Use context to stop sending values rather than trying to detect channel close

client/main.go

@@ -1,6 +1,7 @@
 package client
 
 import (
+	"context"
 	"errors"
 	"net"
 	"reflect"
@@ -46,7 +47,7 @@ func New(conn net.Conn, cf codec.CodecFunc) *Client {
 }
 
 // Call calls a method on the server
-func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) error {
+func (c *Client) Call(ctx context.Context, rcvr, method string, arg interface{}, ret interface{}) error {
 	// Create new v4 UUOD
 	id, err := uuid.NewV4()
 	if err != nil {
@@ -54,6 +55,8 @@ func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) err
 	}
 	idStr := id.String()
 
+	ctxDoneVal := reflect.ValueOf(ctx.Done())
+
 	// Create new channel using the generated ID
 	c.chMtx.Lock()
 	c.chs[idStr] = make(chan *types.Response, 1)
@@ -106,12 +109,12 @@ func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) err
 		c.chs[chID] = make(chan *types.Response, 5)
 		c.chMtx.Unlock()
 
-		channelClosed := false
 		go func() {
 			// Get type of channel elements
 			chElemType := retVal.Type().Elem()
 			// For every value received from channel
 			for val := range c.chs[chID] {
+				//s := time.Now()
 				if val.ChannelDone {
 					// Close and delete channel
 					c.chMtx.Lock()
@@ -121,9 +124,6 @@ func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) err
 
 					// Close return channel
 					retVal.Close()
-
-					channelClosed = true
-
 					break
 				}
 				// Get reflect value from channel response
@@ -139,25 +139,20 @@ func (c *Client) Call(rcvr, method string, arg interface{}, ret interface{}) err
 					rVal = newVal
 				}
 
-				// Send value to channel
-				retVal.Send(rVal)
-			}
-		}()
-
-		go func() {
-			for {
-				val, ok := retVal.Recv()
-				if !ok && val.IsValid() {
-					break
-				}
-			}
-			if !channelClosed {
-				c.Call("lrpc", "ChannelDone", id, nil)
+				chosen, _, _ := reflect.Select([]reflect.SelectCase{
+					{Dir: reflect.SelectSend, Chan: retVal, Send: rVal},
+					{Dir: reflect.SelectRecv, Chan: ctxDoneVal, Send: reflect.Value{}},
+				})
+				if chosen == 1 {
+					c.Call(context.Background(), "lrpc", "ChannelDone", id, nil)
 					// Close and delete channel
 					c.chMtx.Lock()
 					close(c.chs[chID])
 					delete(c.chs, chID)
 					c.chMtx.Unlock()
+
+					retVal.Close()
+				}
 			}
 		}()
 	} else {

examples/client/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"encoding/gob"
 	"fmt"
 	"net"
@@ -12,21 +13,23 @@ import (
 func main() {
 	gob.Register([2]int{})
 
+	ctx := context.Background()
+
 	conn, _ := net.Dial("tcp", "localhost:9090")
 	c := client.New(conn, codec.Gob)
 	defer c.Close()
 
 	var add int
-	c.Call("Arith", "Add", [2]int{5, 5}, &add)
+	c.Call(ctx, "Arith", "Add", [2]int{5, 5}, &add)
 
 	var sub int
-	c.Call("Arith", "Sub", [2]int{5, 5}, &sub)
+	c.Call(ctx, "Arith", "Sub", [2]int{5, 5}, &sub)
 
 	var mul int
-	c.Call("Arith", "Mul", [2]int{5, 5}, &mul)
+	c.Call(ctx, "Arith", "Mul", [2]int{5, 5}, &mul)
 
 	var div int
-	c.Call("Arith", "Div", [2]int{5, 5}, &div)
+	c.Call(ctx, "Arith", "Div", [2]int{5, 5}, &div)
 
 	fmt.Printf(
 		"add: %d, sub: %d, mul: %d, div: %d\n",