Re: [boost] [thread] feature request priority

Subject: Re: [boost] [thread] feature request priority
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2012-01-03 08:17:57

Vicente J. Botet Escriba wrote:
>
> Respect to
>
> #5150<https://svn.boost.org/trac/boost/ticket/5150>
> boost::thread does not print or return the error value when
> creating a thread fails.
>
> I planed to implement it via
>
> #6230 <https://svn.boost.org/trac/boost/ticket/6230> Follows
> the exception reporting mechanism as defined in the c++11

I presume by referring to #6230 that you'll throw an exception of type system_error for #5150's case.  If so, I agree.

> and
> #3696 <https://svn.boost.org/trac/boost/ticket/3696> Boost
> Thread library lacks any way to set priority of threads
> via
>
> #2741  proposal to manage portable and non portable thread attributes
> <https://svn.boost.org/trac/boost/ticket/2741>

Using a thread_attributes class seems fine, but there are a few issues with #2741:

1. thread::thread_attributes makes for a redundant name.  Either "thread_attributes" or "thread::attributes" would be better.

2. The constructors that take a thread_attributes argument should overload the existing constructors, not replace them.  (The class definition in #2741 suggests the possibility of no backward compatibility, but I think that is important.)

3. You could support a portable interface for thread priorities, but you'd need to determine how to normalize thread priorities since different OSes offer different ranges of priority values.  It might be that the portable interface provides only partial prioritization support for some platforms, requiring the use of a native API when that's insufficient.  That would give some support for portable code, even if a modest utility that might be enough for many applications.  Then again, the result might be so anemic that it would never be used.

4. I wonder if a thread should own its attributes such that clients can query for them later:

   thread_attributes const &
   thread::attributes() const;

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com

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