Added delete option to database storage.

venv/Lib/site-packages/grpc/_simple_stubs.py

@@ -0,0 +1,493 @@
+# Copyright 2020 The 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.
+"""Functions that obviate explicit stubs and explicit channels."""
+
+import collections
+import datetime
+import os
+import logging
+import threading
+from typing import (Any, AnyStr, Callable, Dict, Iterator, Optional, Sequence,
+                    Tuple, TypeVar, Union)
+
+import grpc
+from grpc.experimental import experimental_api
+
+RequestType = TypeVar('RequestType')
+ResponseType = TypeVar('ResponseType')
+
+OptionsType = Sequence[Tuple[str, str]]
+CacheKey = Tuple[str, OptionsType, Optional[grpc.ChannelCredentials], Optional[
+    grpc.Compression]]
+
+_LOGGER = logging.getLogger(__name__)
+
+_EVICTION_PERIOD_KEY = "GRPC_PYTHON_MANAGED_CHANNEL_EVICTION_SECONDS"
+if _EVICTION_PERIOD_KEY in os.environ:
+    _EVICTION_PERIOD = datetime.timedelta(
+        seconds=float(os.environ[_EVICTION_PERIOD_KEY]))
+    _LOGGER.debug("Setting managed channel eviction period to %s",
+                  _EVICTION_PERIOD)
+else:
+    _EVICTION_PERIOD = datetime.timedelta(minutes=10)
+
+_MAXIMUM_CHANNELS_KEY = "GRPC_PYTHON_MANAGED_CHANNEL_MAXIMUM"
+if _MAXIMUM_CHANNELS_KEY in os.environ:
+    _MAXIMUM_CHANNELS = int(os.environ[_MAXIMUM_CHANNELS_KEY])
+    _LOGGER.debug("Setting maximum managed channels to %d", _MAXIMUM_CHANNELS)
+else:
+    _MAXIMUM_CHANNELS = 2**8
+
+_DEFAULT_TIMEOUT_KEY = "GRPC_PYTHON_DEFAULT_TIMEOUT_SECONDS"
+if _DEFAULT_TIMEOUT_KEY in os.environ:
+    _DEFAULT_TIMEOUT = float(os.environ[_DEFAULT_TIMEOUT_KEY])
+    _LOGGER.debug("Setting default timeout seconds to %f", _DEFAULT_TIMEOUT)
+else:
+    _DEFAULT_TIMEOUT = 60.0
+
+
+def _create_channel(target: str, options: Sequence[Tuple[str, str]],
+                    channel_credentials: Optional[grpc.ChannelCredentials],
+                    compression: Optional[grpc.Compression]) -> grpc.Channel:
+    if channel_credentials is grpc.experimental.insecure_channel_credentials():
+        _LOGGER.debug(f"Creating insecure channel with options '{options}' " +
+                      f"and compression '{compression}'")
+        return grpc.insecure_channel(target,
+                                     options=options,
+                                     compression=compression)
+    else:
+        _LOGGER.debug(
+            f"Creating secure channel with credentials '{channel_credentials}', "
+            + f"options '{options}' and compression '{compression}'")
+        return grpc.secure_channel(target,
+                                   credentials=channel_credentials,
+                                   options=options,
+                                   compression=compression)
+
+
+class ChannelCache:
+    # NOTE(rbellevi): Untyped due to reference cycle.
+    _singleton = None
+    _lock: threading.RLock = threading.RLock()
+    _condition: threading.Condition = threading.Condition(lock=_lock)
+    _eviction_ready: threading.Event = threading.Event()
+
+    _mapping: Dict[CacheKey, Tuple[grpc.Channel, datetime.datetime]]
+    _eviction_thread: threading.Thread
+
+    def __init__(self):
+        self._mapping = collections.OrderedDict()
+        self._eviction_thread = threading.Thread(
+            target=ChannelCache._perform_evictions, daemon=True)
+        self._eviction_thread.start()
+
+    @staticmethod
+    def get():
+        with ChannelCache._lock:
+            if ChannelCache._singleton is None:
+                ChannelCache._singleton = ChannelCache()
+        ChannelCache._eviction_ready.wait()
+        return ChannelCache._singleton
+
+    def _evict_locked(self, key: CacheKey):
+        channel, _ = self._mapping.pop(key)
+        _LOGGER.debug("Evicting channel %s with configuration %s.", channel,
+                      key)
+        channel.close()
+        del channel
+
+    @staticmethod
+    def _perform_evictions():
+        while True:
+            with ChannelCache._lock:
+                ChannelCache._eviction_ready.set()
+                if not ChannelCache._singleton._mapping:
+                    ChannelCache._condition.wait()
+                elif len(ChannelCache._singleton._mapping) > _MAXIMUM_CHANNELS:
+                    key = next(iter(ChannelCache._singleton._mapping.keys()))
+                    ChannelCache._singleton._evict_locked(key)
+                    # And immediately reevaluate.
