On Tue, May 11, 2004 at 11:05:23AM -0700, Ranjan Bagchi wrote:
> Hi --
> 
> I'm writing some code which will end up executing concurrently on 
> several OS processes.  I'd like to serialize access to some specific OS 
> resources (for instance, writing to a single file).  The Unix module 
> doesn't appear to offer anything like a critical section or an OS 
> mutex.  Is there a preferred way to do this? 

What about Unix.lockf?

Rich.

val lockf : file_descr -> lock_command -> int -> unit
(** [lockf fd cmd size] puts a lock on a region of the file opened
   as [fd]. The region starts at the current read/write position for
   [fd] (as set by {!Unix.lseek}), and extends [size] bytes forward if
   [size] is positive, [size] bytes backwards if [size] is negative,
   or to the end of the file if [size] is zero.
   A write lock (set with [F_LOCK] or [F_TLOCK]) prevents any other
   process from acquiring a read or write lock on the region.
   A read lock (set with [F_RLOCK] or [F_TRLOCK]) prevents any other
   process from acquiring a write lock on the region, but lets
   other processes acquire read locks on it. *)

-- 
Richard Jones. http://www.annexia.org/ http://www.j-london.com/
Merjis Ltd. http://www.merjis.com/ - improving website return on investment
If I have not seen as far as others, it is because I have been
standing in the footprints of giants.  -- from Usenet

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