grpc.py

# -*- coding: utf-8 -*-
# Copyright 2020 Google LLC
#
# 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.
#
import warnings
from typing import Callable, Dict, Optional, Sequence, Tuple, Union

from google.api_core import grpc_helpers  # type: ignore
from google.api_core import gapic_v1  # type: ignore
import google.auth  # type: ignore
from google.auth import credentials as ga_credentials  # type: ignore
from google.auth.transport.grpc import SslCredentials  # type: ignore

import grpc  # type: ignore

from google.cloud.bigquery_storage_v1.types import storage
from google.cloud.bigquery_storage_v1.types import stream
from .base import BigQueryReadTransport, DEFAULT_CLIENT_INFO


class BigQueryReadGrpcTransport(BigQueryReadTransport):
    """gRPC backend transport for BigQueryRead.

    BigQuery Read API.
    The Read API can be used to read data from BigQuery.

    This class defines the same methods as the primary client, so the
    primary client can load the underlying transport implementation
    and call it.

    It sends protocol buffers over the wire using gRPC (which is built on
    top of HTTP/2); the ``grpcio`` package must be installed.
    """

    _stubs: Dict[str, Callable]

    def __init__(
        self,
        *,
        host: str = "bigquerystorage.googleapis.com",
        credentials: ga_credentials.Credentials = None,
        credentials_file: str = None,
        scopes: Sequence[str] = None,
        channel: grpc.Channel = None,
        api_mtls_endpoint: str = None,
        client_cert_source: Callable[[], Tuple[bytes, bytes]] = None,
        ssl_channel_credentials: grpc.ChannelCredentials = None,
        client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
        quota_project_id: Optional[str] = None,
        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
        always_use_jwt_access: Optional[bool] = False,
    ) -> None:
        """Instantiate the transport.

        Args:
            host (Optional[str]):
                 The hostname to connect to.
            credentials (Optional[google.auth.credentials.Credentials]): The
                authorization credentials to attach to requests. These
                credentials identify the application to the service; if none
                are specified, the client will attempt to ascertain the
                credentials from the environment.
                This argument is ignored if ``channel`` is provided.
            credentials_file (Optional[str]): A file with credentials that can
                be loaded with :func:`google.auth.load_credentials_from_file`.
                This argument is ignored if ``channel`` is provided.
            scopes (Optional(Sequence[str])): A list of scopes. This argument is
                ignored if ``channel`` is provided.
            channel (Optional[grpc.Channel]): A ``Channel`` instance through
                which to make calls.
            api_mtls_endpoint (Optional[str]): Deprecated. The mutual TLS endpoint.
                If provided, it overrides the ``host`` argument and tries to create
                a mutual TLS channel with client SSL credentials from
                ``client_cert_source`` or application default SSL credentials.
            client_cert_source (Optional[Callable[[], Tuple[bytes, bytes]]]):
                Deprecated. A callback to provide client SSL certificate bytes and
                private key bytes, both in PEM format. It is ignored if
                ``api_mtls_endpoint`` is None.
            ssl_channel_credentials (grpc.ChannelCredentials): SSL credentials
                for the grpc channel. It is ignored if ``channel`` is provided.
            client_cert_source_for_mtls (Optional[Callable[[], Tuple[bytes, bytes]]]):
                A callback to provide client certificate bytes and private key bytes,
                both in PEM format. It is used to configure a mutual TLS channel. It is
                ignored if ``channel`` or ``ssl_channel_credentials`` is provided.
            quota_project_id (Optional[str]): An optional project to use for billing
                and quota.
            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
                The client info used to send a user-agent string along with
                API requests. If ``None``, then default info will be used.
                Generally, you only need to set this if you're developing
                your own client library.
            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
                be used for service account credentials.

