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1# Copyright 2017 Google LLC All rights reserved.
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.
15"""Helpers for applying Google Cloud Firestore changes in a transaction."""
16from __future__ import annotations
18from typing import TYPE_CHECKING, Any, Callable, Generator, Optional
20from google.api_core import exceptions, gapic_v1
21from google.api_core import retry as retries
23from google.cloud.firestore_v1 import _helpers, batch
24from google.cloud.firestore_v1.base_transaction import (
25 _CANT_BEGIN,
26 _CANT_COMMIT,
27 _CANT_ROLLBACK,
28 _EXCEED_ATTEMPTS_TEMPLATE,
29 _WRITE_READ_ONLY,
30 MAX_ATTEMPTS,
31 BaseTransaction,
32 _BaseTransactional,
33)
34from google.cloud.firestore_v1.document import DocumentReference
35from google.cloud.firestore_v1.query import Query
37# Types needed only for Type Hints
38if TYPE_CHECKING: # pragma: NO COVER
39 from google.cloud.firestore_v1.base_document import DocumentSnapshot
40 from google.cloud.firestore_v1.query_profile import ExplainOptions
41 from google.cloud.firestore_v1.stream_generator import StreamGenerator
43 import datetime
46class Transaction(batch.WriteBatch, BaseTransaction):
47 """Accumulate read-and-write operations to be sent in a transaction.
49 Args:
50 client (:class:`~google.cloud.firestore_v1.client.Client`):
51 The client that created this transaction.
52 max_attempts (Optional[int]): The maximum number of attempts for
53 the transaction (i.e. allowing retries). Defaults to
54 :attr:`~google.cloud.firestore_v1.transaction.MAX_ATTEMPTS`.
55 read_only (Optional[bool]): Flag indicating if the transaction
56 should be read-only or should allow writes. Defaults to
57 :data:`False`.
58 """
60 def __init__(self, client, max_attempts=MAX_ATTEMPTS, read_only=False) -> None:
61 super(Transaction, self).__init__(client)
62 BaseTransaction.__init__(self, max_attempts, read_only)
64 def _add_write_pbs(self, write_pbs: list) -> None:
65 """Add `Write`` protobufs to this transaction.
67 Args:
68 write_pbs (List[google.cloud.firestore_v1.\
69 write.Write]): A list of write protobufs to be added.
71 Raises:
72 ValueError: If this transaction is read-only.
73 """
74 if self._read_only:
75 raise ValueError(_WRITE_READ_ONLY)
77 super(Transaction, self)._add_write_pbs(write_pbs)
79 def _begin(self, retry_id: bytes | None = None) -> None:
80 """Begin the transaction.
82 Args:
83 retry_id (Optional[bytes]): Transaction ID of a transaction to be
84 retried.
86 Raises:
87 ValueError: If the current transaction has already begun.
88 """
89 if self.in_progress:
90 msg = _CANT_BEGIN.format(self._id)
91 raise ValueError(msg)
93 transaction_response = self._client._firestore_api.begin_transaction(
94 request={
95 "database": self._client._database_string,
96 "options": self._options_protobuf(retry_id),
97 },
98 metadata=self._client._rpc_metadata,
99 )
100 self._id = transaction_response.transaction
102 def _rollback(self) -> None:
103 """Roll back the transaction.
105 Raises:
106 ValueError: If no transaction is in progress.
107 google.api_core.exceptions.GoogleAPICallError: If the rollback fails.
108 """
109 if not self.in_progress:
110 raise ValueError(_CANT_ROLLBACK)
112 try:
113 # NOTE: The response is just ``google.protobuf.Empty``.
114 self._client._firestore_api.rollback(
115 request={
116 "database": self._client._database_string,
117 "transaction": self._id,
118 },
119 metadata=self._client._rpc_metadata,
120 )
121 finally:
122 # clean up, even if rollback fails
123 self._clean_up()
125 def _commit(self) -> list:
126 """Transactionally commit the changes accumulated.
128 Returns:
129 List[:class:`google.cloud.firestore_v1.write.WriteResult`, ...]:
130 The write results corresponding to the changes committed, returned
131 in the same order as the changes were applied to this transaction.
