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from __future__ import annotations
import os
import platform
from contextlib import AsyncExitStack
from datetime import datetime, timezone
from inspect import isawaitable
from logging import Logger, getLogger
from typing import Any, Callable, Iterable, Optional
from uuid import UUID
import anyio
from anyio import TASK_STATUS_IGNORED, create_task_group, get_cancelled_exc_class
from anyio.abc import CancelScope
from ..abc import AsyncDataStore, DataStore, EventSource, Job
from ..datastores.async_.sync_adapter import AsyncDataStoreAdapter
from ..enums import JobOutcome, RunState
from ..events import (
AsyncEventHub, Event, JobAdded, JobCancelled, JobCompleted, JobDeadlineMissed, JobFailed,
JobStarted, SubscriptionToken, WorkerStarted, WorkerStopped)
from ..structures import JobResult
class AsyncWorker(EventSource):
"""Runs jobs locally in a task group."""
_stop_event: Optional[anyio.Event] = None
_state: RunState = RunState.stopped
_acquire_cancel_scope: Optional[CancelScope] = None
_datastore_subscription: SubscriptionToken
_wakeup_event: anyio.Event
def __init__(self, data_store: DataStore | AsyncDataStore, *,
max_concurrent_jobs: int = 100, identity: Optional[str] = None,
logger: Optional[Logger] = None):
self.max_concurrent_jobs = max_concurrent_jobs
self.identity = identity or f'{platform.node()}-{os.getpid()}-{id(self)}'
self.logger = logger or getLogger(__name__)
self._acquired_jobs: set[Job] = set()
self._exit_stack = AsyncExitStack()
self._events = AsyncEventHub()
self._running_jobs: set[UUID] = set()
if self.max_concurrent_jobs < 1:
raise ValueError('max_concurrent_jobs must be at least 1')
if isinstance(data_store, DataStore):
self.data_store = AsyncDataStoreAdapter(data_store)
else:
self.data_store = data_store
@property
def state(self) -> RunState:
return self._state
async def __aenter__(self):
self._state = RunState.starting
self._wakeup_event = anyio.Event()
await self._exit_stack.__aenter__()
await self._exit_stack.enter_async_context(self._events)
# Initialize the data store
await self._exit_stack.enter_async_context(self.data_store)
relay_token = self._events.relay_events_from(self.data_store)
self._exit_stack.callback(self.data_store.unsubscribe, relay_token)
# Wake up the worker if the data store emits a significant job event
wakeup_token = self.data_store.subscribe(
lambda event: self._wakeup_event.set(), {JobAdded})
self._exit_stack.callback(self.data_store.unsubscribe, wakeup_token)
# Start the actual worker
task_group = create_task_group()
await self._exit_stack.enter_async_context(task_group)
await task_group.start(self.run)
return self
async def __aexit__(self, exc_type, exc_val, exc_tb):
self._state = RunState.stopping
self._wakeup_event.set()
await self._exit_stack.__aexit__(exc_type, exc_val, exc_tb)
del self._wakeup_event
def subscribe(self, callback: Callable[[Event], Any],
event_types: Optional[Iterable[type[Event]]] = None) -> SubscriptionToken:
return self._events.subscribe(callback, event_types)
def unsubscribe(self, token: SubscriptionToken) -> None:
self._events.unsubscribe(token)
async def run(self, *, task_status=TASK_STATUS_IGNORED) -> None:
if self._state is not RunState.starting:
raise RuntimeError(f'This function cannot be called while the worker is in the '
f'{self._state} state')
# Signal that the worker has started
self._state = RunState.started
task_status.started()
self._events.publish(WorkerStarted())
try:
async with create_task_group() as tg:
while self._state is RunState.started:
limit = self.max_concurrent_jobs - len(self._running_jobs)
jobs = await self.data_store.acquire_jobs(self.identity, limit)
for job in jobs:
task = await self.data_store.get_task(job.task_id)
self._running_jobs.add(job.id)
tg.start_soon(self._run_job, job, task.func)
await self._wakeup_event.wait()
self._wakeup_event = anyio.Event()
except get_cancelled_exc_class():
pass
except BaseException as exc:
self._state = RunState.stopped
self._events.publish(WorkerStopped(exception=exc))
raise
self._state = RunState.stopped
self._events.publish(WorkerStopped())
async def _run_job(self, job: Job, func: Callable) -> None:
try:
# Check if the job started before the deadline
start_time = datetime.now(timezone.utc)
if job.start_deadline is not None and start_time > job.start_deadline:
self._events.publish(JobDeadlineMissed.from_job(job, start_time))
return
self._events.publish(JobStarted.from_job(job, start_time))
try:
retval = func(*job.args, **job.kwargs)
if isawaitable(retval):
retval = await retval
except get_cancelled_exc_class():
with CancelScope(shield=True):
result = JobResult(job_id=job.id, outcome=JobOutcome.cancelled)
await self.data_store.release_job(self.identity, job.task_id, result)
self._events.publish(JobCancelled.from_job(job, start_time))
except BaseException as exc:
result = JobResult(job_id=job.id, outcome=JobOutcome.failure, exception=exc)
await self.data_store.release_job(self.identity, job.task_id, result)
self._events.publish(JobFailed.from_exception(job, start_time, exc))
if not isinstance(exc, Exception):
raise
else:
result = JobResult(job_id=job.id, outcome=JobOutcome.success, return_value=retval)
await self.data_store.release_job(self.identity, job.task_id, result)
self._events.publish(JobCompleted.from_retval(job, start_time, retval))
finally:
self._running_jobs.remove(job.id)
# async def stop(self, force: bool = False) -> None:
# self._running = False
# if self._acquire_cancel_scope:
# self._acquire_cancel_scope.cancel()
#
# if force and self._task_group:
# self._task_group.cancel_scope.cancel()
#
# async def wait_until_stopped(self) -> None:
# if self._stop_event:
# await self._stop_event.wait()
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