+                else:
+                    key, (_, eviction_time) = next(
+                        iter(ChannelCache._singleton._mapping.items()))
+                    now = datetime.datetime.now()
+                    if eviction_time <= now:
+                        ChannelCache._singleton._evict_locked(key)
+                        continue
+                    else:
+                        time_to_eviction = (eviction_time - now).total_seconds()
+                        # NOTE: We aim to *eventually* coalesce to a state in
+                        # which no overdue channels are in the cache and the
+                        # length of the cache is longer than _MAXIMUM_CHANNELS.
+                        # We tolerate momentary states in which these two
+                        # criteria are not met.
+                        ChannelCache._condition.wait(timeout=time_to_eviction)
+
+    def get_channel(self, target: str, options: Sequence[Tuple[str, str]],
+                    channel_credentials: Optional[grpc.ChannelCredentials],
+                    insecure: bool,
+                    compression: Optional[grpc.Compression]) -> grpc.Channel:
+        if insecure and channel_credentials:
+            raise ValueError("The insecure option is mutually exclusive with " +
+                             "the channel_credentials option. Please use one " +
+                             "or the other.")
+        if insecure:
+            channel_credentials = grpc.experimental.insecure_channel_credentials(
+            )
+        elif channel_credentials is None:
+            _LOGGER.debug("Defaulting to SSL channel credentials.")
+            channel_credentials = grpc.ssl_channel_credentials()
+        key = (target, options, channel_credentials, compression)
+        with self._lock:
+            channel_data = self._mapping.get(key, None)
+            if channel_data is not None:
+                channel = channel_data[0]
+                self._mapping.pop(key)
+                self._mapping[key] = (channel, datetime.datetime.now() +
+                                      _EVICTION_PERIOD)
+                return channel
+            else:
+                channel = _create_channel(target, options, channel_credentials,
+                                          compression)
+                self._mapping[key] = (channel, datetime.datetime.now() +
+                                      _EVICTION_PERIOD)
+                if len(self._mapping) == 1 or len(
+                        self._mapping) >= _MAXIMUM_CHANNELS:
+                    self._condition.notify()
+                return channel
+
+    def _test_only_channel_count(self) -> int:
+        with self._lock:
+            return len(self._mapping)
+
+
+@experimental_api
+def unary_unary(
+        request: RequestType,
+        target: str,
+        method: str,
+        request_serializer: Optional[Callable[[Any], bytes]] = None,
+        response_deserializer: Optional[Callable[[bytes], Any]] = None,
+        options: Sequence[Tuple[AnyStr, AnyStr]] = (),
+        channel_credentials: Optional[grpc.ChannelCredentials] = None,
+        insecure: bool = False,
+        call_credentials: Optional[grpc.CallCredentials] = None,
+        compression: Optional[grpc.Compression] = None,
+        wait_for_ready: Optional[bool] = None,
+        timeout: Optional[float] = _DEFAULT_TIMEOUT,
+        metadata: Optional[Sequence[Tuple[str, Union[str, bytes]]]] = None
+) -> ResponseType:
+    """Invokes a unary-unary RPC without an explicitly specified channel.
+
+    THIS IS AN EXPERIMENTAL API.
+
+    This is backed by a per-process cache of channels. Channels are evicted
+    from the cache after a fixed period by a background. Channels will also be
+    evicted if more than a configured maximum accumulate.
+
+    The default eviction period is 10 minutes. One may set the environment
+    variable "GRPC_PYTHON_MANAGED_CHANNEL_EVICTION_SECONDS" to configure this.
+
+    The default maximum number of channels is 256. One may set the
+    environment variable "GRPC_PYTHON_MANAGED_CHANNEL_MAXIMUM" to configure
+    this.
+
+    Args:
+      request: An iterator that yields request values for the RPC.
+      target: The server address.
+      method: The name of the RPC method.
+      request_serializer: Optional :term:`serializer` for serializing the request
+        message. Request goes unserialized in case None is passed.
