Fixed #21553 -- Ensured unusable database connections get closed. (5f2f47fd) · Commits · Dom Sekotill / django

django/db/backends/init.py

+6 −1

Original line number	Diff line number	Diff line
		@@ -351,9 +351,14 @@ class BaseDatabaseWrapper(object):
		def is_usable(self):
		"""
		Tests if the database connection is usable.

		This function may assume that self.connection is not None.

		Actual implementations should take care not to raise exceptions
		as that may prevent Django from recycling unusable connections.
		"""
		raise NotImplementedError('subclasses of BaseDatabaseWrapper may require an is_usable() method')
		raise NotImplementedError(
		"subclasses of BaseDatabaseWrapper may require an is_usable() method")

		def close_if_unusable_or_obsolete(self):
		"""

+1 −1

Original line number	Diff line number	Diff line
		@@ -552,7 +552,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
		def is_usable(self):
		try:
		self.connection.ping()
		except DatabaseError:
		except Database.Error:
		return False
		else:
		return True

+1 −1

Original line number	Diff line number	Diff line
		@@ -704,7 +704,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
		else:
		# Use a cx_Oracle cursor directly, bypassing Django's utilities.
		self.connection.cursor().execute("SELECT 1 FROM DUAL")
		except DatabaseError:
		except Database.Error:
		return False
		else:
		return True

+1 −1

Original line number	Diff line number	Diff line
		@@ -210,7 +210,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
		try:
		# Use a psycopg cursor directly, bypassing Django's utilities.
		self.connection.cursor().execute("SELECT 1")
		except DatabaseError:
		except Database.Error:
		return False
		else:
		return True

+31 −0

Original line number	Diff line number	Diff line
		@@ -665,6 +665,37 @@ class BackendTestCase(TestCase):
		self.assertTrue(cursor.closed)


		class IsUsableTests(TransactionTestCase):
		# Avoid using a regular TestCase because Django really dislikes closing
		# the database connection inside a transaction at this point (#21202).

		available_apps = []

		# Unfortunately with sqlite3 the in-memory test database cannot be closed.
		@skipUnlessDBFeature('test_db_allows_multiple_connections')
		def test_is_usable_after_database_disconnects(self):
		"""
		Test that is_usable() doesn't crash when the database disconnects.

		Regression for #21553.
		"""
		# Open a connection to the database.
		with connection.cursor():
		pass
		# Emulate a connection close by the database.
		connection._close()
		# Even then is_usable() should not raise an exception.
		try:
		self.assertFalse(connection.is_usable())
		finally:
		# Clean up the mess created by connection._close(). Since the
		# connection is already closed, this crashes on some backends.
		try:
		connection.close()
		except Exception:
		pass


		# We don't make these tests conditional because that means we would need to
		# check and differentiate between:
		# * MySQL+InnoDB, MySQL+MYISAM (something we currently can't do).