[Ace-users] [ace-users] Container classes in Shared Memory

[Douglas C. Schmidt]

Hi,

> I’m a newbie to ACE, just started about a week ago. I’ve been trying to create a common object for Inter Process
> Communication so that all processes running can post/receive messages from one another. It’s proving to be quite a
> difficult task and could use some help. I’m on a windows xp sp2 box using MS Visual Studio 05 to build ACE.

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> I can easily and successfully create a Hash map in shared memory using ACE_Hash_Map_With_Allocator holding my user defined
> class StaticQueue. With Two processes running I’m successful in finding each StaticQueue in the hash map. I can retrieve
> the bool value defined in the StaticQueue without a problem. However, the StaticQueue Class also has an ACE_Message_Queue*
> as a class variable. When I try to use this variable I receive memory access violations as runtime errors.
> 
>  In a single process I can create a StaticQueue in the hash map, Find the StaticQueue in the hash map, and Process the
> messages in the ACE message queue. However when I have 2 processes running one creates the StaticQueue, the other finds it
> but has an invalid pointer to the ACE_message_Queue.
> 
> Obviously, the memory for the ACE_Message_Queue is not in shared memory. Is it possible to create the ACE_Message_Queue’s
> memory in shared memory?

No, there's no (portable) way to do this since that class uses virtual
methods.  This is a C++ issue, not an ACE issue per se.  Please see the
discussions about this in C++NPv1 <www.cs.wustl.edu/~schmidt/ACE/book1>.

Thanks,

        Doug