Uploaded Test files

venv/Lib/site-packages/tornado/platform/asyncio.py

@@ -0,0 +1,611 @@
+"""Bridges between the `asyncio` module and Tornado IOLoop.
+
+.. versionadded:: 3.2
+
+This module integrates Tornado with the ``asyncio`` module introduced
+in Python 3.4. This makes it possible to combine the two libraries on
+the same event loop.
+
+.. deprecated:: 5.0
+
+   While the code in this module is still used, it is now enabled
+   automatically when `asyncio` is available, so applications should
+   no longer need to refer to this module directly.
+
+.. note::
+
+   Tornado is designed to use a selector-based event loop. On Windows,
+   where a proactor-based event loop has been the default since Python 3.8,
+   a selector event loop is emulated by running ``select`` on a separate thread.
+   Configuring ``asyncio`` to use a selector event loop may improve performance
+   of Tornado (but may reduce performance of other ``asyncio``-based libraries
+   in the same process).
+"""
+
+import asyncio
+import atexit
+import concurrent.futures
+import errno
+import functools
+import select
+import socket
+import sys
+import threading
+import typing
+from tornado.gen import convert_yielded
+from tornado.ioloop import IOLoop, _Selectable
+
+from typing import Any, TypeVar, Awaitable, Callable, Union, Optional, List, Tuple, Dict
+
+if typing.TYPE_CHECKING:
+    from typing import Set  # noqa: F401
+    from typing_extensions import Protocol
+
+    class _HasFileno(Protocol):
+        def fileno(self) -> int:
+            pass
+
+    _FileDescriptorLike = Union[int, _HasFileno]
+
+_T = TypeVar("_T")
+
+
+# Collection of selector thread event loops to shut down on exit.
+_selector_loops = set()  # type: Set[AddThreadSelectorEventLoop]
+
+
+def _atexit_callback() -> None:
+    for loop in _selector_loops:
+        with loop._select_cond:
+            loop._closing_selector = True
+            loop._select_cond.notify()
+        try:
+            loop._waker_w.send(b"a")
+        except BlockingIOError:
+            pass
+        # If we don't join our (daemon) thread here, we may get a deadlock
+        # during interpreter shutdown. I don't really understand why. This
+        # deadlock happens every time in CI (both travis and appveyor) but
+        # I've never been able to reproduce locally.
+        loop._thread.join()
+    _selector_loops.clear()
+
+
+atexit.register(_atexit_callback)
+
+
+class BaseAsyncIOLoop(IOLoop):
+    def initialize(  # type: ignore
+        self, asyncio_loop: asyncio.AbstractEventLoop, **kwargs: Any
+    ) -> None:
+        # asyncio_loop is always the real underlying IOLoop. This is used in
+        # ioloop.py to maintain the asyncio-to-ioloop mappings.
+        self.asyncio_loop = asyncio_loop
+        # selector_loop is an event loop that implements the add_reader family of
+        # methods. Usually the same as asyncio_loop but differs on platforms such
+        # as windows where the default event loop does not implement these methods.
+        self.selector_loop = asyncio_loop
+        if hasattr(asyncio, "ProactorEventLoop") and isinstance(
+            asyncio_loop, asyncio.ProactorEventLoop  # type: ignore
+        ):
+            # Ignore this line for mypy because the abstract method checker
+            # doesn't understand dynamic proxies.
+            self.selector_loop = AddThreadSelectorEventLoop(asyncio_loop)  # type: ignore
+        # Maps fd to (fileobj, handler function) pair (as in IOLoop.add_handler)
+        self.handlers = {}  # type: Dict[int, Tuple[Union[int, _Selectable], Callable]]
+        # Set of fds listening for reads/writes
+        self.readers = set()  # type: Set[int]
+        self.writers = set()  # type: Set[int]
+        self.closing = False
+        # If an asyncio loop was closed through an asyncio interface
+        # instead of IOLoop.close(), we'd never hear about it and may
+        # have left a dangling reference in our map. In case an
+        # application (or, more likely, a test suite) creates and
+        # destroys a lot of event loops in this way, check here to
+        # ensure that we don't have a lot of dead loops building up in
+        # the map.
