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Fixed #19274 -- Made db connection creation overridable in subclasses 

Connection creation was done in db backend ._cursor() call. This
included taking a new connection if needed, initializing the session
state for the new connection and finally creating the connection.

To allow easier modifying of these steps in subclasses (for example to
support connection pools) the _cursor() now calls get_new_connection()
and init_connection_state() if there isn't an existing connection. This
was done for all non-gis core backends. In addition the parameters used
for taking a connection are now created by get_connection_params().

We should also do the same for gis backends and encourage 3rd party
backends to use the same pattern. The pattern is not enforced in code,
and as the backends are private API this will not be required by
documentation either.
This commit is contained in:
Anssi Kääriäinen 2012-11-26 22:42:27 +02:00
parent 2ea80b94d7
commit 1893467784
4 changed files with 183 additions and 140 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
django/db/backends/mysql/base.py
View File

@ -372,14 +372,10 @@ class DatabaseWrapper(BaseDatabaseWrapper):
self.connection.ping()
return True
except DatabaseError:
self.connection.close()
self.connection = None
self.close()
return False
def _cursor(self):
new_connection = False
if not self._valid_connection():
new_connection = True
def get_connection_params(self):
kwargs = {
'conv': django_conversions,
'charset': 'utf8',
@ -402,17 +398,30 @@ class DatabaseWrapper(BaseDatabaseWrapper):
# "UPDATE", not the number of changed rows.
kwargs['client_flag'] = CLIENT.FOUND_ROWS
kwargs.update(settings_dict['OPTIONS'])
self.connection = Database.connect(**kwargs)
self.connection.encoders[SafeText] = self.connection.encoders[six.text_type]
self.connection.encoders[SafeBytes] = self.connection.encoders[bytes]
connection_created.send(sender=self.__class__, connection=self)
return kwargs
def get_new_connection(self, conn_params):
conn = Database.connect(**conn_params)
conn.encoders[SafeText] = conn.encoders[six.text_type]
conn.encoders[SafeBytes] = conn.encoders[bytes]
return conn
def init_connection_state(self):
cursor = self.connection.cursor()
if new_connection:
# SQL_AUTO_IS_NULL in MySQL controls whether an AUTO_INCREMENT column
# on a recently-inserted row will return when the field is tested for
# NULL. Disabling this value brings this aspect of MySQL in line with
# SQL standards.
cursor.execute('SET SQL_AUTO_IS_NULL = 0')
cursor.close()
def _cursor(self):
if not self._valid_connection():
conn_params = self.get_connection_params()
self.connection = self.get_new_connection(conn_params)
self.init_connection_state()
connection_created.send(sender=self.__class__, connection=self)
cursor = self.connection.cursor()
return CursorWrapper(cursor)
def _rollback(self):
@ -433,8 +442,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
server_info = self.connection.get_server_info()
if new_connection:
# Make sure we close the connection
self.connection.close()
self.connection = None
self.close()
m = server_version_re.match(server_info)
if not m:
raise Exception('Unable to determine MySQL version from version string %r' % server_info)

32
django/db/backends/oracle/base.py
View File

@ -489,15 +489,21 @@ class DatabaseWrapper(BaseDatabaseWrapper):
return "%s/%s@%s" % (settings_dict['USER'],
settings_dict['PASSWORD'], dsn)
def _cursor(self):
cursor = None
if not self._valid_connection():
conn_string = convert_unicode(self._connect_string())
def create_cursor(self, conn):
return FormatStylePlaceholderCursor(conn)
def get_connection_params(self):
conn_params = self.settings_dict['OPTIONS'].copy()
if 'use_returning_into' in conn_params:
del conn_params['use_returning_into']
self.connection = Database.connect(conn_string, **conn_params)
cursor = FormatStylePlaceholderCursor(self.connection)
return conn_params
def get_new_connection(self, conn_params):
conn_string = convert_unicode(self._connect_string())
return Database.connect(conn_string, **conn_params)
def init_connection_state(self):
cursor = self.create_cursor(self.connection)
# Set the territory first. The territory overrides NLS_DATE_FORMAT
# and NLS_TIMESTAMP_FORMAT to the territory default. When all of
# these are set in single statement it isn't clear what is supposed
@ -511,13 +517,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
"ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS'"
" NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF'"
+ (" TIME_ZONE = 'UTC'" if settings.USE_TZ else ''))
cursor.close()
if 'operators' not in self.__dict__:
# Ticket #14149: Check whether our LIKE implementation will
# work for this connection or we need to fall back on LIKEC.
# This check is performed only once per DatabaseWrapper
# instance per thread, since subsequent connections will use
# the same settings.
cursor = self.create_cursor(self.connection)
try:
cursor.execute("SELECT 1 FROM DUAL WHERE DUMMY %s"
% self._standard_operators['contains'],
@ -526,6 +533,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
self.operators = self._likec_operators
else:
self.operators = self._standard_operators
cursor.close()
try:
self.oracle_version = int(self.connection.version.split('.')[0])
@ -545,10 +553,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
# Django docs specify cx_Oracle version 4.3.1 or higher, but
# stmtcachesize is available only in 4.3.2 and up.
pass
def _cursor(self):
if not self._valid_connection():
conn_params = self.get_connection_params()
self.connection = self.get_new_connection(conn_params)
self.init_connection_state()
connection_created.send(sender=self.__class__, connection=self)
if not cursor:
cursor = FormatStylePlaceholderCursor(self.connection)
return cursor
return self.create_cursor(self.connection)
# Oracle doesn't support savepoint commits. Ignore them.
def _savepoint_commit(self, sid):

