|
| 1 | +# Copyright 2022 Google LLC |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +# you may not use this file except in compliance with the License. |
| 5 | +# You may obtain a copy of the License at |
| 6 | +# |
| 7 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +# See the License for the specific language governing permissions and |
| 13 | +# limitations under the License. |
| 14 | + |
| 15 | +"""Futures for extended long-running operations returned from Google Cloud APIs. |
| 16 | +
|
| 17 | +These futures can be used to synchronously wait for the result of a |
| 18 | +long-running operations using :meth:`ExtendedOperation.result`: |
| 19 | +
|
| 20 | +.. code-block:: python |
| 21 | +
|
| 22 | + extended_operation = my_api_client.long_running_method() |
| 23 | +
|
| 24 | + extended_operation.result() |
| 25 | +
|
| 26 | +Or asynchronously using callbacks and :meth:`Operation.add_done_callback`: |
| 27 | +
|
| 28 | +.. code-block:: python |
| 29 | +
|
| 30 | + extended_operation = my_api_client.long_running_method() |
| 31 | +
|
| 32 | + def my_callback(ex_op): |
| 33 | + print(f"Operation {ex_op.name} completed") |
| 34 | +
|
| 35 | + extended_operation.add_done_callback(my_callback) |
| 36 | +
|
| 37 | +""" |
| 38 | + |
| 39 | +importthreading |
| 40 | + |
| 41 | +fromgoogle.api_coreimportexceptions |
| 42 | +fromgoogle.api_core.futureimportpolling |
| 43 | + |
| 44 | + |
| 45 | +classExtendedOperation(polling.PollingFuture): |
| 46 | +"""An ExtendedOperation future for interacting with a Google API Long-Running Operation. |
| 47 | +
|
| 48 | + Args: |
| 49 | + extended_operation (proto.Message): The initial operation. |
| 50 | + refresh (Callable[[], type(extended_operation)]): A callable that returns |
| 51 | + the latest state of the operation. |
| 52 | + cancel (Callable[[], None]): A callable that tries to cancel the operation. |
| 53 | + retry: Optional(google.api_core.retry.Retry): The retry configuration used |
| 54 | + when polling. This can be used to control how often :meth:`done` |
| 55 | + is polled. Regardless of the retry's ``deadline``, it will be |
| 56 | + overridden by the ``timeout`` argument to :meth:`result`. |
| 57 | +
|
| 58 | + Note: Most long-running API methods use google.api_core.operation.Operation |
| 59 | + This class is a wrapper for a subset of methods that use alternative |
| 60 | + Long-Running Operation (LRO) semantics. |
| 61 | +
|
| 62 | + Note: there is not a concrete type the extended operation must be. |
| 63 | + It MUST have fields that correspond to the following, POSSIBLY WITH DIFFERENT NAMES: |
| 64 | + * name: str |
| 65 | + * status: Union[str, bool, enum.Enum] |
| 66 | + * error_code: int |
| 67 | + * error_message: str |
| 68 | + """ |
| 69 | + |
| 70 | +def__init__( |
| 71 | +self,extended_operation,refresh,cancel,retry=polling.DEFAULT_RETRY |
| 72 | + ): |
| 73 | +super().__init__(retry=retry) |
| 74 | +self._extended_operation=extended_operation |
| 75 | +self._refresh=refresh |
| 76 | +self._cancel=cancel |
| 77 | +# Note: the extended operation does not give a good way to indicate cancellation. |
| 78 | +# We make do with manually tracking cancellation and checking for doneness. |
| 79 | +self._cancelled=False |
| 80 | +self._completion_lock=threading.Lock() |
| 81 | +# Invoke in case the operation came back already complete. |
| 82 | +self._handle_refreshed_operation() |
| 83 | + |
| 84 | +# Note: the following four properties MUST be overridden in a subclass |
| 85 | +# if, and only if, the fields in the corresponding extended operation message |
| 86 | +# have different names. |
| 87 | +# |
| 88 | +# E.g. we have an extended operation class that looks like |
| 89 | +# |
| 90 | +# class MyOperation(proto.Message): |
| 91 | +# moniker = proto.Field(proto.STRING, number=1) |
| 92 | +# status_msg = proto.Field(proto.STRING, number=2) |
| 93 | +# optional http_error_code = proto.Field(proto.INT32, number=3) |
| 94 | +# optional http_error_msg = proto.Field(proto.STRING, number=4) |
| 95 | +# |
| 96 | +# the ExtendedOperation subclass would provide property overrrides that map |
| 97 | +# to these (poorly named) fields. |
| 98 | +@property |
| 99 | +defname(self): |
| 100 | +returnself._extended_operation.name |