+        #
+        # TODO(bdarnell): consider making self.asyncio_loop a weakref
+        # for AsyncIOMainLoop and make _ioloop_for_asyncio a
+        # WeakKeyDictionary.
+        for loop in list(IOLoop._ioloop_for_asyncio):
+            if loop.is_closed():
+                del IOLoop._ioloop_for_asyncio[loop]
+        IOLoop._ioloop_for_asyncio[asyncio_loop] = self
+
+        self._thread_identity = 0
+
+        super().initialize(**kwargs)
+
+        def assign_thread_identity() -> None:
+            self._thread_identity = threading.get_ident()
+
+        self.add_callback(assign_thread_identity)
+
+    def close(self, all_fds: bool = False) -> None:
+        self.closing = True
+        for fd in list(self.handlers):
+            fileobj, handler_func = self.handlers[fd]
+            self.remove_handler(fd)
+            if all_fds:
+                self.close_fd(fileobj)
+        # Remove the mapping before closing the asyncio loop. If this
+        # happened in the other order, we could race against another
+        # initialize() call which would see the closed asyncio loop,
+        # assume it was closed from the asyncio side, and do this
+        # cleanup for us, leading to a KeyError.
+        del IOLoop._ioloop_for_asyncio[self.asyncio_loop]
+        if self.selector_loop is not self.asyncio_loop:
+            self.selector_loop.close()
+        self.asyncio_loop.close()
+
+    def add_handler(
+        self, fd: Union[int, _Selectable], handler: Callable[..., None], events: int
+    ) -> None:
+        fd, fileobj = self.split_fd(fd)
+        if fd in self.handlers:
+            raise ValueError("fd %s added twice" % fd)
+        self.handlers[fd] = (fileobj, handler)
+        if events & IOLoop.READ:
+            self.selector_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
+            self.readers.add(fd)
+        if events & IOLoop.WRITE:
+            self.selector_loop.add_writer(fd, self._handle_events, fd, IOLoop.WRITE)
+            self.writers.add(fd)
+
+    def update_handler(self, fd: Union[int, _Selectable], events: int) -> None:
+        fd, fileobj = self.split_fd(fd)
+        if events & IOLoop.READ:
+            if fd not in self.readers:
+                self.selector_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
+                self.readers.add(fd)
+        else:
+            if fd in self.readers:
+                self.selector_loop.remove_reader(fd)
+                self.readers.remove(fd)
+        if events & IOLoop.WRITE:
+            if fd not in self.writers:
+                self.selector_loop.add_writer(fd, self._handle_events, fd, IOLoop.WRITE)
+                self.writers.add(fd)
+        else:
+            if fd in self.writers:
+                self.selector_loop.remove_writer(fd)
+                self.writers.remove(fd)
+
+    def remove_handler(self, fd: Union[int, _Selectable]) -> None:
+        fd, fileobj = self.split_fd(fd)
+        if fd not in self.handlers:
+            return
+        if fd in self.readers:
+            self.selector_loop.remove_reader(fd)
+            self.readers.remove(fd)
+        if fd in self.writers:
+            self.selector_loop.remove_writer(fd)
+            self.writers.remove(fd)
+        del self.handlers[fd]
+
+    def _handle_events(self, fd: int, events: int) -> None:
+        fileobj, handler_func = self.handlers[fd]
+        handler_func(fileobj, events)
+
+    def start(self) -> None:
+        try:
+            old_loop = asyncio.get_event_loop()
+        except (RuntimeError, AssertionError):
+            old_loop = None  # type: ignore
+        try:
+            self._setup_logging()
+            asyncio.set_event_loop(self.asyncio_loop)
+            self.asyncio_loop.run_forever()
+        finally:
+            asyncio.set_event_loop(old_loop)
+
+    def stop(self) -> None:
+        self.asyncio_loop.stop()
+
+    def call_at(
+        self, when: float, callback: Callable[..., None], *args: Any, **kwargs: Any
+    ) -> object:
+        # asyncio.call_at supports *args but not **kwargs, so bind them here.