132 A write result contains an ``update_time`` field.
134 Raises:
135 ValueError: If no transaction is in progress.
136 """
137 if not self.in_progress:
138 raise ValueError(_CANT_COMMIT)
140 commit_response = self._client._firestore_api.commit(
141 request={
142 "database": self._client._database_string,
143 "writes": self._write_pbs,
144 "transaction": self._id,
145 },
146 metadata=self._client._rpc_metadata,
147 )
149 self._clean_up()
150 self.write_results = list(commit_response.write_results)
151 self.commit_time = commit_response.commit_time
152 return self.write_results
154 def get_all(
155 self,
156 references: list,
157 retry: retries.Retry | object | None = gapic_v1.method.DEFAULT,
158 timeout: float | None = None,
159 *,
160 read_time: datetime.datetime | None = None,
161 ) -> Generator[DocumentSnapshot, Any, None]:
162 """Retrieves multiple documents from Firestore.
164 Args:
165 references (List[.DocumentReference, ...]): Iterable of document
166 references to be retrieved.
167 retry (google.api_core.retry.Retry): Designation of what errors, if any,
168 should be retried. Defaults to a system-specified policy.
169 timeout (float): The timeout for this request. Defaults to a
170 system-specified value.
171 read_time (Optional[datetime.datetime]): If set, reads documents as they were at the given
172 time. This must be a timestamp within the past one hour, or if Point-in-Time Recovery
173 is enabled, can additionally be a whole minute timestamp within the past 7 days. If no
174 timezone is specified in the :class:`datetime.datetime` object, it is assumed to be UTC.
176 Yields:
177 .DocumentSnapshot: The next document snapshot that fulfills the
178 query, or :data:`None` if the document does not exist.
179 """
180 kwargs = _helpers.make_retry_timeout_kwargs(retry, timeout)
181 if read_time is not None:
182 kwargs["read_time"] = read_time
183 return self._client.get_all(references, transaction=self, **kwargs)
185 def get(
186 self,
187 ref_or_query: DocumentReference | Query,
188 retry: retries.Retry | object | None = gapic_v1.method.DEFAULT,
189 timeout: Optional[float] = None,
190 *,
191 explain_options: Optional[ExplainOptions] = None,
192 read_time: Optional[datetime.datetime] = None,
193 ) -> StreamGenerator[DocumentSnapshot] | Generator[DocumentSnapshot, Any, None]:
194 """Retrieve a document or a query result from the database.
196 Args:
197 ref_or_query (DocumentReference | Query):
198 The document references or query object to return.
199 retry (google.api_core.retry.Retry): Designation of what errors, if any,
200 should be retried. Defaults to a system-specified policy.
201 timeout (float): The timeout for this request. Defaults to a
202 system-specified value.
203 explain_options
204 (Optional[:class:`~google.cloud.firestore_v1.query_profile.ExplainOptions`]):
205 Options to enable query profiling for this query. When set,
206 explain_metrics will be available on the returned generator.
207 Can only be used when running a query, not a document reference.
208 read_time (Optional[datetime.datetime]): If set, reads documents as they were at the given
209 time. This must be a timestamp within the past one hour, or if Point-in-Time Recovery
210 is enabled, can additionally be a whole minute timestamp within the past 7 days. If no
211 timezone is specified in the :class:`datetime.datetime` object, it is assumed to be UTC.
213 Yields:
214 .DocumentSnapshot: The next document snapshot that fulfills the
215 query, or :data:`None` if the document does not exist.
217 Raises:
218 ValueError: if `ref_or_query` is not one of the supported types, or
219 explain_options is provided when `ref_or_query` is a document
220 reference.
221 """
222 kwargs = _helpers.make_retry_timeout_kwargs(retry, timeout)
223 if read_time is not None:
224 kwargs["read_time"] = read_time
225 if isinstance(ref_or_query, DocumentReference):
226 if explain_options is not None:
227 raise ValueError(
228 "When type of `ref_or_query` is `AsyncDocumentReference`, "
229 "`explain_options` cannot be provided."