| 101 | + |
| 102 | +@property |
| 103 | +defstatus(self): |
| 104 | +returnself._extended_operation.status |
| 105 | + |
| 106 | +@property |
| 107 | +deferror_code(self): |
| 108 | +returnself._extended_operation.error_code |
| 109 | + |
| 110 | +@property |
| 111 | +deferror_message(self): |
| 112 | +returnself._extended_operation.error_message |
| 113 | + |
| 114 | +defdone(self,retry=polling.DEFAULT_RETRY): |
| 115 | +self._refresh_and_update(retry) |
| 116 | +returnself._extended_operation.done |
| 117 | + |
| 118 | +defcancel(self): |
| 119 | +ifself.done(): |
| 120 | +returnFalse |
| 121 | + |
| 122 | +self._cancel() |
| 123 | +self._cancelled=True |
| 124 | +returnTrue |
| 125 | + |
| 126 | +defcancelled(self): |
| 127 | +# TODO(dovs): there is not currently a good way to determine whether the |
| 128 | +# operation has been cancelled. |
| 129 | +# The best we can do is manually keep track of cancellation |
| 130 | +# and check for doneness. |
| 131 | +ifnotself._cancelled: |
| 132 | +returnFalse |
| 133 | + |
| 134 | +self._refresh_and_update() |
| 135 | +returnself._extended_operation.done |
| 136 | + |
| 137 | +def_refresh_and_update(self,retry=polling.DEFAULT_RETRY): |
| 138 | +ifnotself._extended_operation.done: |
| 139 | +self._extended_operation=self._refresh(retry=retry) |
| 140 | +self._handle_refreshed_operation() |
| 141 | + |
| 142 | +def_handle_refreshed_operation(self): |
| 143 | +withself._completion_lock: |
| 144 | +ifnotself._extended_operation.done: |
| 145 | +return |
| 146 | + |
| 147 | +ifself.error_codeandself.error_message: |
| 148 | +exception=exceptions.from_http_status( |
| 149 | +status_code=self.error_code, |
| 150 | +message=self.error_message, |
| 151 | +response=self._extended_operation, |
| 152 | + ) |
| 153 | +self.set_exception(exception) |
| 154 | +elifself.error_codeorself.error_message: |
| 155 | +exception=exceptions.GoogleAPICallError( |
| 156 | +f"Unexpected error{self.error_code}:{self.error_message}" |
| 157 | + ) |
| 158 | +self.set_exception(exception) |
| 159 | +else: |
| 160 | +# Extended operations have no payload. |
| 161 | +self.set_result(None) |
| 162 | + |
| 163 | +@classmethod |
| 164 | +defmake(cls,refresh,cancel,extended_operation,**kwargs): |
| 165 | +""" |
| 166 | + Return an instantiated ExtendedOperation (or child) that wraps |
| 167 | + * a refresh callable |
| 168 | + * a cancel callable (can be a no-op) |
| 169 | + * an initial result |
| 170 | +
|
| 171 | + .. note:: |
| 172 | + It is the caller's responsibility to set up refresh and cancel |
| 173 | + with their correct request argument. |
| 174 | + The reason for this is that the services that use Extended Operations |
| 175 | + have rpcs that look something like the following: |
| 176 | +
|
| 177 | + // service.proto |
| 178 | + service MyLongService { |
| 179 | + rpc StartLongTask(StartLongTaskRequest) returns (ExtendedOperation) { |
| 180 | + option (google.cloud.operation_service) = "CustomOperationService"; |
| 181 | + } |
| 182 | + } |
| 183 | +
|
| 184 | + service CustomOperationService { |
| 185 | + rpc Get(GetOperationRequest) returns (ExtendedOperation) { |
| 186 | + option (google.cloud.operation_polling_method) = true; |
| 187 | + } |
| 188 | + } |
| 189 | +
|
| 190 | + Any info needed for the poll, e.g. a name, path params, etc. |
| 191 | + is held in the request, which the initial client method is in a much |
| 192 | + better position to make made because the caller made the initial request. |
| 193 | +
|
| 194 | + TL;DR: the caller sets up closures for refresh and cancel that carry |
| 195 | + the properly configured requests. |
| 196 | +
|
| 197 | + Args: |
| 198 | + refresh (Callable[Optional[Retry]][type(extended_operation)]): A callable that |
| 199 | + returns the latest state of the operation. |
| 200 | + cancel (Callable[][Any]): A callable that tries to cancel the operation |
| 201 | + on a best effort basis. |
| 202 | + extended_operation (Any): The initial response of the long running method. |
| 203 | + See the docstring for ExtendedOperation.__init__ for requirements on |
| 204 | + the type and fields of extended_operation |
| 205 | + """ |
| 206 | +returncls(extended_operation,refresh,cancel,**kwargs) |