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

[Arne Vajhøj]

On 1/11/2019 10:03 PM, Dave Froble wrote:
> 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.

Obviously the DLM code need to treat range locks different than
other locks.

Arne