Experimental Physics and
Industrial Control System

Maren Purves <[email protected]> · Tue, 3 Feb 2009 06:51:26 -1000 (HST)

On Tue, 3 Feb 2009, Benjamin Franksen wrote:

On Monday 02 February 2009 23:18, Maren Purves wrote:

Benjamin Franksen wrote:

On Montag, 2. Februar 2009, Till Straumann wrote:

Benjamin Franksen wrote:

Our idea for an efficient implementation is based on the observation
that in a typical EPICS database there are only very few fields per
record that actually receive dbPuts (or get updated directly from
within base). Only for these fields is it necessary to provide
storage for the time of the last update. This storage will be
allocated on demand; each record must maintain a (typically very
short) list of (field index, timestamp) pairs; let us call it the
'field update list' or short 'update list'. When reading the
timestamp for a field, first search the update list and use the
contained stamp if one is found, otherwise use the TIME field of the
record.

How does that implement (b) ? If a field is never updated,
shouldn't that field then report the time when iocInit() was
executed?

Ah, a good objection. It looks as if we need to distinguish between
fields that have

 i)   never been changed (timestamp = iocInit time)

only if PINI=Yes?

Surely not. Every field gets initialized at startup. PINI should be treated
like all other processing.

I use TIME=0000 (etc., not sure about exact format) in trouble shooting
new stuff a lot, and I'd like to have it kept as a feature for records
when PINI is NO. It's much easier to find all the zeros than the UDF
field.

You can see that as a feature request, and if people disagree, then,
obviously not. But for me it's a "nice to have".

Aloha,
Maren

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System