CODEWITHSUNDEEP
erlang
grifaton
grifaton

Reputation: 4046

Erlang: receive statement with multiple timeout clauses

Is it possible for a receive statement to have multiple timeout clauses, and if so, what is the correct syntax?

I want to do something like

foo(Timout1, Timeout2) ->
    receive
    after
        Timeout1 ->
            doSomething1();
        Timeout2 ->
            doSomething2()
    end.

where, depending on which of Timeout1 or Timeout2 is smaller, doSomething1() or doSomething2 is called. However, the above code causes a syntax error.

If, as I'm beginning to suspect, this is not possible, what is the best way to achieve the same outcome in a suitable Erlangy manner?

Thanks in advance!

Upvotes: 2

Views: 1466

Answers (2)

Hynek -Pichi- Vychodil
Hynek -Pichi- Vychodil

Reputation: 26121

No, you can't. Just decide what to do before receive.

foo(Timeout1, Timeout2) ->
    {Timeout, ToDo} = if Timeout1 < Timeout2 -> {Timout1, fun doSomething1/0};
                         true -> {Timeout2, fun doSomething2/0} end,
    receive
    after Timeout -> ToDo()
    end.

or

foo(Timeout1, Timeout2) when Timeout1 < Timeout2 ->
    receive
    after Timeout1 -> doSomething1()
    end;
foo(_, Timeout2) ->
    receive
    after Timeout2 -> doSomething2()
    end.

etc.

Upvotes: 4

jldupont
jldupont

Reputation: 96746

You should probably use a combination of 'gen_fsm' and 'timer:send_after'.

Upvotes: 0

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