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156 lines
3.9 KiB
Python
156 lines
3.9 KiB
Python
"""Cross-interpreter Queues High Level Module."""
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import queue
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import time
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import weakref
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import _xxinterpchannels as _channels
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import _xxinterpchannels as _queues
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# aliases:
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from _xxinterpchannels import (
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ChannelError as QueueError,
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ChannelNotFoundError as QueueNotFoundError,
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)
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__all__ = [
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'create', 'list_all',
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'Queue',
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'QueueError', 'QueueNotFoundError', 'QueueEmpty', 'QueueFull',
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]
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def create(maxsize=0):
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"""Return a new cross-interpreter queue.
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The queue may be used to pass data safely between interpreters.
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"""
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# XXX honor maxsize
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qid = _queues.create()
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return Queue._with_maxsize(qid, maxsize)
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def list_all():
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"""Return a list of all open queues."""
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return [Queue(qid)
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for qid in _queues.list_all()]
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class QueueEmpty(queue.Empty):
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"""Raised from get_nowait() when the queue is empty.
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It is also raised from get() if it times out.
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"""
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class QueueFull(queue.Full):
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"""Raised from put_nowait() when the queue is full.
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It is also raised from put() if it times out.
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"""
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_known_queues = weakref.WeakValueDictionary()
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class Queue:
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"""A cross-interpreter queue."""
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@classmethod
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def _with_maxsize(cls, id, maxsize):
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if not isinstance(maxsize, int):
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raise TypeError(f'maxsize must be an int, got {maxsize!r}')
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elif maxsize < 0:
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maxsize = 0
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else:
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maxsize = int(maxsize)
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self = cls(id)
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self._maxsize = maxsize
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return self
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def __new__(cls, id, /):
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# There is only one instance for any given ID.
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if isinstance(id, int):
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id = _channels._channel_id(id, force=False)
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elif not isinstance(id, _channels.ChannelID):
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raise TypeError(f'id must be an int, got {id!r}')
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key = int(id)
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try:
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self = _known_queues[key]
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except KeyError:
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self = super().__new__(cls)
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self._id = id
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self._maxsize = 0
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_known_queues[key] = self
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return self
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def __repr__(self):
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return f'{type(self).__name__}({self.id})'
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def __hash__(self):
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return hash(self._id)
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@property
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def id(self):
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return int(self._id)
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@property
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def maxsize(self):
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return self._maxsize
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@property
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def _info(self):
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return _channels.get_info(self._id)
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def empty(self):
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return self._info.count == 0
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def full(self):
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if self._maxsize <= 0:
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return False
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return self._info.count >= self._maxsize
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def qsize(self):
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return self._info.count
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def put(self, obj, timeout=None):
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# XXX block if full
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_channels.send(self._id, obj, blocking=False)
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def put_nowait(self, obj):
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# XXX raise QueueFull if full
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return _channels.send(self._id, obj, blocking=False)
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def get(self, timeout=None, *,
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_sentinel=object(),
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_delay=10 / 1000, # 10 milliseconds
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):
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"""Return the next object from the queue.
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This blocks while the queue is empty.
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"""
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if timeout is not None:
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timeout = int(timeout)
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if timeout < 0:
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raise ValueError(f'timeout value must be non-negative')
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end = time.time() + timeout
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obj = _channels.recv(self._id, _sentinel)
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while obj is _sentinel:
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time.sleep(_delay)
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if timeout is not None and time.time() >= end:
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raise QueueEmpty
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obj = _channels.recv(self._id, _sentinel)
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return obj
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def get_nowait(self, *, _sentinel=object()):
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"""Return the next object from the channel.
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If the queue is empty then raise QueueEmpty. Otherwise this
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is the same as get().
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"""
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obj = _channels.recv(self._id, _sentinel)
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if obj is _sentinel:
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raise QueueEmpty
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return obj
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# XXX add this:
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#_channels._register_queue_type(Queue)
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