eptm_dashboard/.venv/lib/python3.12/site-packages/reflex/istate/proxy.py

796 lines
27 KiB
Python

"""A module to hold state proxy classes."""
from __future__ import annotations
import asyncio
import copy
import dataclasses
import functools
import inspect
import json
import sys
from collections.abc import Callable, Sequence
from importlib.util import find_spec
from types import MethodType
from typing import TYPE_CHECKING, Any, SupportsIndex, TypeVar
import wrapt
from reflex_base.event import Event
from reflex_base.event.context import EventContext
from reflex_base.utils.exceptions import ImmutableStateError
from reflex_base.utils.serializers import can_serialize, serialize, serializer
from reflex_base.vars.base import Var
from typing_extensions import Self
from reflex.istate.manager.token import BaseStateToken
if TYPE_CHECKING:
from reflex.state import BaseState, StateUpdate
T_STATE = TypeVar("T_STATE", bound="BaseState")
T = TypeVar("T")
class StateProxy(wrapt.ObjectProxy):
"""Proxy of a state instance to control mutability of vars for a background task.
Since a background task runs against a state instance without holding the
state_manager lock for the token, the reference may become stale if the same
state is modified by another event handler.
The proxy object ensures that writes to the state are blocked unless
explicitly entering a context which refreshes the state from state_manager
and holds the lock for the token until exiting the context. After exiting
the context, a StateUpdate may be emitted to the frontend to notify the
client of the state change.
A background task will be passed the `StateProxy` as `self`, so mutability
can be safely performed inside an `async with self` block.
class State(rx.State):
counter: int = 0
@rx.event(background=True)
async def bg_increment(self):
await asyncio.sleep(1)
async with self:
self.counter += 1
"""
def __init__(
self,
state_instance: BaseState,
event: Event | None = None,
parent_state_proxy: StateProxy | None = None,
):
"""Create a proxy for a state instance.
If `get_state` is used on a StateProxy, the resulting state will be
linked to the given state via parent_state_proxy. The first state in the
chain is the state that initiated the background task.
Args:
state_instance: The state instance to proxy.
event: The event associated with the state modification context.
parent_state_proxy: The parent state proxy, for linked mutability and context tracking.
"""
super().__init__(state_instance)
self._self_event = event
self._self_substate_path = tuple(state_instance.get_full_name().split("."))
self._self_substate_token = BaseStateToken(
ident=EventContext.get().token,
cls=state_instance.__class__,
)
self._self_actx = None
self._self_mutable = False
self._self_actx_lock = asyncio.Lock()
self._self_actx_lock_holder = None
self._self_parent_state_proxy = parent_state_proxy
def _is_mutable(self) -> bool:
"""Check if the state is mutable.
Returns:
Whether the state is mutable.
"""
if self._self_parent_state_proxy is not None:
return self._self_parent_state_proxy._is_mutable() or self._self_mutable
return self._self_mutable
async def __aenter__(self) -> Self:
"""Enter the async context manager protocol.
Sets mutability to True and enters the `App.modify_state` async context,
which refreshes the state from state_manager and holds the lock for the
given state token until exiting the context.
Background tasks should avoid blocking calls while inside the context.
Returns:
This StateProxy instance in mutable mode.
Raises:
ImmutableStateError: If the state is already mutable.
"""
if self._self_parent_state_proxy is not None:
from reflex.state import State
parent_state = (
await self._self_parent_state_proxy.__aenter__()
).__wrapped__
super().__setattr__(
"__wrapped__",
await parent_state.get_state(
State.get_class_substate(self._self_substate_path)
),
)
return self
current_task = asyncio.current_task()
if (
self._self_actx_lock.locked()
and current_task == self._self_actx_lock_holder
):
msg = "The state is already mutable. Do not nest `async with self` blocks."
raise ImmutableStateError(msg)
ctx = EventContext.get()
await self._self_actx_lock.acquire()
try:
self._self_actx_lock_holder = current_task
self._self_actx = ctx.state_manager.modify_state_with_links(
token=self._self_substate_token, event=self._self_event
)
mutable_state = await self._self_actx.__aenter__()
self._self_mutable = True
super().__setattr__(
"__wrapped__", mutable_state.get_substate(self._self_substate_path)
)
except (Exception, asyncio.CancelledError):
# Restore the proxy to a consistent state since __aexit__ will not be called when __aenter__ raises.
await self.__aexit__(*sys.exc_info())
raise
return self
async def __aexit__(self, *exc_info: Any) -> None:
"""Exit the async context manager protocol.
