Re: Integration of Psycopg with XTA

Sorry for disturbing with my previous email... :(It was my fault: I didn't remember to check the key associated to the pointer in the capsule, now it's "psycopg2.connection.native_connection"...
Everything works as expected, get_native_connection() can be even inlined like below:
xar1 = PostgresqlXaResource(rm1.get_native_connection(), "PostgreSQL", "dbname=testdb")

Thank you so much for your support.Kind RegardsCh.F.

Il domenica 7 ottobre 2018, 18:42:31 CEST, Christian Ferrari <camauz(at)yahoo(dot)com> ha scritto:

Hi Federico,I've just tryed out commit https://github.com/fogzot/psycopg2/commit/81addddaee2c690e925bb8f381e7bcb02ca97687 : get_native_connection() is in the interface, but unfortunately it seems to work differently than the old _raw_pgconn.
Here's my code snippet:
pgconn = rm1.get_native_connection()#pgconn = rm1._raw_pgconn                                                       
xar1 = PostgresqlXaResource(pgconn, "PostgreSQL", "dbname=testdb")

using get_native_connection(), I catch an error from XTA, the PGconn pointer is null.
I have reversed back to commit https://github.com/fogzot/psycopg2/commit/ccae5cae34051d6640ec6cbce6d9313778c509d3 : _raw_pgconn works as before.
Here's the code snippet:
#pgconn = rm1.get_native_connection()                                           
pgconn = rm1._raw_pgconn
xar1 = PostgresqlXaResource(pgconn, "PostgreSQL", "dbname=testdb")

It works fine.
Should "get_native_connection()" used differently than "_raw_pgconn" ? What type of data are necessary to investigate the issue?
Thanks in advanceKind RegardsCh.F.

-------------------------------------------------------------
Good design can't stop bad implementation

Il domenica 7 ottobre 2018, 13:56:49 CEST, Federico Di Gregorio <fog(at)dndg(dot)it> ha scritto:

On 10/05/2018 06:02 PM, Christian Ferrari wrote:
> In a previous mail I stated something like "the name of the method
> doesn't matter"...
> ... after better thinking I realized a decent name might be better than
> other ones...
> Let me say:
>
> get_native_conn()
> get_native_connection()
>
> might be better than "get_/something/_pgconn" because the same type of
> method could be useful for other databases in the future...
> More or less all the databases use a "native connection", only
> PostgreSQL uses "PGconn connection".

After some more checking I discovered that it isn't possible to
"invalidate" a PyCapsule so there is no way to tell if the pointer
inside it is still a valid libpq connection.

The current code (feel free to pull) adds a new method

get_native_connection()

that raise an exception if called on a closed connection. I better like
a method here because it gives the idea that you need to call it every
time you want a Capsule to pass to the target C API.

I also added some docs and a dumb test.

https://github.com/fogzot/psycopg2/tree/feature-expose-pgconn

@Daniele, if Christian reports no problems I'll merge this later for 2.8.

federico

--
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