Re: [boost] [thread] RFC standard proposed mutex, read-write mutex, condition

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2007-08-22 12:35:36

On Aug 22, 2007, at 10:42 AM, David Abrahams wrote:

>
> on Wed Aug 22 2007, Howard Hinnant <hinnant-AT-twcny.rr.com> wrote:
>
>>> "However if the external mutex is (or is layout compatible with) a
>>> pthread_mutex_t, then there is no need for the internal
>>> pthread_mutex_t. When one wants to wait, one simply waits on the
>>> external pthread_mutex_t with the internal pthread_cond_t."
>>>
>>> This smells a little fishy.  It seems to imply that pthreads can  
>>> wait
>>> on any old data type that happens to be layout-compatible with
>>> pthread_mutex_t.  Is that really true?
>>
>> Perhaps the wording isn't precise enough.
>>
>> The intent is that on pthreads:
>
> <snip explanation that doesn't mention layout-compatibility>
>
> Sure.  But where does the layout-compatibility thing come in?  Your
> example uses the native pthread types, not arbitrary types
> layout-compatible with those.

The vendor will decide on which mutex types it is appropriate to make  
this specialization/optimization.  I used "layout-compatible" in an  
attempt to communicate which std-defined mutex types would be  
appropriate for the vendor to specialize on.

-Howard