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Async client uses tasks instead of threads
PYTHON-4725 - Async client should use tasks for SDAM instead of threads PYTHON-4860 - Async client should use asyncio.Lock and asyncio.Condition PYTHON-4941 - Synchronous unified test runner being used in asynchronous tests PYTHON-4843 - Async test suite should use a single event loop PYTHON-4945 - Fix test cleanups for mongoses Co-authored-by: Iris <[email protected]>
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| Original file line number | Diff line number | Diff line change |
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| # Copyright (c) 2001-2024 Python Software Foundation; All Rights Reserved | ||
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| """Lock and Condition classes vendored from https://github.com/python/cpython/blob/main/Lib/asyncio/locks.py | ||
| to port 3.13 fixes to older versions of Python. | ||
| Can be removed once we drop Python 3.12 support.""" | ||
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| from __future__ import annotations | ||
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| import collections | ||
| import threading | ||
| from asyncio import events, exceptions | ||
| from typing import Any, Coroutine, Optional | ||
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| _global_lock = threading.Lock() | ||
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| class _LoopBoundMixin: | ||
| _loop = None | ||
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| def _get_loop(self) -> Any: | ||
| loop = events._get_running_loop() | ||
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| if self._loop is None: | ||
| with _global_lock: | ||
| if self._loop is None: | ||
| self._loop = loop | ||
| if loop is not self._loop: | ||
| raise RuntimeError(f"{self!r} is bound to a different event loop") | ||
| return loop | ||
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| class _ContextManagerMixin: | ||
| async def __aenter__(self) -> None: | ||
| await self.acquire() # type: ignore[attr-defined] | ||
| # We have no use for the "as ..." clause in the with | ||
| # statement for locks. | ||
| return | ||
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| async def __aexit__(self, exc_type: Any, exc: Any, tb: Any) -> None: | ||
| self.release() # type: ignore[attr-defined] | ||
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| class Lock(_ContextManagerMixin, _LoopBoundMixin): | ||
| """Primitive lock objects. | ||
| A primitive lock is a synchronization primitive that is not owned | ||
| by a particular task when locked. A primitive lock is in one | ||
| of two states, 'locked' or 'unlocked'. | ||
| It is created in the unlocked state. It has two basic methods, | ||
| acquire() and release(). When the state is unlocked, acquire() | ||
| changes the state to locked and returns immediately. When the | ||
| state is locked, acquire() blocks until a call to release() in | ||
| another task changes it to unlocked, then the acquire() call | ||
| resets it to locked and returns. The release() method should only | ||
| be called in the locked state; it changes the state to unlocked | ||
| and returns immediately. If an attempt is made to release an | ||
| unlocked lock, a RuntimeError will be raised. | ||
| When more than one task is blocked in acquire() waiting for | ||
| the state to turn to unlocked, only one task proceeds when a | ||
| release() call resets the state to unlocked; successive release() | ||
| calls will unblock tasks in FIFO order. | ||
| Locks also support the asynchronous context management protocol. | ||
| 'async with lock' statement should be used. | ||
| Usage: | ||
| lock = Lock() | ||
| ... | ||
| await lock.acquire() | ||
| try: | ||
| ... | ||
| finally: | ||
| lock.release() | ||
| Context manager usage: | ||
| lock = Lock() | ||
| ... | ||
| async with lock: | ||
| ... | ||
| Lock objects can be tested for locking state: | ||
| if not lock.locked(): | ||
| await lock.acquire() | ||
| else: | ||
| # lock is acquired | ||
| ... | ||
| """ | ||
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| def __init__(self) -> None: | ||
| self._waiters: Optional[collections.deque] = None | ||
| self._locked = False | ||
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| def __repr__(self) -> str: | ||
| res = super().__repr__() | ||
| extra = "locked" if self._locked else "unlocked" | ||
| if self._waiters: | ||
| extra = f"{extra}, waiters:{len(self._waiters)}" | ||
| return f"<{res[1:-1]} [{extra}]>" | ||
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| def locked(self) -> bool: | ||
| """Return True if lock is acquired.""" | ||
| return self._locked | ||
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| async def acquire(self) -> bool: | ||
| """Acquire a lock. | ||
| This method blocks until the lock is unlocked, then sets it to | ||
| locked and returns True. | ||
| """ | ||
| # Implement fair scheduling, where thread always waits | ||
| # its turn. Jumping the queue if all are cancelled is an optimization. | ||
| if not self._locked and ( | ||
| self._waiters is None or all(w.cancelled() for w in self._waiters) | ||
| ): | ||
| self._locked = True | ||
| return True | ||
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| if self._waiters is None: | ||
| self._waiters = collections.deque() | ||
| fut = self._get_loop().create_future() | ||
| self._waiters.append(fut) | ||
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| try: | ||
| try: | ||
| await fut | ||
| finally: | ||
| self._waiters.remove(fut) | ||
| except exceptions.CancelledError: | ||
| # Currently the only exception designed be able to occur here. | ||
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| # Ensure the lock invariant: If lock is not claimed (or about | ||
| # to be claimed by us) and there is a Task in waiters, | ||
| # ensure that the Task at the head will run. | ||
| if not self._locked: | ||
| self._wake_up_first() | ||
| raise | ||
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| # assert self._locked is False | ||
| self._locked = True | ||
| return True | ||
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| def release(self) -> None: | ||