Sets proxy mutability to False and persists any state changes.
Args:
exc_info: The exception info tuple.
"""
if self._self_parent_state_proxy is not None:
await self._self_parent_state_proxy.__aexit__(*exc_info)
return
try:
if self._self_mutable and self._self_actx is not None:
root_state = self.__wrapped__._get_root_state()
delta = await root_state._get_resolved_delta()
root_state._clean()
# When the frontend vars are modified emit the delta to the frontend.
if delta:
ctx = EventContext.get()
await ctx.emit_delta(delta)
finally:
try:
if self._self_mutable and self._self_actx is not None:
await self._self_actx.__aexit__(*exc_info)
finally:
self._self_actx = None
self._self_mutable = False
self._self_actx_lock_holder = None
self._self_actx_lock.release()
def __enter__(self):
"""Enter the regular context manager protocol.
This is not supported for background tasks, and exists only to raise a more useful exception
when the StateProxy is used incorrectly.
Raises:
TypeError: always, because only async contextmanager protocol is supported.
"""
msg = "Background task must use `async with self` to modify state."
raise TypeError(msg)
def __exit__(self, *exc_info: Any) -> None:
"""Exit the regular context manager protocol.
Args:
exc_info: The exception info tuple.
"""
def __getattr__(self, name: str) -> Any:
"""Get the attribute from the underlying state instance.
Args:
name: The name of the attribute.
Returns:
The value of the attribute.
Raises:
ImmutableStateError: If the state is not in mutable mode.
"""
if name in ["substates", "parent_state"] and not self._is_mutable():
msg = (
"Background task StateProxy is immutable outside of a context "
"manager. Use `async with self` to modify state."
)
raise ImmutableStateError(msg)
value = super().__getattr__(name) # pyright: ignore[reportAttributeAccessIssue]
if not name.startswith("_self_") and isinstance(value, MutableProxy):
# ensure mutations to these containers are blocked unless proxy is _mutable
return ImmutableMutableProxy(
wrapped=value.__wrapped__,
state=self,
field_name=value._self_field_name,
)
if isinstance(value, functools.partial) and value.args[0] is self.__wrapped__:
# Rebind event handler to the proxy instance
value = functools.partial(
value.func,
self,
*value.args[1:],
**value.keywords,
)
if isinstance(value, MethodType) and value.__self__ is self.__wrapped__:
# Rebind methods to the proxy instance
value = type(value)(value.__func__, self)
return value
def __setattr__(self, name: str, value: Any) -> None:
"""Set the attribute on the underlying state instance.
If the attribute is internal, set it on the proxy instance instead.
Args:
name: The name of the attribute.
value: The value of the attribute.
Raises:
ImmutableStateError: If the state is not in mutable mode.
"""
if (
name.startswith("_self_") # wrapper attribute
or self._is_mutable() # lock held
# non-persisted state attribute
or name in self.__wrapped__.get_skip_vars()
):
super().__setattr__(name, value)
return
msg = (
"Background task StateProxy is immutable outside of a context "
"manager. Use `async with self` to modify state."
)
raise ImmutableStateError(msg)
def get_substate(self, path: Sequence[str]) -> BaseState:
"""Only allow substate access with lock held.
Args:
path: The path to the substate.
Returns:
The substate.
Raises:
ImmutableStateError: If the state is not in mutable mode.
"""
if not self._is_mutable():
msg = (
"Background task StateProxy is immutable outside of a context "
"manager. Use `async with self` to modify state."
)
raise ImmutableStateError(msg)
return self.__wrapped__.get_substate(path)
async def get_state(self, state_cls: type[T_STATE]) -> T_STATE:
"""Get an instance of the state associated with this token.
Args:
state_cls: The class of the state.
Returns:
The state.
Raises:
ImmutableStateError: If the state is not in mutable mode.
"""
if not self._is_mutable():
msg = (
"Background task StateProxy is immutable outside of a context "
"manager. Use `async with self` to modify state."
)
raise ImmutableStateError(msg)
return type(self)(
await self.__wrapped__.get_state(state_cls),
event=self._self_event,
parent_state_proxy=self,
) # pyright: ignore [reportReturnType]
async def _as_state_update(self, *args, **kwargs) -> StateUpdate:
"""Temporarily allow mutability to access parent_state.
Args:
*args: The args to pass to the underlying state instance.
