Re: [boost] Re: Lock Classes: Does anyone care.

From: Kevin Atkinson (kevin_at_[hidden])
Date: 2003-02-19 21:21:49

On Wed, 19 Feb 2003, Kevin Atkinson wrote:

> On Wed, 19 Feb 2003, Alexander Terekhov wrote:
> 
> >   struct pthread_mutex_t_ {
> > 
> >     /* ... */
> > 
> > #ifdef __cplusplus
> > 
> >     __copy_ctor(const pthread_mutex_t_&) {
> >       throw "Don't do this!";
> >     }
> > 
> > #endif
> > 
> >   };
> >   typedef struct pthread_mutex_t_ pthread_mutex_t;
> 
> I do not know where it is implemented, it is not on my system, this way
> but I think what I did should be perfectly legal as I am merely initializing
> the class.  In fact having ANY constructor will prevent the statement
> "pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER" from working on my
> system and probably others which IS legal.  This is because if you have ANY
> contractor defined and PTHREAD_MUTEX_INITIALIZER is a macro which uses the
> "{...}" form you will get something like this "...must be initialized by
> constructor, not by `{...}'.
> 
> I have changed the definition to:
> 
> #ifdef FAST_MUTEX_INIT_DESTROY
>   static const pthread_mutex_t MUTEX_INIT = PTHREAD_MUTEX_INITIALIZER;
> #endif
> 
>   class Mutex {
>     pthread_mutex_t l_;
>   private:
>     Mutex(const Mutex &);
>     void operator=(const Mutex &);
>   public:
> #ifdef FAST_MUTEX_INIT_DESTROY
>     Mutex() : l_(MUTEX_INIT) {}
> #else
>     Mutex() {pthread_mutex_init(&l_, 0);}
>     ~Mutex() {pthread_mutex_destroy($l_);}

That '$' should be a '&'.  Sorry I didn't actually try to compile it.

> #endif
>     void lock() {pthread_mutex_lock(&l_);}
>     void unlock() {pthread_mutex_unlock(&l_);}
>   };
> 
> I hope your happy now.  So stupid systems that have pthread_mutex_t 
> defined that way will work.
> 
> Anyway.  My locking primitives are designed to be on top of any locking 
> mechanism, so this is a minor issue.

-- 
http://kevin.atkinson.dhs.org