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from __future__ import annotations
from bisect import bisect_left, insort_right
from collections import defaultdict
from datetime import MAXYEAR, datetime, timedelta, timezone
from typing import Any, Callable, Dict, Iterable, List, Optional, Set, Type
from uuid import UUID
from ... import events
from ...abc import DataStore, Job, Schedule
from ...events import (
EventHub, JobAdded, ScheduleAdded, ScheduleRemoved, ScheduleUpdated, SubscriptionToken)
from ...exceptions import ConflictingIdError
from ...policies import ConflictPolicy
from ...structures import JobResult
from ...util import reentrant
max_datetime = datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=timezone.utc)
class ScheduleState:
__slots__ = 'schedule', 'next_fire_time', 'acquired_by', 'acquired_until'
def __init__(self, schedule: Schedule):
self.schedule = schedule
self.next_fire_time = self.schedule.next_fire_time
self.acquired_by: Optional[str] = None
self.acquired_until: Optional[datetime] = None
def __lt__(self, other):
if self.next_fire_time is None:
return False
elif other.next_fire_time is None:
return self.next_fire_time is not None
else:
return self.next_fire_time < other.next_fire_time
def __eq__(self, other):
if isinstance(other, ScheduleState):
return self.schedule == other.schedule
return NotImplemented
def __hash__(self):
return hash(self.schedule.id)
def __repr__(self):
return (f'<{self.__class__.__name__} id={self.schedule.id!r} '
f'task_id={self.schedule.task_id!r} next_fire_time={self.next_fire_time}>')
class JobState:
__slots__ = 'job', 'created_at', 'acquired_by', 'acquired_until'
def __init__(self, job: Job):
self.job = job
self.created_at = datetime.now(timezone.utc)
self.acquired_by: Optional[str] = None
self.acquired_until: Optional[datetime] = None
def __lt__(self, other):
return self.created_at < other.created_at
def __eq__(self, other):
return self.job.id == other.job.id
def __hash__(self):
return hash(self.job.id)
def __repr__(self):
return f'<{self.__class__.__name__} id={self.job.id!r} task_id={self.job.task_id!r}>'
@reentrant
class MemoryDataStore(DataStore):
def __init__(self, lock_expiration_delay: float = 30):
self.lock_expiration_delay = lock_expiration_delay
self._events = EventHub()
self._schedules: List[ScheduleState] = []
self._schedules_by_id: Dict[str, ScheduleState] = {}
self._schedules_by_task_id: Dict[str, Set[ScheduleState]] = defaultdict(set)
self._jobs: List[JobState] = []
self._jobs_by_id: Dict[UUID, JobState] = {}
self._jobs_by_task_id: Dict[str, Set[JobState]] = defaultdict(set)
self._job_results: Dict[UUID, JobResult] = {}
def _find_schedule_index(self, state: ScheduleState) -> Optional[int]:
left_index = bisect_left(self._schedules, state)
right_index = bisect_left(self._schedules, state)
return self._schedules.index(state, left_index, right_index + 1)
def _find_job_index(self, state: JobState) -> Optional[int]:
left_index = bisect_left(self._jobs, state)
right_index = bisect_left(self._jobs, state)
return self._jobs.index(state, left_index, right_index + 1)
def __enter__(self):
self._events.__enter__()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self._events.__exit__(exc_type, exc_val, exc_tb)
def subscribe(self, callback: Callable[[events.Event], Any],
event_types: Optional[Iterable[Type[events.Event]]] = None) -> SubscriptionToken:
return self._events.subscribe(callback, event_types)
def unsubscribe(self, token: events.SubscriptionToken) -> None:
self._events.unsubscribe(token)
def get_schedules(self, ids: Optional[Set[str]] = None) -> List[Schedule]:
return [state.schedule for state in self._schedules
if ids is None or state.schedule.id in ids]
def add_schedule(self, schedule: Schedule, conflict_policy: ConflictPolicy) -> None:
old_state = self._schedules_by_id.get(schedule.id)
if old_state is not None:
if conflict_policy is ConflictPolicy.do_nothing:
