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Subject: Re: [boost] Executor associated to the future continuations (was [thread] boost::future::then)
From: Vladimir Prus (vladimir.prus_at_[hidden])
Date: 2015-10-30 03:08:26

On 29-Oct-15 11:00 PM, Vicente J. Botet Escriba wrote:
> Le 29/10/15 14:09, Vicente J. Botet Escriba a écrit :
>> Le 29/10/15 11:13, Vladimir Prus a écrit :
>>> On 29-Oct-15 12:49 PM, Vicente J. Botet Escriba wrote:
>>>> Le 29/10/15 10:08, Vladimir Prus a écrit :
>>>>> On 11-Oct-15 9:30 PM, Vicente J. Botet Escriba wrote:
>>>>>> Le 10/10/15 16:58, Vicente J. Botet Escriba a écrit :
>>>>>>> Le 10/10/15 15:26, Vicente J. Botet Escriba a écrit :
>>>>>>>> Le 10/10/15 07:57, Vladimir Prus a écrit :
>>>>> Vicente,
>>>>> I've created a very early experiment, here:
>>>>> Does it look generally right for you?
>>>> I don't know Qt. It seems ok beside tht fact that you create an Executor for each Task. Maybe this is not important for
>>>> you as your Executor class is adapting Qt.
>>> It's not hugely important, since in practice the work performance is orders of magnitude longer
>>> than QObject creation. Anyway, I possibly can create an executor per thread on demand, and reuse them.
>> Don't worry with the new version where you will give the Executor at promise creation the cost will be minimal in your
>> case.
> Hrr, I'm not able to remove completely the Executor type erasure as the type of f2 would depend on the Executor
> associated to the shared state of f1, that is unknown.
> MyExecutor ex;
> auto f1 = async(ex, cont);
> auto f2 = f1.then(launch::inherit, cont);
> So, f1 could have a shared_state that depends on MyExecutor, however f2 would have an shared state that depends on the
> type erased boost::executor.

Okay, but does it matter much for performance?

> That means that it is better for the user to store the specific executor in some way and use it as follow
> auto f2 = f1.then(ex, cont);

I've tried to do so, at:

This initial version was straight-forward, though it will probably need further tweaks for production use.

What does boost::future::then do right now if the continuation returns boost::future, is it unwrapped

Vladimir Prus

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