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596 lines
16 KiB
596 lines
16 KiB
from collections import deque
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from dataclasses import dataclass
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from types import TracebackType
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from typing import Deque, Optional, Tuple, Type
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from warnings import warn
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from ..lowlevel import cancel_shielded_checkpoint, checkpoint, checkpoint_if_cancelled
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from ._compat import DeprecatedAwaitable
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from ._eventloop import get_asynclib
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from ._exceptions import BusyResourceError, WouldBlock
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from ._tasks import CancelScope
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from ._testing import TaskInfo, get_current_task
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@dataclass(frozen=True)
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class EventStatistics:
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"""
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:ivar int tasks_waiting: number of tasks waiting on :meth:`~.Event.wait`
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"""
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tasks_waiting: int
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@dataclass(frozen=True)
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class CapacityLimiterStatistics:
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"""
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:ivar int borrowed_tokens: number of tokens currently borrowed by tasks
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:ivar float total_tokens: total number of available tokens
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:ivar tuple borrowers: tasks or other objects currently holding tokens borrowed from this
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limiter
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:ivar int tasks_waiting: number of tasks waiting on :meth:`~.CapacityLimiter.acquire` or
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:meth:`~.CapacityLimiter.acquire_on_behalf_of`
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"""
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borrowed_tokens: int
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total_tokens: float
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borrowers: Tuple[object, ...]
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tasks_waiting: int
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@dataclass(frozen=True)
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class LockStatistics:
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"""
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:ivar bool locked: flag indicating if this lock is locked or not
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:ivar ~anyio.TaskInfo owner: task currently holding the lock (or ``None`` if the lock is not
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held by any task)
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:ivar int tasks_waiting: number of tasks waiting on :meth:`~.Lock.acquire`
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"""
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locked: bool
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owner: Optional[TaskInfo]
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tasks_waiting: int
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@dataclass(frozen=True)
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class ConditionStatistics:
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"""
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:ivar int tasks_waiting: number of tasks blocked on :meth:`~.Condition.wait`
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:ivar ~anyio.LockStatistics lock_statistics: statistics of the underlying :class:`~.Lock`
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"""
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tasks_waiting: int
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lock_statistics: LockStatistics
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@dataclass(frozen=True)
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class SemaphoreStatistics:
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"""
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:ivar int tasks_waiting: number of tasks waiting on :meth:`~.Semaphore.acquire`
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"""
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tasks_waiting: int
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class Event:
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def __new__(cls) -> "Event":
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return get_asynclib().Event()
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def set(self) -> DeprecatedAwaitable:
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"""Set the flag, notifying all listeners."""
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raise NotImplementedError
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def is_set(self) -> bool:
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"""Return ``True`` if the flag is set, ``False`` if not."""
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raise NotImplementedError
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async def wait(self) -> None:
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"""
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Wait until the flag has been set.
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If the flag has already been set when this method is called, it returns immediately.
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"""
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raise NotImplementedError
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def statistics(self) -> EventStatistics:
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"""Return statistics about the current state of this event."""
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raise NotImplementedError
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class Lock:
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_owner_task: Optional[TaskInfo] = None
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def __init__(self) -> None:
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self._waiters: Deque[Tuple[TaskInfo, Event]] = deque()
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async def __aenter__(self) -> None:
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await self.acquire()
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> None:
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self.release()
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async def acquire(self) -> None:
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"""Acquire the lock."""
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await checkpoint_if_cancelled()
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try:
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self.acquire_nowait()
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except WouldBlock:
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task = get_current_task()
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event = Event()
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token = task, event
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self._waiters.append(token)
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try:
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await event.wait()
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except BaseException:
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if not event.is_set():
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self._waiters.remove(token)
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elif self._owner_task == task:
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self.release()
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raise
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assert self._owner_task == task
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else:
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try:
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await cancel_shielded_checkpoint()
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except BaseException:
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self.release()
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raise
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def acquire_nowait(self) -> None:
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"""
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Acquire the lock, without blocking.
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:raises ~WouldBlock: if the operation would block
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"""
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task = get_current_task()
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if self._owner_task == task:
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raise RuntimeError("Attempted to acquire an already held Lock")
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if self._owner_task is not None:
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raise WouldBlock
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self._owner_task = task
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def release(self) -> DeprecatedAwaitable:
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"""Release the lock."""
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if self._owner_task != get_current_task():
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raise RuntimeError("The current task is not holding this lock")
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if self._waiters:
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self._owner_task, event = self._waiters.popleft()
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event.set()
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else:
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del self._owner_task
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return DeprecatedAwaitable(self.release)
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def locked(self) -> bool:
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"""Return True if the lock is currently held."""
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return self._owner_task is not None
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def statistics(self) -> LockStatistics:
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"""
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Return statistics about the current state of this lock.
