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from __future__ import annotations
import math
import sys
from abc import ABCMeta, abstractmethod
from collections.abc import AsyncIterator, Awaitable, Mapping
from os import PathLike
from signal import Signals
from socket import AddressFamily, SocketKind, socket
from typing import (
IO,
TYPE_CHECKING,
Any,
Callable,
ContextManager,
Sequence,
TypeVar,
overload,
)
if sys.version_info >= (3, 11):
from typing import TypeVarTuple, Unpack
else:
from typing_extensions import TypeVarTuple, Unpack
if TYPE_CHECKING:
from typing import Literal
from .._core._synchronization import CapacityLimiter, Event
from .._core._tasks import CancelScope
from .._core._testing import TaskInfo
from ..from_thread import BlockingPortal
from ._sockets import (
ConnectedUDPSocket,
ConnectedUNIXDatagramSocket,
IPSockAddrType,
SocketListener,
SocketStream,
UDPSocket,
UNIXDatagramSocket,
UNIXSocketStream,
)
from ._subprocesses import Process
from ._tasks import TaskGroup
from ._testing import TestRunner
T_Retval = TypeVar("T_Retval")
PosArgsT = TypeVarTuple("PosArgsT")
class AsyncBackend(metaclass=ABCMeta):
@classmethod
@abstractmethod
def run(
cls,
func: Callable[[Unpack[PosArgsT]], Awaitable[T_Retval]],
args: tuple[Unpack[PosArgsT]],
kwargs: dict[str, Any],
options: dict[str, Any],
) -> T_Retval:
"""
Run the given coroutine function in an asynchronous event loop.
The current thread must not be already running an event loop.
:param func: a coroutine function
:param args: positional arguments to ``func``
:param kwargs: positional arguments to ``func``
:param options: keyword arguments to call the backend ``run()`` implementation
with
:return: the return value of the coroutine function
"""
@classmethod
@abstractmethod
def current_token(cls) -> object:
"""
:return:
"""
@classmethod
@abstractmethod
def current_time(cls) -> float:
"""
Return the current value of the event loop's internal clock.
:return: the clock value (seconds)
"""
@classmethod
@abstractmethod
def cancelled_exception_class(cls) -> type[BaseException]:
"""Return the exception class that is raised in a task if it's cancelled."""
@classmethod
@abstractmethod
async def checkpoint(cls) -> None:
"""
Check if the task has been cancelled, and allow rescheduling of other tasks.
This is effectively the same as running :meth:`checkpoint_if_cancelled` and then
:meth:`cancel_shielded_checkpoint`.
"""
@classmethod
async def checkpoint_if_cancelled(cls) -> None:
"""
Check if the current task group has been cancelled.
This will check if the task has been cancelled, but will not allow other tasks
to be scheduled if not.
"""
if cls.current_effective_deadline() == -math.inf:
await cls.checkpoint()
@classmethod
async def cancel_shielded_checkpoint(cls) -> None:
"""
Allow the rescheduling of other tasks.
This will give other tasks the opportunity to run, but without checking if the
current task group has been cancelled, unlike with :meth:`checkpoint`.
"""
with cls.create_cancel_scope(shield=True):
await cls.sleep(0)
@classmethod
@abstractmethod
async def sleep(cls, delay: float) -> None:
"""
Pause the current task for the specified duration.
:param delay: the duration, in seconds
"""
@classmethod
@abstractmethod
def create_cancel_scope(
cls, *, deadline: float = math.inf, shield: bool = False
) -> CancelScope:
pass
@classmethod
@abstractmethod
def current_effective_deadline(cls) -> float:
"""
Return the nearest deadline among all the cancel scopes effective for the
current task.
