Re: [Boost-users] [Boost Interprocess] - Shared Memory File - Corruption

From: Srinivas Gardas (gardas_at_[hidden])
Date: 2008-01-11 11:24:51

Thanks so much Ion!
It worked fine.. now I just have to wait and see that my problem doesn't
arise again..

Sreenu

On 1/10/08, Ion Gaztañaga <igaztanaga_at_[hidden]> wrote:
>
> Srinivas Gardas escribió:
> > Hi,
> > I am a little confused about how to make 'interprocess_mutex' part of
> the
> > 'managed_shared_memory' object which actually represents the
> shared_memory?
> > Is there a base class or something that can take the mutex?
> >
> > I placed an '*interprocess_mutex*' as a member variable *in the class
> that
> > contains my 'managed_shared_memory'* object as a member variable and was
> > locking it in the methods that accessed the shared memory. I guess this
> did
> > not work out as I believe what I did effectively locked the object of my
> > class that was holding the embers. And since this is not actually the
> shaed
> > resource between the processes it didn't work out..
> >
> > I'd really appreciate if you could provide an example of just show me
> bbased
> > on my initial code.. how the 'managed_shared_memory' can be locked using
> the
> > mutex.
> >
> > Sreenu
>
>
> Just create the mutex like you create the list and use scoped_lock to
> lock and unlock it more easily (pseudo_code, not compiled):
>
> using namespace boost::interprocess;
>
> interprocess_mutex *mut = m_shMemPtr->find_or_construct
> <interprocess_mutext>("PROCESS-SHARED MUTEX")();
>
> struct_a stOne;
> strcpy(stOne.sym, "ABCDE");
> strcpy(stOne.desc, "FGHIJK");
> stOne.price = 10.25;
>
> { //Begin of locked scope
>
>   //Now lock the mutex to protect concurrent access
>   //to the list
>   scoped_lock<interprocess_mutex> locker(*mut);
>
>   //Do the operation
>   m_pList->push_back(stOne);
>
>   //Mutex will be unlocked by locker's destructor
> } //End of locked scope
>
> The other process should also lock the same mutex when operating with
> the list so that  one process is blocked while the other one is
> manipulating the list. There are several alternatives to build the mutex
> in the segment but I think this is the simplest one.
>
> Regards,
>
> Ion
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