[ZODB-Dev] Can I abort part of a transaction setting self._p_changed=0?

[Steve Spicklemire]

Thanks Michel! That gives me hope this this might just work. ;-)

-steve

Michel Pelletier wrote:
> 
> On Thu, 28 Jun 2001, Steve Spicklemire wrote:
> 
> > Hmm.. so either this question was:
> >
> > 1) Totally unclear and therefore unanswerable
> >
> > 2) Totally stupid and therefore not worth the time ... or..
> >
> > 3) So far out that nobody really knows...
> >
> > In case it's (1) I should clarify that by 'self.CommitObject', I mean
> > "export self as a .zexp/.xml to CVS (or something)".
> 
> That was definatly a confusing part.
> 
> > does that help? I is (2)? I can't believe it's (3), but if so... I
> > should start digging in the code.
> >
> > def CommitMetaDataOfObjectManager(self, anObjectManager):
> >
> >         holder = anObjectManager._objects
> >         delete anObjectManager._objects
> >         result = self.CommitObject(anObjectManager)
> >         anObjectManager._objects = holder
> >         return result
> >
> > so that the 'committed' objectManager is stripped of it's objects,
> > committed, and then it's objects are restored. (it would be great if
> > ObjectManager could present an interface that did that!). The problem is
> > that fiddling with _objects will set the _p_changed flag and introduce
> > an unwanted side effect of updating ZODB. Can I force _p_changed=0?
> > Would that make this a thinkable possibility?
> 
> I just looked at cPersistence.c, and it looks like you *can* set
> _p_changed to 0.  But I'm not expert, so I'll let *you* make the call
> (excerpted from _setattro):
> 
>  if(name[3]=='c' && strcmp(name+4,"hanged")==0)
>    {
>      if (! v)
>        {
>          /* delatter is used to invalidate the object
>             *even* if it has changed.
>           */
>          if (self->state != cPersistent_GHOST_STATE)
>            self->state = cPersistent_UPTODATE_STATE;
>          v=Py_None;
>        }
>      if (v==Py_None)
>        {
>          v=PyObject_GetAttr(OBJECT(self), py__p_deactivate);
>          if (v) { ASSIGN(v, PyObject_CallObject(v, NULL)); }
>          if (v) { Py_DECREF(v); }
>          self->state=cPersistent_GHOST_STATE;
>          return 0;
>        }
>      if (PyObject_IsTrue(v)) return changed(self);
>      if (self->state >= 0) self->state=cPersistent_UPTODATE_STATE;
>      return 0;
>    }
> 
> It looks to me like the if(!v) clause is checking to see if the value
> is 0 and setting the objects state to cPersistent_UPTODATE_STATE.  The
> if(PyObject_IsTrue(v)) clause looks like it's calling change().
> 
> -Michel