Problem: structure's field is not replaced with fresh value if it is zero after an rpc call. Here is minimal code sample:
package main
import (
"fmt"
"log"
"net"
"net/rpc"
)
type RpcObject int
type Reply struct {
A int
}
func (*RpcObject) GetSlice(req int, reply *[]Reply) error {
*reply = []Reply{{0}, {158}}
return nil
}
func Serve() {
addr, err := net.ResolveTCPAddr("tcp", "0.0.0.0:12345")
if err != nil {
log.Fatal(err)
}
inbound, err := net.ListenTCP("tcp", addr)
if err != nil {
log.Fatal(err)
}
handler := new(RpcObject)
rpc.Register(handler)
rpc.Accept(inbound)
}
func main() {
go Serve()
var err error
var client *rpc.Client
for client, err = rpc.Dial("tcp", "localhost:12345"); err != nil; client, err = rpc.Dial("tcp", "localhost:12345") {
fmt.Println("connecting...")
}
reply := []Reply{{225}, {9946}}
client.Call("RpcObject.GetSlice", 0, &reply)
fmt.Println(reply)
}
Output: [{225} {158}]
I assume it is a problem with gob format, however I am not sure. Does someone know how to fix this?
The application produced the expected results. The gob encoder does not transmit the first element in the reply slice because the element is the zero value. The decoder does not set the first element in main's
reply
slice because a value was not received for that element.Decode to a zero value if you do not want to set defaults for values missing from the reply: