ashb commented on a change in pull request #13930:
URL: https://github.com/apache/airflow/pull/13930#discussion_r567838256
##########
File path: airflow/models/dag.py
##########
@@ -109,6 +110,308 @@ def get_last_dagrun(dag_id, session,
include_externally_triggered=False):
return query.first()
+class AbstractTimetable(LoggingMixin):
+ """Abstract class for Timetable."""
+
+ @abstractmethod
+ def normalized_schedule_interval(self) -> Optional[ScheduleInterval]:
+ raise NotImplementedError()
+
+ @abstractmethod
+ def date_range(
+ self,
+ start_date: datetime,
+ num: Optional[int] = None,
+ end_date: Optional[datetime] = timezone.utcnow(),
+ ) -> List[datetime]:
+ raise NotImplementedError()
+
+ @abstractmethod
+ def following_schedule(self, dttm):
+ raise NotImplementedError()
+
+ @abstractmethod
+ def previous_schedule(self, dttm):
+ raise NotImplementedError()
+
+ @abstractmethod
+ def next_dagrun_info(
+ self,
+ date_last_automated_dagrun: Optional[pendulum.DateTime],
+ tasks,
+ ) -> Tuple[Optional[pendulum.DateTime], Optional[pendulum.DateTime]]:
+ raise NotImplementedError()
+
+ @abstractmethod
+ def get_run_dates(self, start_date, end_date=None):
+ raise NotImplementedError()
+
+
+class CronTimetable(AbstractTimetable):
+ """Timetable implementation for Cron."""
+
+ def __init__(
+ self,
+ schedule_interval=None,
+ timezone=None,
+ catchup=None,
+ start_date=None,
+ end_date=None,
+ ):
+ self.schedule_interval = schedule_interval
+ self.timezone = timezone
+ self.catchup = catchup
+ self.start_date = start_date
+ self.end_date = end_date
+
+ def normalized_schedule_interval(self) -> Optional[ScheduleInterval]:
+ """
+ Returns Normalized Schedule Interval. This is used internally by the
Scheduler to
+ schedule DAGs.
+
+ 1. Converts Cron Preset to a Cron Expression (e.g ``@monthly`` to ``0
0 1 * *``)
+ 2. If Schedule Interval is "@once" return "None"
+ 3. If not (1) or (2) returns schedule_interval
+ """
+ if isinstance(self.schedule_interval, str) and self.schedule_interval
in cron_presets:
+ _schedule_interval = cron_presets.get(self.schedule_interval) #
type: Optional[ScheduleInterval]
+ elif self.schedule_interval == '@once':
+ _schedule_interval = None
+ else:
+ _schedule_interval = self.schedule_interval
+ return _schedule_interval
+
+ def is_fixed_time_schedule(self):
+ """
+ Figures out if the DAG schedule has a fixed time (e.g. 3 AM).
+
+ :return: True if the schedule has a fixed time, False if not.
+ """
+ now = datetime.now()
+ cron = croniter(self.normalized_schedule_interval(), now)
+
+ start = cron.get_next(datetime)
+ cron_next = cron.get_next(datetime)
+
+ if cron_next.minute == start.minute and cron_next.hour == start.hour:
+ return True
+
+ return False
+
+ def date_range(
+ self,
+ start_date: datetime,
+ num: Optional[int] = None,
+ end_date: Optional[datetime] = timezone.utcnow(),
+ ) -> List[datetime]:
+ if num is not None:
+ end_date = None
+ return utils_date_range(
+ start_date=start_date, end_date=end_date, num=num,
delta=self.normalized_schedule_interval()
+ )
+
+ def following_schedule(self, dttm):
+ """
+ Calculates the following schedule for this dag in UTC.
