mirror of https://github.com/nocturn9x/giambio.git
124 lines
4.3 KiB
Python
124 lines
4.3 KiB
Python
"""
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Higher-level context manager(s) for async pools
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Copyright (C) 2020 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 giambio
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from giambio.task import Task
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from typing import List, Optional, Callable, Coroutine, Any
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class TaskManager:
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"""
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An asynchronous context manager for giambio, similar to trio's nurseries
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:param timeout: The pool's timeout length in seconds, if any, defaults to None
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:type timeout: float, optional
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:param raise_on_timeout: Whether to catch a TooSlowError exception when the pool's
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timeout expires or not. Defaults to True
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:type raise_on_timeout: bool, optional
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"""
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def __init__(self, current_task: Task, timeout: float = None, raise_on_timeout: bool = False) -> None:
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"""
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Object constructor
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"""
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# All the tasks that belong to this pool
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self.tasks: List[Task] = []
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# Whether we have been cancelled or not
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self.cancelled: bool = False
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# The clock time of when we started running, used for
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# timeouts expiration
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self.started: float = giambio.clock()
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# The pool's timeout (in seconds)
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if timeout:
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self.timeout: float = self.started + timeout
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else:
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self.timeout = None
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# Whether our timeout expired or not
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self.timed_out: bool = False
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# Internal check so users don't try
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# to use the pool manually
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self._proper_init = False
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# We keep track of any inner pools to propagate
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# exceptions properly
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self.enclosed_pool: Optional["giambio.context.TaskManager"] = None
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# Do we raise an error after timeout?
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self.raise_on_timeout: bool = raise_on_timeout
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# The task that created the pool. We keep track of
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# it because we only cancel ourselves if this task
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# errors out (so if the error is caught before reaching
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# it we just do nothing)
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self.owner: Task = current_task
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async def spawn(self, func: Callable[..., Coroutine[Any, Any, Any]], *args, **kwargs) -> "giambio.task.Task":
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"""
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Spawns a child task
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"""
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assert self._proper_init, "Cannot use improperly initialized pool"
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self.tasks.append(await giambio.traps.create_task(func, self, *args, **kwargs))
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return self.tasks[-1]
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async def __aenter__(self):
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"""
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Implements the asynchronous context manager interface,
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"""
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self._proper_init = True
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return self
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async def __aexit__(self, exc_type: Exception, exc: Exception, tb):
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"""
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Implements the asynchronous context manager interface, joining
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all the tasks spawned inside the pool
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"""
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try:
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for task in self.tasks:
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# This forces the interpreter to stop at the
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# end of the block and wait for all
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# children to exit
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await task.join()
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self.tasks.remove(task)
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except giambio.exceptions.TooSlowError:
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if self.raise_on_timeout:
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raise
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finally:
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self._proper_init = False
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if isinstance(exc, giambio.exceptions.TooSlowError) and not self.raise_on_timeout:
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return True
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async def cancel(self):
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"""
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Cancels the pool entirely, iterating over all
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the pool's tasks and cancelling them
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"""
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# TODO: This breaks, somehow, investigation needed
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for task in self.tasks:
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await task.cancel()
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self.tasks.remove(task)
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def done(self) -> bool:
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"""
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Returns True if all the tasks inside the
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pool have exited, False otherwise
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"""
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return self._proper_init and all([task.done() for task in self.tasks])
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