| """Release a lock. | ||
| When the lock is locked, reset it to unlocked, and return. | ||
| If any other tasks are blocked waiting for the lock to become | ||
| unlocked, allow exactly one of them to proceed. | ||
| When invoked on an unlocked lock, a RuntimeError is raised. | ||
| There is no return value. | ||
| """ | ||
| if self._locked: | ||
| self._locked = False | ||
| self._wake_up_first() | ||
| else: | ||
| raise RuntimeError("Lock is not acquired.") | ||
|
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| def _wake_up_first(self) -> None: | ||
| """Ensure that the first waiter will wake up.""" | ||
| if not self._waiters: | ||
| return | ||
| try: | ||
| fut = next(iter(self._waiters)) | ||
| except StopIteration: | ||
| return | ||
|
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| # .done() means that the waiter is already set to wake up. | ||
| if not fut.done(): | ||
| fut.set_result(True) | ||
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| class Condition(_ContextManagerMixin, _LoopBoundMixin): | ||
| """Asynchronous equivalent to threading.Condition. | ||
| This class implements condition variable objects. A condition variable | ||
| allows one or more tasks to wait until they are notified by another | ||
| task. | ||
| A new Lock object is created and used as the underlying lock. | ||
| """ | ||
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| def __init__(self, lock: Optional[Lock] = None) -> None: | ||
| if lock is None: | ||
| lock = Lock() | ||
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| self._lock = lock | ||
| # Export the lock's locked(), acquire() and release() methods. | ||
| self.locked = lock.locked | ||
| self.acquire = lock.acquire | ||
| self.release = lock.release | ||
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| self._waiters: collections.deque = collections.deque() | ||
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| def __repr__(self) -> str: | ||
| res = super().__repr__() | ||
| extra = "locked" if self.locked() else "unlocked" | ||
| if self._waiters: | ||
| extra = f"{extra}, waiters:{len(self._waiters)}" | ||
| return f"<{res[1:-1]} [{extra}]>" | ||
|
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| async def wait(self) -> bool: | ||
| """Wait until notified. | ||
| If the calling task has not acquired the lock when this | ||
| method is called, a RuntimeError is raised. | ||
| This method releases the underlying lock, and then blocks | ||
| until it is awakened by a notify() or notify_all() call for | ||
| the same condition variable in another task. Once | ||
| awakened, it re-acquires the lock and returns True. | ||
| This method may return spuriously, | ||
| which is why the caller should always | ||
| re-check the state and be prepared to wait() again. | ||
| """ | ||
| if not self.locked(): | ||
| raise RuntimeError("cannot wait on un-acquired lock") | ||
|
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| fut = self._get_loop().create_future() | ||
| self.release() | ||
| try: | ||
| try: | ||
| self._waiters.append(fut) | ||
| try: | ||
| await fut | ||
| return True | ||
| finally: | ||
| self._waiters.remove(fut) | ||
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| finally: | ||
| # Must re-acquire lock even if wait is cancelled. | ||
| # We only catch CancelledError here, since we don't want any | ||
| # other (fatal) errors with the future to cause us to spin. | ||
| err = None | ||
| while True: | ||
| try: | ||
| await self.acquire() | ||
| break | ||
| except exceptions.CancelledError as e: | ||
| err = e | ||
|
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| if err is not None: | ||
| try: | ||
| raise err # Re-raise most recent exception instance. | ||
| finally: | ||
| err = None # Break reference cycles. | ||
| except BaseException: | ||
| # Any error raised out of here _may_ have occurred after this Task | ||
| # believed to have been successfully notified. | ||
| # Make sure to notify another Task instead. This may result | ||
| # in a "spurious wakeup", which is allowed as part of the | ||
| # Condition Variable protocol. | ||
| self._notify(1) | ||
| raise | ||
|
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| async def wait_for(self, predicate: Any) -> Coroutine: | ||
| """Wait until a predicate becomes true. | ||
| The predicate should be a callable whose result will be | ||
| interpreted as a boolean value. The method will repeatedly | ||
| wait() until it evaluates to true. The final predicate value is | ||
| the return value. | ||
| """ | ||
| result = predicate() | ||
| while not result: | ||
| await self.wait() | ||
| result = predicate() | ||
| return result | ||
|
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| def notify(self, n: int = 1) -> None: | ||
| """By default, wake up one task waiting on this condition, if any. | ||
| If the calling task has not acquired the lock when this method | ||
| is called, a RuntimeError is raised. | ||
| This method wakes up n of the tasks waiting for the condition | ||
| variable; if fewer than n are waiting, they are all awoken. | ||
| Note: an awakened task does not actually return from its | ||
| wait() call until it can reacquire the lock. Since notify() does | ||
| not release the lock, its caller should. | ||
| """ | ||
| if not self.locked(): | ||
| raise RuntimeError("cannot notify on un-acquired lock") | ||
| self._notify(n) | ||
|
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| def _notify(self, n: int) -> None: | ||
| idx = 0 | ||
| for fut in self._waiters: | ||
| if idx >= n: | ||
| break | ||
|
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| if not fut.done(): | ||
| idx += 1 | ||
| fut.set_result(False) | ||
|
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| def notify_all(self) -> None: | ||
| """Wake up all tasks waiting on this condition. This method acts | ||
| like notify(), but wakes up all waiting tasks instead of one. If the | ||
| calling task has not acquired the lock when this method is called, | ||
| a RuntimeError is raised. | ||
| """ | ||
| self.notify(len(self._waiters)) |
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