149 lines
4.8 KiB
Python
149 lines
4.8 KiB
Python
# Copyright 2015 gRPC authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utilities for the gRPC Python Beta API."""
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import threading
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import time
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# implementations is referenced from specification in this module.
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from grpc.beta import implementations # pylint: disable=unused-import
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from grpc.beta import interfaces
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from grpc.framework.foundation import callable_util
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from grpc.framework.foundation import future
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_DONE_CALLBACK_EXCEPTION_LOG_MESSAGE = (
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'Exception calling connectivity future "done" callback!')
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class _ChannelReadyFuture(future.Future):
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def __init__(self, channel):
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self._condition = threading.Condition()
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self._channel = channel
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self._matured = False
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self._cancelled = False
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self._done_callbacks = []
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def _block(self, timeout):
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until = None if timeout is None else time.time() + timeout
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with self._condition:
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while True:
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if self._cancelled:
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raise future.CancelledError()
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elif self._matured:
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return
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else:
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if until is None:
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self._condition.wait()
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else:
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remaining = until - time.time()
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if remaining < 0:
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raise future.TimeoutError()
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else:
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self._condition.wait(timeout=remaining)
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def _update(self, connectivity):
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with self._condition:
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if (not self._cancelled and
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connectivity is interfaces.ChannelConnectivity.READY):
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self._matured = True
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self._channel.unsubscribe(self._update)
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self._condition.notify_all()
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done_callbacks = tuple(self._done_callbacks)
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self._done_callbacks = None
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else:
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return
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for done_callback in done_callbacks:
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callable_util.call_logging_exceptions(
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done_callback, _DONE_CALLBACK_EXCEPTION_LOG_MESSAGE, self)
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def cancel(self):
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with self._condition:
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if not self._matured:
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self._cancelled = True
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self._channel.unsubscribe(self._update)
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self._condition.notify_all()
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done_callbacks = tuple(self._done_callbacks)
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self._done_callbacks = None
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else:
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return False
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for done_callback in done_callbacks:
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callable_util.call_logging_exceptions(
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done_callback, _DONE_CALLBACK_EXCEPTION_LOG_MESSAGE, self)
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return True
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def cancelled(self):
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with self._condition:
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return self._cancelled
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def running(self):
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with self._condition:
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return not self._cancelled and not self._matured
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def done(self):
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with self._condition:
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return self._cancelled or self._matured
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def result(self, timeout=None):
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self._block(timeout)
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return None
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def exception(self, timeout=None):
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self._block(timeout)
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return None
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def traceback(self, timeout=None):
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self._block(timeout)
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return None
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def add_done_callback(self, fn):
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with self._condition:
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if not self._cancelled and not self._matured:
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self._done_callbacks.append(fn)
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return
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fn(self)
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def start(self):
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with self._condition:
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self._channel.subscribe(self._update, try_to_connect=True)
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def __del__(self):
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with self._condition:
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if not self._cancelled and not self._matured:
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self._channel.unsubscribe(self._update)
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def channel_ready_future(channel):
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"""Creates a future.Future tracking when an implementations.Channel is ready.
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Cancelling the returned future.Future does not tell the given
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implementations.Channel to abandon attempts it may have been making to
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connect; cancelling merely deactivates the return future.Future's
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subscription to the given implementations.Channel's connectivity.
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Args:
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channel: An implementations.Channel.
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Returns:
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A future.Future that matures when the given Channel has connectivity
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interfaces.ChannelConnectivity.READY.
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"""
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ready_future = _ChannelReadyFuture(channel)
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ready_future.start()
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return ready_future
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