feat: DB-API driver + unit tests

google/cloud/spanner_dbapi/__init__.py

@@ -0,0 +1,85 @@
+# Copyright 2020 Google LLC
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Connection-based DB API for Cloud Spanner."""
+
+from google.cloud.spanner_dbapi.connection import Connection
+from google.cloud.spanner_dbapi.connection import connect
+
+from google.cloud.spanner_dbapi.cursor import Cursor
+
+from google.cloud.spanner_dbapi.exceptions import DatabaseError
+from google.cloud.spanner_dbapi.exceptions import DataError
+from google.cloud.spanner_dbapi.exceptions import Error
+from google.cloud.spanner_dbapi.exceptions import IntegrityError
+from google.cloud.spanner_dbapi.exceptions import InterfaceError
+from google.cloud.spanner_dbapi.exceptions import InternalError
+from google.cloud.spanner_dbapi.exceptions import NotSupportedError
+from google.cloud.spanner_dbapi.exceptions import OperationalError
+from google.cloud.spanner_dbapi.exceptions import ProgrammingError
+from google.cloud.spanner_dbapi.exceptions import Warning
+
+from google.cloud.spanner_dbapi.parse_utils import get_param_types
+
+from google.cloud.spanner_dbapi.types import BINARY
+from google.cloud.spanner_dbapi.types import DATETIME
+from google.cloud.spanner_dbapi.types import NUMBER
+from google.cloud.spanner_dbapi.types import ROWID
+from google.cloud.spanner_dbapi.types import STRING
+from google.cloud.spanner_dbapi.types import Binary
+from google.cloud.spanner_dbapi.types import Date
+from google.cloud.spanner_dbapi.types import DateFromTicks
+from google.cloud.spanner_dbapi.types import Time
+from google.cloud.spanner_dbapi.types import TimeFromTicks
+from google.cloud.spanner_dbapi.types import Timestamp
+from google.cloud.spanner_dbapi.types import TimestampStr
+from google.cloud.spanner_dbapi.types import TimestampFromTicks
+
+from google.cloud.spanner_dbapi.version import DEFAULT_USER_AGENT
+
+apilevel = "2.0"  # supports DP-API 2.0 level.
+paramstyle = "format"  # ANSI C printf format codes, e.g. ...WHERE name=%s.
+
+# Threads may share the module, but not connections. This is a paranoid threadsafety
+# level, but it is necessary for starters to use when debugging failures.
+# Eventually once transactions are working properly, we'll update the
+# threadsafety level.
+threadsafety = 1
+
+
+__all__ = [
+    "Connection",
+    "connect",
+    "Cursor",
+    "DatabaseError",
+    "DataError",
+    "Error",
+    "IntegrityError",
+    "InterfaceError",
+    "InternalError",
+    "NotSupportedError",
+    "OperationalError",
+    "ProgrammingError",
+    "Warning",
+    "DEFAULT_USER_AGENT",
+    "apilevel",
+    "paramstyle",
+    "threadsafety",
+    "get_param_types",
+    "Binary",
+    "Date",
+    "DateFromTicks",
+    "Time",
+    "TimeFromTicks",
+    "Timestamp",
+    "TimestampFromTicks",
+    "BINARY",
+    "STRING",
+    "NUMBER",
+    "DATETIME",
+    "ROWID",
+    "TimestampStr",
+]