+      response_deserializer: Optional :term:`deserializer` for deserializing the response
+        message. Response goes undeserialized in case None is passed.
+      options: An optional list of key-value pairs (:term:`channel_arguments` in gRPC Core
+        runtime) to configure the channel.
+      channel_credentials: A credential applied to the whole channel, e.g. the
+        return value of grpc.ssl_channel_credentials() or
+        grpc.insecure_channel_credentials().
+      insecure: If True, specifies channel_credentials as
+        :term:`grpc.insecure_channel_credentials()`. This option is mutually
+        exclusive with the `channel_credentials` option.
+      call_credentials: A call credential applied to each call individually,
+        e.g. the output of grpc.metadata_call_credentials() or
+        grpc.access_token_call_credentials().
+      compression: An optional value indicating the compression method to be
+        used over the lifetime of the channel, e.g. grpc.Compression.Gzip.
+      wait_for_ready: An optional flag indicating whether the RPC should fail
+        immediately if the connection is not ready at the time the RPC is
+        invoked, or if it should wait until the connection to the server
+        becomes ready. When using this option, the user will likely also want
+        to set a timeout. Defaults to True.
+      timeout: An optional duration of time in seconds to allow for the RPC,
+        after which an exception will be raised. If timeout is unspecified,
+        defaults to a timeout controlled by the
+        GRPC_PYTHON_DEFAULT_TIMEOUT_SECONDS environment variable. If that is
+        unset, defaults to 60 seconds. Supply a value of None to indicate that
+        no timeout should be enforced.
+      metadata: Optional metadata to send to the server.
+
+    Returns:
+      The response to the RPC.
+    """
+    channel = ChannelCache.get().get_channel(target, options,
+                                             channel_credentials, insecure,
+                                             compression)
+    multicallable = channel.unary_unary(method, request_serializer,
+                                        response_deserializer)
+    wait_for_ready = wait_for_ready if wait_for_ready is not None else True
+    return multicallable(request,
+                         metadata=metadata,
+                         wait_for_ready=wait_for_ready,
+                         credentials=call_credentials,
+                         timeout=timeout)
+
+
+@experimental_api
+def unary_stream(
+        request: RequestType,
+        target: str,
+        method: str,
+        request_serializer: Optional[Callable[[Any], bytes]] = None,
+        response_deserializer: Optional[Callable[[bytes], Any]] = None,
+        options: Sequence[Tuple[AnyStr, AnyStr]] = (),
+        channel_credentials: Optional[grpc.ChannelCredentials] = None,
+        insecure: bool = False,
+        call_credentials: Optional[grpc.CallCredentials] = None,
+        compression: Optional[grpc.Compression] = None,
+        wait_for_ready: Optional[bool] = None,
+        timeout: Optional[float] = _DEFAULT_TIMEOUT,
+        metadata: Optional[Sequence[Tuple[str, Union[str, bytes]]]] = None
+) -> Iterator[ResponseType]:
+    """Invokes a unary-stream RPC without an explicitly specified channel.
+
+    THIS IS AN EXPERIMENTAL API.
+
+    This is backed by a per-process cache of channels. Channels are evicted
+    from the cache after a fixed period by a background. Channels will also be
+    evicted if more than a configured maximum accumulate.
+
+    The default eviction period is 10 minutes. One may set the environment
+    variable "GRPC_PYTHON_MANAGED_CHANNEL_EVICTION_SECONDS" to configure this.
+
+    The default maximum number of channels is 256. One may set the
+    environment variable "GRPC_PYTHON_MANAGED_CHANNEL_MAXIMUM" to configure
+    this.
+
+    Args:
+      request: An iterator that yields request values for the RPC.
+      target: The server address.
+      method: The name of the RPC method.
+      request_serializer: Optional :term:`serializer` for serializing the request
+        message. Request goes unserialized in case None is passed.
+      response_deserializer: Optional :term:`deserializer` for deserializing the response
+        message. Response goes undeserialized in case None is passed.
+      options: An optional list of key-value pairs (:term:`channel_arguments` in gRPC Core
+        runtime) to configure the channel.
+      channel_credentials: A credential applied to the whole channel, e.g. the
+        return value of grpc.ssl_channel_credentials().
+      insecure: If True, specifies channel_credentials as
+        :term:`grpc.insecure_channel_credentials()`. This option is mutually
+        exclusive with the `channel_credentials` option.
+      call_credentials: A call credential applied to each call individually,
+        e.g. the output of grpc.metadata_call_credentials() or
+        grpc.access_token_call_credentials().
