Re: [gnome-db] 2 issues with GdaConnection

["Vivien Malerba" <vmalerba gmail com>]

On Sat, Mar 22, 2008 at 10:58 PM, Mark Johnson <mrj001 shaw ca> wrote:
>
> Vivien Malerba wrote:
>  >>  >
>  >>  I don't think I have 2 references to the connection.  I've attached a
>  >>  current snapshot of my file to let you see it.  It's a work in progress
>  >>  for a test case for one of my bugs.
>  >>
>  >
>  > The problem comes from the fact that when you call
>  > g_object_unref(pConn), there is still an object holding a reference on
>  > the pConn object, it is the GdaDataModel returned from the
>  > gda_connection_statement_execute_select() function (which you ignore
>  > in your example but still exists). Here is attached your example,
>  > modified to show the reference count on the pConn object.
>  >
>  > Cheers,
>  >
>  > Vivien
>  >
>  Thanks, that fixed it.  The g_object_unref now does close the
>  connection, so no unexpected EOF in the PostgreSQL log.
>
>  This is something I find difficult in glib/gnome programming in general
>  - how to know when something needs to be unref'ed, and when something
>  else might be keeping a reference to your object.  For example, nothing
>  in the gda_connection_statement_execute or
>  gda_connection_statement_execute_select documentation indicates that the
>  connection reference count will be incremented.  The GdaDataModel page
>  does not even contain the word connection.

The idea is that for any function which creates a new object, then you
need to call g_object_unref() on the object, otherwise you must
consider that the returned object is valid only within your function
body (and if you wat to keep it, call g_object_ref() and
g_object_unref() when done with it).

The reason the GdaDataModel keeps a reference on the connection is
that some implementations need to execute some queries when they are
used (like for cursor based access and for the soon-to-come dete model
modification).

Don't hesitate to signal any part of the doc you find misleading or
unclear about that point.

Cheers,

Vivien