[Cython] Speedup module-level lookup

[Robert Bradshaw]

On Wed, Jan 18, 2012 at 11:53 PM, Vitja Makarov <vitja.makarov at gmail.com> wrote:
> 2012/1/19 Vitja Makarov <vitja.makarov at gmail.com>:
>> 2012/1/19 Robert Bradshaw <robertwb at math.washington.edu>:
>>> I think the right thing to do here is make all module-level globals
>>> into "cdef public" attributes, i.e. C globals with getters and setters
>>> for Python space. I'm not sure whether this would best be done by
>>> creating a custom dict or module subclass, but it would probably be
>>> cleaner and afford much more than a 1.6x speedup.
>>>
>>> - Robert
>>>
>>> On Wed, Jan 18, 2012 at 12:30 PM, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>>>> I tried to optimize module lookups (__pyx_m) by caching internal PyDict state.
>>>>
>>>> In this example bar() is 1.6 time faster (500us against 842us):
>>>>
>>>> C = 123
>>>> def foo(a):
>>>>     return C * adef bar():
>>>>     for i in range(10000):        foo(i)
>>>> Here is proof of
>>>> concept:https://github.com/vitek/cython/commit/1d134fe54a74e6fc6d39d09973db499680b2a8d9
>>>>
>>>> So the question is: does it worth it?
>>>>
>>
>> Yes, nice idea.
>> It's possible to subclass PyModuleObject and I didn't find any use of
>> PyModule_CheckExact() in CPython's sources:
>>
>> import types
>> import sys
>>
>> global_foo = 1234
>>
>> class CustomModule(types.ModuleType):
>>    def __init__(self, name):
>>        types.ModuleType.__init__(self, name)
>>        sys.modules[name] = self
>>
>>    @property
>>    def foo(self):
>>        return global_foo
>>
>>    @foo.setter
>>    def foo(self, value):
>>        global global_foo
>>        global_foo = value
>>
>> CustomModule('foo')
>>
>> import foo
>> print foo.foo
>>
>
> But this seems to break globals().

How so? We have to hack globals() to get it to work for a Cython
module anyways. (I wonder if this must return a dict, or would any
mapping (or subclass of dict) be sufficient...)

- Robert