You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
102 lines
2.7 KiB
102 lines
2.7 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
|
|
|
|
from typing import Dict
|
|
|
|
import dns.exception
|
|
|
|
# pylint: disable=unused-import
|
|
from dns._asyncbackend import ( # noqa: F401 lgtm[py/unused-import]
|
|
Backend,
|
|
DatagramSocket,
|
|
Socket,
|
|
StreamSocket,
|
|
)
|
|
|
|
# pylint: enable=unused-import
|
|
|
|
_default_backend = None
|
|
|
|
_backends: Dict[str, Backend] = {}
|
|
|
|
# Allow sniffio import to be disabled for testing purposes
|
|
_no_sniffio = False
|
|
|
|
|
|
class AsyncLibraryNotFoundError(dns.exception.DNSException):
|
|
pass
|
|
|
|
|
|
def get_backend(name: str) -> Backend:
|
|
"""Get the specified asynchronous backend.
|
|
|
|
*name*, a ``str``, the name of the backend. Currently the "trio"
|
|
and "asyncio" backends are available.
|
|
|
|
Raises NotImplementedError 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 == "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() -> str:
|
|
"""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")
|
|
|
|
|
|
def get_default_backend() -> 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: str) -> Backend:
|
|
"""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
|