Python uwsgidecorator @spool() allows keyword arguments to leak between spooler function calls

[jsivak]

Found using Python 2.7 and uWSGI 2.0.6.

Executing @spool() decorated functions in this order will result in 'arg3' still being passed to the "do_something()" task on the 3rd call, even though it wasn't explicitly passed.

Example:

spooler_tasks.do_something({'arg1': 'in do_something', 'arg2': 'value2'})
spooler_tasks.do_something({'arg1': 'in do_something', 'arg2': 'value2', 'arg3': 'value3'})
spooler_tasks.do_something({'arg1': 'in do_something', 'arg2': 'value2'})

The problem appears to be in the handling of the arguments variable in uwsgidecorators.py around line 70.

class _spoolraw(object):

    def __call__(self, *args, **kwargs):
        arguments = self.base_dict
        if not self.pass_arguments:
            if len(args) > 0:
                arguments.update(args[0])
            if kwargs:
                arguments.update(kwargs)
        else:
            spooler_args = {}
            for key in ('message_dict', 'spooler', 'priority', 'at', 'body'):
                if key in kwargs:
                    spooler_args.update({key: kwargs.pop(key)})
            arguments.update(spooler_args)
            arguments.update({'args': pickle.dumps(args), 'kwargs': pickle.dumps(kwargs)})
        return uwsgi.spool(arguments)

    # For backward compatibility (uWSGI < 1.9.13)
    def spool(self, *args, **kwargs):
        return self.__class__.__call__(self, *args, **kwargs)

    def __init__(self, f, pass_arguments):
        if not 'spooler' in uwsgi.opt:
            raise Exception(
                "you have to enable the uWSGI spooler to use @%s decorator" % self.__class__.__name__)
        self.f = f
        spooler_functions[self.f.__name__] = self.f
        # For backward compatibility (uWSGI < 1.9.13)
        self.f.spool = self.__call__
        self.pass_arguments = pass_arguments
        self.base_dict = {'ud_spool_func': self.f.__name__}

I believe the assignment of arguments = self.base_dict needs to be set to a copy of self.base_dict, not a reference, so the correct line should be arguments = self.base_dict.copy(). Currently arguments is getting the reference to self.base_dict and any keyword args that are being passed to the @spool() decorated function are being added/remembered across function calls to the decorated function, which is more obvious when the number of keyword arguments to a single spooled function changes.

I believe a shallow copy of self.base_dict should work, but not 100% sure on that.

[jsivak]

Is this the correct place to file this bug?

[unbit]

Yes for sure, sorry for the late, checking it.

[unbit]

We are refactoring the spool decorator to fix this issue and to correctly support python 3. Thanks for your report

[aldur]

It should be fixed now, thanks for your report.

[jsivak]

So this should be in the next (2.0.8) release?

[unbit]

@jsivak You can already use it with

pip install uwsgidecorators

@aldur splitted it a couple of days ago

[jsivak]

Ah, thanks! I didn't realize it was going to be released "outside" of the main uwsgi package.