retry.erl

%%
retry_delayed(Fn, DelayMs, TotalElapsedMs) when is_function(Fn),
                                                is_integer(DelayMs),
                                                is_integer(TotalElapsedMs),
                                                TotalElapsedMs > DelayMs ->
    retry_delayed2(Fn, DelayMs, TotalElapsedMs, ordsets:new()).                                      

retry_delayed2(Fn, DelayMs, TotalElapsedMs1, Errors1) ->
    NowStart = now_ms(),
    case Fn() of
        Result when Result == ok orelse (is_tuple(Result) andalso element(1, Result) == ok) ->
            Result;
        Error ->
            Errors2 = ordsets:add_element(Error, Errors1),
            Elapsed = now_ms() - NowStart,
            TotalElapsedMs2 = TotalElapsedMs1 - Elapsed,
            case TotalElapsedMs2 =< 0 of
                true ->
                    {error, ordsets:to_list(Errors2)};
                false ->
                    timer:sleep(DelayMs),
                    retry_delayed2(Fn, DelayMs, TotalElapsedMs2-DelayMs, Errors2)
            end
    end.

now_ms() ->
    {Megasecs, Secs, Microsecs} = erlang:now(),
    (Megasecs*1000000000) + (Secs*1000) + (Microsecs div  1000).