path: root/src/apscheduler/datastores/sync/memory.py

from __future__ import annotations

from bisect import bisect_left, insort_right
from collections import defaultdict
from datetime import MAXYEAR, datetime, timedelta, timezone
from functools import partial
from typing import Any, Callable, Iterable, Optional, Type
from uuid import UUID

import attr

from ... import events
from ...abc import DataStore, Job, Schedule
from ...enums import ConflictPolicy
from ...events import (
    EventHub, JobAdded, ScheduleAdded, ScheduleRemoved, ScheduleUpdated, SubscriptionToken,
    TaskAdded, TaskRemoved, TaskUpdated)
from ...exceptions import ConflictingIdError, TaskLookupError
from ...structures import JobResult, Task
from ...util import reentrant

max_datetime = datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=timezone.utc)


@attr.define
class TaskState:
    task: Task
    running_jobs: int = 0
    saved_state: Any = None

    def __eq__(self, other):
        return self.task.id == other.task.id


@attr.define
class ScheduleState:
    schedule: Schedule
    next_fire_time: Optional[datetime] = attr.field(init=False, eq=False)
    acquired_by: Optional[str] = attr.field(init=False, eq=False, default=None)
    acquired_until: Optional[datetime] = attr.field(init=False, eq=False, default=None)

    def __attrs_post_init__(self):
        self.next_fire_time = self.schedule.next_fire_time

    def __eq__(self, other):
        return self.schedule.id == other.schedule.id

    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 __hash__(self):
        return hash(self.schedule.id)


@attr.define(order=True)
class JobState:
    job: Job = attr.field(order=False)
    created_at: datetime = attr.field(init=False, factory=partial(datetime.now, timezone.utc))
    acquired_by: Optional[str] = attr.field(eq=False, order=False, default=None)
    acquired_until: Optional[datetime] = attr.field(eq=False, order=False, default=None)

    def __eq__(self, other):
        return self.job.id == other.job.id

    def __hash__(self):
        return hash(self.job.id)


@reentrant
@attr.define(eq=False)
class MemoryDataStore(DataStore):
    lock_expiration_delay: float = 30
    _events: EventHub = attr.Factory(EventHub)
    _tasks: dict[str, TaskState] = attr.Factory(dict)
    _schedules: list[ScheduleState] = attr.Factory(list)
    _schedules_by_id: dict[str, ScheduleState] = attr.Factory(dict)
    _schedules_by_task_id: dict[str, set[ScheduleState]] = attr.Factory(partial(defaultdict, set))
    _jobs: list[JobState] = attr.Factory(list)
    _jobs_by_id: dict[UUID, JobState] = attr.Factory(dict)
    _jobs_by_task_id: dict[str, set[JobState]] = attr.Factory(partial(defaultdict, set))
    _job_results: dict[UUID, JobResult] = attr.Factory(dict)

    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_task(self, task: Task) -> None:
        task_exists = task.id in self._tasks
        self._tasks[task.id] = TaskState(task)
        if task_exists:
            self._events.publish(TaskUpdated(task_id=task.id))
        else:
            self._events.publish(TaskAdded(task_id=task.id))

    def remove_task(self, task_id: str) -> None:
        try:
            del self._tasks[task_id]
        except KeyError:
            raise TaskLookupError(task_id) from None

        self._events.publish(TaskRemoved(task_id=task_id))

    def get_task(self, task_id: str) -> Task:
        try:
            return self._tasks[task_id].task
        except KeyError:
            raise TaskLookupError(task_id) from None

    def get_tasks(self) -> list[Task]:
        return sorted((state.task for state in self._tasks.values()), key=lambda task: task.id)

    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 index, job_state in enumerate(self._jobs):
            task_state = self._tasks[job_state.job.task_id]

            # Skip already acquired jobs (unless the acquisition lock has expired)
            if job_state.acquired_by is not None:
                if job_state.acquired_until >= now:
                    continue
                else:
                    task_state.running_jobs -= 1

            # Check if the task allows one more job to be started
            if (task_state.task.max_running_jobs is not None
                    and task_state.running_jobs >= task_state.task.max_running_jobs):
                continue

            # Mark the job as acquired by this worker
            jobs.append(job_state.job)
            job_state.acquired_by = worker_id
            job_state.acquired_until = now + timedelta(seconds=self.lock_expiration_delay)

            # Increment the number of running jobs for this task
            task_state.running_jobs += 1

            # Exit the loop if enough jobs have been acquired
            if len(jobs) == limit:
                break

        return jobs

    def release_job(self, worker_id: str, job: Job, result: Optional[JobResult]) -> None:
        # Delete the job
        job_state = self._jobs_by_id.pop(job.id)
        self._jobs_by_task_id[job.task_id].remove(job_state)
        index = self._find_job_index(job_state)
        del self._jobs[index]

        # Decrement the number of running jobs for this task
        task_state = self._tasks.get(job.task_id)
        if task_state is not None:
            task_state.running_jobs -= 1

        # 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)