synapse-product/synapse/storage/engines/postgres.py

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# -*- coding: utf-8 -*-
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# Copyright 2015, 2016 OpenMarket Ltd
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#
# 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.
from ._base import IncorrectDatabaseSetup
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class PostgresEngine(object):
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single_threaded = False
def __init__(self, database_module, database_config):
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self.module = database_module
self.module.extensions.register_type(self.module.extensions.UNICODE)
self.synchronous_commit = database_config.get("synchronous_commit", True)
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def check_database(self, 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.rst for more information."
% (rows[0][0],)
)
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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
)
# 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 = db_conn.cursor()
cursor.execute("SET synchronous_commit TO OFF")
cursor.close()
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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
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return error.pgcode in ["40001", "40P01"]
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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,))
def get_next_state_group_id(self, txn):
"""Returns an int that can be used as a new state_group ID
"""
txn.execute("SELECT nextval('state_group_id_seq')")
return txn.fetchone()[0]