Using multiple DBs?

[donn]

In issue #4692:

If you use db = odb.dbDatabase.create() then you get a db with no Logger that can't issue messages. I suggest you just use the API that works.

The problem with that is while odb.dbDatabase.create() allows multiple DBs to exist simultaneously, the new API does not. We do have a number of scripts that operate on two databases simultaneously. Problem is, now we have three ways of doing this, none of which are ideal:

1. This fails with "No logger is installed in odb."

   def _2r1w_db_old(db1_in, db2_in, db_out):
       db1 = odb.dbDatabase.create()
       db1 = odb.read_db(db1, db1_in)
       db2 = odb.dbDatabase.create()
       db2 = odb.read_db(db2, db2_in)
       odb.write_db(db1, db_out)

2. This fails with "You can't load a new db file as the db is already populated"

   def _2r1w_db_new(db1_in, db2_in, db_out):
       ord_tech1 = Tech()
       design1 = Design(ord_tech1)
       design1.readDb(db1_in)
       
       ord_tech2 = Tech()
       design2 = Design(ord_tech2)
       design2.readDb(db2_in)
       
       design1.writeDb(db_out)

3. This works, but is horrifying and is likely to fail for multiple reasons in the future.

   def _2r1w_db_mix(db1_in, db2_in, db_out):
       ord_tech1 = Tech()
       design1 = Design(ord_tech1)
       design1.readDb(db1_in)
       
       db2 = odb.dbDatabase.create()
       db2.setLogger(design1.getLogger())
       db2 = odb.read_db(db2, db2_in)
   
       design1.writeDb(db_out)

Advice?

[maliberty]

I'm curious what your use case is for multiple dbs. I guess you are only use odb APIs as nothing else in OR is likely to work in such a scenario.

We could add an API to setup the logger.

[donn]

Correct, just ODB APIs- a couple things like comparing pins, grafting some instances from one design into another, etc.

The logger setup API would be appreciated.

[maliberty]

Does this satisfy your needs

from openroad import Design, Tech
import odb

ord_tech1 = Tech()
design1 = Design(ord_tech1)
design1.readDb('odb/test/data/design.odb')

db2 = Design.createDetachedDb()
db2 = odb.read_db(db2, 'odb/test/data/design.odb')

design1.writeDb('db1.odb')
odb.write_db(db2, 'db2.odb')

[maliberty]

Supporting multiple designs is a goal but it won't happen quickly.

[donn]

It would do, presuming all odb APIs still work

[maliberty]

Done #4749

The odb APIs should be fine.