CODEWITHSUNDEEP
gotimecastingflags
Hace
Hace

Reputation: 1421

Golang: How to convert int to calculate into time.duration

I'm new to GoLang and at the moment at a loss why the compiler does not accept a particular line of code.

I've got this working example for creating a timeout when dialing:

    conn, err := grpc.Dial(*connAddress,
      grpc.WithInsecure(),
      grpc.WithBlock(),                  // will block till the connection is available
      grpc.WithTimeout(100*time.Second)) // times out after 100 seconds

Now the hardcoded 100 there is not nice, so I would like to make that a commandline variable via a flag, like so:

    connTimeout := flag.Int64("connection-timeout", 100, "give the timeout for dialing connection x")
...
    conn, err := grpc.Dial(*connAddress,
      grpc.WithInsecure(),
      grpc.WithBlock(),
      grpc.WithTimeout(*connTimeout*time.Second))

However this gives the following compilation error:

mismatched types int64 and time.Duration

So apparently I can't use the int64 flag variable directly to calculate a duration but a number can?

Eventually I found a solution for using the flag variable by creating a variable related to time.Duration first:

var timeoutduration = time.Duration(*distributorTimeout) * time.Second
    // create distributor connection
    conn, err := grpc.Dial(*connAddress,
        grpc.WithBlock(),
        grpc.WithTimeout(timeoutduration))

The above seems to work as expected: the dialing is tried for as long as the commandline parameter given (default 100) and than throws a message that the connection could not be made. Good.

However: How come directly using the int64 flag-variable is not possible for calculating a time.Duration, in other words what is the difference for golang between the number 100 and the variable that contains the int64?

Upvotes: 1

Views: 10509

Answers (1)

zerkms
zerkms

Reputation: 255155

grpc.WithTimeout(100*time.Second) and grpc.WithTimeout(*connTimeout*time.Second) does not because of assignability rules:

the latter expression satisfies none of those, and the former satisfies the

  • x is an untyped constant representable by a value of type T.

rule

Upvotes: 2

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