        Raises:
          google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
              creation failed for any reason.
          google.api_core.exceptions.DuplicateCredentialArgs: If both ``credentials``
              and ``credentials_file`` are passed.
        """
        self._grpc_channel = None
        self._ssl_channel_credentials = ssl_channel_credentials
        self._stubs: Dict[str, Callable] = {}

        if api_mtls_endpoint:
            warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
        if client_cert_source:
            warnings.warn("client_cert_source is deprecated", DeprecationWarning)

        if channel:
            # Ignore credentials if a channel was passed.
            credentials = False
            # If a channel was explicitly provided, set it.
            self._grpc_channel = channel
            self._ssl_channel_credentials = None

        else:
            if api_mtls_endpoint:
                host = api_mtls_endpoint

                # Create SSL credentials with client_cert_source or application
                # default SSL credentials.
                if client_cert_source:
                    cert, key = client_cert_source()
                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
                        certificate_chain=cert, private_key=key
                    )
                else:
                    self._ssl_channel_credentials = SslCredentials().ssl_credentials

            else:
                if client_cert_source_for_mtls and not ssl_channel_credentials:
                    cert, key = client_cert_source_for_mtls()
                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
                        certificate_chain=cert, private_key=key
                    )

        # The base transport sets the host, credentials and scopes
        super().__init__(
            host=host,
            credentials=credentials,
            credentials_file=credentials_file,
            scopes=scopes,
            quota_project_id=quota_project_id,
            client_info=client_info,
            always_use_jwt_access=always_use_jwt_access,
        )

        if not self._grpc_channel:
            self._grpc_channel = type(self).create_channel(
                self._host,
                credentials=self._credentials,
                credentials_file=credentials_file,
                scopes=self._scopes,
                ssl_credentials=self._ssl_channel_credentials,
                quota_project_id=quota_project_id,
                options=[
                    ("grpc.max_send_message_length", -1),
                    ("grpc.max_receive_message_length", -1),
                ],
            )

        # Wrap messages. This must be done after self._grpc_channel exists
        self._prep_wrapped_messages(client_info)

    @classmethod
    def create_channel(
        cls,
        host: str = "bigquerystorage.googleapis.com",
        credentials: ga_credentials.Credentials = None,
        credentials_file: str = None,
        scopes: Optional[Sequence[str]] = None,
        quota_project_id: Optional[str] = None,
        **kwargs,
    ) -> grpc.Channel:
        """Create and return a gRPC channel object.
        Args:
            host (Optional[str]): The host for the channel to use.
            credentials (Optional[~.Credentials]): The
                authorization credentials to attach to requests. These
                credentials identify this application to the service. If
                none are specified, the client will attempt to ascertain
                the credentials from the environment.
            credentials_file (Optional[str]): A file with credentials that can
                be loaded with :func:`google.auth.load_credentials_from_file`.
                This argument is mutually exclusive with credentials.
            scopes (Optional[Sequence[str]]): A optional list of scopes needed for this
                service. These are only used when credentials are not specified and
                are passed to :func:`google.auth.default`.
            quota_project_id (Optional[str]): An optional project to use for billing
                and quota.
            kwargs (Optional[dict]): Keyword arguments, which are passed to the
                channel creation.
        Returns:
            grpc.Channel: A gRPC channel object.

        Raises:
            google.api_core.exceptions.DuplicateCredentialArgs: If both ``credentials``
              and ``credentials_file`` are passed.
        """

        return grpc_helpers.create_channel(
            host,
            credentials=credentials,
            credentials_file=credentials_file,
            quota_project_id=quota_project_id,
            default_scopes=cls.AUTH_SCOPES,
            scopes=scopes,
            default_host=cls.DEFAULT_HOST,
            **kwargs,
        )

    @property
    def grpc_channel(self) -> grpc.Channel:
        """Return the channel designed to connect to this service.
        """
        return self._grpc_channel

    @property
    def create_read_session(
        self,
    ) -> Callable[[storage.CreateReadSessionRequest], stream.ReadSession]:
        r"""Return a callable for the create read session method over gRPC.

        Creates a new read session. A read session divides
        the contents of a BigQuery table into one or more
        streams, which can then be used to read data from the
        table. The read session also specifies properties of the
        data to be read, such as a list of columns or a push-
        down filter describing the rows to be returned.

        A particular row can be read by at most one stream. When
        the caller has reached the end of each stream in the
        session, then all the data in the table has been read.

