python-spanner-orm/spanner_orm/api.py at main · 7dracoder/python-spanner-orm · GitHub

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# 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

# https://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.

"""Class that handles API calls to Spanner."""

import abc

from typing import Any, Callable, Dict, Iterable, Optional, TypeVar, Union

import warnings

from google.api_core import client_options as api_client_options

from google.api_core import exceptions

from google.auth import credentials as auth_credentials

from google.cloud import spanner

from google.cloud.spanner_v1 import database as spanner_database

from google.cloud.spanner_v1 import pool as spanner_pool

from spanner_orm import error

CallableReturn = TypeVar('CallableReturn')

class SpannerRetryableApi(abc.ABC):

def _ensure_session(self, api_method, *args, **kwargs):

try:

return api_method(*args, **kwargs)

except exceptions.NotFound as e:

# https://cloud.google.com/spanner/docs/sessions#handle_deleted_sessions

# states that Spanner may delete existing sessions for various reasons.

if not 'Session not found' in e.message:

raise

spanner_api().spanner_connection.connect()

return api_method(*args, **kwargs)

class SpannerReadApi(SpannerRetryableApi):

"""Handles sending read requests to Spanner."""

@property

@abc.abstractmethod

def _connection(self) -> spanner_database.Database:

raise NotImplementedError

def run_read_only(self, method: Callable[..., CallableReturn], *args: Any,

**kwargs: Any) -> CallableReturn:

"""Wraps read-only queries in a read transaction.

The callable will be executed with the read transaction (Snapshot from

the Spanner client library)passed to it as the first argument.

Args:

method: The method that will be run in the transaction

*args: Positional arguments that will be passed to `method`

**kwargs: Keyword arguments that will be passed to `method`

Returns:

The return value from `method` will be returned from this method

"""

return self._ensure_session(self._run_read_only, method, *args, **kwargs)

def _run_read_only(self, method, *args, **kwargs):

with self._connection.snapshot(multi_use=True) as snapshot:

return method(snapshot, *args, **kwargs)

class SpannerWriteApi(SpannerRetryableApi):

"""Handles sending write requests to Spanner."""

@property

@abc.abstractmethod

def _connection(self) -> spanner_database.Database:

raise NotImplementedError

def run_write(self, method: Callable[..., CallableReturn], *args: Any,

**kwargs: Any) -> CallableReturn:

"""Wraps read-write queries in a write transaction.

The callable will be executed with the write transaction passed to it as

the first argument. If the transaction aborts (usually because the data

the write operation depended on has changed since the start of the

transaction), the callable will continue to be retried until success or

30 seconds has passed.

Args:

method: The method that will be run in the transaction

*args: Positional arguments that will be passed to `method`

**kwargs: Keyword arguments that will be passed to `method`

Returns:

The return value from `method` will be returned from this method

"""

return self._ensure_session(self._connection.run_in_transaction, method,

*args, **kwargs)

class SpannerConnection:

"""Class that handles connecting to a Spanner database."""

def __init__(

self,

instance: str,

database: str,

project: Optional[str] = None,

credentials: Optional[auth_credentials.Credentials] = None,

pool: Optional[spanner_pool.AbstractSessionPool] = None,

create_ddl: Optional[Iterable[str]] = None,

client_options: Union[api_client_options.ClientOptions, Dict[Any, Any],

None] = None,

"""Connects to the specified Spanner database."""

self._instance = instance

self._database = database

self._project = project

self._credentials = credentials

self._pool = pool

self._create_ddl = create_ddl

self._client_options = client_options

self.connect()

def connect(self):

"""Establish a new connection to the specified Spanner database."""

client = spanner.Client(

project=self._project,

credentials=self._credentials,

client_options=self._client_options,

)

instance = client.instance(self._instance)

self.database = instance.database(

self._database, pool=self._pool, ddl_statements=self._create_ddl or ())

class SpannerApi(SpannerReadApi, SpannerWriteApi):

"""Class that handles reading from and writing to Spanner tables."""

def __init__(self, connection: SpannerConnection):

self._spanner_connection = connection

@property

def spanner_connection(self) -> SpannerConnection:

"""Connection to the database."""

return self._spanner_connection

@property

def _connection(self):

return self._spanner_connection.database

_api = None # type: Optional[SpannerApi]

def connect(

instance: str,

database: str,

project: Optional[str] = None,

credentials: Optional[auth_credentials.Credentials] = None,

pool: Optional[spanner_pool.AbstractSessionPool] = None) -> SpannerApi:

"""Connects to the Spanner database and sets the global spanner_api.

Deprecated in favor of from_connection().

"""

warnings.warn(

DeprecationWarning(

'Please use '

'spanner_orm.from_connection(spanner_orm.SpannerConnection(...))'))

connection = SpannerConnection(

instance, database, project=project, credentials=credentials, pool=pool)

return from_connection(connection)

def from_connection(connection: SpannerConnection) -> SpannerApi:

"""Sets the global spanner_api from the provided connection."""

global _api

_api = SpannerApi(connection)

return _api

def hangup() -> None:

"""Clears the global spanner_api."""

global _api

_api = None

def spanner_api() -> SpannerApi:

"""Returns the global spanner_api if it has been set."""

if not _api:

raise error.SpannerError('Must connect to Spanner before calling APIs')

return _api

python-spanner-orm/spanner_orm/api.py at main · 7dracoder/python-spanner-orm · GitHub

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