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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 platform
import sqlite3
import struct
import threading
from typing import TYPE_CHECKING, Any, List, Mapping, Optional
from synapse.storage.engines import BaseDatabaseEngine
from synapse.storage.types import Cursor
if TYPE_CHECKING:
from synapse.storage.database import LoggingDatabaseConnection
class Sqlite3Engine(BaseDatabaseEngine[sqlite3.Connection, sqlite3.Cursor]):
def __init__(self, database_config: Mapping[str, Any]):
super().__init__(sqlite3, database_config)
database = database_config.get("args", {}).get("database")
self._is_in_memory = database in (
None,
":memory:",
)
# A connection to a database that has already been prepared, to use as a
# base for an in-memory connection. This is used during unit tests to
# speed up setting up the DB.
self._prepped_conn: Optional[sqlite3.Connection] = database_config.get(
"_TEST_PREPPED_CONN"
)
if platform.python_implementation() == "PyPy":
# pypy's sqlite3 module doesn't handle bytearrays, convert them
# back to bytes.
sqlite3.register_adapter(bytearray, lambda array: bytes(array))
# The current max state_group, or None if we haven't looked
# in the DB yet.
self._current_state_group_id = None
self._current_state_group_id_lock = threading.Lock()
@property
def single_threaded(self) -> bool:
return True
@property
def supports_using_any_list(self) -> bool:
"""Do we support using `a = ANY(?)` and passing a list"""
return False
@property
def supports_returning(self) -> bool:
"""Do we support the `RETURNING` clause in insert/update/delete?"""
return sqlite3.sqlite_version_info >= (3, 35, 0)
@property
def supports_select_distinct_on(self) -> bool:
"""Do we support the `DISTINCT ON` clause in SELECT?"""
return False
@property
def supports_sequences(self) -> bool:
"""Do we support the `CREATE SEQUENCE` clause?"""
return False
def check_database(
self, db_conn: sqlite3.Connection, allow_outdated_version: bool = False
) -> None:
if not allow_outdated_version:
# Synapse is untested against older SQLite versions, and we don't want
# to let users upgrade to a version of Synapse with broken support for their
# sqlite version, because it risks leaving them with a half-upgraded db.
if sqlite3.sqlite_version_info < (3, 27, 0):
raise RuntimeError("Synapse requires sqlite 3.27 or above.")
def check_new_database(self, txn: Cursor) -> None:
"""Gets called when setting up a brand new database. This allows us to
apply stricter checks on new databases versus existing database.
"""
def convert_param_style(self, sql: str) -> str:
return sql
def on_new_connection(self, db_conn: "LoggingDatabaseConnection") -> None:
# We need to import here to avoid an import loop.
from synapse.storage.prepare_database import prepare_database
if self._is_in_memory:
# In memory databases need to be rebuilt each time. Ideally we'd
# reuse the same connection as we do when starting up, but that
# would involve using adbapi before we have started the reactor.
#
# If we have a `prepped_conn` we can use that to initialise the DB,
# otherwise we need to call `prepare_database`.
if self._prepped_conn is not None:
# Initialise the new DB from the pre-prepared DB.
assert isinstance(db_conn.conn, sqlite3.Connection)
self._prepped_conn.backup(db_conn.conn)
else:
prepare_database(db_conn, self, config=None)
db_conn.create_function("rank", 1, _rank)
db_conn.execute("PRAGMA foreign_keys = ON;")
# Enable WAL.
# see https://www.sqlite.org/wal.html
db_conn.execute("PRAGMA journal_mode = WAL;")
db_conn.commit()
def is_deadlock(self, error: Exception) -> bool:
return False
def is_connection_closed(self, conn: sqlite3.Connection) -> bool:
return False
def lock_table(self, txn: Cursor, table: str) -> None:
return
@property
def server_version(self) -> str:
"""Gets a string giving the server version. For example: '3.22.0'."""
return "%i.%i.%i" % sqlite3.sqlite_version_info
@property
def row_id_name(self) -> str:
return "rowid"
def in_transaction(self, conn: sqlite3.Connection) -> bool:
return conn.in_transaction
def attempt_to_set_autocommit(
self, conn: sqlite3.Connection, autocommit: bool
) -> None:
# Twisted doesn't let us set attributes on the connections, so we can't
# set the connection to autocommit mode.
pass
def attempt_to_set_isolation_level(
self, conn: sqlite3.Connection, isolation_level: Optional[int]
) -> None:
# All transactions are SERIALIZABLE by default in sqlite
pass
@staticmethod
def executescript(cursor: sqlite3.Cursor, script: str) -> None:
"""Execute a chunk of SQL containing multiple semicolon-delimited statements.
Python's built-in SQLite driver does not allow you to do this with DBAPI2's
`execute`:
> execute() will only execute a single SQL statement. If you try to execute more
> than one statement with it, it will raise a Warning. Use executescript() if
> you want to execute multiple SQL statements with one call.
The script is prefixed with a `BEGIN TRANSACTION`, since the docs for
`executescript` warn:
> If there is a pending transaction, an implicit COMMIT statement is executed
> first. No other implicit transaction control is performed; any transaction
> control must be added to sql_script.
"""
# The implementation of `executescript` can be found at
# https://github.com/python/cpython/blob/3.11/Modules/_sqlite/cursor.c#L1035.
cursor.executescript(f"BEGIN TRANSACTION; {script}")
# Following functions taken from: https://github.com/coleifer/peewee
def _parse_match_info(buf: bytes) -> List[int]:
bufsize = len(buf)
return [struct.unpack("@I", buf[i : i + 4])[0] for i in range(0, bufsize, 4)]
def _rank(raw_match_info: bytes) -> float:
"""Handle match_info called w/default args 'pcx' - based on the example rank
function http://sqlite.org/fts3.html#appendix_a
"""
match_info = _parse_match_info(raw_match_info)
score = 0.0
p, c = match_info[:2]
for phrase_num in range(p):
phrase_info_idx = 2 + (phrase_num * c * 3)
for col_num in range(c):
col_idx = phrase_info_idx + (col_num * 3)
x1, x2 = match_info[col_idx : col_idx + 2]
if x1 > 0:
score += float(x1) / x2
return score
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