Fixed #15802 -- pyscopg2 sometimes fail to close the connection when it's...

from django.db.backends.postgresql_psycopg2.version import get_version

from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection

from django.utils.safestring import SafeUnicode, SafeString

from django.utils.log import getLogger

try:

    import psycopg2 as Database

psycopg2.extensions.register_adapter(SafeString, psycopg2.extensions.QuotedString)

psycopg2.extensions.register_adapter(SafeUnicode, psycopg2.extensions.QuotedString)

logger = getLogger('django.db.backends')

class CursorWrapper(object):

    """

    A thin wrapper around psycopg2's normal cursor class so that we can catch

        self.cursor().execute('SET CONSTRAINTS ALL IMMEDIATE')

        self.cursor().execute('SET CONSTRAINTS ALL DEFERRED')

    def close(self):

        if self.connection is None:

            return

        try:

            self.connection.close()

            self.connection = None

        except psycopg2.Error:

            # In some cases (database restart, network connection lost etc...)

            # the connection to the database is lost without giving Django a

            # notification. If we don't set self.connection to None, the error

            # will occur a every request.

            self.connection = None

            logger.warning('psycopg2 error while closing the connection.',

                exc_info=sys.exc_info()

            )

            raise

    def _get_pg_version(self):

        if self._pg_version is None:

            self._pg_version = get_version(self.connection)