Python django.db.connection 模块，in_atomic_block() 实例源码

def run_once(self, exclude_ids=[]):
        assert not connection.in_atomic_block
        return self._run_once(exclude_ids=exclude_ids)

def set_rollback():
    if hasattr(transaction, 'set_rollback'):
        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
            # If running in >=1.6 then mark a rollback as required,
            # and allow it to be handled by Django.
            if connection.in_atomic_block:
                transaction.set_rollback(True)
    elif transaction.is_managed():
        # Otherwise handle it explicitly if in managed mode.
        if transaction.is_dirty():
            transaction.rollback()
        transaction.leave_transaction_management()
    else:
        # transaction not managed
        pass

def set_rollback():
    if hasattr(transaction, 'set_rollback'):
        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
            # If running in >=1.6 then mark a rollback as required,
            # and allow it to be handled by Django.
            if connection.in_atomic_block:
                transaction.set_rollback(True)
    elif transaction.is_managed():
        # Otherwise handle it explicitly if in managed mode.
        if transaction.is_dirty():
            transaction.rollback()
        transaction.leave_transaction_management()
    else:
        # transaction not managed
        pass

def set_rollback():
    if hasattr(transaction, 'set_rollback'):
        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
            # If running in >=1.6 then mark a rollback as required,
            # and allow it to be handled by Django.
            if connection.in_atomic_block:
                transaction.set_rollback(True)
    elif transaction.is_managed():
        # Otherwise handle it explicitly if in managed mode.
        if transaction.is_dirty():
            transaction.rollback()
        transaction.leave_transaction_management()
    else:
        # transaction not managed
        pass

def set_rollback():
    if hasattr(transaction, 'set_rollback'):
        if connection.settings_dict.get('ATOMIC_REQUESTS', False):
            # If running in >=1.6 then mark a rollback as required,
            # and allow it to be handled by Django.
            if connection.in_atomic_block:
                transaction.set_rollback(True)
    elif transaction.is_managed():
        # Otherwise handle it explicitly if in managed mode.
        if transaction.is_dirty():
            transaction.rollback()
        transaction.leave_transaction_management()
    else:
        # transaction not managed
        pass

def __enter__(self):
        """Obtain lock using pg_advisory_xact_lock()."""
        if not connection.in_atomic_block:
            raise DatabaseLockAttemptOutsideTransaction(self)
        with closing(connection.cursor()) as cursor:
            query = "SELECT %s(%%s, %%s)" % self.lock
            cursor.execute(query, self)
            if cursor.fetchone() == (False,):
                raise DatabaseLockNotHeld(self)