Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project

Subject: Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
From: Giovanni Piero Deretta (gpderetta_at_[hidden])
Date: 2013-05-02 07:37:53

Hi Vincente,

On Wed, May 1, 2013 at 11:42 PM, Vicente J. Botet Escriba
<vicente.botet_at_[hidden]> wrote:
[...]
>
> I have just read N3388 - Using Asio with C++11 and a think I start to
> understand the ASIO design.
> Could we say the completion handlers are continuations?
> And that the user use to master which thread executes the continuation by
> calling the io_service::run() function?

Pretty much, except that multiple threads can call io_service::run
concurrently. Basically Boost.Asio is a work sharing queue plus a
collection of waitqueues to wait for specific events.

> And that io_service can have associated also several threads (to form a
> thread pool).

The associated threads are exactly those that are currently calling
io_service::run.

> And that in order to avoid data races the user uses strands to serialize the
> completion handlers that have access to shared data?

That's one way, but not the only way.

>
> While continuation passing style could be well adapted to protocols (and
> surely it is) , there are other domains that would prefer to write his code
> in a more linear way. It is true that with C++11 lambdas the continuation
> passing style is less opaque.

That's orthogonal. Boost.Asio provides the funding blocks. A nicer
interface that doesn't require an explicit continuation passing style
transformation can be built with Boost.Context or a similar library.
But it probably needs a future implementation that integrates with
ASIO, which is one of the point of Niall Douglas.

See the recent discussion about "library support for async/await pattern".

-- gpd