[REBOL] Concurrent access to data file

[CRS - Psy Sel/SPO, COUSSEMENT Christophe, CPN]

Hi REBOLians:

I'm confronted with a little but important problem...

I'm using a block structure for storing data on a server.
40 PC's -soon 80- could potentialy dump their data on the same time into one
single data file on the server.
Because we using Win NT -which I do not trust for reability-, I use a system
of token to insure concurrent access to the file:

<snip>

forever [
        either all [(count<= 20) token?] [
                count: count + 1
                ;--- attempt to reserve token
                if error? err: try [write token-file now (true)][
                        disarm err
                            return false
                ]
                wait 5  ;--- take delay to be sure token is written
                        ;--- try write operations
                        answers: load local-file 
                        either error? err: try [save remote-file append load
remote-file answers (true)][
                         ;--- release token
                                delete token-file
                                disarm err
                                return false
                        ][
                                ;--- release token
                                delete token-file
                                delete local-file
                                return true
                        ]
                        
        ][
                return false
        ]
]

token?: func [][
        return not exists? rejoin [global-answer-path global-token]
]

</snip>

The token is just a text file in this case, and gives the PC the right to
"talk" to the server.
The proc checks for the existence of a token on the server, for a maximum of
20 times. If there's no token on the server, it writes its own one, dump the
data and release the token.
Empirically, I had to set a delay of 5 sec to ensure the token is written,
because of the slow network connection.

Well, my question is not about straight REBOL, but more a matter of
methodology :

The procedure works, but, as you can imagine, it is not very efficient for
so many PC working and dumping together. 
How can I achieve a better performence regarding concurrent access in REBOL
on WinNT, which can garanty me no data will be lost ?

Best regard,

chr==


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