Re: [Tarantool-patches] [PATCH v4 1/3] gc/xlog: delay xlog cleanup until relays are subscribed

[Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

On 25.03.2021 22:02, Cyrill Gorcunov via Tarantool-patches wrote:
> On Thu, Mar 25, 2021 at 08:59:53PM +0100, Vladislav Shpilevoy wrote:
>>>  static double
>>>  box_check_wal_cleanup_delay(void)
>>>  {
>>> +	const double MAX_TIMEOUT = TIMEOUT_INFINITY;
>>> +	const double MIN_TIMEOUT = 0.001;
>>
>> I am going to repeat it here from what I said verbally and
>> in the chat - don't restrict the timeout. We never restrict
>> any timeouts. TIMEOUT_INFINITY is not literally double inf
>> value. It is just some huge but valid double value. User in
>> his code can have a bigger definition of what is infinity.
>>
>> The same with the min. Why do you limit it from below? I don't
>> see a single reason for doing so. Only reasons against that -
>> it is inconsistent with the other timeouts we have, and might
>> conflict with how each particular user understand the "minimal"
>> timeout.
> 
> Most important reason is an epsilon value on hw level, how many
> users remember what exactly range the "machine zero" covers?

I don't remember, and I don't see why should I really. What is the
reason you ban 0.0009 but allow 0.001? This looks random and does
not protect from anything.

> Do we really want to allow precision close to nanoseconds?

We allow double. Whatever precision it gives.