Re: [Boost-Users] Macintosh Carbon Thread Error with Boost 1.30.0

From: Bobby Thomale (bobby-thomale_at_[hidden])
Date: 2003-04-11 14:59:43

> You are right, there is no lightweight mutex for Carbon since nobody
> submitted one. :-)
> 
> In Boost 1.29 and earlier, the #error was commented out, and shared_ptr
> silently fell back to the non-thread safe implementation.
> 
> If you don't need a thread safe shared_ptr, you can replace the #error with
> 
> #  include <boost/detail/lwm_nop.hpp>
> 
> If you need the thread safety, and you are familiar with Carbon MP tasks,
> you can write a lightweight mutex implementation for this platform and
> submit it for inclusion. Or you can simply typedef boost::mutex as
> boost::detail::lightweight_mutex, if you don't mind linking with
> Boost.Threads.
> 
> HTH

That helps tremendously.

I do have a couple questions though.

1.  How non-thread-safe is the non-thread-safe implementation?  As long as a
shared_ptr is only used in one thread am I ok?  Or is there issues even
there if I am creating shared ptrs in more than one thread?  (Like are they
sharing some kind of custom allocator?)

Just curious what guaruntees there are there (if any) without the mutex.

2.  I may consider writing an implementation for Mac.  As far as I know
there is not any sort of mutex in the MP library that is faster and lighter
weight than the MP critical section stuff which I am sure boost::mutex uses
- but it would be extrordinarily helpful for me if there was a header-only
mutex implementation for the shared_ptr to use on Mac so I don't have to
link Boost threads into all of my projects.

I have a central library that uses shared_ptr heavily, and it also contains
some thread code.  A lot of projects share that library, but I only link the
thread stuff in if I actually use the thread-dependent parts of the library.

If I were to write one who would I give it to to consider for inclusion?

                                -- Bobby

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Bobby Thomale
Senior Software Developer
Inoveon Corporation
http://www.inoveon.com/
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