108 lines
3.9 KiB
Python
108 lines
3.9 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from ._base import IncorrectDatabaseSetup
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class PostgresEngine(object):
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single_threaded = False
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def __init__(self, database_module, database_config):
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self.module = database_module
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self.module.extensions.register_type(self.module.extensions.UNICODE)
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self.synchronous_commit = database_config.get("synchronous_commit", True)
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self._version = None # unknown as yet
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def check_database(self, txn):
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txn.execute("SHOW SERVER_ENCODING")
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rows = txn.fetchall()
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if rows and rows[0][0] != "UTF8":
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raise IncorrectDatabaseSetup(
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"Database has incorrect encoding: '%s' instead of 'UTF8'\n"
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"See docs/postgres.rst for more information." % (rows[0][0],)
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)
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def convert_param_style(self, sql):
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return sql.replace("?", "%s")
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def on_new_connection(self, db_conn):
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# Get the version of PostgreSQL that we're using. As per the psycopg2
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# docs: The number is formed by converting the major, minor, and
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# revision numbers into two-decimal-digit numbers and appending them
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# together. For example, version 8.1.5 will be returned as 80105
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self._version = db_conn.server_version
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db_conn.set_isolation_level(
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self.module.extensions.ISOLATION_LEVEL_REPEATABLE_READ
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)
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# Set the bytea output to escape, vs the default of hex
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cursor = db_conn.cursor()
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cursor.execute("SET bytea_output TO escape")
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# Asynchronous commit, don't wait for the server to call fsync before
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# ending the transaction.
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# https://www.postgresql.org/docs/current/static/wal-async-commit.html
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if not self.synchronous_commit:
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cursor.execute("SET synchronous_commit TO OFF")
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cursor.close()
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@property
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def can_native_upsert(self):
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"""
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Can we use native UPSERTs? This requires PostgreSQL 9.5+.
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"""
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return self._version >= 90500
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def is_deadlock(self, error):
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if isinstance(error, self.module.DatabaseError):
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# https://www.postgresql.org/docs/current/static/errcodes-appendix.html
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# "40001" serialization_failure
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# "40P01" deadlock_detected
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return error.pgcode in ["40001", "40P01"]
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return False
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def is_connection_closed(self, conn):
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return bool(conn.closed)
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def lock_table(self, txn, table):
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txn.execute("LOCK TABLE %s in EXCLUSIVE MODE" % (table,))
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def get_next_state_group_id(self, txn):
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"""Returns an int that can be used as a new state_group ID
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"""
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txn.execute("SELECT nextval('state_group_id_seq')")
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return txn.fetchone()[0]
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@property
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def server_version(self):
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"""Returns a string giving the server version. For example: '8.1.5'
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Returns:
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string
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"""
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# note that this is a bit of a hack because it relies on on_new_connection
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# having been called at least once. Still, that should be a safe bet here.
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numver = self._version
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assert numver is not None
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# https://www.postgresql.org/docs/current/libpq-status.html#LIBPQ-PQSERVERVERSION
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if numver >= 100000:
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return "%i.%i" % (numver / 10000, numver % 10000)
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else:
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return "%i.%i.%i" % (numver / 10000, (numver % 10000) / 100, numver % 100)
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