+        # We do not synchronize self.time and asyncio_loop.time, so
+        # convert from absolute to relative.
+        return self.asyncio_loop.call_later(
+            max(0, when - self.time()),
+            self._run_callback,
+            functools.partial(callback, *args, **kwargs),
+        )
+
+    def remove_timeout(self, timeout: object) -> None:
+        timeout.cancel()  # type: ignore
+
+    def add_callback(self, callback: Callable, *args: Any, **kwargs: Any) -> None:
+        if threading.get_ident() == self._thread_identity:
+            call_soon = self.asyncio_loop.call_soon
+        else:
+            call_soon = self.asyncio_loop.call_soon_threadsafe
+        try:
+            call_soon(self._run_callback, functools.partial(callback, *args, **kwargs))
+        except RuntimeError:
+            # "Event loop is closed". Swallow the exception for
+            # consistency with PollIOLoop (and logical consistency
+            # with the fact that we can't guarantee that an
+            # add_callback that completes without error will
+            # eventually execute).
+            pass
+        except AttributeError:
+            # ProactorEventLoop may raise this instead of RuntimeError
+            # if call_soon_threadsafe races with a call to close().
+            # Swallow it too for consistency.
+            pass
+
+    def add_callback_from_signal(
+        self, callback: Callable, *args: Any, **kwargs: Any
+    ) -> None:
+        try:
+            self.asyncio_loop.call_soon_threadsafe(
+                self._run_callback, functools.partial(callback, *args, **kwargs)
+            )
+        except RuntimeError:
+            pass
+
+    def run_in_executor(
+        self,
+        executor: Optional[concurrent.futures.Executor],
+        func: Callable[..., _T],
+        *args: Any
+    ) -> Awaitable[_T]:
+        return self.asyncio_loop.run_in_executor(executor, func, *args)
+
+    def set_default_executor(self, executor: concurrent.futures.Executor) -> None:
+        return self.asyncio_loop.set_default_executor(executor)
+
+
+class AsyncIOMainLoop(BaseAsyncIOLoop):
+    """``AsyncIOMainLoop`` creates an `.IOLoop` that corresponds to the
+    current ``asyncio`` event loop (i.e. the one returned by
+    ``asyncio.get_event_loop()``).
+
+    .. deprecated:: 5.0
+
+       Now used automatically when appropriate; it is no longer necessary
+       to refer to this class directly.
+
+    .. versionchanged:: 5.0
+
+       Closing an `AsyncIOMainLoop` now closes the underlying asyncio loop.
+    """
+
+    def initialize(self, **kwargs: Any) -> None:  # type: ignore
+        super().initialize(asyncio.get_event_loop(), **kwargs)
+
+    def make_current(self) -> None:
+        # AsyncIOMainLoop already refers to the current asyncio loop so
+        # nothing to do here.
+        pass
+
+
+class AsyncIOLoop(BaseAsyncIOLoop):
+    """``AsyncIOLoop`` is an `.IOLoop` that runs on an ``asyncio`` event loop.
+    This class follows the usual Tornado semantics for creating new
+    ``IOLoops``; these loops are not necessarily related to the
+    ``asyncio`` default event loop.
+
+    Each ``AsyncIOLoop`` creates a new ``asyncio.EventLoop``; this object
+    can be accessed with the ``asyncio_loop`` attribute.
+
+    .. versionchanged:: 5.0
+
+       When an ``AsyncIOLoop`` becomes the current `.IOLoop`, it also sets
+       the current `asyncio` event loop.
+
+    .. deprecated:: 5.0
+
+       Now used automatically when appropriate; it is no longer necessary
+       to refer to this class directly.
