Mailing List Archive

Log message for revision 41611:
Explicitly set transaction isolation level and client_encoding setting.
Catch deadlock and serialization exceptions and reraise them as Retry
exceptions, causing Z3 to retry the transaction.



Changed:
U psycopgda/trunk/adapter.py

-=-
Modified: psycopgda/trunk/adapter.py
===================================================================
--- psycopgda/trunk/adapter.py 2006-02-12 18:07:46 UTC (rev 41610)
+++ psycopgda/trunk/adapter.py 2006-02-13 00:44:23 UTC (rev 41611)
@@ -1,6 +1,6 @@
##############################################################################
#
-# Copyright (c) 2002-2004 Zope Corporation and Contributors.
+# Copyright (c) 2002-2006 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
@@ -15,12 +15,18 @@

$Id$
"""
-from zope.app.rdb import ZopeDatabaseAdapter, parseDSN
+from zope.app.rdb import (
+ ZopeDatabaseAdapter, parseDSN, ZopeConnection, ZopeCursor
+ )
+from zope.app.rdb.interfaces import DatabaseException
+from zope.publisher.interfaces import Retry

from datetime import date, time, datetime, timedelta
import psycopg
import re
+import sys

+PG_ENCODING = 'UTF-8'

# These OIDs are taken from include/server/pg_type.h from PostgreSQL headers.
# Unfortunatelly psycopg does not export them as constants, and
@@ -321,17 +327,86 @@
it might be something like '1 month', which is a variable number of days.
"""

+ def connect(self):
+ if not self.isConnected():
+ try:
+ self._v_connection = PsycopgConnection(
+ self._connection_factory(), self
+ )
+ except psycopg.Error, error:
+ raise DatabaseException, str(error)
+
def _connection_factory(self):
"""Create a Psycopg DBI connection based on the DSN"""
+ registerTypes(PG_ENCODING)
conn_info = parseDSN(self.dsn)
conn_list = []
for dsnname, optname in dsn2option_mapping.iteritems():
if conn_info[dsnname]:
conn_list.append('%s=%s' % (optname, conn_info[dsnname]))
conn_str = ' '.join(conn_list)
- self._registerTypes()
- return psycopg.connect(conn_str)
+ connection = psycopg.connect(conn_str)

- def _registerTypes(self):
- """Register type conversions for psycopg"""
- registerTypes(self.getEncoding())
+ # Ensure we are in SERIALIZABLE transaction isolation level.
+ # This is the default under psycopg1, but changed to READ COMMITTED
+ # under psycopg2. This should become an option if anyone wants
+ # different isolation levels.
+ connection.set_isolation_level(3)
+
+ # Ensure the client_encoding for this connection matches PG_ENCODING
+ cur = connection.cursor()
+ cur.execute("SET client_encoding TO UNICODE")
+ connection.commit()
+ return connection
+
+
+def _handle_psycopg_exception(error):
+ """Called from a exception handler for psycopg.Error.
+
+ If we have a serialization exception or a deadlock, we should retry the
+ transaction by raising a Retry exception. Otherwise, we reraise.
+ """
+ if not error.args:
+ raise
+ msg = error.args[0]
+ # These messages are from PostgreSQL 8.0. They may change between
+ # PostgreSQL releases - if so, the different messages should be added
+ # rather than the existing ones changed so this logic works with
+ # different versions.
+ if msg.startswith(
+ 'ERROR: could not serialize access due to concurrent update'
+ ):
+ raise Retry(sys.exc_info())
+ if msg.startswith('ERROR: deadlock detected'):
+ raise Retry(sys.exc_info())
+ raise
+
+
+class PsycopgConnection(ZopeConnection):
+ def cursor(self):
+ """See IZopeConnection"""
+ return PsycopgCursor(self.conn.cursor(), self)
+
+ def commit(self):
+ try:
+ ZopeConnection.commit(self)
+ except psycopg.Error, error:
+ _handle_psycopg_exception(error)
+
+
+class PsycopgCursor(ZopeCursor):
+ def execute(self, operation, parameters=None):
+ """See IZopeCursor"""
+ try:
+ return ZopeCursor.execute(self, operation, parameters)
+ except psycopg.Error, error:
+ _handle_psycopg_exception(error)
+
+ def executemany(operation, seq_of_parameters=None):
+ """See IZopeCursor"""
+ raise RuntimeError, 'Oos'
+ try:
+ return ZopeCursor.execute(self, operation, seq_of_parameters)
+ except psycopg.Error, error:
+ _handle_psycopg_exception(error)
+

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