+
+ :param dttm: utc datetime
+ :return: utc datetime
+ """
+ if isinstance(self.normalized_schedule_interval(), str):
+ # we don't want to rely on the transitions created by
+ # croniter as they are not always correct
+ dttm = pendulum.instance(dttm)
+ naive = timezone.make_naive(dttm, self.timezone)
+ cron = croniter(self.normalized_schedule_interval(), naive)
+
+ # We assume that DST transitions happen on the minute/hour
+ if not self.is_fixed_time_schedule():
+ # relative offset (eg. every 5 minutes)
+ delta = cron.get_next(datetime) - naive
+ following = dttm.in_timezone(self.timezone) + delta
+ else:
+ # absolute (e.g. 3 AM)
+ naive = cron.get_next(datetime)
+ tz = pendulum.timezone(self.timezone.name)
+ following = timezone.make_aware(naive, tz)
+ return timezone.convert_to_utc(following)
+ elif self.normalized_schedule_interval() is not None:
+ return timezone.convert_to_utc(dttm +
self.normalized_schedule_interval())
+
+ def previous_schedule(self, dttm):
+ """
+ Calculates the previous schedule for this dag in UTC
+
+ :param dttm: utc datetime
+ :return: utc datetime
+ """
+ if isinstance(self.normalized_schedule_interval(), str):
+ # we don't want to rely on the transitions created by
+ # croniter as they are not always correct
+ dttm = pendulum.instance(dttm)
+ naive = timezone.make_naive(dttm, self.timezone)
+ cron = croniter(self.normalized_schedule_interval(), naive)
+
+ # We assume that DST transitions happen on the minute/hour
+ if not self.is_fixed_time_schedule():
+ # relative offset (eg. every 5 minutes)
+ delta = naive - cron.get_prev(datetime)
+ previous = dttm.in_timezone(self.timezone) - delta
+ else:
+ # absolute (e.g. 3 AM)
+ naive = cron.get_prev(datetime)
+ tz = pendulum.timezone(self.timezone.name)
+ previous = timezone.make_aware(naive, tz)
+ return timezone.convert_to_utc(previous)
+ elif self.normalized_schedule_interval() is not None:
+ return timezone.convert_to_utc(dttm -
self.normalized_schedule_interval())
+
+ def next_dagrun_info(
+ self,
+ date_last_automated_dagrun: Optional[pendulum.DateTime],
+ tasks,
+ ) -> Tuple[Optional[pendulum.DateTime], Optional[pendulum.DateTime]]:
+ """
+ Get information about the next DagRun of this dag after
``date_last_automated_dagrun`` -- the
+ execution date, and the earliest it could be scheduled
+
+ :param date_last_automated_dagrun: The max(execution_date) of existing
+ "automated" DagRuns for this dag (scheduled or backfill, but not
+ manual)
+ """
+ if (
+ self.schedule_interval == "@once" and date_last_automated_dagrun
+ ) or self.schedule_interval is None:
+ # Manual trigger, or already created the run for @once, can short
circuit
+ return (None, None)
+ next_execution_date =
self._next_dagrun_after_date(date_last_automated_dagrun, tasks)
+
+ if next_execution_date is None:
+ return (None, None)
+
+ if self.schedule_interval == "@once":
+ # For "@once" it can be created "now"
+ return (next_execution_date, next_execution_date)
+
+ return (next_execution_date,
self.following_schedule(next_execution_date))
+
+ def _next_dagrun_after_date(self, date_last_automated_dagrun:
Optional[pendulum.DateTime], tasks):
+ """
+ Get the next execution date after the given
``date_last_automated_dagrun``, according to
+ schedule_interval, start_date, end_date etc. This doesn't check max
active run or any other
+ "concurrency" type limits, it only performs calculations based on the
various date and interval fields
+ of this dag and it's tasks.
+
+ :param date_last_automated_dagrun: The execution_date of the last
scheduler or
+ backfill triggered run for this dag
+ :type date_last_automated_dagrun: pendulum.Pendulum
+ """
+ if not self.schedule_interval:
+ return None
+
+ # don't schedule @once again
+ if self.schedule_interval == '@once' and date_last_automated_dagrun:
+ return None
+
+ # don't do scheduler catchup for dag's that don't have dag.catchup =
True
+ if not (self.catchup or self.schedule_interval == '@once'):
+ # The logic is that we move start_date up until
+ # one period before, so that timezone.utcnow() is AFTER
+ # the period end, and the job can be created...
+ now = timezone.utcnow()
+ next_start = self.following_schedule(now)
+ last_start = self.previous_schedule(now)
+ if next_start <= now or isinstance(self.schedule_interval,
timedelta):
+ new_start = last_start
+ else:
+ new_start = self.previous_schedule(last_start)
+
+ if self.start_date:
+ if new_start >= self.start_date:
+ self.start_date = new_start
+ else:
+ self.start_date = new_start
+
+ next_run_date = None
+ if not date_last_automated_dagrun:
+ # First run
+ task_start_dates = [t.start_date for t in tasks if t.start_date]
+ if task_start_dates:
+ next_run_date = self._normalize_schedule(min(task_start_dates))
+ self.log.debug("Next run date based on tasks %s",
next_run_date)
+ else:
+ next_run_date = self.following_schedule(date_last_automated_dagrun)
+
+ if date_last_automated_dagrun and next_run_date:
+ while next_run_date <= date_last_automated_dagrun:
+ next_run_date = self.following_schedule(next_run_date)
+
+ # don't ever schedule prior to the dag's start_date
+ if self.start_date:
+ next_run_date = self.start_date if not next_run_date else
max(next_run_date, self.start_date)
+ if next_run_date == self.start_date:
+ next_run_date = self._normalize_schedule(self.start_date)
+
+ self.log.debug("Dag start date: %s. Next run date: %s",
self.start_date, next_run_date)
+
+ # Don't schedule a dag beyond its end_date (as specified by the dag
param)
+ if next_run_date and self.end_date and next_run_date > self.end_date:
+ return None
+
+ # Don't schedule a dag beyond its end_date (as specified by the task
params)
+ # Get the min task end date, which may come from the dag.default_args
+ task_end_dates = [t.end_date for t in tasks if t.end_date]
+ if task_end_dates and next_run_date:
+ min_task_end_date = min(task_end_dates)
+ if next_run_date > min_task_end_date:
+ return None
Review comment:
Some of this feels like it should be in the base timetable class -- or
at least, each timetable subclass shouldn't be responsible for implementing
this check etc.
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