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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 logging
from synapse.storage.engines._base import BaseDatabaseEngine, IncorrectDatabaseSetup
from synapse.storage.types import Connection
logger = logging.getLogger(__name__)
class PostgresEngine(BaseDatabaseEngine):
def __init__(self, database_module, database_config):
super().__init__(database_module, database_config)
self.module.extensions.register_type(self.module.extensions.UNICODE)
# Disables passing `bytes` to txn.execute, c.f. #6186. If you do
# actually want to use bytes than wrap it in `bytearray`.
def _disable_bytes_adapter(_):
raise Exception("Passing bytes to DB is disabled.")
self.module.extensions.register_adapter(bytes, _disable_bytes_adapter)
self.synchronous_commit = database_config.get("synchronous_commit", True)
self._version = None # unknown as yet
@property
def single_threaded(self) -> bool:
return False
def check_database(self, db_conn, allow_outdated_version: bool = False):
# Get the version of PostgreSQL that we're using. As per the psycopg2
# docs: The number is formed by converting the major, minor, and
# revision numbers into two-decimal-digit numbers and appending them
# together. For example, version 8.1.5 will be returned as 80105
self._version = db_conn.server_version
# Are we on a supported PostgreSQL version?
if not allow_outdated_version and self._version < 90600:
raise RuntimeError("Synapse requires PostgreSQL 9.6 or above.")
with db_conn.cursor() as txn:
txn.execute("SHOW SERVER_ENCODING")
rows = txn.fetchall()
if rows and rows[0][0] != "UTF8":
raise IncorrectDatabaseSetup(
"Database has incorrect encoding: '%s' instead of 'UTF8'\n"
"See docs/postgres.md for more information." % (rows[0][0],)
)
txn.execute(
"SELECT datcollate, datctype FROM pg_database WHERE datname = current_database()"
)
collation, ctype = txn.fetchone()
if collation != "C":
logger.warning(
"Database has incorrect collation of %r. Should be 'C'\n"
"See docs/postgres.md for more information.",
collation,
)
if ctype != "C":
logger.warning(
"Database has incorrect ctype of %r. Should be 'C'\n"
"See docs/postgres.md for more information.",
ctype,
)
def check_new_database(self, txn):
"""Gets called when setting up a brand new database. This allows us to
apply stricter checks on new databases versus existing database.
"""
txn.execute(
"SELECT datcollate, datctype FROM pg_database WHERE datname = current_database()"
)
collation, ctype = txn.fetchone()
errors = []
if collation != "C":
errors.append(" - 'COLLATE' is set to %r. Should be 'C'" % (collation,))
if ctype != "C":
errors.append(" - 'CTYPE' is set to %r. Should be 'C'" % (ctype,))
if errors:
raise IncorrectDatabaseSetup(
"Database is incorrectly configured:\n\n%s\n\n"
"See docs/postgres.md for more information." % ("\n".join(errors))
)
def convert_param_style(self, sql):
return sql.replace("?", "%s")
def on_new_connection(self, db_conn):
db_conn.set_isolation_level(
self.module.extensions.ISOLATION_LEVEL_REPEATABLE_READ
)
# Set the bytea output to escape, vs the default of hex
cursor = db_conn.cursor()
cursor.execute("SET bytea_output TO escape")
# Asynchronous commit, don't wait for the server to call fsync before
# ending the transaction.
# https://www.postgresql.org/docs/current/static/wal-async-commit.html
if not self.synchronous_commit:
cursor.execute("SET synchronous_commit TO OFF")
cursor.close()
db_conn.commit()
@property
def can_native_upsert(self):
"""
Can we use native UPSERTs?
"""
return True
@property
def supports_using_any_list(self):
"""Do we support using `a = ANY(?)` and passing a list"""
return True
@property
def supports_returning(self) -> bool:
"""Do we support the `RETURNING` clause in insert/update/delete?"""
return True
def is_deadlock(self, error):
if isinstance(error, self.module.DatabaseError):
# https://www.postgresql.org/docs/current/static/errcodes-appendix.html
# "40001" serialization_failure
# "40P01" deadlock_detected
return error.pgcode in ["40001", "40P01"]
return False
def is_connection_closed(self, conn):
return bool(conn.closed)
def lock_table(self, txn, table):
txn.execute("LOCK TABLE %s in EXCLUSIVE MODE" % (table,))
@property
def server_version(self):
"""Returns a string giving the server version. For example: '8.1.5'
Returns:
string
"""
# note that this is a bit of a hack because it relies on check_database
# having been called. Still, that should be a safe bet here.
numver = self._version
assert numver is not None
# https://www.postgresql.org/docs/current/libpq-status.html#LIBPQ-PQSERVERVERSION
if numver >= 100000:
return "%i.%i" % (numver / 10000, numver % 10000)
else:
return "%i.%i.%i" % (numver / 10000, (numver % 10000) / 100, numver % 100)
def in_transaction(self, conn: Connection) -> bool:
return conn.status != self.module.extensions.STATUS_READY # type: ignore
def attempt_to_set_autocommit(self, conn: Connection, autocommit: bool):
return conn.set_session(autocommit=autocommit) # type: ignore
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