cpython/Doc/library/asyncio-exceptions.rst

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.. currentmodule:: asyncio
.. _asyncio-exceptions:
==========
Exceptions
==========
.. exception:: TimeoutError
The operation has exceeded the given deadline.
.. important::
This exception is different from the builtin :exc:`TimeoutError`
exception.
.. exception:: CancelledError
The operation has been cancelled.
This exception can be caught to perform custom operations
when asyncio Tasks are cancelled. In almost all situations the
exception must always be re-raised.
.. important::
This exception is a subclass of :exc:`Exception`, so it can be
accidentally suppressed by ``try..except`` block::
try:
await operation
except Exception:
# The cancellation is broken because the *except* block
# suppresses the CancelledError exception.
log.log('an error has occurred')
Instead, the following pattern should be used::
try:
await operation
except asyncio.CancelledError:
raise
except Exception:
log.log('an error has occurred')
.. exception:: InvalidStateError
Invalid internal state of :class:`Task` or :class:`Future`.
Can be raised in situations like setting a result value for a
*Future* object that already has a result value set.
.. exception:: SendfileNotAvailableError
The "sendfile" syscall is not available for the given
socket or file type.
A subclass of :exc:`RuntimeError`.
.. exception:: IncompleteReadError
Incomplete read error.
Raised by :ref:`asyncio streams <asyncio-streams>` APIs.
This exception is a subclass of :exc:`EOFError`.
.. attribute:: expected
Total number (:class:`int`) of expected bytes.
.. attribute:: partial
Read :class:`bytes` string before the end of stream was reached.
.. exception:: LimitOverrunError
Reached the buffer limit while looking for a separator.
Raised by :ref:`asyncio streams <asyncio-streams>` APIs.
.. attribute:: consumed
Total number of to be consumed bytes.