Record Locking in FoxPro - How does it work internally ?

[filibuster]

Hi all,

I'm trying to understand how record locking works internally in FoxPro.

My guesses:
- It must be implemented serer-side to allow multiple clients.
- It cannot be implemented on file level, because file operations are not exclusive (one would have to open a file exclusively to set a flag in a file in an atomic way)
- FoxPro uses some sort of Semaphore/Lock provided by the File Server

I also found (a pretty old) post which said that FoxPro wouldn't work with a Samba File Server (

http://lists.samba.org/pipermail/samba/1999-October/044235.html)...

Thanks

 

[rgbean]

Most OS's have (at least) two types of locking schemes. The first is the full file, and the second is a from location, to location in the file type. Since DBFs have fixed length records, it would be trivial for FP to calculate the from-to for a given record to lock. I believe this is how FoxPro locks records in DOS, Windows and Novell servers.

Rick