threads and database

[Ruslan Zasukhin]

On 6/24/04 4:47 PM, "olivier vidal" <vidal_olivier at yahoo.fr> wrote:

> thank you very much Marc and Ruslan.
> 
> Imagine a shop.
> In this shop, there is a single computer.
> 4 screens and 4 mice are connected on this computer.

You mean 4 physical monitors! Aha.
Only 4 mice? What about keyboards?

It look you try create old good terminals :-)

> (4 screens : mode
> "Extended Desktop" on Mac, with special graphics board. 4 screens
> behave as a single screen.

4 monitors form a single virtual screen. Clear.

> (Example: 4 screens with a resolution of
> 1024X768 will give the illusion for the computer of a single screen of
> 4096X768))
> 
> Imagine a software (or driver) which allows the use of several mice
> simultaneously on the same computer. Mice which can be simultaneously
> clicked.

> There are several salesmen and every salesman can use a screen and a
> mouse ( a "virtual computer") to make a sale or for example see the
> stock of an product.

> The salesmen must be able to use "4 virtual computers" simultaneously.

> Naturally, the software must be fast and it does not have to it have of
> wait in the screen there.

Ok

> The idea is to use a single software on this computer.

Yes, in this configuration you need SIGNLE APPLICATION
Because you run like a single user for MacOS.

You cannot start in MacOS 4 different copies of apps with the same name,
right? Although it is possible to make 4 copies of the same app with
different names and run them all in the same time.

> I also think that the best solution is to use a single window
> distributed on 4 screens (a single window or a single application, so
> that on 4 screens every window of screen is active and answers the
> click first one).

Single app, which allow open ANY number of windows.
In your case will be opened 4 windows.

Each window use own Valentina cursor.
Each window play role of separate user.
Each window may have own thread.

> As there is only a single computer, I think effectively that the access
> to the database should be very fast, even with 4 simultaneous attempts
> of access.

Exactly. No network. No any protocol or sockets.

You set e.g. 20MB cache for Valentina.
A lots of data in RAM.

> Is it even really necessary in that case (for the database) to use
> threads? (Ruslan, in realbasic threads is slow). There will be little
> of update on the data, a great majority of cursors will be shared lock
> (read only) and if it is not possible temporarily to access to data, I
> can re-try in a loop. It should be very fast and there should be no
> wait (I hope). ??

Well. Then this is RB issue:
    what is better: threads or timer.

You can work with one thread, no problems.
Cursors still are independent and lock records.

> On the other hand, for the graphic interface and the posting, I suppose
> that I should use threads. (Other solution?)
> 
> I hope that Realsoftware is quickly going to correct the problem of
> speed with threads.

-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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