client support for rpc cancel (#249)

pkg/wshrpc/wshclient/wshclientutil.go

@@ -57,27 +57,30 @@ func sendRpcRequestResponseStreamHelper[T any](w *wshutil.WshRpc, command string
 	if err != nil {
 		rtnErr(respChan, err)
 		return respChan
-	} else {
-		go func() {
-			defer close(respChan)
-			for {
-				if reqHandler.ResponseDone() {
-					break
-				}
-				resp, err := reqHandler.NextResponse()
-				if err != nil {
-					respChan <- wshrpc.RespOrErrorUnion[T]{Error: err}
-					break
-				}
-				var respData T
-				err = utilfn.ReUnmarshal(&respData, resp)
-				if err != nil {
-					respChan <- wshrpc.RespOrErrorUnion[T]{Error: err}
-					break
-				}
-				respChan <- wshrpc.RespOrErrorUnion[T]{Response: respData}
-			}
-		}()
 	}
+	opts.StreamCancelFn = func() {
+		// TODO coordinate the cancel with the for loop below
+		reqHandler.SendCancel()
+	}
+	go func() {
+		defer close(respChan)
+		for {
+			if reqHandler.ResponseDone() {
+				break
+			}
+			resp, err := reqHandler.NextResponse()
+			if err != nil {
+				respChan <- wshrpc.RespOrErrorUnion[T]{Error: err}
+				break
+			}
+			var respData T
+			err = utilfn.ReUnmarshal(&respData, resp)
+			if err != nil {
+				respChan <- wshrpc.RespOrErrorUnion[T]{Error: err}
+				break
+			}
+			respChan <- wshrpc.RespOrErrorUnion[T]{Response: respData}
+		}
+	}()
 	return respChan
 }

pkg/wshrpc/wshrpctypes.go

@@ -105,6 +105,8 @@ type RpcOpts struct {
 	Timeout    int    `json:"timeout,omitempty"`
 	NoResponse bool   `json:"noresponse,omitempty"`
 	Route      string `json:"route,omitempty"`
+
+	StreamCancelFn func() `json:"-"` // this is an *output* parameter, set by the handler
 }
 
 type RpcContext struct {