        Data is assigned to each stream such that roughly the
        same number of rows can be read from each stream.
        Because the server-side unit for assigning data is
        collections of rows, the API does not guarantee that
        each stream will return the same number or rows.
        Additionally, the limits are enforced based on the
        number of pre-filtered rows, so some filters can lead to
        lopsided assignments.

        Read sessions automatically expire 6 hours after they
        are created and do not require manual clean-up by the
        caller.

        Returns:
            Callable[[~.CreateReadSessionRequest],
                    ~.ReadSession]:
                A function that, when called, will call the underlying RPC
                on the server.
        """
        # Generate a "stub function" on-the-fly which will actually make
        # the request.
        # gRPC handles serialization and deserialization, so we just need
        # to pass in the functions for each.
        if "create_read_session" not in self._stubs:
            self._stubs["create_read_session"] = self.grpc_channel.unary_unary(
                "/google.cloud.bigquery.storage.v1.BigQueryRead/CreateReadSession",
                request_serializer=storage.CreateReadSessionRequest.serialize,
                response_deserializer=stream.ReadSession.deserialize,
            )
        return self._stubs["create_read_session"]

    @property
    def read_rows(
        self,
    ) -> Callable[[storage.ReadRowsRequest], storage.ReadRowsResponse]:
        r"""Return a callable for the read rows method over gRPC.

        Reads rows from the stream in the format prescribed
        by the ReadSession. Each response contains one or more
        table rows, up to a maximum of 100 MiB per response;
        read requests which attempt to read individual rows
        larger than 100 MiB will fail.

        Each request also returns a set of stream statistics
        reflecting the current state of the stream.

        Returns:
            Callable[[~.ReadRowsRequest],
                    ~.ReadRowsResponse]:
                A function that, when called, will call the underlying RPC
                on the server.
        """
        # Generate a "stub function" on-the-fly which will actually make
        # the request.
        # gRPC handles serialization and deserialization, so we just need
        # to pass in the functions for each.
        if "read_rows" not in self._stubs:
            self._stubs["read_rows"] = self.grpc_channel.unary_stream(
                "/google.cloud.bigquery.storage.v1.BigQueryRead/ReadRows",
                request_serializer=storage.ReadRowsRequest.serialize,
                response_deserializer=storage.ReadRowsResponse.deserialize,
            )
        return self._stubs["read_rows"]

    @property
    def split_read_stream(
        self,
    ) -> Callable[[storage.SplitReadStreamRequest], storage.SplitReadStreamResponse]:
        r"""Return a callable for the split read stream method over gRPC.

        Splits a given ``ReadStream`` into two ``ReadStream`` objects.
        These ``ReadStream`` objects are referred to as the primary and
        the residual streams of the split. The original ``ReadStream``
        can still be read from in the same manner as before. Both of the
        returned ``ReadStream`` objects can also be read from, and the
        rows returned by both child streams will be the same as the rows
        read from the original stream.

        Moreover, the two child streams will be allocated back-to-back
        in the original ``ReadStream``. Concretely, it is guaranteed
        that for streams original, primary, and residual, that
        original[0-j] = primary[0-j] and original[j-n] = residual[0-m]
        once the streams have been read to completion.

        Returns:
            Callable[[~.SplitReadStreamRequest],
                    ~.SplitReadStreamResponse]:
                A function that, when called, will call the underlying RPC
                on the server.
        """
        # Generate a "stub function" on-the-fly which will actually make
        # the request.
        # gRPC handles serialization and deserialization, so we just need
        # to pass in the functions for each.
        if "split_read_stream" not in self._stubs:
            self._stubs["split_read_stream"] = self.grpc_channel.unary_unary(
                "/google.cloud.bigquery.storage.v1.BigQueryRead/SplitReadStream",
                request_serializer=storage.SplitReadStreamRequest.serialize,
                response_deserializer=storage.SplitReadStreamResponse.deserialize,
            )
        return self._stubs["split_read_stream"]

    def close(self):
        self.grpc_channel.close()


__all__ = ("BigQueryReadGrpcTransport",)