Re: [Dev-C++] how to update data constantly?

A cheaper form of mutex for Win32 applications are the critical
sections. In some situations a semaphore may be suitable.

/pwm

On Wed, 5 Dec 2007, Chris Miller wrote:

> On Dec 5, 2007 1:10 PM, Jessica Chen <jes...@gm...> wrote:
> > My whole projects have two thread.
> > one thread is reading RS-232 communication port.
> > another thread is Win32 GUI to display the data got from RS-232
> > communication port.
> >
> > The design I had is:
> > Buttons on Win32 GUI.
> > So when the button is clicked, the corresponding data is read from RS232
> > thread, and display in the GUI thread.
> >
> > BUT I want to have a constantly updated display.  That is, there is NO
> > button to trigger the data update.
> > When the data of RS232 thread is updated, my display of GUI thread need to
> > be updated.
> > What should I design?
> >
> > My consideration for the design is:
> > add a constant interval timer to trigger the data update.
> >  but how to implement it?
> > and do you have any other good idea?
>
> A commonly used technique is to have the GUI thread check the reader
> thread every X miliseconds.  This requires that you use a mutex to
> lock the data while it's being read, otherwise you might incur the
> wrath of undefined behavior when reading memory that's currently being
> written to.
>
> What if you had a dual-core CPU, and you managed to send a read
> request exactly when you sent a write request?  Something tells me
> that's not possible because of the mutexes in the lower-level
> implementation, but it would be interesting to see which request the
> memory controller disregards.
>
>
> I'm not sure how to implement a mutex in a Win32 thread, however,
> pthreads is only a wrapper on top of Win32, so it can be done (I
> didn't notice any special code in the pthreads sources when I glossed
> over them).
>
> --
> Registered Linux Addict #431495
> http://profile.xfire.com/mrstalinman
> John 3:16!
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