[ros-dev] Re: [ros-diffs] [gedmurphy] 19312: Improve stopping control of the service

[Murphy, Ged (Bolton)]

> -----Original Message-----
> From: Thomas Weidenmueller [mailto:w3seek at reactos.com] 
> Sent: 18 November 2005 12:03
> To: ReactOS Development List
> Subject: Re: [ros-dev] Re: [ros-diffs] [gedmurphy] 19312: 
> Improve stopping control of the service
> 
> 
> Murphy, Ged (Bolton) wrote:
> > This function is new to me. 
> Now that you're writing multithreaded code it's about time to learn
> about these functions ;)
> 
> > I'm just doing a bit of research on it now to better 
> understand it, but
> > could you just give me a bit of background of the 
> difference between this,
> > and using something like a mutex or CS, and why it's better in this
> > scenario?
> Of course you can use mutexes or critical sections, but for 
> this purpose
> interlocked operations are much more lightweight because with 
> mutexes or
> critical sections you'd have to protect the read operation as 
> well. The
> Interlocked* functions basically guarantee that a certain 
> operation on a
> variable shared by multiple threads is performed in an atomic 
> matter. I
> probably should mention that reads are always atomic, so reading a
> variable with the size smaller or equal as the size of a 
> general purpose
> register does not need to be protected, writes however have 
> to be protected.
> 
> You should read the following articles:
> http://msdn.microsoft.com/library/default.asp?url=/library/en-
> us/dllproc/base/interlocked_variable_access.asp
> http://blogs.msdn.com/oldnewthing/archive/2004/09/15/229915.aspx


Thanks for the info, much appreciated.
I've been reading up on Interlocked Variable Access this morning and have
now implemented it into the code.

Ged.



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