Building cx_Oracle v6 with a system-delivered libodpic.so

[jmcp]

I'm updating the https://github.com/oracle/solaris-userland integration of cx_Oracle to bring in
v6.x, and observe that as currently written, v6 requires the source of a version of ODPI-C to
be compiled in, rather than allowing for a system- or otherwise-delivered version to be linked
in.

The delivery of ODPI-C for Solaris is going to be packaged per solaris-userland processes
and installed into /usr/lib/ + /usr/lib/$(MACH64), and we'd really rather not have to grab a copy
of ODPI-C's source so we can build cx_Oracle.

These two patch files enable separating out ODPI-C from cx_Oracle; I think it would be worthwhile
to include in cx_Oracle as a general configuration feature.

setup.py.patch.txt
cx_Oracle.c.patch.txt

[cjbj]

Any use of an external ODPI-C library would need to verify its version was compatible with that required by cx_Oracle.

[anthony-tuininga]

Agreed. ODPI-C does this automatically, however. Taking a quick peek at the patch, I don't think we want to assume that on SunOS a system supplied libodpic.so is available. I realise that you intend to do so, but others may not. The presence of an environment variable such as ODPIC_LIB_DIR might be sufficient. I'll give it some thought and get back to you later.

[cjbj]

Ack.

[jmcp]

I'm happy with the ODPIC_LIB_DIR idea.

@cjbj how would I track the version required? Is there any sort of interface stability guarantee for either ODPI-C or cx_Oracle?

[cjbj]

@jmcp The stated compat is in: https://oracle.github.io/odpi/doc/public_functions/dpiContext.html#c.dpiContext_create

Tracking what versions any driver installed requires is an open question. Are you creating cx_Oracle packages?

[jmcp]

@cjbj yes, I am creating packages. I've currently got ODPI-C v2.0.2 and cx_Oracle 6.0.2 lined up just about ready for integration.

On the topic of interface stability, since I'm thinking of Solaris' way of handling these things I'll take that offline.

[anthony-tuininga]

@jmcp, I have just added a patch to setup.py that permits building of cx_Oracle with a pre-compiled version of ODPI-C. To do so, you simply need to set the environment variables ODPIC_INC_DIR and ODPIC_LIB_DIR. Once both are set, the values of these variables will be used to locate the dpi.h include file and the libodpic.so shared library and the source will be ignored. I trust that is acceptable to you? Please confirm. Thanks!

[jmcp]

Yes, that works for me. Thankyou!