plexpy/lib/dns/asyncbackend.py
dependabot[bot] 3c93b5600f
Bump dnspython from 2.0.0 to 2.2.0 (#1618)
* Bump dnspython from 2.0.0 to 2.2.0

Bumps [dnspython]() from 2.0.0 to 2.2.0.

---
updated-dependencies:
- dependency-name: dnspython
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update dnspython==2.2.0

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]
2022-01-25 11:08:24 -08:00

102 lines
3.0 KiB
Python

# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
import dns.exception
# pylint: disable=unused-import
from dns._asyncbackend import Socket, DatagramSocket, \
StreamSocket, Backend # noqa:
# pylint: enable=unused-import
_default_backend = None
_backends = {}
# Allow sniffio import to be disabled for testing purposes
_no_sniffio = False
class AsyncLibraryNotFoundError(dns.exception.DNSException):
pass
def get_backend(name):
"""Get the specified asynchronous backend.
*name*, a ``str``, the name of the backend. Currently the "trio",
"curio", and "asyncio" backends are available.
Raises NotImplementError if an unknown backend name is specified.
"""
# pylint: disable=import-outside-toplevel,redefined-outer-name
backend = _backends.get(name)
if backend:
return backend
if name == 'trio':
import dns._trio_backend
backend = dns._trio_backend.Backend()
elif name == 'curio':
import dns._curio_backend
backend = dns._curio_backend.Backend()
elif name == 'asyncio':
import dns._asyncio_backend
backend = dns._asyncio_backend.Backend()
else:
raise NotImplementedError(f'unimplemented async backend {name}')
_backends[name] = backend
return backend
def sniff():
"""Attempt to determine the in-use asynchronous I/O library by using
the ``sniffio`` module if it is available.
Returns the name of the library, or raises AsyncLibraryNotFoundError
if the library cannot be determined.
"""
# pylint: disable=import-outside-toplevel
try:
if _no_sniffio:
raise ImportError
import sniffio
try:
return sniffio.current_async_library()
except sniffio.AsyncLibraryNotFoundError:
raise AsyncLibraryNotFoundError('sniffio cannot determine ' +
'async library')
except ImportError:
import asyncio
try:
asyncio.get_running_loop()
return 'asyncio'
except RuntimeError:
raise AsyncLibraryNotFoundError('no async library detected')
except AttributeError: # pragma: no cover
# we have to check current_task on 3.6
if not asyncio.Task.current_task():
raise AsyncLibraryNotFoundError('no async library detected')
return 'asyncio'
def get_default_backend():
"""Get the default backend, initializing it if necessary.
"""
if _default_backend:
return _default_backend
return set_default_backend(sniff())
def set_default_backend(name):
"""Set the default backend.
It's not normally necessary to call this method, as
``get_default_backend()`` will initialize the backend
appropriately in many cases. If ``sniffio`` is not installed, or
in testing situations, this function allows the backend to be set
explicitly.
"""
global _default_backend
_default_backend = get_backend(name)
return _default_backend