[boost] Re: Boost.Threads: Do we need all those mutexes?

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2004-07-13 18:48:57

On Jul 13, 2004, at 3:59 PM, Peter Dimov wrote:

> Hm. Where were we.

What?! I thought you were holding the map! <quickly looks for road 
signs>.  OMG we're lost!

> Oh yes.

<phew!> :-)

> - mutex::timed_lock: optional.

<nod>

> - timed_mutex: in the std or not?

well, in boost anyway with the intent of proposing for std, I vote yes.

> - recursive_mutex: in the std? Seems so.

<nod>

> - condition::wait with recursive_mutex: compiles?

<nod>, but I could be persuaded otherwise if we can detect a recursive 
mutex at compile time.

> - condition::wait with recursive_mutex locked more than once: defined? 
> if
> so, how?

This is the big question in my mind right now.  I know how to make it 
work with a home-grown recursive mutex.  But I don't know how to make 
it work with a native recursive mutex, combined with a native 
condition.  I'm somewhat surprised that it doesn't just work.  
Alexander, can we send a bug report to the pthreads guys?  Or would we 
just be laughed out of the room?  I'm not educated enough to know what 
the problems are to making it work.  And clearly it doesn't work today, 
so it's a problem whether or not it can be fixed.  <sigh>  That 
probably backs us into undefined behavior if the mutex is recursively 
locked, or refusing to compile at all with a recursive mutex.  I'm 
unsure at this point which would be the better option.

-Howard