Added delete option to database storage.

venv/Lib/site-packages/grpc/beta/utilities.py

@@ -0,0 +1,149 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
+"""Utilities for the gRPC Python Beta API."""
+
+import threading
+import time
+
+# implementations is referenced from specification in this module.
+from grpc.beta import implementations  # pylint: disable=unused-import
+from grpc.beta import interfaces
+from grpc.framework.foundation import callable_util
+from grpc.framework.foundation import future
+
+_DONE_CALLBACK_EXCEPTION_LOG_MESSAGE = (
+    'Exception calling connectivity future "done" callback!')
+
+
+class _ChannelReadyFuture(future.Future):
+
+    def __init__(self, channel):
+        self._condition = threading.Condition()
+        self._channel = channel
+
+        self._matured = False
+        self._cancelled = False
+        self._done_callbacks = []
+
+    def _block(self, timeout):
+        until = None if timeout is None else time.time() + timeout
+        with self._condition:
+            while True:
+                if self._cancelled:
+                    raise future.CancelledError()
+                elif self._matured:
+                    return
+                else:
+                    if until is None:
+                        self._condition.wait()
+                    else:
+                        remaining = until - time.time()
+                        if remaining < 0:
+                            raise future.TimeoutError()
+                        else:
+                            self._condition.wait(timeout=remaining)
+
+    def _update(self, connectivity):
+        with self._condition:
+            if (not self._cancelled and
+                    connectivity is interfaces.ChannelConnectivity.READY):
+                self._matured = True
+                self._channel.unsubscribe(self._update)
+                self._condition.notify_all()
+                done_callbacks = tuple(self._done_callbacks)
+                self._done_callbacks = None
+            else:
+                return
+
+        for done_callback in done_callbacks:
+            callable_util.call_logging_exceptions(
+                done_callback, _DONE_CALLBACK_EXCEPTION_LOG_MESSAGE, self)
+
+    def cancel(self):
+        with self._condition:
+            if not self._matured:
+                self._cancelled = True
+                self._channel.unsubscribe(self._update)
+                self._condition.notify_all()
+                done_callbacks = tuple(self._done_callbacks)
+                self._done_callbacks = None
+            else:
+                return False
+
+        for done_callback in done_callbacks:
+            callable_util.call_logging_exceptions(
+                done_callback, _DONE_CALLBACK_EXCEPTION_LOG_MESSAGE, self)
+
+        return True
+
+    def cancelled(self):
+        with self._condition:
+            return self._cancelled
+
+    def running(self):
+        with self._condition:
+            return not self._cancelled and not self._matured
+
+    def done(self):
+        with self._condition:
+            return self._cancelled or self._matured
+
+    def result(self, timeout=None):
+        self._block(timeout)
+        return None
+
+    def exception(self, timeout=None):
+        self._block(timeout)
+        return None
+
+    def traceback(self, timeout=None):
+        self._block(timeout)
+        return None
+
+    def add_done_callback(self, fn):
+        with self._condition:
+            if not self._cancelled and not self._matured:
+                self._done_callbacks.append(fn)
+                return
+
+        fn(self)
+
+    def start(self):
+        with self._condition:
+            self._channel.subscribe(self._update, try_to_connect=True)
+
+    def __del__(self):
+        with self._condition:
+            if not self._cancelled and not self._matured:
+                self._channel.unsubscribe(self._update)
+
+
+def channel_ready_future(channel):
+    """Creates a future.Future tracking when an implementations.Channel is ready.
+
+  Cancelling the returned future.Future does not tell the given
+  implementations.Channel to abandon attempts it may have been making to
+  connect; cancelling merely deactivates the return future.Future's
+  subscription to the given implementations.Channel's connectivity.
+
+  Args:
+    channel: An implementations.Channel.
+
+  Returns:
+    A future.Future that matures when the given Channel has connectivity
+      interfaces.ChannelConnectivity.READY.
+  """
+    ready_future = _ChannelReadyFuture(channel)
+    ready_future.start()
+    return ready_future