+      compression: An optional value indicating the compression method to be
+        used over the lifetime of the channel, e.g. grpc.Compression.Gzip.
+      wait_for_ready: An optional flag indicating whether the RPC should fail
+        immediately if the connection is not ready at the time the RPC is
+        invoked, or if it should wait until the connection to the server
+        becomes ready. When using this option, the user will likely also want
+        to set a timeout. Defaults to True.
+      timeout: An optional duration of time in seconds to allow for the RPC,
+        after which an exception will be raised. If timeout is unspecified,
+        defaults to a timeout controlled by the
+        GRPC_PYTHON_DEFAULT_TIMEOUT_SECONDS environment variable. If that is
+        unset, defaults to 60 seconds. Supply a value of None to indicate that
+        no timeout should be enforced.
+      metadata: Optional metadata to send to the server.
+
+    Returns:
+      An iterator of responses.
+    """
+    channel = ChannelCache.get().get_channel(target, options,
+                                             channel_credentials, insecure,
+                                             compression)
+    multicallable = channel.unary_stream(method, request_serializer,
+                                         response_deserializer)
+    wait_for_ready = wait_for_ready if wait_for_ready is not None else True
+    return multicallable(request,
+                         metadata=metadata,
+                         wait_for_ready=wait_for_ready,
+                         credentials=call_credentials,
+                         timeout=timeout)
+
+
+@experimental_api
+def stream_unary(
+        request_iterator: Iterator[RequestType],
+        target: str,
+        method: str,
+        request_serializer: Optional[Callable[[Any], bytes]] = None,
+        response_deserializer: Optional[Callable[[bytes], Any]] = None,
+        options: Sequence[Tuple[AnyStr, AnyStr]] = (),
+        channel_credentials: Optional[grpc.ChannelCredentials] = None,
+        insecure: bool = False,
+        call_credentials: Optional[grpc.CallCredentials] = None,
+        compression: Optional[grpc.Compression] = None,
+        wait_for_ready: Optional[bool] = None,
+        timeout: Optional[float] = _DEFAULT_TIMEOUT,
+        metadata: Optional[Sequence[Tuple[str, Union[str, bytes]]]] = None
+) -> ResponseType:
+    """Invokes a stream-unary RPC without an explicitly specified channel.
+
+    THIS IS AN EXPERIMENTAL API.
+
+    This is backed by a per-process cache of channels. Channels are evicted
+    from the cache after a fixed period by a background. Channels will also be
+    evicted if more than a configured maximum accumulate.
+
+    The default eviction period is 10 minutes. One may set the environment
+    variable "GRPC_PYTHON_MANAGED_CHANNEL_EVICTION_SECONDS" to configure this.
+
+    The default maximum number of channels is 256. One may set the
+    environment variable "GRPC_PYTHON_MANAGED_CHANNEL_MAXIMUM" to configure
+    this.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      target: The server address.
+      method: The name of the RPC method.
+      request_serializer: Optional :term:`serializer` for serializing the request
+        message. Request goes unserialized in case None is passed.
+      response_deserializer: Optional :term:`deserializer` for deserializing the response
+        message. Response goes undeserialized in case None is passed.
+      options: An optional list of key-value pairs (:term:`channel_arguments` in gRPC Core
+        runtime) to configure the channel.
+      channel_credentials: A credential applied to the whole channel, e.g. the
+        return value of grpc.ssl_channel_credentials().
+      call_credentials: A call credential applied to each call individually,
+        e.g. the output of grpc.metadata_call_credentials() or
+        grpc.access_token_call_credentials().
+      insecure: If True, specifies channel_credentials as
+        :term:`grpc.insecure_channel_credentials()`. This option is mutually
+        exclusive with the `channel_credentials` option.
+      compression: An optional value indicating the compression method to be
+        used over the lifetime of the channel, e.g. grpc.Compression.Gzip.
+      wait_for_ready: An optional flag indicating whether the RPC should fail
+        immediately if the connection is not ready at the time the RPC is
+        invoked, or if it should wait until the connection to the server
+        becomes ready. When using this option, the user will likely also want
+        to set a timeout. Defaults to True.
+      timeout: An optional duration of time in seconds to allow for the RPC,
+        after which an exception will be raised. If timeout is unspecified,
+        defaults to a timeout controlled by the
+        GRPC_PYTHON_DEFAULT_TIMEOUT_SECONDS environment variable. If that is
+        unset, defaults to 60 seconds. Supply a value of None to indicate that
+        no timeout should be enforced.