google/cloud/spanner_dbapi/_helpers.py

@@ -0,0 +1,153 @@
+# Copyright 2020 Google LLC
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+from google.cloud.spanner_dbapi.parse_utils import get_param_types
+from google.cloud.spanner_dbapi.parse_utils import parse_insert
+from google.cloud.spanner_dbapi.parse_utils import sql_pyformat_args_to_spanner
+from google.cloud.spanner_v1 import param_types
+
+
+SQL_LIST_TABLES = """
+            SELECT
+              t.table_name
+            FROM
+              information_schema.tables AS t
+            WHERE
+              t.table_catalog = '' and t.table_schema = ''
+            """
+
+SQL_GET_TABLE_COLUMN_SCHEMA = """SELECT
+                COLUMN_NAME, IS_NULLABLE, SPANNER_TYPE
+            FROM
+                INFORMATION_SCHEMA.COLUMNS
+            WHERE
+                TABLE_SCHEMA = ''
+            AND
+                TABLE_NAME = @table_name
+            """
+
+# This table maps spanner_types to Spanner's data type sizes as per
+#   https://cloud.google.com/spanner/docs/data-types#allowable-types
+# It is used to map `display_size` to a known type for Cursor.description
+# after a row fetch.
+# Since ResultMetadata
+#   https://cloud.google.com/spanner/docs/reference/rest/v1/ResultSetMetadata
+# does not send back the actual size, we have to lookup the respective size.
+# Some fields' sizes are dependent upon the dynamic data hence aren't sent back
+# by Cloud Spanner.
+code_to_display_size = {
+    param_types.BOOL.code: 1,
+    param_types.DATE.code: 4,
+    param_types.FLOAT64.code: 8,
+    param_types.INT64.code: 8,
+    param_types.TIMESTAMP.code: 12,
+}
+
+
+def _execute_insert_heterogenous(transaction, sql_params_list):
+    for sql, params in sql_params_list:
+        sql, params = sql_pyformat_args_to_spanner(sql, params)
+        param_types = get_param_types(params)
+        res = transaction.execute_sql(sql, params=params, param_types=param_types)
+        # TODO: File a bug with Cloud Spanner and the Python client maintainers
+        # about a lost commit when res isn't read from.
+        _ = list(res)
+
+
+def _execute_insert_homogenous(transaction, parts):
+    # Perform an insert in one shot.
+    table = parts.get("table")
+    columns = parts.get("columns")
+    values = parts.get("values")
+    return transaction.insert(table, columns, values)
+
+
+def handle_insert(connection, sql, params):
+    parts = parse_insert(sql, params)
+
+    # The split between the two styles exists because:
+    # in the common case of multiple values being passed
+    # with simple pyformat arguments,
+    #   SQL: INSERT INTO T (f1, f2) VALUES (%s, %s, %s)
+    #   Params:   [(1, 2, 3, 4, 5, 6, 7, 8, 9, 10,)]
+    # we can take advantage of a single RPC with:
+    #       transaction.insert(table, columns, values)
+    # instead of invoking:
+    #   with transaction:
+    #       for sql, params in sql_params_list:
+    #           transaction.execute_sql(sql, params, param_types)
+    # which invokes more RPCs and is more costly.
+
+    if parts.get("homogenous"):
+        # The common case of multiple values being passed in
+        # non-complex pyformat args and need to be uploaded in one RPC.
+        return connection.database.run_in_transaction(_execute_insert_homogenous, parts)
+    else:
+        # All the other cases that are esoteric and need
+        #   transaction.execute_sql
+        sql_params_list = parts.get("sql_params_list")
+        return connection.database.run_in_transaction(
+            _execute_insert_heterogenous, sql_params_list
+        )
+
+
+class ColumnInfo:
+    """Row column description object."""
+
+    def __init__(
+        self,
+        name,
+        type_code,
+        display_size=None,
+        internal_size=None,
+        precision=None,
+        scale=None,
+        null_ok=False,
+    ):
+        self.name = name
+        self.type_code = type_code
+        self.display_size = display_size
+        self.internal_size = internal_size
+        self.precision = precision
+        self.scale = scale
+        self.null_ok = null_ok
+
+        self.fields = (
+            self.name,
+            self.type_code,
+            self.display_size,
+            self.internal_size,
+            self.precision,
+            self.scale,
+            self.null_ok,
+        )
+
+    def __repr__(self):
+        return self.__str__()
+
+    def __getitem__(self, index):
+        return self.fields[index]
+
+    def __str__(self):
+        str_repr = ", ".join(
+            filter(
+                lambda part: part is not None,
+                [
+                    "name='%s'" % self.name,
+                    "type_code=%d" % self.type_code,
+                    "display_size=%d" % self.display_size
+                    if self.display_size
+                    else None,
+                    "internal_size=%d" % self.internal_size
+                    if self.internal_size
+                    else None,
+                    "precision='%s'" % self.precision if self.precision else None,
+                    "scale='%s'" % self.scale if self.scale else None,
+                    "null_ok='%s'" % self.null_ok if self.null_ok else None,
+                ],
+            )
+        )
+        return "ColumnInfo(%s)" % str_repr