230 )
231 return self._client.get_all([ref_or_query], transaction=self, **kwargs)
232 elif isinstance(ref_or_query, Query):
233 if explain_options is not None:
234 kwargs["explain_options"] = explain_options
235 return ref_or_query.stream(transaction=self, **kwargs)
236 else:
237 raise ValueError(
238 'Value for argument "ref_or_query" must be a DocumentReference or a Query.'
239 )
242class _Transactional(_BaseTransactional):
243 """Provide a callable object to use as a transactional decorater.
245 This is surfaced via
246 :func:`~google.cloud.firestore_v1.transaction.transactional`.
248 Args:
249 to_wrap (Callable[[:class:`~google.cloud.firestore_v1.transaction.Transaction`, ...], Any]):
250 A callable that should be run (and retried) in a transaction.
251 """
253 def __init__(self, to_wrap) -> None:
254 super(_Transactional, self).__init__(to_wrap)
256 def _pre_commit(self, transaction: Transaction, *args, **kwargs) -> Any:
257 """Begin transaction and call the wrapped callable.
259 Args:
260 transaction
261 (:class:`~google.cloud.firestore_v1.transaction.Transaction`):
262 A transaction to execute the callable within.
263 args (Tuple[Any, ...]): The extra positional arguments to pass
264 along to the wrapped callable.
265 kwargs (Dict[str, Any]): The extra keyword arguments to pass
266 along to the wrapped callable.
268 Returns:
269 Any: result of the wrapped callable.
271 Raises:
272 Exception: Any failure caused by ``to_wrap``.
273 """
274 # Force the ``transaction`` to be not "in progress".
275 transaction._clean_up()
276 transaction._begin(retry_id=self.retry_id)
278 # Update the stored transaction IDs.
279 self.current_id = transaction._id
280 if self.retry_id is None:
281 self.retry_id = self.current_id
282 return self.to_wrap(transaction, *args, **kwargs)
284 def __call__(self, transaction: Transaction, *args, **kwargs):
285 """Execute the wrapped callable within a transaction.
287 Args:
288 transaction
289 (:class:`~google.cloud.firestore_v1.transaction.Transaction`):
290 A transaction to execute the callable within.
291 args (Tuple[Any, ...]): The extra positional arguments to pass
292 along to the wrapped callable.
293 kwargs (Dict[str, Any]): The extra keyword arguments to pass
294 along to the wrapped callable.
296 Returns:
297 Any: The result of the wrapped callable.
299 Raises:
300 ValueError: If the transaction does not succeed in
301 ``max_attempts``.
302 """
303 self._reset()
304 retryable_exceptions = (
305 (exceptions.Aborted) if not transaction._read_only else ()
306 )
307 last_exc = None
309 try:
310 for attempt in range(transaction._max_attempts):
311 result = self._pre_commit(transaction, *args, **kwargs)
312 try:
313 transaction._commit()
314 return result
315 except retryable_exceptions as exc:
316 last_exc = exc
317 # Retry attempts that result in retryable exceptions
318 # Subsequent requests will use the failed transaction ID as part of
319 # the ``BeginTransactionRequest`` when restarting this transaction
320 # (via ``options.retry_transaction``). This preserves the "spot in
321 # line" of the transaction, so exponential backoff is not required
322 # in this case.
323 # retries exhausted
324 # wrap the last exception in a ValueError before raising
325 msg = _EXCEED_ATTEMPTS_TEMPLATE.format(transaction._max_attempts)
326 raise ValueError(msg) from last_exc
327 except BaseException: # noqa: B901
328 # rollback the transaction on any error
329 # errors raised during _rollback will be chained to the original error through __context__
330 transaction._rollback()
331 raise
334def transactional(to_wrap: Callable) -> _Transactional:
335 """Decorate a callable so that it runs in a transaction.
337 Args:
338 to_wrap
339 (Callable[[:class:`~google.cloud.firestore_v1.transaction.Transaction`, ...], Any]):
340 A callable that should be run (and retried) in a transaction.
342 Returns:
343 Callable[[:class:`~google.cloud.firestore_v1.transaction.Transaction`, ...], Any]:
344 the wrapped callable.
345 """
346 return _Transactional(to_wrap)