Subj : Re: static member variable
To   : comp.programming.threads
From : Gianni Mariani
Date : Wed Feb 23 2005 09:08 am

nin234@yahoo.com wrote:
> I tried searching the newgroups for an answer to this question. I
> found
>  many related topics, but didn't find the exact answer I am looking
> for.

..... snip

>     class srvLog
>    {
>        static int nLglvl;

.... snip

>  Logging is controlled by the nLglvl static variable. This is part of
> a daemon. So the logging is to a file and the value of nLglvl will be
> set by a command line tool.
>  My questions are the following
>  1) Is the value of nLglvl shared by threadA, threadB and main()
> thread.

Yes srvLog::nLglvl exists in exactly one place - that's what static means.

> 
>  2)Where should I call setlvl()?

Anywhere you like.

>  3) If the answer to 1) is yes. Is it really required to use locking
> in
>  this scenario. Because the change to the value of nLglvl will be
>  infrequent and I can live with some bad reads.

Locking is not required since synchronizing with the change is not 
important.  You may want to make it volatile

> 
>  I am using POSIX threads. Linux and solaris are the current
>  environments. It must be portable to all unix flavors. 

You might want to look at a C++ library like boost, or Austria C++.

.