[libvirt] [PATCH python] Optimize callback lookup in event handlers

[Daniel P. Berrange]

On Wed, Dec 04, 2013 at 05:06:19PM +0000, Daniel P. Berrange wrote:
> On Tue, Dec 03, 2013 at 09:36:28AM -0700, Eric Blake wrote:
> > On 12/03/2013 09:01 AM, Daniel P. Berrange wrote:
> > > From: "Daniel P. Berrange" <berrange at redhat.com>
> > > 
> > > The event handler code currently invokes PyImport_ImportModule
> > > which is very heavyweight. This is not in fact required, since
> > > we know the libvirt module has already been imported. We can
> > > thus use PyImport_ImportModuleNoBlock and do away with the
> > > global variables caching the imported module reference.
> > > 
> > > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> > > ---
> > >  libvirt-override.c | 35 +++++++++++------------------------
> > >  1 file changed, 11 insertions(+), 24 deletions(-)
> > > 
> > 
> > > -    /* Bogus (char *) cast for RHEL-5 python API brokenness */
> > > -    libvirt_module = PyImport_ImportModule((char *)"libvirt");
> > > -    if (!libvirt_module) {
> > > -        DEBUG("%s Error importing libvirt module\n", __FUNCTION__);
> > > +getLibvirtDictObject(void) {
> > > +    PyObject *libvirt_mod;
> > > +    PyObject *libvirt_dict;
> > > +
> > > +    libvirt_mod = PyImport_ImportModuleNoBlock("libvirt");
> > 
> > Do we still need the bogus cast?  (I guess I should try building
> > libvirt-python on my RHEL-5 VM...)
> 
> I just tested the build with RHEL-5.10 and it was fine - I verified
> the header declares the parameter const, so presumably the flaw was
> fixed at some point.

Damn, I screwed up and logged into the wrong VM when testing this.
It does not in fact work in RHEL-5, python 2.4, so I've reverted
this commit entirely. The PyImport_ImportModuleNoBlock function
does not exist.

Daniel
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