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In order to send not more than 100 e-mail messages per day, I create the following logic in my application:

  1. all e-mail messages to be sent are stored in Datastore;
  2. there is a cron job, which runs every 15 minutes;
  3. this job is to send e-mail messages from the queue;
  4. prior to reading messages from the Datastore queue, the job reads the value from the memcache (is_todays_quota_exceeded);
  5. if it is not, try to send messages. If successful, update queue status for this message. If it fails with apiproxy_errors.OverQuotaError, write is_todays_quota_exceeded equal to 1.

The problem I have is that I should store memcache value till the end of GAE day (i.e. till the quota is replenished). How can I calculate that in seconds?

Daily quotas are replenished daily at midnight Pacific time.

Upd. I've tried the following:

now = datetime.datetime.now()
current_time = datetime.datetime(year=now.year, month=now.month, day=now.day, hour=now.hour, minute=now.minute, second=now.second)
end_of_today = datetime.datetime(year=now.year, month=now.month, day=now.day, hour=23, minute=59, second=59)
diff = end_of_today - current_time
logging.info(diff.total_seconds())

But it fails at the last line - 'datetime.timedelta' object has no attribute 'total_seconds'. I use Python 2.5, looks like total_seconds was implemented later.

Upd2. The following helps to calculate number of seconds till end of today:

now = datetime.datetime.utcnow()
diff = (23*60*60 + 59*60 + 59*60) - (now.hour*60*60 - now.minute*60 - now.second*60)
logging.info(diff)
LA_
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1 Answers1

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You cloud have another cron job that runs before midnight Pacific time every day to reset this value.

If you want to calculate the end of the day, do something like this:

>>> from datetime import datetime
>>> timestamp = datetime.utcnow()
>>> end_of_day = datetime(year=timestamp.year, month=timestamp.month, day=timestamp.day, hour=23, minute=59, second=59)
>>> end_of_day
datetime.datetime(2013, 3, 17, 23, 59, 59)

Or you could simply check if the datetime.utcnow().hour is 0 you know that the day just started and act accordingly.

Lipis
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  • Hmm, interesting idea ;). But I think it will complicate the app logic, so would prefer to calculate & define correct time for memcache storage. – LA_ Mar 17 '13 at 13:16
  • I don't think that this complicates it in any way.. it's a very simple cron job that resets the day! You could add more clean up stuff there... and as for the calculating the time, what stops you to use the `datatime.utcnow()`? – Lipis Mar 17 '13 at 13:22
  • With regards to the calculation - the first question I have is how to calculate end of today? Is it `datetime(year=datetime.now().year, month=datetime.now().month, day=datetime.now().day, hour=23, minute=59, second=60)`? – LA_ Mar 17 '13 at 13:57
  • @LA_ More or less yes.. second should be 59 and it's better to use a variable to be sure that the now() will not return two different values. I updated my answer – Lipis Mar 17 '13 at 14:59
  • Thanks for your help. I've just realized that your solution with the cron task is more correct - even if I setup memcache till end of day, datastore still will keep original value, which I should update. – LA_ Mar 17 '13 at 15:31