Re: [Threads-devel] boost::condition and Lock concept

From: Anthony Williams (anthony_at_[hidden])
Date: 2007-12-06 03:02:43

Quoting Frank Mori Hess <frank.hess_at_[hidden]>:

> On Tuesday 27 November 2007 03:06 am, Anthony Williams wrote:
>> The new trunk code provides two condition variable types:
>> condition_variable and condition_variable_any.
>>
>> condition_variable works with unique_lock<mutex> ONLY, and the function
>> signatures are explicit about that. condition_variable_any will work with
>> anything that supports unlock() and lock().
>
> Is it possible to make condition_variable_any work with recursive   
> mutexes?  It
> seems like an additional interface on the lock would be required, since a
> recursive mutex may still be locked by the current thread even after calling
> unlock().

I think that would be dangerous. If you don't know how many times  
you've locked the recursive mutex when you call wait() (in order to  
unlock all but one prior to the call), then you might be unlocking the  
mutex when a layer above you is expecting it to still be locked and  
has incomplete changes that are protected by the lock.

Anthony
-- 
Anthony Williams
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