**kwargs: The kwargs to pass to the underlying state instance.
Returns:
The state update.
"""
original_mutable = self._self_mutable
self._self_mutable = True
try:
return await self.__wrapped__._as_state_update(*args, **kwargs)
finally:
self._self_mutable = original_mutable
class ReadOnlyStateProxy(StateProxy):
"""A read-only proxy for a state."""
def __setattr__(self, name: str, value: Any) -> None:
"""Prevent setting attributes on the state for read-only proxy.
Args:
name: The attribute name.
value: The attribute value.
Raises:
NotImplementedError: Always raised when trying to set an attribute on proxied state.
"""
if name.startswith("_self_"):
# Special case attributes of the proxy itself, not applied to the wrapped object.
super().__setattr__(name, value)
return
msg = "This is a read-only state proxy."
raise NotImplementedError(msg)
def mark_dirty(self):
"""Mark the state as dirty.
Raises:
NotImplementedError: Always raised when trying to mark the proxied state as dirty.
"""
msg = "This is a read-only state proxy."
raise NotImplementedError(msg)
MUTABLE_TYPES = (
list,
dict,
set,
)
if find_spec("sqlalchemy"):
from sqlalchemy.orm import DeclarativeBase
MUTABLE_TYPES += (DeclarativeBase,)
if find_spec("pydantic"):
from pydantic import BaseModel
MUTABLE_TYPES += (BaseModel,)
class MutableProxy(wrapt.ObjectProxy):
"""A proxy for a mutable object that tracks changes."""
# Hint for finding the base class of the proxy.
__base_proxy__ = "MutableProxy"
# Methods on wrapped objects which should mark the state as dirty.
__mark_dirty_attrs__ = {
"add",
"append",
"clear",
"difference_update",
"discard",
"extend",
"insert",
"intersection_update",
"pop",
"popitem",
"remove",
"reverse",
"setdefault",
"sort",
"symmetric_difference_update",
"update",
}
# Methods on wrapped objects might return mutable objects that should be tracked.
__wrap_mutable_attrs__ = {
"get",
"setdefault",
}
# Dynamically generated classes for tracking dataclass mutations.
__dataclass_proxies__: dict[str, type] = {}
def __new__(cls, wrapped: Any, *args, **kwargs) -> MutableProxy:
"""Create a proxy instance for a mutable object that tracks changes.
Args:
wrapped: The object to proxy.
*args: Other args passed to MutableProxy (ignored).
**kwargs: Other kwargs passed to MutableProxy (ignored).
Returns:
The proxy instance.
"""
if dataclasses.is_dataclass(wrapped):
wrapped_cls = type(wrapped)
wrapper_cls_name = wrapped_cls.__name__ + cls.__name__
# Find the associated class
if wrapper_cls_name not in cls.__dataclass_proxies__:
# Create a new class that has the __dataclass_fields__ defined
cls.__dataclass_proxies__[wrapper_cls_name] = type(
wrapper_cls_name,
(cls,),
{
dataclasses._FIELDS: getattr( # pyright: ignore [reportAttributeAccessIssue]
wrapped_cls,
dataclasses._FIELDS, # pyright: ignore [reportAttributeAccessIssue]
),
},
)
cls = cls.__dataclass_proxies__[wrapper_cls_name]
return super().__new__(cls) # pyright: ignore[reportArgumentType]
def __init__(self, wrapped: Any, state: BaseState, field_name: str):
"""Create a proxy for a mutable object that tracks changes.
Args:
wrapped: The object to proxy.
state: The state to mark dirty when the object is changed.
field_name: The name of the field on the state associated with the
wrapped object.
"""
super().__init__(wrapped)
self._self_state = state
self._self_field_name = field_name
def __repr__(self) -> str:
"""Get the representation of the wrapped object.
Returns:
The representation of the wrapped object.
"""
return f"{type(self).__name__}({self.__wrapped__})"
def _mark_dirty(
self,
wrapped: Callable | None = None,
instance: BaseState | None = None,
args: tuple = (),
kwargs: dict | None = None,
) -> Any:
"""Mark the state as dirty, then call a wrapped function.
Intended for use with `FunctionWrapper` from the `wrapt` library.
Args:
wrapped: The wrapped function.
instance: The instance of the wrapped function.
args: The args for the wrapped function.
kwargs: The kwargs for the wrapped function.
Returns:
The result of the wrapped function.
