[Info-vax] Most popular application programming languages on VMS ?

[Dave Froble]

On 1/11/2019 8:35 PM, Arne Vajhøj wrote:
> On 1/10/2019 5:00 PM, Dave Froble wrote:
>>> The CRTL uses the DLM with the range feature (don't think of them as
>>> bytes in a file, but just a specialization of a normal named lock) to
>>> be notified of multiple programs that are using the CRTL's
>>> implementation of fcntl().
>>>
>>> http://pubs.opengroup.org/onlinepubs/9699919799/ and search for
>>> "fcntl".
>>
>> I'll take a look, but, I don't see how any resource name, being
>> treated solely as a resource name, could implement numeric range
>> (better term than byte range) locking.
>
> Why not?
>
> Traditional:
>
> process A takes out lock on "FOOBAR"
> process B tries to take out lock on "FOOBAR"
> DLM tell B to wait because "FOOBAR" is taken
>
> Range:
>
> process A takes out lock on "FOOBAR" 1-1000
> process B tries to take out lock on "FOOBAR" 501-1500
> DLM tell B to wait because "FOOBAR" 501-1000 is taken

I'm pretty sure that the DLM does not do any wildcard stuff with 
resource name.  It uses only exact matches.

Now, if the DLM knew about other types of locks, then it could treat a 
resource name (or other data field) as a numeric range, and have a 
routine to compare the data looking for intersections.

John is claiming it's in there.  I don't have sources.  Without 
documentation, it might as well not be in there.


-- 
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486