
 
-	// when request holds one of more subscribe requests this allows these subscriptions to be actived
+	// when request holds one of more subscribe requests this allows these subscriptions to be activated
 	for _, c := range callbacks {
 		c()
 	}
@@ -410,7 +409,7 @@ func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, Error)
 			continue
 		}
 
-		if r.isPubSub && r.method == unsubscribeMethod {
+		if r.isPubSub && strings.HasSuffix(r.method, unsubscribeMethodSuffix) {
 			requests[i] = &serverRequest{id: r.id, isUnsubscribe: true}
 			argTypes := []reflect.Type{reflect.TypeOf("")} // expect subscription id as first arg
 			if args, err := codec.ParseRequestArguments(argTypes, r.params); err == nil {
@@ -439,7 +438,7 @@ func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, Error)
 					}
 				}
 			} else {
-				requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{subscribeMethod, r.method}}
+				requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{r.method, r.method}}
 			}
 			continue
 		}

rpc/subscription.go

@@ -35,8 +35,9 @@ type ID string
 // a Subscription is created by a notifier and tight to that notifier. The client can use
 // this subscription to wait for an unsubscribe request for the client, see Err().
 type Subscription struct {
-	ID  ID
-	err chan error // closed on unsubscribe
+	ID        ID
+	namespace string
+	err       chan error // closed on unsubscribe
 }
 
 // Err returns a channel that is closed when the client send an unsubscribe request.
@@ -78,7 +79,7 @@ func NotifierFromContext(ctx context.Context) (*Notifier, bool) {
 // are dropped until the subscription is marked as active. This is done
 // by the RPC server after the subscription ID is send to the client.
 func (n *Notifier) CreateSubscription() *Subscription {
-	s := &Subscription{NewID(), make(chan error)}
+	s := &Subscription{ID: NewID(), err: make(chan error)}
 	n.subMu.Lock()
 	n.inactive[s.ID] = s
 	n.subMu.Unlock()
@@ -91,9 +92,9 @@ func (n *Notifier) Notify(id ID, data interface{}) error {
 	n.subMu.RLock()
 	defer n.subMu.RUnlock()
 
-	_, active := n.active[id]
+	sub, active := n.active[id]
 	if active {
-		notification := n.codec.CreateNotification(string(id), data)
+		notification := n.codec.CreateNotification(string(id), sub.namespace, data)
 		if err := n.codec.Write(notification); err != nil {
 			n.codec.Close()
 			return err
@@ -124,10 +125,11 @@ func (n *Notifier) unsubscribe(id ID) error {
 // notifications are dropped. This method is called by the RPC server after
 // the subscription ID was sent to client. This prevents notifications being
 // send to the client before the subscription ID is send to the client.
-func (n *Notifier) activate(id ID) {
+func (n *Notifier) activate(id ID, namespace string) {
 	n.subMu.Lock()
 	defer n.subMu.Unlock()
 	if sub, found := n.inactive[id]; found {
+		sub.namespace = namespace
 		n.active[id] = sub
 		delete(n.inactive, id)
 	}