Thanks Yunhong for pointing this issue out and submitting a patch in quick order.
Your reasoning for switching from if offset to if offset is None, in order to avoid including the offset==0 case, makes perfect sense. You'll just have to propose the change first to openstack-common, from where it will be copied to the nova, glance etc. codebases. Cheers, Eoghan ----- Original Message ----- > I create a patch for it https://review.openstack.org/#/c/12705/ and > please help to review. > > Thanks > --jyh > > > -----Original Message----- > > From: openstack-bounces+yunhong.jiang=intel....@lists.launchpad.net > > [mailto:openstack-bounces+yunhong.jiang=intel....@lists.launchpad.net] > > On > > Behalf Of Jiang, Yunhong > > Sent: Monday, September 10, 2012 8:17 AM > > To: Robert Collins > > Cc: openstack@lists.launchpad.net > > Subject: Re: [Openstack] One potential issue on the > > normalize_time() in > > timeutils > > > > Rob, thanks for comments. > > I totally agree with you that aware datetime object is better than > > naive one. > > The key thing is, utcnow() will return naive object, that means in > > some time, we > > have to use naive object to compare with utcnow(), and we need a > > conversion > > function to convert from aware to naive. The normalize_time() is > > the best > > candidate for this purpose, but it will fail to convert to naive > > datetime object in > > some situation. That's why I send the mail. I just want to change > > the > > normalize_time() to make sure it will always return naive object. > > > > Thanks > > --jyh > > > > > -----Original Message----- > > > From: Robert Collins [mailto:robe...@robertcollins.net] > > > Sent: Monday, September 10, 2012 3:25 AM > > > To: Jiang, Yunhong > > > Cc: egl...@redhat.com; openstack@lists.launchpad.net > > > Subject: Re: [Openstack] One potential issue on the > > > normalize_time() > > > in timeutils > > > > > > On Mon, Sep 10, 2012 at 3:09 AM, Jiang, Yunhong > > > <yunhong.ji...@intel.com> > > > wrote: > > > > Hi, Eoghan and all, > > > > > > > > When I implement an enhancement to trusted_filter, I > > > > need > > > > utilize > > > timeutils() to parse ISO time. However, I suspect there is one > > > potential issue in > > > normalize_time() and want to get some input from your side. > > > > > > > > In normalize_time(), if the parameter "timestamp" is an > > > > aware > > > object (http://docs.python.org/library/datetime.html) , it's > > > output > > > will vary depends on the input. If the timestamp is UTC time, it > > > will > > > be return as is without convention, i.e still an aware object. > > > However, if it's not an UTC time, it will be converted to be a > > > naive object. > > > > This mean that the function will return different type > > > > depends on > > > input, that's not so good IMHO. > > > > > > > > The worse is, any compare/substract between naïve > > > > object and > > > > aware object will fail. Because the timeutils.utcnow() and > > > > datetime.datetime.now() returns naive object, so > > > > compare/substract > > > > between the uctnow() and normalize_time() may fail, or not, > > > > depends > > > > on input from the API user. I'm a bit surprised that > > > > changes-since > > > > works on such situation :) > > > > > > > > I suspect this is caused by the "if offset". When > > > > timestamp > > > > is > > > naïve object, the offset is None. Thus check "if offset" will > > > avoid > > > operation type exception. However, if the timestamp is UTC time, > > > the > > > offset will be date.timeslot(0), which will return false also for > > > "if offset". > > > > > > > > Are there any special reason that we need keep aware > > > > object > > > > if > > > input is at UTC time already? Can I changes the function to > > > always > > > return naive object? If yes, I can create a patch for it. > > > > > > You are probably better off creating an aware datetime object, > > > and > > > using them pervasively across the codebase, than using naive > > > objects. > > > As you note, they are not interoperable, and I've seen countless > > > bugs > > > where folk try to mix and match. If we want to show local date > > > time to > > > users *anywhere*, we'll need TZ aware objects, which is why that > > > variation is the one to standardise on. Otherwise, you end up > > > with > > > multiple conversion points, and you can guarantee that at least > > > one will get it > > wrong. > > > > > > -Rob > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~openstack > > Post to : openstack@lists.launchpad.net > > Unsubscribe : https://launchpad.net/~openstack > > More help : https://help.launchpad.net/ListHelp > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp > _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
