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

From: David Abrahams (dave_at_[hidden])
Date: 2007-08-27 10:06:16

on Sun Aug 26 2007, Beman Dawes <bdawes-AT-acm.org> wrote:

> David Abrahams wrote:
>> on Fri Aug 24 2007, Howard Hinnant <howard.hinnant-AT-gmail.com> wrote:
>> 
>>> The above appears to be a reasonable and valid use case to me for  
>>> "correcting" the condition/mutex binding.  The retooling operation is  
>>> a rare (exceptional) event.  Using exceptions for this makes the main  
>>> processing routine simpler/cleaner as it does not have to deal with  
>>> the complication of retooling.
>>>
>>> In summary, we have valid use cases for both not checking condition/ 
>>> mutex consistency, and for checking condition/mutex consistency, with  
>>> both use cases built on "correctness" concerns as opposed to  
>>> "performance" concerns.  Where this leads us next, I'm not yet sure...
>> 
>> This is exactly the sort of use case in which I'd want to have
>> complete control of detecting the need for an exception and throwing
>> it myself.  And, as described in http://tinyurl.com/2ph58t, if you
>> rely on the std's checking and exception here you end up with the same
>> exception representing a severe programming error in one part of the
>> program and an expected, recoverable condition in another.  At some
>> point up the call stack, you don't know which is which.  I would
>> always want a specific "retooling" exception for the non-error case.
>> 
>> And, I repeat, when the mutex mismatch *does* represent an error, I
>> *really* don't want a mandated throw.
>
> So would you like to see two classes?

Probably not (see below).

> One (Peter suggested "condition") that asserts on mutex mismatch, 

We don't mandate asserts in the standard.

> and another (Peter suggested "checked_condition" ) that throws on
> mutex mismatch.

I think the need for a throw is sufficiently rare that I don't want a
whole library component for it.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com
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