[mod_python] Re: PyThreadState_Swap(NULL)

On 20/08/2006, at 6:25 PM, Graham Dumpleton wrote:

>
> On 20/08/2006, at 6:08 PM, Graham Dumpleton wrote:
>
>> Have been busy and have added minimal set of functions to mod_python
>> and exporting them for use in other modules. This code is now checked
>> into subversion trunk for 3.3.
>>
>> As an example, here is how it could be used:
>
> And here is a replacement example that fixes up some stupid mistakes
> with cleaning up data.
>
>     optfn_mp_acquire_interpreter("main_interpreter");
>
>     request_obj = optfn_mp_get_request_object(r);
>
>     m = PyImport_ImportModule("mod_python.testhandler");
>     if (m) {
>         d = PyModule_GetDict(m);
>         o = PyDict_GetItemString(d, "handler");
>
>         if (o) {
>             PyObject *a = NULL;
>             PyObject *r = NULL;
>
>             a = Py_BuildValue("(O)", request_obj);
>             r = PyEval_CallObject(o, a);
>
>             Py_DECREF(a);
>
>             if (r == NULL)
>                 result = HTTP_INTERNAL_SERVER_ERROR;
>             else if (!PyInt_Check(r))
>                 result = HTTP_INTERNAL_SERVER_ERROR;
>             else
>                 result = PyInt_AsLong(r);
>
>             Py_XDECREF(r);
>         }
>         else {
>             result = HTTP_INTERNAL_SERVER_ERROR;
>         }
>     }
>     else {
>         result = HTTP_INTERNAL_SERVER_ERROR;
>     }
>
>     Py_XDECREF(m);
>     Py_XDECREF(o);
>
>     Py_XDECREF(request_obj);

Whoops (AGAIN).

Neither 'o' or 'request_obj' should be DECREF'd. This is because 'o' is
a borrowed reference, and 'request_obj' is destroyed automatically when
the cleanup handler runs.

I'll fix attachment to issue after a bit more testing. Works like a  
charm now,
problem only showed up when mixing requests against this code with
requests against standard mod_python handlers. :-(

>     optfn_mp_release_interpreter();
>
>     return result;
>
> I ended up replacing the attachment to the JIRA issue a couple of  
> times,
> so watch out for moving targets. :-)
>
> Graham