:return:
- a clock value from the event loop's internal clock
- ``inf`` if there is no deadline in effect
- ``-inf`` if the current scope has been cancelled
:rtype: float
"""
@classmethod
@abstractmethod
def create_task_group(cls) -> TaskGroup:
pass
@classmethod
@abstractmethod
def create_event(cls) -> Event:
pass
@classmethod
@abstractmethod
def create_capacity_limiter(cls, total_tokens: float) -> CapacityLimiter:
pass
@classmethod
@abstractmethod
async def run_sync_in_worker_thread(
cls,
func: Callable[[Unpack[PosArgsT]], T_Retval],
args: tuple[Unpack[PosArgsT]],
abandon_on_cancel: bool = False,
limiter: CapacityLimiter | None = None,
) -> T_Retval:
pass
@classmethod
@abstractmethod
def check_cancelled(cls) -> None:
pass
@classmethod
@abstractmethod
def run_async_from_thread(
cls,
func: Callable[[Unpack[PosArgsT]], Awaitable[T_Retval]],
args: tuple[Unpack[PosArgsT]],
token: object,
) -> T_Retval:
pass
@classmethod
@abstractmethod
def run_sync_from_thread(
cls,
func: Callable[[Unpack[PosArgsT]], T_Retval],
args: tuple[Unpack[PosArgsT]],
token: object,
) -> T_Retval:
pass
@classmethod
@abstractmethod
def create_blocking_portal(cls) -> BlockingPortal:
pass
@classmethod
@overload
async def open_process(
cls,
command: str | bytes,
*,
shell: Literal[True],
stdin: int | IO[Any] | None,
stdout: int | IO[Any] | None,
stderr: int | IO[Any] | None,
cwd: str | bytes | PathLike[str] | None = None,
env: Mapping[str, str] | None = None,
start_new_session: bool = False,
) -> Process:
pass
@classmethod
@overload
async def open_process(
cls,
command: Sequence[str | bytes],
*,
shell: Literal[False],
stdin: int | IO[Any] | None,
stdout: int | IO[Any] | None,
stderr: int | IO[Any] | None,
cwd: str | bytes | PathLike[str] | None = None,
env: Mapping[str, str] | None = None,
start_new_session: bool = False,
) -> Process:
pass
@classmethod
@abstractmethod
async def open_process(
cls,
command: str | bytes | Sequence[str | bytes],
*,
shell: bool,
stdin: int | IO[Any] | None,
stdout: int | IO[Any] | None,
stderr: int | IO[Any] | None,
cwd: str | bytes | PathLike[str] | None = None,
env: Mapping[str, str] | None = None,
start_new_session: bool = False,
) -> Process:
pass
@classmethod
@abstractmethod
def setup_process_pool_exit_at_shutdown(cls, workers: set[Process]) -> None:
pass
@classmethod
@abstractmethod
async def connect_tcp(
cls, host: str, port: int, local_address: IPSockAddrType | None = None
) -> SocketStream:
pass
@classmethod
@abstractmethod
async def connect_unix(cls, path: str | bytes) -> UNIXSocketStream:
pass
@classmethod
@abstractmethod
def create_tcp_listener(cls, sock: socket) -> SocketListener:
pass
@classmethod
@abstractmethod
def create_unix_listener(cls, sock: socket) -> SocketListener:
pass
@classmethod
@abstractmethod
async def create_udp_socket(
cls,
family: AddressFamily,
local_address: IPSockAddrType | None,
remote_address: IPSockAddrType | None,
reuse_port: bool,
) -> UDPSocket | ConnectedUDPSocket:
pass
@classmethod
@overload
async def create_unix_datagram_socket(
cls, raw_socket: socket, remote_path: None
) -> UNIXDatagramSocket:
...
@classmethod
@overload
async def create_unix_datagram_socket(
cls, raw_socket: socket, remote_path: str | bytes
) -> ConnectedUNIXDatagramSocket:
...
@classmethod
@abstractmethod
async def create_unix_datagram_socket(
cls, raw_socket: socket, remote_path: str | bytes | None
) -> UNIXDatagramSocket | ConnectedUNIXDatagramSocket:
pass
@classmethod
@abstractmethod
async def getaddrinfo(
cls,
host: bytes | str | None,
port: str | int | None,
*,
family: int | AddressFamily = 0,
type: int | SocketKind = 0,
proto: int = 0,
flags: int = 0,
) -> list[
tuple[
AddressFamily,
SocketKind,
int,
str,
tuple[str, int] | tuple[str, int, int, int],
]
]:
pass
@classmethod
@abstractmethod
async def getnameinfo(
cls, sockaddr: IPSockAddrType, flags: int = 0
) -> tuple[str, str]:
pass
@classmethod
@abstractmethod
async def wait_socket_readable(cls, sock: socket) -> None:
pass
@classmethod
@abstractmethod
async def wait_socket_writable(cls, sock: socket) -> None:
pass
@classmethod
@abstractmethod
def current_default_thread_limiter(cls) -> CapacityLimiter:
pass
@classmethod
@abstractmethod
def open_signal_receiver(
cls, *signals: Signals
) -> ContextManager[AsyncIterator[Signals]]:
pass
@classmethod
@abstractmethod
def get_current_task(cls) -> TaskInfo:
pass
@classmethod
@abstractmethod
def get_running_tasks(cls) -> list[TaskInfo]:
pass
@classmethod
@abstractmethod
async def wait_all_tasks_blocked(cls) -> None:
pass
@classmethod
@abstractmethod
def create_test_runner(cls, options: dict[str, Any]) -> TestRunner:
pass
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