+    """
+
+    def initialize(self, **kwargs: Any) -> None:  # type: ignore
+        self.is_current = False
+        loop = asyncio.new_event_loop()
+        try:
+            super().initialize(loop, **kwargs)
+        except Exception:
+            # If initialize() does not succeed (taking ownership of the loop),
+            # we have to close it.
+            loop.close()
+            raise
+
+    def close(self, all_fds: bool = False) -> None:
+        if self.is_current:
+            self.clear_current()
+        super().close(all_fds=all_fds)
+
+    def make_current(self) -> None:
+        if not self.is_current:
+            try:
+                self.old_asyncio = asyncio.get_event_loop()
+            except (RuntimeError, AssertionError):
+                self.old_asyncio = None  # type: ignore
+            self.is_current = True
+        asyncio.set_event_loop(self.asyncio_loop)
+
+    def _clear_current_hook(self) -> None:
+        if self.is_current:
+            asyncio.set_event_loop(self.old_asyncio)
+            self.is_current = False
+
+
+def to_tornado_future(asyncio_future: asyncio.Future) -> asyncio.Future:
+    """Convert an `asyncio.Future` to a `tornado.concurrent.Future`.
+
+    .. versionadded:: 4.1
+
+    .. deprecated:: 5.0
+       Tornado ``Futures`` have been merged with `asyncio.Future`,
+       so this method is now a no-op.
+    """
+    return asyncio_future
+
+
+def to_asyncio_future(tornado_future: asyncio.Future) -> asyncio.Future:
+    """Convert a Tornado yieldable object to an `asyncio.Future`.
+
+    .. versionadded:: 4.1
+
+    .. versionchanged:: 4.3
+       Now accepts any yieldable object, not just
+       `tornado.concurrent.Future`.
+
+    .. deprecated:: 5.0
+       Tornado ``Futures`` have been merged with `asyncio.Future`,
+       so this method is now equivalent to `tornado.gen.convert_yielded`.
+    """
+    return convert_yielded(tornado_future)
+
+
+if sys.platform == "win32" and hasattr(asyncio, "WindowsSelectorEventLoopPolicy"):
+    # "Any thread" and "selector" should be orthogonal, but there's not a clean
+    # interface for composing policies so pick the right base.
+    _BasePolicy = asyncio.WindowsSelectorEventLoopPolicy  # type: ignore
+else:
+    _BasePolicy = asyncio.DefaultEventLoopPolicy
+
+
+class AnyThreadEventLoopPolicy(_BasePolicy):  # type: ignore
+    """Event loop policy that allows loop creation on any thread.
+
+    The default `asyncio` event loop policy only automatically creates
+    event loops in the main threads. Other threads must create event
+    loops explicitly or `asyncio.get_event_loop` (and therefore
+    `.IOLoop.current`) will fail. Installing this policy allows event
+    loops to be created automatically on any thread, matching the
+    behavior of Tornado versions prior to 5.0 (or 5.0 on Python 2).
+
+    Usage::
+
+        asyncio.set_event_loop_policy(AnyThreadEventLoopPolicy())
+
+    .. versionadded:: 5.0
+
+    """
+
+    def get_event_loop(self) -> asyncio.AbstractEventLoop:
+        try:
+            return super().get_event_loop()
+        except (RuntimeError, AssertionError):
+            # This was an AssertionError in Python 3.4.2 (which ships with Debian Jessie)
+            # and changed to a RuntimeError in 3.4.3.
+            # "There is no current event loop in thread %r"
+            loop = self.new_event_loop()
+            self.set_event_loop(loop)
+            return loop
+
+
+class AddThreadSelectorEventLoop(asyncio.AbstractEventLoop):
+    """Wrap an event loop to add implementations of the ``add_reader`` method family.
+
+    Instances of this class start a second thread to run a selector.
+    This thread is completely hidden from the user; all callbacks are
+    run on the wrapped event loop's thread.