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.. versionadded:: 3.0
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"""
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return LockStatistics(self.locked(), self._owner_task, len(self._waiters))
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class Condition:
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_owner_task: Optional[TaskInfo] = None
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def __init__(self, lock: Optional[Lock] = None):
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self._lock = lock or Lock()
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self._waiters: Deque[Event] = deque()
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async def __aenter__(self) -> None:
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await self.acquire()
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> None:
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self.release()
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def _check_acquired(self) -> None:
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if self._owner_task != get_current_task():
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raise RuntimeError("The current task is not holding the underlying lock")
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async def acquire(self) -> None:
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"""Acquire the underlying lock."""
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await self._lock.acquire()
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self._owner_task = get_current_task()
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def acquire_nowait(self) -> None:
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"""
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Acquire the underlying lock, without blocking.
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:raises ~WouldBlock: if the operation would block
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"""
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self._lock.acquire_nowait()
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self._owner_task = get_current_task()
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def release(self) -> DeprecatedAwaitable:
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"""Release the underlying lock."""
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self._lock.release()
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return DeprecatedAwaitable(self.release)
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def locked(self) -> bool:
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"""Return True if the lock is set."""
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return self._lock.locked()
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def notify(self, n: int = 1) -> None:
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"""Notify exactly n listeners."""
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self._check_acquired()
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for _ in range(n):
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try:
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event = self._waiters.popleft()
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except IndexError:
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break
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event.set()
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def notify_all(self) -> None:
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"""Notify all the listeners."""
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self._check_acquired()
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for event in self._waiters:
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event.set()
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self._waiters.clear()
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async def wait(self) -> None:
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"""Wait for a notification."""
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await checkpoint()
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event = Event()
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self._waiters.append(event)
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self.release()
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try:
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await event.wait()
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except BaseException:
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if not event.is_set():
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self._waiters.remove(event)
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raise
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finally:
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with CancelScope(shield=True):
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await self.acquire()
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def statistics(self) -> ConditionStatistics:
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"""
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Return statistics about the current state of this condition.
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.. versionadded:: 3.0
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"""
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return ConditionStatistics(len(self._waiters), self._lock.statistics())
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class Semaphore:
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def __init__(self, initial_value: int, *, max_value: Optional[int] = None):
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if not isinstance(initial_value, int):
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raise TypeError("initial_value must be an integer")
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if initial_value < 0:
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raise ValueError("initial_value must be >= 0")
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if max_value is not None:
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if not isinstance(max_value, int):
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raise TypeError("max_value must be an integer or None")
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if max_value < initial_value:
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raise ValueError(
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"max_value must be equal to or higher than initial_value"
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)
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self._value = initial_value
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self._max_value = max_value
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self._waiters: Deque[Event] = deque()
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async def __aenter__(self) -> "Semaphore":
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await self.acquire()
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return self
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> None:
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self.release()
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async def acquire(self) -> None:
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"""Decrement the semaphore value, blocking if necessary."""
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await checkpoint_if_cancelled()
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try:
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self.acquire_nowait()
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except WouldBlock:
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event = Event()
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self._waiters.append(event)
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try:
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await event.wait()
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except BaseException:
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if not event.is_set():
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self._waiters.remove(event)
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else:
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self.release()
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raise
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else:
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try:
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await cancel_shielded_checkpoint()
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except BaseException:
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self.release()
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raise
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def acquire_nowait(self) -> None:
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"""
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Acquire the underlying lock, without blocking.
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:raises ~WouldBlock: if the operation would block
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"""
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if self._value == 0:
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raise WouldBlock
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self._value -= 1
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def release(self) -> DeprecatedAwaitable:
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"""Increment the semaphore value."""
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if self._max_value is not None and self._value == self._max_value:
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raise ValueError("semaphore released too many times")
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if self._waiters:
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self._waiters.popleft().set()
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else:
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self._value += 1
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return DeprecatedAwaitable(self.release)
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@property
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def value(self) -> int:
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"""The current value of the semaphore."""
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return self._value
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@property
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def max_value(self) -> Optional[int]:
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"""The maximum value of the semaphore."""
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return self._max_value
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def statistics(self) -> SemaphoreStatistics:
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"""
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Return statistics about the current state of this semaphore.
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.. versionadded:: 3.0
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"""
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return SemaphoreStatistics(len(self._waiters))
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class CapacityLimiter:
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def __new__(cls, total_tokens: float) -> "CapacityLimiter":
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return get_asynclib().CapacityLimiter(total_tokens)
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async def __aenter__(self) -> None:
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raise NotImplementedError
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> Optional[bool]:
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raise NotImplementedError
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@property
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def total_tokens(self) -> float:
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"""
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The total number of tokens available for borrowing.
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This is a read-write property. If the total number of tokens is increased, the
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proportionate number of tasks waiting on this limiter will be granted their tokens.
