Re: DLL and synchronizing global data

From:

"Alex Blekhman" <xfkt@oohay.moc>

Newsgroups:

microsoft.public.vc.language

Date:

Wed, 20 Sep 2006 14:18:05 +0300

Message-ID:

<uHeezZK3GHA.4748@TK2MSFTNGP04.phx.gbl>

"Mark Baldwin" wrote:

I have a DLL that contains global data. The data is
initialized from DllMain
during DLL_PROCESS_ATTACH and destroyed during
DLL_PROCESS_DETACH. Once
initialized, the global data is only read from and not
modified at all.

My question is what sort of protection should I provide,
if any, to this
global data. I have done some testing and everything
appears to work with no
synchronization at all, my concern is that problems might
appear when
running on multiprocessor machines, something I can't test
for at the
moment.

Usually you need to synchronize an access to data if you
change it. If it never changes there is nothing to
synchronize.

Just imagine that you and your friend have a piece of paper.
You want to write short story on it together. So, you need
to synchronize an access to the paper, otherwise you will
interfere with each other and just trash the paper. Once the
story is written you pin the paper in a hallway and
everybody can read it simultaneously. Paper never changes
from now on, hence no need to synchronize.