+
+    This class is used automatically by Tornado; applications should not need
+    to refer to it directly.
+
+    It is safe to wrap any event loop with this class, although it only makes sense
+    for event loops that do not implement the ``add_reader`` family of methods
+    themselves (i.e. ``WindowsProactorEventLoop``)
+
+    Closing the ``AddThreadSelectorEventLoop`` also closes the wrapped event loop.
+
+    """
+
+    # This class is a __getattribute__-based proxy. All attributes other than those
+    # in this set are proxied through to the underlying loop.
+    MY_ATTRIBUTES = {
+        "_consume_waker",
+        "_select_cond",
+        "_select_args",
+        "_closing_selector",
+        "_thread",
+        "_handle_event",
+        "_readers",
+        "_real_loop",
+        "_start_select",
+        "_run_select",
+        "_handle_select",
+        "_wake_selector",
+        "_waker_r",
+        "_waker_w",
+        "_writers",
+        "add_reader",
+        "add_writer",
+        "close",
+        "remove_reader",
+        "remove_writer",
+    }
+
+    def __getattribute__(self, name: str) -> Any:
+        if name in AddThreadSelectorEventLoop.MY_ATTRIBUTES:
+            return super().__getattribute__(name)
+        return getattr(self._real_loop, name)
+
+    def __init__(self, real_loop: asyncio.AbstractEventLoop) -> None:
+        self._real_loop = real_loop
+
+        # Create a thread to run the select system call. We manage this thread
+        # manually so we can trigger a clean shutdown from an atexit hook. Note
+        # that due to the order of operations at shutdown, only daemon threads
+        # can be shut down in this way (non-daemon threads would require the
+        # introduction of a new hook: https://bugs.python.org/issue41962)
+        self._select_cond = threading.Condition()
+        self._select_args = (
+            None
+        )  # type: Optional[Tuple[List[_FileDescriptorLike], List[_FileDescriptorLike]]]
+        self._closing_selector = False
+        self._thread = threading.Thread(
+            name="Tornado selector", daemon=True, target=self._run_select,
+        )
+        self._thread.start()
+        # Start the select loop once the loop is started.
+        self._real_loop.call_soon(self._start_select)
+
+        self._readers = {}  # type: Dict[_FileDescriptorLike, Callable]
+        self._writers = {}  # type: Dict[_FileDescriptorLike, Callable]
+
+        # Writing to _waker_w will wake up the selector thread, which
+        # watches for _waker_r to be readable.
+        self._waker_r, self._waker_w = socket.socketpair()
+        self._waker_r.setblocking(False)
+        self._waker_w.setblocking(False)
+        _selector_loops.add(self)
+        self.add_reader(self._waker_r, self._consume_waker)
+
+    def __del__(self) -> None:
+        # If the top-level application code uses asyncio interfaces to
+        # start and stop the event loop, no objects created in Tornado
+        # can get a clean shutdown notification. If we're just left to
+        # be GC'd, we must explicitly close our sockets to avoid
+        # logging warnings.
+        _selector_loops.discard(self)
+        self._waker_r.close()
+        self._waker_w.close()
+
+    def close(self) -> None:
+        with self._select_cond:
+            self._closing_selector = True
+            self._select_cond.notify()
+        self._wake_selector()
+        self._thread.join()
+        _selector_loops.discard(self)
+        self._waker_r.close()
+        self._waker_w.close()
+        self._real_loop.close()
+
+    def _wake_selector(self) -> None:
+        try:
+            self._waker_w.send(b"a")
+        except BlockingIOError:
+            pass
+
+    def _consume_waker(self) -> None:
+        try:
+            self._waker_r.recv(1024)
+        except BlockingIOError:
+            pass
+
+    def _start_select(self) -> None:
+        # Capture reader and writer sets here in the event loop
+        # thread to avoid any problems with concurrent
+        # modification while the select loop uses them.