17
django/db/backends/postgresql_psycopg2/base.py
View File

@ -156,9 +156,8 @@ class DatabaseWrapper(BaseDatabaseWrapper):
return self._pg_version
pg_version = property(_get_pg_version)
def _cursor(self):
def get_connection_params(self):
settings_dict = self.settings_dict
if self.connection is None:
if not settings_dict['NAME']:
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured(
@ -178,7 +177,13 @@ class DatabaseWrapper(BaseDatabaseWrapper):
conn_params['host'] = settings_dict['HOST']
if settings_dict['PORT']:
conn_params['port'] = settings_dict['PORT']
self.connection = Database.connect(**conn_params)
return conn_params
def get_new_connection(self, conn_params):
return Database.connect(**conn_params)
def init_connection_state(self):
settings_dict = self.settings_dict
self.connection.set_client_encoding('UTF8')
tz = 'UTC' if settings.USE_TZ else settings_dict.get('TIME_ZONE')
if tz:
@ -198,6 +203,12 @@ class DatabaseWrapper(BaseDatabaseWrapper):
self.ops.set_time_zone_sql(), [tz])
self.connection.set_isolation_level(self.isolation_level)
self._get_pg_version()
def _cursor(self):
if self.connection is None:
conn_params = self.get_connection_params()
self.connection = self.get_new_connection(conn_params)
self.init_connection_state()
connection_created.send(sender=self.__class__, connection=self)
cursor = self.connection.cursor()
cursor.tzinfo_factory = utc_tzinfo_factory if settings.USE_TZ else None

24
django/db/backends/sqlite3/base.py
View File

@ -266,7 +266,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
self.introspection = DatabaseIntrospection(self)
self.validation = BaseDatabaseValidation(self)
def _sqlite_create_connection(self):
def get_connection_params(self):
settings_dict = self.settings_dict
if not settings_dict['NAME']:
from django.core.exceptions import ImproperlyConfigured
@ -293,12 +293,24 @@ class DatabaseWrapper(BaseDatabaseWrapper):
RuntimeWarning
)
kwargs.update({'check_same_thread': False})
self.connection = Database.connect(**kwargs)
return kwargs
def get_new_connection(self, conn_params):
conn = Database.connect(**conn_params)
# Register extract, date_trunc, and regexp functions.
self.connection.create_function("django_extract", 2, _sqlite_extract)
self.connection.create_function("django_date_trunc", 2, _sqlite_date_trunc)
self.connection.create_function("regexp", 2, _sqlite_regexp)
self.connection.create_function("django_format_dtdelta", 5, _sqlite_format_dtdelta)
conn.create_function("django_extract", 2, _sqlite_extract)
conn.create_function("django_date_trunc", 2, _sqlite_date_trunc)
conn.create_function("regexp", 2, _sqlite_regexp)
conn.create_function("django_format_dtdelta", 5, _sqlite_format_dtdelta)
return conn
def init_connection_state(self):
pass
def _sqlite_create_connection(self):
conn_params = self.get_connection_params()
self.connection = self.get_new_connection(conn_params)
self.init_connection_state()
connection_created.send(sender=self.__class__, connection=self)
def _cursor(self):