enforce Kernel/KernelInvariant on CPython side in ARTIQ #163

New Issue

sb10q · 2022-01-10T15:37:52+08:00

sb10q commented

2022-01-10 15:37:52 +08:00

preliminary code from @ychenfo

from inspect import getfullargspec, isclass, getmro
from functools import wraps
from types import SimpleNamespace
from numpy import int32, int64
from typing import Generic, TypeVar, get_origin

T = TypeVar('T')
class Kernel(Generic[T]):
    pass

allow_kernel_read = False

def nac3(cls):
    """
    Decorates a class to be analyzed by NAC3.
    All classes containing kernels or portable methods must use this decorator.
    """
    if not isclass(cls):
        raise ValueError("nac3 annotation decorator should only be applied to classes")
    
    # python does not allow setting magic method on specific instances 
    # (https://docs.python.org/3/reference/datamodel.html#special-method-lookup).
    # use this set to keep track of those custom class instances that are
    # assigned to the `Kernel` fields of a class
    # NOTE: this might affect python gc?
    cls.__nac3_kernel_only_instances__ = set()

    def apply_kernel_only_constraints(val):
        kernel_only_set = getattr(type(val), '__nac3_kernel_only_instances__', None)
        if kernel_only_set is None:
            return
        else:
            for (_, attr_val) in val.__dict__.items():
                if not (attr_val == val):
                    apply_kernel_only_constraints(attr_val)
            kernel_only_set.add(val)

    if not cls.__setattr__ in {base.__setattr__ for base in cls.__bases__}:
        raise ValueError("custom __setattr__ is not supported in kernel classes")
    
    register_class(cls)

    immutable_fields = {
        n for b in getmro(cls)
            for (n, ty) in b.__dict__.get('__annotations__', {}).items() if get_origin(ty) == Kernel
    }
    def __setattr__(obj, key, value):
        if obj in type(obj).__nac3_kernel_only_instances__:
            raise TypeError("attempting to write to kernel only variable")
        # should allow init to set value, if no attribute then allow to set attr, then
        # recursively apply constraint to all the fields of that specific object,
        # regardless of whether they are marked with `Kernel` or not
        if key in immutable_fields:
            if hasattr(obj, key):
                raise TypeError("attempting to write to kernel only variable")
            else:
                apply_kernel_only_constraints(value)
        object.__setattr__(obj, key, value)

    def __getattribute__(obj, key):        
        # need to use `object.__getattribute__` to get attr before checking
        # the key in immutable_fields for `__init__`.
        # since that in `__init__` when setting a instance variable like `self.a = 3`
        # the sequence of internal magic call is still calling cls.__getattribute__(self, 'a')
        # first, and if only "AttributeError" is raised, it will then call `__setattr__`
        # if we raise `TypeError` too early, python will just halt at this `TypeError`.
        attr = object.__getattribute__(obj, key)
        if not allow_kernel_read:
            if obj in type(obj).__nac3_kernel_only_instances__:
                raise TypeError("attempting to read kernel only variable")
            if key in immutable_fields:
                raise TypeError("attempting to read kernel only variable")
        return attr
    
    cls.__setattr__ = __setattr__
    cls.__getattribute__ = __getattribute__

    return cls

preliminary code from @ychenfo ```python from inspect import getfullargspec, isclass, getmro from functools import wraps from types import SimpleNamespace from numpy import int32, int64 from typing import Generic, TypeVar, get_origin T = TypeVar('T') class Kernel(Generic[T]): pass allow_kernel_read = False def nac3(cls): """ Decorates a class to be analyzed by NAC3. All classes containing kernels or portable methods must use this decorator. """ if not isclass(cls): raise ValueError("nac3 annotation decorator should only be applied to classes") # python does not allow setting magic method on specific instances # (https://docs.python.org/3/reference/datamodel.html#special-method-lookup). # use this set to keep track of those custom class instances that are # assigned to the `Kernel` fields of a class # NOTE: this might affect python gc? cls.__nac3_kernel_only_instances__ = set() def apply_kernel_only_constraints(val): kernel_only_set = getattr(type(val), '__nac3_kernel_only_instances__', None) if kernel_only_set is None: return else: for (_, attr_val) in val.__dict__.items(): if not (attr_val == val): apply_kernel_only_constraints(attr_val) kernel_only_set.add(val) if not cls.__setattr__ in {base.__setattr__ for base in cls.__bases__}: raise ValueError("custom __setattr__ is not supported in kernel classes") register_class(cls) immutable_fields = { n for b in getmro(cls) for (n, ty) in b.__dict__.get('__annotations__', {}).items() if get_origin(ty) == Kernel } def __setattr__(obj, key, value): if obj in type(obj).__nac3_kernel_only_instances__: raise TypeError("attempting to write to kernel only variable") # should allow init to set value, if no attribute then allow to set attr, then # recursively apply constraint to all the fields of that specific object, # regardless of whether they are marked with `Kernel` or not if key in immutable_fields: if hasattr(obj, key): raise TypeError("attempting to write to kernel only variable") else: apply_kernel_only_constraints(value) object.__setattr__(obj, key, value) def __getattribute__(obj, key): # need to use `object.__getattribute__` to get attr before checking # the key in immutable_fields for `__init__`. # since that in `__init__` when setting a instance variable like `self.a = 3` # the sequence of internal magic call is still calling cls.__getattribute__(self, 'a') # first, and if only "AttributeError" is raised, it will then call `__setattr__` # if we raise `TypeError` too early, python will just halt at this `TypeError`. attr = object.__getattribute__(obj, key) if not allow_kernel_read: if obj in type(obj).__nac3_kernel_only_instances__: raise TypeError("attempting to read kernel only variable") if key in immutable_fields: raise TypeError("attempting to read kernel only variable") return attr cls.__setattr__ = __setattr__ cls.__getattribute__ = __getattribute__ return cls ```

sb10q self-assigned this 2022-01-10 15:37:52 +08:00

Sign in to join this conversation.