+        with self._select_cond:
+            assert self._select_args is None
+            self._select_args = (list(self._readers.keys()), list(self._writers.keys()))
+            self._select_cond.notify()
+
+    def _run_select(self) -> None:
+        while True:
+            with self._select_cond:
+                while self._select_args is None and not self._closing_selector:
+                    self._select_cond.wait()
+                if self._closing_selector:
+                    return
+                assert self._select_args is not None
+                to_read, to_write = self._select_args
+                self._select_args = None
+
+            # We use the simpler interface of the select module instead of
+            # the more stateful interface in the selectors module because
+            # this class is only intended for use on windows, where
+            # select.select is the only option. The selector interface
+            # does not have well-documented thread-safety semantics that
+            # we can rely on so ensuring proper synchronization would be
+            # tricky.
+            try:
+                # On windows, selecting on a socket for write will not
+                # return the socket when there is an error (but selecting
+                # for reads works). Also select for errors when selecting
+                # for writes, and merge the results.
+                #
+                # This pattern is also used in
+                # https://github.com/python/cpython/blob/v3.8.0/Lib/selectors.py#L312-L317
+                rs, ws, xs = select.select(to_read, to_write, to_write)
+                ws = ws + xs
+            except OSError as e:
+                # After remove_reader or remove_writer is called, the file
+                # descriptor may subsequently be closed on the event loop
+                # thread. It's possible that this select thread hasn't
+                # gotten into the select system call by the time that
+                # happens in which case (at least on macOS), select may
+                # raise a "bad file descriptor" error. If we get that
+                # error, check and see if we're also being woken up by
+                # polling the waker alone. If we are, just return to the
+                # event loop and we'll get the updated set of file
+                # descriptors on the next iteration. Otherwise, raise the
+                # original error.
+                if e.errno == getattr(errno, "WSAENOTSOCK", errno.EBADF):
+                    rs, _, _ = select.select([self._waker_r.fileno()], [], [], 0)
+                    if rs:
+                        ws = []
+                    else:
+                        raise
+                else:
+                    raise
+            self._real_loop.call_soon_threadsafe(self._handle_select, rs, ws)
+
+    def _handle_select(
+        self, rs: List["_FileDescriptorLike"], ws: List["_FileDescriptorLike"]
+    ) -> None:
+        for r in rs:
+            self._handle_event(r, self._readers)
+        for w in ws:
+            self._handle_event(w, self._writers)
+        self._start_select()
+
+    def _handle_event(
+        self, fd: "_FileDescriptorLike", cb_map: Dict["_FileDescriptorLike", Callable],
+    ) -> None:
+        try:
+            callback = cb_map[fd]
+        except KeyError:
+            return
+        callback()
+
+    def add_reader(
+        self, fd: "_FileDescriptorLike", callback: Callable[..., None], *args: Any
+    ) -> None:
+        self._readers[fd] = functools.partial(callback, *args)
+        self._wake_selector()
+
+    def add_writer(
+        self, fd: "_FileDescriptorLike", callback: Callable[..., None], *args: Any
+    ) -> None:
+        self._writers[fd] = functools.partial(callback, *args)
+        self._wake_selector()
+
+    def remove_reader(self, fd: "_FileDescriptorLike") -> None:
+        del self._readers[fd]
+        self._wake_selector()
+
+    def remove_writer(self, fd: "_FileDescriptorLike") -> None:
+        del self._writers[fd]
+        self._wake_selector()

venv/Lib/site-packages/tornado/platform/caresresolver.py

@@ -0,0 +1,89 @@
+import pycares  # type: ignore
+import socket
+
+from tornado.concurrent import Future
+from tornado import gen
+from tornado.ioloop import IOLoop
+from tornado.netutil import Resolver, is_valid_ip
+
+import typing
+
+if typing.TYPE_CHECKING:
+    from typing import Generator, Any, List, Tuple, Dict  # noqa: F401
+
+
+class CaresResolver(Resolver):
+    """Name resolver based on the c-ares library.
