143 lines
4.4 KiB
Python
143 lines
4.4 KiB
Python
"""
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aiosched: Yet another Python async scheduler
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Copyright (C) 2022 nocturn9x
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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https:www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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"""
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import warnings
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from enum import Enum, auto
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from typing import Coroutine, Any
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from dataclasses import dataclass, field
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class TaskState(Enum):
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"""
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An enumeration of task states
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"""
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# Task has been created and is
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# ready to run
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INIT: int = auto()
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# Task is executing synchronous code
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RUN: int = auto()
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# Task is waiting on an I/O resource
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IO: int = auto()
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# Task is sleeping or waiting on an
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# event
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PAUSED: int = auto()
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# Task has exited with an exception
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CRASHED: int = auto()
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# Task has been cancelled (either
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# explicitly or implicitly)
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CANCELLED: int = auto()
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# Task has finished executing normally
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FINISHED: int = auto()
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@dataclass
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class Task:
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"""
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A simple wrapper around a coroutine object
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"""
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# The name of the task. Usually this equals self.coroutine.__name__,
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# but it may fall back to repr(self.coroutine)
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name: str
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# The underlying coroutine object to wrap
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coroutine: Coroutine
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# This attribute will be None unless the task raised an error
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exc: BaseException | None = None
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# The return value of the coroutine
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result: Any | None = None
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# Task status
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state: int = TaskState.INIT
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# This attribute counts how many times the task's run() method has been called
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steps: int = 0
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# Simple optimization to improve the selector's efficiency. Stores the task's last
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# I/O operation as well as a reference to the file descriptor it was performed on
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last_io: tuple[int, Any] | None = None
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# All the tasks waiting on this task's completion
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joiners: set["Task"] = field(default_factory=set)
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# Whether this task has a pending cancellation scheduled. This allows us to delay
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# cancellation delivery as soon as the task calls another loop primitive
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pending_cancellation: bool = False
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# The time when the task was put on the waiting queue
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paused_when: float = 0.0
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# The next deadline, in terms of the absolute clock of the loop, associated to the task
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next_deadline: float = 0.0
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# Is this task within a context? This is needed to fix a bug that would occur when
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# the event loop tries to raise the exception caused by first task that kicked the
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# loop even if that context already ignored said error
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context: "TaskContext" = None
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# We propagate exception only at the first call to wait()
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propagate: bool = True
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def run(self, what: Any | None = None):
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"""
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Simple abstraction layer over a coroutine's send method.
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Does nothing if the task has already exited
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:param what: The object that has to be sent to the coroutine,
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defaults to None
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:type what: Any, optional
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"""
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if self.done():
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return
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return self.coroutine.send(what)
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def throw(self, err: BaseException):
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"""
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Simple abstraction layer over a coroutine's throw method.
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Does nothing if the task has already exited
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:param err: The exception that has to be raised inside
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the task
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:type err: BaseException
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"""
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if self.done():
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return
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return self.coroutine.throw(err)
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def __hash__(self):
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"""
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Implements hash(self)
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"""
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return hash(self.coroutine)
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def done(self):
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"""
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Returns True if the task is not running,
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False otherwise
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"""
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return self.state in [
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TaskState.CANCELLED,
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TaskState.CRASHED,
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TaskState.FINISHED,
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]
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def __del__(self):
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"""
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Task destructor
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"""
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if not self.done():
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warnings.warn(f"task '{self.name}' was destroyed, but it has not completed yet")
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if self.last_io:
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warnings.warn(f"task '{self.name}' was destroyed, but it has pending I/O")
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