On 27/10/2011 17:43, John Scoles wrote:
Hmm....!!
Well yes could be done but not as part of any release of DBD::Oracle it would
have to be you own hacked version
Why is that John? What is the problem with returning a C pointer via a
DBD::Oracle attribute? It is just a pointer to some memory and loads of
XS modules do this. There is an Oracle OCI module I played with for a
short time but it is problematic to build. I looked at it as I could
implement OCI calls separately from DBD::Oracle. I don't seem the harm
in exposing OCI handles via DBD::Oracle - it would be useful for people
like the OP.
A few pointers to start.
You will not be able to 'get' a handle and retrun it as a Scalar it will only
ever be a pointer so you will just get some sort of number,
You would simly edit the Oracle.xs file
add in the includes to your C++ .h files
then add a few extra
'ora_'
functions to take care of you C++ calls;
A quick example
void
ora_some_c_call(dbh)
SV *dbh
PREINIT:
D_imp_dbh(dbh); //this gets all the OCI handles for you (see dbdimp.h for
the sturct imp_dbh_st)
CODE:
MYSomeC_Plus_Plus_method(dbh->envhp,dbh->svchp,dbh->seshp,dbh->srvhp);
He does not need to do this surely. So long as the C++ code and
DBD::Oracle XS is running in the same process the pointers obtained from
DBD::Oracle are just as valid in the C++ code as XS. However, if the
code is multi-threaded there could be issues of multiple threads
accessing the OCI handles at the same time.
Myself I would write a small 'c' wrapper that would call you c++ and just a
single .XS function that calls that small 'c' wrapper to fire your function.
My impression was that this was already done.
I quote:
"I have created some Perl bindings for some existing custom C++ libraries."
Martin
--
Martin J. Evans
Easysoft Limited
http://www.easysoft.com
Hope this helps
Cheers
John
Date: Thu, 27 Oct 2011 09:48:54 -0400
From: bro...@deseret.com
To: byter...@hotmail.com
CC: dbi-users@perl.org
Subject: Re: DBI-Users> RE: DBD-Oracle - obtaining OCI handles from $dbh
Yes, I assumed I would need to extend DBD::Oracle is some manner
to allow those handles to be extracted from a $dbh object.
The specific OCI handles that the C++ libraries use are
- Environment handle
- Service Context handle
- Session handle
- Server handle
My initial thought process on how it might work is this
Create a method in the DBD::Oracle XS code to retrieve those
handles and return them back to Perl space as a scalar.
Then with the Perl scalars that hold the OCI handles obtained from
$dbh, pass those values to my Perl bindings to the custom C++ libraries.
(I would need to extend the C++ libraries to allow the set methods
to the objects that hold those OCI handles).
...then the C++ libraries should work the same.
The motivation for this approach is that I have a large code base
of these C++ libraries that have been tested, so it would cost
prohibitive to simply replace them with a pure Perl implementation.
However, it is so much easier to work with Perl and DBI, it would
be useful to have DBI connect to the database and do some table
lookups. The C++ code could then be integrated seemlessly with my
Perl code. As time allows, I would gradually peel away functionality
from the legacy C++ libraries and implement it in Perl. But to
ease the migration path, this approach seemed to have some merits.
Quoting John Scoles (byter...@hotmail.com):
Date: Wed, 26 Oct 2011 21:46:30 -0400
From: bro...@deseret.com
To: dbi-users@perl.org
Subject: DBD-Oracle - obtaining OCI handles from $dbh
I have created some Perl bindings for some existing custom C++
libraries.
One of these C++ libraries implements a class that uses Oracle
OCI calls.
I would like to create a connection to the Oracle database
using Perl's DBI (DBD::Oracle) module, and then ideally share
that connection with the C++ libraries.
This would require me to extract the Oracle OCI handles from
the $dbh object...and then pass them to the C++ libraries.
What would be the best way to get access to the underlying
Oracle OCI handles from a $dbh object?
Hmm! Interesting concept. Which OCI handles are we talking about??
Like Matin said you would have to do that with .XS and you would pass I guess a
pointer to the
'C' struct that holds the pointers to DBD::Oraclles pointers?
You would have to cast that struct into you C++ somehow??
There would be a good number of handles to pass over. You might be able to find
them by looking at the Perl process tree
and finding the SV that holds the struct and then sening that over?
All just guesses on my part.
Interesting concept non the less.
Cheers
John