+
+    This is a non-blocking and non-threaded resolver.  It may not produce
+    the same results as the system resolver, but can be used for non-blocking
+    resolution when threads cannot be used.
+
+    c-ares fails to resolve some names when ``family`` is ``AF_UNSPEC``,
+    so it is only recommended for use in ``AF_INET`` (i.e. IPv4).  This is
+    the default for ``tornado.simple_httpclient``, but other libraries
+    may default to ``AF_UNSPEC``.
+
+    .. versionchanged:: 5.0
+       The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+    """
+
+    def initialize(self) -> None:
+        self.io_loop = IOLoop.current()
+        self.channel = pycares.Channel(sock_state_cb=self._sock_state_cb)
+        self.fds = {}  # type: Dict[int, int]
+
+    def _sock_state_cb(self, fd: int, readable: bool, writable: bool) -> None:
+        state = (IOLoop.READ if readable else 0) | (IOLoop.WRITE if writable else 0)
+        if not state:
+            self.io_loop.remove_handler(fd)
+            del self.fds[fd]
+        elif fd in self.fds:
+            self.io_loop.update_handler(fd, state)
+            self.fds[fd] = state
+        else:
+            self.io_loop.add_handler(fd, self._handle_events, state)
+            self.fds[fd] = state
+
+    def _handle_events(self, fd: int, events: int) -> None:
+        read_fd = pycares.ARES_SOCKET_BAD
+        write_fd = pycares.ARES_SOCKET_BAD
+        if events & IOLoop.READ:
+            read_fd = fd
+        if events & IOLoop.WRITE:
+            write_fd = fd
+        self.channel.process_fd(read_fd, write_fd)
+
+    @gen.coroutine
+    def resolve(
+        self, host: str, port: int, family: int = 0
+    ) -> "Generator[Any, Any, List[Tuple[int, Any]]]":
+        if is_valid_ip(host):
+            addresses = [host]
+        else:
+            # gethostbyname doesn't take callback as a kwarg
+            fut = Future()  # type: Future[Tuple[Any, Any]]
+            self.channel.gethostbyname(
+                host, family, lambda result, error: fut.set_result((result, error))
+            )
+            result, error = yield fut
+            if error:
+                raise IOError(
+                    "C-Ares returned error %s: %s while resolving %s"
+                    % (error, pycares.errno.strerror(error), host)
+                )
+            addresses = result.addresses
+        addrinfo = []
+        for address in addresses:
+            if "." in address:
+                address_family = socket.AF_INET
+            elif ":" in address:
+                address_family = socket.AF_INET6
+            else:
+                address_family = socket.AF_UNSPEC
+            if family != socket.AF_UNSPEC and family != address_family:
+                raise IOError(
+                    "Requested socket family %d but got %d" % (family, address_family)
+                )
+            addrinfo.append((typing.cast(int, address_family), (address, port)))
+        return addrinfo

venv/Lib/site-packages/tornado/platform/twisted.py

@@ -0,0 +1,146 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+"""Bridges between the Twisted package and Tornado.
+"""
+
+import socket
+import sys
+
+import twisted.internet.abstract  # type: ignore
+import twisted.internet.asyncioreactor  # type: ignore
+from twisted.internet.defer import Deferred  # type: ignore
+from twisted.python import failure  # type: ignore
+import twisted.names.cache  # type: ignore
+import twisted.names.client  # type: ignore
+import twisted.names.hosts  # type: ignore
+import twisted.names.resolve  # type: ignore
+
+
+from tornado.concurrent import Future, future_set_exc_info
+from tornado.escape import utf8
+from tornado import gen
+from tornado.netutil import Resolver
+
+import typing
+
+if typing.TYPE_CHECKING:
+    from typing import Generator, Any, List, Tuple  # noqa: F401
+
+
+class TwistedResolver(Resolver):
+    """Twisted-based asynchronous resolver.