return
elif conflict_policy is ConflictPolicy.exception:
raise ConflictingIdError(schedule.id)
index = self._find_schedule_index(old_state)
del self._schedules[index]
self._schedules_by_task_id[old_state.schedule.task_id].remove(old_state)
state = ScheduleState(schedule)
self._schedules_by_id[schedule.id] = state
self._schedules_by_task_id[schedule.task_id].add(state)
insort_right(self._schedules, state)
if old_state is not None:
event = ScheduleUpdated(schedule_id=schedule.id,
next_fire_time=schedule.next_fire_time)
else:
event = ScheduleAdded(schedule_id=schedule.id,
next_fire_time=schedule.next_fire_time)
self._events.publish(event)
def remove_schedules(self, ids: Iterable[str]) -> None:
for schedule_id in ids:
state = self._schedules_by_id.pop(schedule_id, None)
if state:
self._schedules.remove(state)
event = ScheduleRemoved(schedule_id=state.schedule.id)
self._events.publish(event)
def acquire_schedules(self, scheduler_id: str, limit: int) -> List[Schedule]:
now = datetime.now(timezone.utc)
schedules: List[Schedule] = []
for state in self._schedules:
if state.next_fire_time is None or state.next_fire_time > now:
# The schedule is either paused or not yet due
break
elif state.acquired_by is not None:
if state.acquired_by != scheduler_id and now <= state.acquired_until:
# The schedule has been acquired by another scheduler and the timeout has not
# expired yet
continue
schedules.append(state.schedule)
state.acquired_by = scheduler_id
state.acquired_until = now + timedelta(seconds=self.lock_expiration_delay)
if len(schedules) == limit:
break
return schedules
def release_schedules(self, scheduler_id: str, schedules: List[Schedule]) -> None:
# Send update events for schedules that have a next time
finished_schedule_ids: List[str] = []
for s in schedules:
if s.next_fire_time is not None:
# Remove the schedule
schedule_state = self._schedules_by_id.get(s.id)
index = self._find_schedule_index(schedule_state)
del self._schedules[index]
# Readd the schedule to its new position
schedule_state.next_fire_time = s.next_fire_time
schedule_state.acquired_by = None
schedule_state.acquired_until = None
insort_right(self._schedules, schedule_state)
event = ScheduleUpdated(schedule_id=s.id, next_fire_time=s.next_fire_time)
self._events.publish(event)
else:
finished_schedule_ids.append(s.id)
# Remove schedules that didn't get a new next fire time
self.remove_schedules(finished_schedule_ids)
def get_next_schedule_run_time(self) -> Optional[datetime]:
return self._schedules[0].next_fire_time if self._schedules else None
def add_job(self, job: Job) -> None:
state = JobState(job)
self._jobs.append(state)
self._jobs_by_id[job.id] = state
self._jobs_by_task_id[job.task_id].add(state)
event = JobAdded(job_id=job.id, task_id=job.task_id, schedule_id=job.schedule_id,
tags=job.tags)
self._events.publish(event)
def get_jobs(self, ids: Optional[Iterable[UUID]] = None) -> List[Job]:
if ids is not None:
ids = frozenset(ids)
return [state.job for state in self._jobs if ids is None or state.job.id in ids]
def acquire_jobs(self, worker_id: str, limit: Optional[int] = None) -> List[Job]:
now = datetime.now(timezone.utc)
jobs: List[Job] = []
for state in self._jobs:
if state.acquired_by is not None and state.acquired_until >= now:
continue
jobs.append(state.job)
state.acquired_by = worker_id
state.acquired_until = now + timedelta(seconds=self.lock_expiration_delay)
if len(jobs) == limit:
break
return jobs
def release_job(self, worker_id: str, job_id: UUID, result: Optional[JobResult]) -> None:
# Delete the job
state = self._jobs_by_id.pop(job_id)
self._jobs_by_task_id[state.job.task_id].remove(state)
index = self._find_job_index(state)
del self._jobs[index]
# Record the result
self._job_results[job_id] = result
def get_job_result(self, job_id: UUID) -> Optional[JobResult]:
return self._job_results.pop(job_id, None)
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