"""
self._self_state.dirty_vars.add(self._self_field_name)
self._self_state._mark_dirty()
if wrapped is not None:
return wrapped(*args, **(kwargs or {}))
return None
@staticmethod
def _is_called_from_dataclasses_internal() -> bool:
"""Check if the current function is called from dataclasses helper.
Returns:
Whether the current function is called from dataclasses internal code.
"""
# Walk up the stack a bit to see if we are called from dataclasses
# internal code, for example `asdict` or `astuple`.
frame = inspect.currentframe()
for _ in range(5):
# Why not `inspect.stack()` -- this is much faster!
if not (frame := frame and frame.f_back):
break
if inspect.getfile(frame) == dataclasses.__file__:
return True
return False
def _wrap_recursive(self, value: Any) -> Any:
"""Wrap a value recursively if it is mutable.
Args:
value: The value to wrap.
Returns:
The wrapped value.
"""
# When called from dataclasses internal code, return the unwrapped value
if self._is_called_from_dataclasses_internal():
return value
# If we already have a proxy, unwrap and rewrap to make sure the state
# reference is up to date.
if isinstance(value, MutableProxy):
value = value.__wrapped__
# Recursively wrap mutable types.
if is_mutable_type(type(value)):
base_cls = globals()[self.__base_proxy__]
return base_cls(
wrapped=value,
state=self._self_state,
field_name=self._self_field_name,
)
return value
def _wrap_recursive_decorator(
self, wrapped: Callable, instance: BaseState, args: list, kwargs: dict
) -> Any:
"""Wrap a function that returns a possibly mutable value.
Intended for use with `FunctionWrapper` from the `wrapt` library.
Args:
wrapped: The wrapped function.
instance: The instance of the wrapped function.
args: The args for the wrapped function.
kwargs: The kwargs for the wrapped function.
Returns:
The result of the wrapped function (possibly wrapped in a MutableProxy).
"""
return self._wrap_recursive(wrapped(*args, **kwargs))
def __getattr__(self, __name: str) -> Any:
"""Get the attribute on the proxied object and return a proxy if mutable.
Args:
__name: The name of the attribute.
Returns:
The attribute value.
"""
value = super().__getattr__(__name) # pyright: ignore[reportAttributeAccessIssue]
if callable(value):
if __name in self.__mark_dirty_attrs__:
# Wrap special callables, like "append", which should mark state dirty.
value = wrapt.FunctionWrapper(value, self._mark_dirty)
if __name in self.__wrap_mutable_attrs__:
# Wrap special methods that may return mutable objects tied to the state.
value = wrapt.FunctionWrapper(
value,
self._wrap_recursive_decorator, # pyright: ignore[reportArgumentType]
)
if (
(func := getattr(value, "__func__", None)) is not None
and not inspect.isclass(getattr(value, "__self__", None))
# skip SQLAlchemy instrumented methods
and not getattr(value, "_sa_instrumented", False)
):
# Rebind `self` to the proxy on methods to capture nested mutations.
return functools.partial(func, self)
if is_mutable_type(type(value)) and __name not in (
"__wrapped__",
"_self_state",
"__dict__",
):
# Recursively wrap mutable attribute values retrieved through this proxy.
return self._wrap_recursive(value)
return value
def __getitem__(self, key: Any) -> Any:
"""Get the item on the proxied object and return a proxy if mutable.
Args:
key: The key of the item.
Returns:
The item value.
"""
value = super().__getitem__(key) # pyright: ignore[reportAttributeAccessIssue]
if isinstance(key, slice) and isinstance(value, list):
return [self._wrap_recursive(item) for item in value]
# Recursively wrap mutable items retrieved through this proxy.
return self._wrap_recursive(value)
def __iter__(self) -> Any:
"""Iterate over the proxied object and return a proxy if mutable.
Yields:
Each item value (possibly wrapped in MutableProxy).
"""
for value in super().__iter__(): # pyright: ignore[reportAttributeAccessIssue]
# Recursively wrap mutable items retrieved through this proxy.
yield self._wrap_recursive(value)
def __delattr__(self, name: str):
"""Delete the attribute on the proxied object and mark state dirty.
Args:
name: The name of the attribute.
"""
self._mark_dirty(super().__delattr__, args=(name,))
def __delitem__(self, key: str):
"""Delete the item on the proxied object and mark state dirty.
Args:
key: The key of the item.
