subscriptions specifying zero elements dont work with local channels

[Jeff Hill]

From Sheng Peng:

Here are more details of the issue I ran into:

To simplify the test, I just use the slightly modified caMonitor.c from the template and rename to camon.c.

Here are the results I got:

 -- ca_create_subscription with count 0: Ok for remote PVs (both scalar and array), no good for local PVs (both scalar and array), the callback

event_handler_args.count is always 0 for both local scalar and array and the value is NOT in dbr.

 -- ca_create_subscription with explicit count: no good for local array PVs, scalar is ok since count is always 1.

 -- ca_add_event: Ok for local and remote scalar but not array, as expected.

 -- ca_add_array_event with count 0: does not work for local array PVs.

 -- ca_add_array_event with explicit count: works for local and remote array PVs

So ca_add_<array>_event with explicit count works. With count 0 (which should mean native count of the PV) does not work for local PV.

And ca_create_subscription with count 0 does not work for local PV, does not work for local array event with explicit count.

Original Mantis Bug: mantis-370
    http://www.aps.anl.gov/epics/mantis/view_bug_page.php?f_id=370

[mdavidsaver (mdavidsaver)]

The count==0 case (dynamic array size) for local CA is being worked on.