import attr
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from trio._util import NoPublicConstructor
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class TrioInternalError(Exception):
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"""Raised by :func:`run` if we encounter a bug in Trio, or (possibly) a
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misuse of one of the low-level :mod:`trio.lowlevel` APIs.
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This should never happen! If you get this error, please file a bug.
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Unfortunately, if you get this error it also means that all bets are off –
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Trio doesn't know what is going on and its normal invariants may be void.
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(For example, we might have "lost track" of a task. Or lost track of all
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tasks.) Again, though, this shouldn't happen.
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"""
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class RunFinishedError(RuntimeError):
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"""Raised by `trio.from_thread.run` and similar functions if the
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corresponding call to :func:`trio.run` has already finished.
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"""
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class WouldBlock(Exception):
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"""Raised by ``X_nowait`` functions if ``X`` would block."""
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class Cancelled(BaseException, metaclass=NoPublicConstructor):
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"""Raised by blocking calls if the surrounding scope has been cancelled.
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You should let this exception propagate, to be caught by the relevant
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cancel scope. To remind you of this, it inherits from :exc:`BaseException`
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instead of :exc:`Exception`, just like :exc:`KeyboardInterrupt` and
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:exc:`SystemExit` do. This means that if you write something like::
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try:
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...
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except Exception:
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...
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then this *won't* catch a :exc:`Cancelled` exception.
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You cannot raise :exc:`Cancelled` yourself. Attempting to do so
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will produce a :exc:`TypeError`. Use :meth:`cancel_scope.cancel()
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<trio.CancelScope.cancel>` instead.
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.. note::
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In the US it's also common to see this word spelled "canceled", with
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only one "l". This is a `recent
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<https://books.google.com/ngrams/graph?content=canceled%2Ccancelled&year_start=1800&year_end=2000&corpus=5&smoothing=3&direct_url=t1%3B%2Ccanceled%3B%2Cc0%3B.t1%3B%2Ccancelled%3B%2Cc0>`__
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and `US-specific
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<https://books.google.com/ngrams/graph?content=canceled%2Ccancelled&year_start=1800&year_end=2000&corpus=18&smoothing=3&share=&direct_url=t1%3B%2Ccanceled%3B%2Cc0%3B.t1%3B%2Ccancelled%3B%2Cc0>`__
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innovation, and even in the US both forms are still commonly used. So
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for consistency with the rest of the world and with "cancellation"
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(which always has two "l"s), Trio uses the two "l" spelling
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everywhere.
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"""
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def __str__(self):
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return "Cancelled"
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class BusyResourceError(Exception):
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"""Raised when a task attempts to use a resource that some other task is
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already using, and this would lead to bugs and nonsense.
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For example, if two tasks try to send data through the same socket at the
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same time, Trio will raise :class:`BusyResourceError` instead of letting
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the data get scrambled.
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"""
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class ClosedResourceError(Exception):
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"""Raised when attempting to use a resource after it has been closed.
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Note that "closed" here means that *your* code closed the resource,
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generally by calling a method with a name like ``close`` or ``aclose``, or
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by exiting a context manager. If a problem arises elsewhere – for example,
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because of a network failure, or because a remote peer closed their end of
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a connection – then that should be indicated by a different exception
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class, like :exc:`BrokenResourceError` or an :exc:`OSError` subclass.
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"""
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class BrokenResourceError(Exception):
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"""Raised when an attempt to use a resource fails due to external
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circumstances.
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For example, you might get this if you try to send data on a stream where
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the remote side has already closed the connection.
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You *don't* get this error if *you* closed the resource – in that case you
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get :class:`ClosedResourceError`.
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This exception's ``__cause__`` attribute will often contain more
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information about the underlying error.
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"""
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class EndOfChannel(Exception):
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"""Raised when trying to receive from a :class:`trio.abc.ReceiveChannel`
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that has no more data to receive.
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This is analogous to an "end-of-file" condition, but for channels.
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"""
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