+      metadata: Optional metadata to send to the server.
+
+    Returns:
+      The response to the RPC.
+    """
+    channel = ChannelCache.get().get_channel(target, options,
+                                             channel_credentials, insecure,
+                                             compression)
+    multicallable = channel.stream_unary(method, request_serializer,
+                                         response_deserializer)
+    wait_for_ready = wait_for_ready if wait_for_ready is not None else True
+    return multicallable(request_iterator,
+                         metadata=metadata,
+                         wait_for_ready=wait_for_ready,
+                         credentials=call_credentials,
+                         timeout=timeout)
+
+
+@experimental_api
+def stream_stream(
+        request_iterator: Iterator[RequestType],
+        target: str,
+        method: str,
+        request_serializer: Optional[Callable[[Any], bytes]] = None,
+        response_deserializer: Optional[Callable[[bytes], Any]] = None,
+        options: Sequence[Tuple[AnyStr, AnyStr]] = (),
+        channel_credentials: Optional[grpc.ChannelCredentials] = None,
+        insecure: bool = False,
+        call_credentials: Optional[grpc.CallCredentials] = None,
+        compression: Optional[grpc.Compression] = None,
+        wait_for_ready: Optional[bool] = None,
+        timeout: Optional[float] = _DEFAULT_TIMEOUT,
+        metadata: Optional[Sequence[Tuple[str, Union[str, bytes]]]] = None
+) -> Iterator[ResponseType]:
+    """Invokes a stream-stream RPC without an explicitly specified channel.
+
+    THIS IS AN EXPERIMENTAL API.
+
+    This is backed by a per-process cache of channels. Channels are evicted
+    from the cache after a fixed period by a background. Channels will also be
+    evicted if more than a configured maximum accumulate.
+
+    The default eviction period is 10 minutes. One may set the environment
+    variable "GRPC_PYTHON_MANAGED_CHANNEL_EVICTION_SECONDS" to configure this.
+
+    The default maximum number of channels is 256. One may set the
+    environment variable "GRPC_PYTHON_MANAGED_CHANNEL_MAXIMUM" to configure
+    this.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      target: The server address.
+      method: The name of the RPC method.
+      request_serializer: Optional :term:`serializer` for serializing the request
+        message. Request goes unserialized in case None is passed.
+      response_deserializer: Optional :term:`deserializer` for deserializing the response
+        message. Response goes undeserialized in case None is passed.
+      options: An optional list of key-value pairs (:term:`channel_arguments` in gRPC Core
+        runtime) to configure the channel.
+      channel_credentials: A credential applied to the whole channel, e.g. the
+        return value of grpc.ssl_channel_credentials().
+      call_credentials: A call credential applied to each call individually,
+        e.g. the output of grpc.metadata_call_credentials() or
+        grpc.access_token_call_credentials().
+      insecure: If True, specifies channel_credentials as
+        :term:`grpc.insecure_channel_credentials()`. This option is mutually
+        exclusive with the `channel_credentials` option.
+      compression: An optional value indicating the compression method to be
+        used over the lifetime of the channel, e.g. grpc.Compression.Gzip.
+      wait_for_ready: An optional flag indicating whether the RPC should fail
+        immediately if the connection is not ready at the time the RPC is
+        invoked, or if it should wait until the connection to the server
+        becomes ready. When using this option, the user will likely also want
+        to set a timeout. Defaults to True.
+      timeout: An optional duration of time in seconds to allow for the RPC,
+        after which an exception will be raised. If timeout is unspecified,
+        defaults to a timeout controlled by the
+        GRPC_PYTHON_DEFAULT_TIMEOUT_SECONDS environment variable. If that is
+        unset, defaults to 60 seconds. Supply a value of None to indicate that
+        no timeout should be enforced.
+      metadata: Optional metadata to send to the server.
+
+    Returns:
+      An iterator of responses.
+    """
+    channel = ChannelCache.get().get_channel(target, options,
+                                             channel_credentials, insecure,
+                                             compression)
+    multicallable = channel.stream_stream(method, request_serializer,
+                                          response_deserializer)
+    wait_for_ready = wait_for_ready if wait_for_ready is not None else True
+    return multicallable(request_iterator,
+                         metadata=metadata,
+                         wait_for_ready=wait_for_ready,
+                         credentials=call_credentials,
+                         timeout=timeout)