def _start_a_job(self):
"""Either starts a waiting job and returns a 3-tuple of (job, sz_key, future),
or finds no waiting job and returns a 3-tuple of (None, None, None).
"""
with transaction(self._model_access):
(job, sz_key) = self._get_next_job()
if job is None:
return (None, None, None)
job.started_at = utc_now()
if sz_key:
sz_key.active_job_id = job.id
self._update_job(job, sz_key)
def fxn():
"""Future closure."""
if job.name not in self._job_handlers:
raise KeyError("Bad job name")
self._job_handlers[job.name](job.payload)
future = self._executor.submit(fxn)
return (job, sz_key, future)
def _schedule_jobs(self):
# Don't schedule jobs if the frequency is None
if self._schedule_frequency is None:
return None
# Only perform a diff check if jobs have been scheduled
if self._last_job_scheduling is not None:
ts = utc_now().timestamp()
# If the last scheduling timestamp plus the frequency is greater than the
# current timestamp, it is not yet time to schedule.
if self._last_job_scheduling + self._schedule_frequency > ts:
return None
with transaction(self._model_access):
cr, _ = self._model_access.callproc("schedule_jobs", [])
job_count = self._model_access.get_scalar(cr)
self._last_job_scheduling = utc_now().timestamp()
return job_count
def _finished_job(self, job, sz_key, future):
"""Marks the job as complete.
:param job: the Job instance
:param sz_key: the SerializationKey instance
:param future: the Future instance that handled the job
"""
error_message = exception_to_message(future.exception())
job.update(completed_at=utc_now(), error_message=error_message)
if sz_key:
sz_key.active_job_id = None
with transaction(self._model_access):
self._update_job(job, sz_key)
def to_now(_): """Returns the current timestamp, with a utc timezone.""" return date.utc_now()
def _get_ts(self, seconds_in_future=0): return utc_now() + timedelta(seconds=seconds_in_future)