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# Copyright 2015, 2016 OpenMarket Ltd
#
# 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 abc
from enum import IntEnum
from typing import TYPE_CHECKING, Any, Generic, Mapping, Optional, TypeVar
from synapse.storage.types import Connection, Cursor, DBAPI2Module
if TYPE_CHECKING:
from synapse.storage.database import LoggingDatabaseConnection
class IsolationLevel(IntEnum):
READ_COMMITTED: int = 1
REPEATABLE_READ: int = 2
SERIALIZABLE: int = 3
class IncorrectDatabaseSetup(RuntimeError):
pass
ConnectionType = TypeVar("ConnectionType", bound=Connection)
CursorType = TypeVar("CursorType", bound=Cursor)
class BaseDatabaseEngine(Generic[ConnectionType, CursorType], metaclass=abc.ABCMeta):
def __init__(self, module: DBAPI2Module, config: Mapping[str, Any]):
self.module = module
@property
@abc.abstractmethod
def single_threaded(self) -> bool:
...
@property
@abc.abstractmethod
def supports_using_any_list(self) -> bool:
"""
Do we support using `a = ANY(?)` and passing a list
"""
...
@property
@abc.abstractmethod
def supports_returning(self) -> bool:
"""Do we support the `RETURNING` clause in insert/update/delete?"""
...
@abc.abstractmethod
def check_database(
self, db_conn: ConnectionType, allow_outdated_version: bool = False
) -> None:
...
@abc.abstractmethod
def check_new_database(self, txn: CursorType) -> None:
"""Gets called when setting up a brand new database. This allows us to
apply stricter checks on new databases versus existing database.
"""
...
@abc.abstractmethod
def convert_param_style(self, sql: str) -> str:
...
# This method would ideally take a plain ConnectionType, but it seems that
# the Sqlite engine expects to use LoggingDatabaseConnection.cursor
# instead of sqlite3.Connection.cursor: only the former takes a txn_name.
@abc.abstractmethod
def on_new_connection(self, db_conn: "LoggingDatabaseConnection") -> None:
...
@abc.abstractmethod
def is_deadlock(self, error: Exception) -> bool:
...
@abc.abstractmethod
def is_connection_closed(self, conn: ConnectionType) -> bool:
...
@abc.abstractmethod
def lock_table(self, txn: Cursor, table: str) -> None:
...
@property
@abc.abstractmethod
def server_version(self) -> str:
"""Gets a string giving the server version. For example: '3.22.0'"""
...
@abc.abstractmethod
def in_transaction(self, conn: ConnectionType) -> bool:
"""Whether the connection is currently in a transaction."""
...
@abc.abstractmethod
def attempt_to_set_autocommit(self, conn: ConnectionType, autocommit: bool) -> None:
"""Attempt to set the connections autocommit mode.
When True queries are run outside of transactions.
Note: This has no effect on SQLite3, so callers still need to
commit/rollback the connections.
"""
...
@abc.abstractmethod
def attempt_to_set_isolation_level(
self, conn: ConnectionType, isolation_level: Optional[int]
) -> None:
"""Attempt to set the connections isolation level.
Note: This has no effect on SQLite3, as transactions are SERIALIZABLE by default.
"""
...
@staticmethod
@abc.abstractmethod
def executescript(cursor: CursorType, script: str) -> None:
"""Execute a chunk of SQL containing multiple semicolon-delimited statements.
This is not provided by DBAPI2, and so needs engine-specific support.
Some database engines may automatically COMMIT the ongoing transaction both
before and after executing the script.
"""
...
@classmethod
def execute_script_file(cls, cursor: CursorType, filepath: str) -> None:
"""Execute a file containing multiple semicolon-delimited SQL statements.
This is not provided by DBAPI2, and so needs engine-specific support.
"""
with open(filepath, "rt") as f:
cls.executescript(cursor, f.read())
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