"""
self._mark_dirty(super().__delitem__, args=(key,)) # pyright: ignore[reportAttributeAccessIssue]
def __setitem__(self, key: str, value: Any):
"""Set the item on the proxied object and mark state dirty.
Args:
key: The key of the item.
value: The value of the item.
"""
self._mark_dirty(super().__setitem__, args=(key, value)) # pyright: ignore[reportAttributeAccessIssue]
def __setattr__(self, name: str, value: Any):
"""Set the attribute on the proxied object and mark state dirty.
If the attribute starts with "_self_", then the state is NOT marked
dirty as these are internal proxy attributes.
Args:
name: The name of the attribute.
value: The value of the attribute.
"""
if name.startswith("_self_"):
# Special case attributes of the proxy itself, not applied to the wrapped object.
super().__setattr__(name, value)
return
self._mark_dirty(super().__setattr__, args=(name, value))
def __copy__(self) -> Any:
"""Return a copy of the proxy.
Returns:
A copy of the wrapped object, unconnected to the proxy.
"""
return copy.copy(self.__wrapped__)
def __deepcopy__(self, memo: dict[int, Any] | None = None) -> Any:
"""Return a deepcopy of the proxy.
Args:
memo: The memo dict to use for the deepcopy.
Returns:
A deepcopy of the wrapped object, unconnected to the proxy.
"""
return copy.deepcopy(self.__wrapped__, memo=memo)
def __reduce_ex__(self, protocol_version: SupportsIndex):
"""Serialize the wrapped object for pickle, stripping off the proxy.
Returns a function that reconstructs to the wrapped object directly,
ensuring pickle's memo system correctly tracks object identity.
Args:
protocol_version: The protocol version.
Returns:
Tuple that reconstructs to the wrapped object.
"""
return (_unwrap_for_pickle, (self.__wrapped__,))
def _unwrap_for_pickle(obj: T) -> T:
"""Return the object unchanged. Used by MutableProxy.__reduce_ex__."""
return obj
@serializer
def serialize_mutable_proxy(mp: MutableProxy):
"""Return the wrapped value of a MutableProxy.
Args:
mp: The MutableProxy to serialize.
Returns:
The wrapped object.
"""
obj = mp.__wrapped__
if can_serialize(type(obj)):
return serialize(obj)
return obj
_orig_json_encoder_default = json.JSONEncoder.default
def _json_encoder_default_wrapper(self: json.JSONEncoder, o: Any) -> Any:
"""Wrap JSONEncoder.default to handle MutableProxy objects.
Args:
self: the JSONEncoder instance.
o: the object to serialize.
Returns:
A JSON-able object.
"""
try:
return o.__wrapped__
except AttributeError:
pass
return _orig_json_encoder_default(self, o)
json.JSONEncoder.default = _json_encoder_default_wrapper
class ImmutableMutableProxy(MutableProxy):
"""A proxy for a mutable object that tracks changes.
This wrapper comes from StateProxy, and will raise an exception if an attempt is made
to modify the wrapped object when the StateProxy is immutable.
"""
# Ensure that recursively wrapped proxies use ImmutableMutableProxy as base.
__base_proxy__ = "ImmutableMutableProxy"
def _mark_dirty(
self,
wrapped: Callable | None = None,
instance: BaseState | None = None,
args: tuple = (),
kwargs: dict | None = None,
) -> Any:
"""Raise an exception when an attempt is made to modify the object.
Intended for use with `FunctionWrapper` from the `wrapt` library.
Args:
wrapped: The wrapped function.
instance: The instance of the wrapped function.
args: The args for the wrapped function.
kwargs: The kwargs for the wrapped function.
Returns:
The result of the wrapped function.
Raises:
ImmutableStateError: if the StateProxy is not mutable.
"""
if not self._self_state._is_mutable(): # pyright: ignore[reportAttributeAccessIssue]
msg = (
"Background task StateProxy is immutable outside of a context "
"manager. Use `async with self` to modify state."
)
raise ImmutableStateError(msg)
return super()._mark_dirty(
wrapped=wrapped, instance=instance, args=args, kwargs=kwargs
)
@functools.lru_cache(maxsize=1024)
def is_mutable_type(type_: type) -> bool:
"""Check if a type is mutable and should be wrapped.
Args:
type_: The type to check.
Returns:
Whether the type is mutable and should be wrapped.
"""
return issubclass(type_, MUTABLE_TYPES) or (
dataclasses.is_dataclass(type_) and not issubclass(type_, Var)
)