Remove grpc.beta._connectivity_channel

This should have been removed in, and has done anything but fail on
import since, 4d425522.

src/python/grpcio/grpc/beta/_connectivity_channel.py

-# Copyright 2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-"""Affords a connectivity-state-listenable channel."""
-
-import threading
-import time
-
-from grpc._adapter import _low
-from grpc._adapter import _types
-from grpc.beta import interfaces
-from grpc.framework.foundation import callable_util
-
-_CHANNEL_SUBSCRIPTION_CALLBACK_ERROR_LOG_MESSAGE = (
-    'Exception calling channel subscription callback!')
-
-_LOW_CONNECTIVITY_STATE_TO_CHANNEL_CONNECTIVITY = {
-    state: connectivity
-    for state, connectivity in zip(_types.ConnectivityState,
-                                   interfaces.ChannelConnectivity)
-}
-
-
-class ConnectivityChannel(object):
-
-    def __init__(self, low_channel):
-        self._lock = threading.Lock()
-        self._low_channel = low_channel
-
-        self._polling = False
-        self._connectivity = None
-        self._try_to_connect = False
-        self._callbacks_and_connectivities = []
-        self._delivering = False
-
-    def _deliveries(self, connectivity):
-        callbacks_needing_update = []
-        for callback_and_connectivity in self._callbacks_and_connectivities:
-            callback, callback_connectivity = callback_and_connectivity
-            if callback_connectivity is not connectivity:
-                callbacks_needing_update.append(callback)
-                callback_and_connectivity[1] = connectivity
-        return callbacks_needing_update
-
-    def _deliver(self, initial_connectivity, initial_callbacks):
-        connectivity = initial_connectivity
-        callbacks = initial_callbacks
-        while True:
-            for callback in callbacks:
-                callable_util.call_logging_exceptions(
-                    callback, _CHANNEL_SUBSCRIPTION_CALLBACK_ERROR_LOG_MESSAGE,
-                    connectivity)
-            with self._lock:
-                callbacks = self._deliveries(self._connectivity)
-                if callbacks:
-                    connectivity = self._connectivity
-                else:
-                    self._delivering = False
-                    return
-
-    def _spawn_delivery(self, connectivity, callbacks):
-        delivering_thread = threading.Thread(
-            target=self._deliver, args=(connectivity, callbacks,))
-        delivering_thread.start()
-        self._delivering = True
-
-    # TODO(issue 3064): Don't poll.
-    def _poll_connectivity(self, low_channel, initial_try_to_connect):
-        try_to_connect = initial_try_to_connect
-        low_connectivity = low_channel.check_connectivity_state(try_to_connect)
-        with self._lock:
-            self._connectivity = _LOW_CONNECTIVITY_STATE_TO_CHANNEL_CONNECTIVITY[
-                low_connectivity]
-            callbacks = tuple(
-                callback
-                for callback, unused_but_known_to_be_none_connectivity in
-                self._callbacks_and_connectivities)
-            for callback_and_connectivity in self._callbacks_and_connectivities:
-                callback_and_connectivity[1] = self._connectivity
-            if callbacks:
-                self._spawn_delivery(self._connectivity, callbacks)
-        completion_queue = _low.CompletionQueue()
-        while True:
-            low_channel.watch_connectivity_state(low_connectivity,
-                                                 time.time() + 0.2,
-                                                 completion_queue, None)
-            event = completion_queue.next()
-            with self._lock:
-                if not self._callbacks_and_connectivities and not self._try_to_connect:
-                    self._polling = False
-                    self._connectivity = None
-                    completion_queue.shutdown()
-                    break
-                try_to_connect = self._try_to_connect
-                self._try_to_connect = False
-            if event.success or try_to_connect:
-                low_connectivity = low_channel.check_connectivity_state(
-                    try_to_connect)
-                with self._lock:
-                    self._connectivity = _LOW_CONNECTIVITY_STATE_TO_CHANNEL_CONNECTIVITY[
-                        low_connectivity]
-                    if not self._delivering:
-                        callbacks = self._deliveries(self._connectivity)
-                        if callbacks:
-                            self._spawn_delivery(self._connectivity, callbacks)
-
-    def subscribe(self, callback, try_to_connect):
-        with self._lock:
-            if not self._callbacks_and_connectivities and not self._polling:
-                polling_thread = threading.Thread(
-                    target=self._poll_connectivity,
-                    args=(self._low_channel, bool(try_to_connect)))
-                polling_thread.start()
-                self._polling = True
-                self._callbacks_and_connectivities.append([callback, None])
-            elif not self._delivering and self._connectivity is not None:
-                self._spawn_delivery(self._connectivity, (callback,))
-                self._try_to_connect |= bool(try_to_connect)
-                self._callbacks_and_connectivities.append(
-                    [callback, self._connectivity])
-            else:
-                self._try_to_connect |= bool(try_to_connect)
-                self._callbacks_and_connectivities.append([callback, None])
-
-    def unsubscribe(self, callback):
-        with self._lock:
-            for index, (subscribed_callback, unused_connectivity
-                       ) in enumerate(self._callbacks_and_connectivities):
-                if callback == subscribed_callback:
-                    self._callbacks_and_connectivities.pop(index)
-                    break
-
-    def low_channel(self):
-        return self._low_channel