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.. versionchanged:: 3.0
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The property is now writable.
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"""
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raise NotImplementedError
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@total_tokens.setter
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def total_tokens(self, value: float) -> None:
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raise NotImplementedError
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async def set_total_tokens(self, value: float) -> None:
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warn(
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"CapacityLimiter.set_total_tokens has been deprecated. Set the value of the"
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'"total_tokens" attribute directly.',
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DeprecationWarning,
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)
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self.total_tokens = value
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@property
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def borrowed_tokens(self) -> int:
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"""The number of tokens that have currently been borrowed."""
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raise NotImplementedError
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@property
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def available_tokens(self) -> float:
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"""The number of tokens currently available to be borrowed"""
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raise NotImplementedError
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def acquire_nowait(self) -> DeprecatedAwaitable:
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"""
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Acquire a token for the current task without waiting for one to become available.
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:raises ~anyio.WouldBlock: if there are no tokens available for borrowing
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"""
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raise NotImplementedError
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def acquire_on_behalf_of_nowait(self, borrower: object) -> DeprecatedAwaitable:
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"""
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Acquire a token without waiting for one to become available.
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:param borrower: the entity borrowing a token
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:raises ~anyio.WouldBlock: if there are no tokens available for borrowing
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"""
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raise NotImplementedError
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async def acquire(self) -> None:
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"""
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Acquire a token for the current task, waiting if necessary for one to become available.
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"""
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raise NotImplementedError
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async def acquire_on_behalf_of(self, borrower: object) -> None:
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"""
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Acquire a token, waiting if necessary for one to become available.
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:param borrower: the entity borrowing a token
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"""
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raise NotImplementedError
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def release(self) -> None:
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"""
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Release the token held by the current task.
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:raises RuntimeError: if the current task has not borrowed a token from this limiter.
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"""
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raise NotImplementedError
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def release_on_behalf_of(self, borrower: object) -> None:
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"""
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Release the token held by the given borrower.
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:raises RuntimeError: if the borrower has not borrowed a token from this limiter.
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"""
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raise NotImplementedError
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def statistics(self) -> CapacityLimiterStatistics:
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"""
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Return statistics about the current state of this limiter.
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.. versionadded:: 3.0
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"""
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raise NotImplementedError
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def create_lock() -> Lock:
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"""
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Create an asynchronous lock.
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:return: a lock object
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.. deprecated:: 3.0
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Use :class:`~Lock` directly.
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"""
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warn("create_lock() is deprecated -- use Lock() directly", DeprecationWarning)
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return Lock()
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def create_condition(lock: Optional[Lock] = None) -> Condition:
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"""
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Create an asynchronous condition.
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:param lock: the lock to base the condition object on
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:return: a condition object
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|
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.. deprecated:: 3.0
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Use :class:`~Condition` directly.
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"""
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warn(
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"create_condition() is deprecated -- use Condition() directly",
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DeprecationWarning,
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)
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return Condition(lock=lock)
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def create_event() -> Event:
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"""
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Create an asynchronous event object.
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:return: an event object
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.. deprecated:: 3.0
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Use :class:`~Event` directly.
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"""
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warn("create_event() is deprecated -- use Event() directly", DeprecationWarning)
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return get_asynclib().Event()
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def create_semaphore(value: int, *, max_value: Optional[int] = None) -> Semaphore:
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"""
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Create an asynchronous semaphore.
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:param value: the semaphore's initial value
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:param max_value: if set, makes this a "bounded" semaphore that raises :exc:`ValueError` if the
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semaphore's value would exceed this number
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:return: a semaphore object
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|
|
.. deprecated:: 3.0
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Use :class:`~Semaphore` directly.
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"""
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warn(
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"create_semaphore() is deprecated -- use Semaphore() directly",
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DeprecationWarning,
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)
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return Semaphore(value, max_value=max_value)
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def create_capacity_limiter(total_tokens: float) -> CapacityLimiter:
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"""
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Create a capacity limiter.
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:param total_tokens: the total number of tokens available for borrowing (can be an integer or
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:data:`math.inf`)
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:return: a capacity limiter object
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|
|
.. deprecated:: 3.0
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Use :class:`~CapacityLimiter` directly.
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"""
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warn(
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"create_capacity_limiter() is deprecated -- use CapacityLimiter() directly",
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DeprecationWarning,
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)
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return get_asynclib().CapacityLimiter(total_tokens)
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class ResourceGuard:
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__slots__ = "action", "_guarded"
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|
def __init__(self, action: str):
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self.action = action
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self._guarded = False
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|
def __enter__(self) -> None:
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if self._guarded:
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raise BusyResourceError(self.action)
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self._guarded = True
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def __exit__(
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self,
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exc_type: Optional[Type[BaseException]],
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|
exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> Optional[bool]:
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self._guarded = False
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|
return None
|