Initial spike with request/event handling

pkg/liveshare/rpc.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"sync"
 	"time"
 
 	"github.com/opentracing/opentracing-go"
@@ -13,15 +14,18 @@ import (
 type rpcClient struct {
 	*jsonrpc2.Conn
 	conn io.ReadWriteCloser
+
+	eventHandlersMu sync.RWMutex
+	eventHandlers   map[string]chan []byte
 }
 
 func newRPCClient(conn io.ReadWriteCloser) *rpcClient {
-	return &rpcClient{conn: conn}
+	return &rpcClient{conn: conn, eventHandlers: make(map[string]chan []byte)}
 }
 
 func (r *rpcClient) connect(ctx context.Context) {
 	stream := jsonrpc2.NewBufferedStream(r.conn, jsonrpc2.VSCodeObjectCodec{})
-	r.Conn = jsonrpc2.NewConn(ctx, stream, nullHandler{})
+	r.Conn = jsonrpc2.NewConn(ctx, stream, newRequestHandler(r))
 }
 
 func (r *rpcClient) do(ctx context.Context, method string, args, result interface{}) error {
@@ -40,7 +44,43 @@ func (r *rpcClient) do(ctx context.Context, method string, args, result interfac
 	return waiter.Wait(waitCtx, result)
 }
 
-type nullHandler struct{}
+func (r *rpcClient) registerEventHandler(eventName string) chan []byte {
+	r.eventHandlersMu.Lock()
+	defer r.eventHandlersMu.Unlock()
 
-func (nullHandler) Handle(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) {
+	if ch, ok := r.eventHandlers[eventName]; ok {
+		return ch
+	}
+
+	ch := make(chan []byte)
+	r.eventHandlers[eventName] = ch
+	return ch
+}
+
+func (r *rpcClient) eventHandler(eventName string) chan []byte {
+	r.eventHandlersMu.RLock()
+	defer r.eventHandlersMu.RUnlock()
+
+	return r.eventHandlers[eventName]
+}
+
+type requestHandler struct {
+	rpcClient *rpcClient
+}
+
+func newRequestHandler(rpcClient *rpcClient) *requestHandler {
+	return &requestHandler{rpcClient: rpcClient}
+}
+
+func (e *requestHandler) Handle(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) {
+	handler := e.rpcClient.eventHandler(req.Method)
+	if handler == nil {
+		return // noop
+	}
+
+	select {
+	case handler <- *req.Params:
+	default:
+		// event handler
+	}
 }