+
+    This is a non-blocking and non-threaded resolver.  It is
+    recommended only when threads cannot be used, since it has
+    limitations compared to the standard ``getaddrinfo``-based
+    `~tornado.netutil.Resolver` and
+    `~tornado.netutil.DefaultExecutorResolver`.  Specifically, it returns at
+    most one result, and arguments other than ``host`` and ``family``
+    are ignored.  It may fail to resolve when ``family`` is not
+    ``socket.AF_UNSPEC``.
+
+    Requires Twisted 12.1 or newer.
+
+    .. versionchanged:: 5.0
+       The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+    """
+
+    def initialize(self) -> None:
+        # partial copy of twisted.names.client.createResolver, which doesn't
+        # allow for a reactor to be passed in.
+        self.reactor = twisted.internet.asyncioreactor.AsyncioSelectorReactor()
+
+        host_resolver = twisted.names.hosts.Resolver("/etc/hosts")
+        cache_resolver = twisted.names.cache.CacheResolver(reactor=self.reactor)
+        real_resolver = twisted.names.client.Resolver(
+            "/etc/resolv.conf", reactor=self.reactor
+        )
+        self.resolver = twisted.names.resolve.ResolverChain(
+            [host_resolver, cache_resolver, real_resolver]
+        )
+
+    @gen.coroutine
+    def resolve(
+        self, host: str, port: int, family: int = 0
+    ) -> "Generator[Any, Any, List[Tuple[int, Any]]]":
+        # getHostByName doesn't accept IP addresses, so if the input
+        # looks like an IP address just return it immediately.
+        if twisted.internet.abstract.isIPAddress(host):
+            resolved = host
+            resolved_family = socket.AF_INET
+        elif twisted.internet.abstract.isIPv6Address(host):
+            resolved = host
+            resolved_family = socket.AF_INET6
+        else:
+            deferred = self.resolver.getHostByName(utf8(host))
+            fut = Future()  # type: Future[Any]
+            deferred.addBoth(fut.set_result)
+            resolved = yield fut
+            if isinstance(resolved, failure.Failure):
+                try:
+                    resolved.raiseException()
+                except twisted.names.error.DomainError as e:
+                    raise IOError(e)
+            elif twisted.internet.abstract.isIPAddress(resolved):
+                resolved_family = socket.AF_INET
+            elif twisted.internet.abstract.isIPv6Address(resolved):
+                resolved_family = socket.AF_INET6
+            else:
+                resolved_family = socket.AF_UNSPEC
+        if family != socket.AF_UNSPEC and family != resolved_family:
+            raise Exception(
+                "Requested socket family %d but got %d" % (family, resolved_family)
+            )
+        result = [(typing.cast(int, resolved_family), (resolved, port))]
+        return result
+
+
+def install() -> None:
+    """Install ``AsyncioSelectorReactor`` as the default Twisted reactor.
+
+    .. deprecated:: 5.1
+
+       This function is provided for backwards compatibility; code
+       that does not require compatibility with older versions of
+       Tornado should use
+       ``twisted.internet.asyncioreactor.install()`` directly.
+
+    .. versionchanged:: 6.0.3
+
+       In Tornado 5.x and before, this function installed a reactor
+       based on the Tornado ``IOLoop``. When that reactor
+       implementation was removed in Tornado 6.0.0, this function was
+       removed as well. It was restored in Tornado 6.0.3 using the
+       ``asyncio`` reactor instead.
+
+    """
+    from twisted.internet.asyncioreactor import install
+
+    install()
+
+
+if hasattr(gen.convert_yielded, "register"):
+
+    @gen.convert_yielded.register(Deferred)  # type: ignore
+    def _(d: Deferred) -> Future:
+        f = Future()  # type: Future[Any]
+
+        def errback(failure: failure.Failure) -> None:
+            try:
+                failure.raiseException()
+                # Should never happen, but just in case
+                raise Exception("errback called without error")
+            except:
+                future_set_exc_info(f, sys.exc_info())
+
+        d.addCallbacks(f.set_result, errback)
+        return f