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import logging |
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from asyncio import Lock |
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from contextlib import AsyncExitStack |
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from copy import copy |
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from typing import ( |
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Optional, |
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Type, |
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TypeVar, |
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Awaitable, |
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Generic, |
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Collection, |
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Union, |
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ContextManager, |
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AsyncContextManager, |
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Iterator, |
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Generator, |
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AsyncGenerator, |
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List, |
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) |
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from lagom.container import Container |
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from lagom.definitions import Alias, ConstructionWithContainer, SingletonWrapper |
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from lagom.exceptions import InvalidDependencyDefinition |
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from lagom.experimental.definitions import AsyncConstructionWithContainer |
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from lagom.interfaces import ReadableContainer, SpecialDepDefinition |
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T = TypeVar("T") |
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class AwaitableSingleton(Generic[T]): |
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instance: Optional[T] |
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constructor: ConstructionWithContainer[Awaitable[T]] |
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container: Container |
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_lock: Lock |
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def __init__(self, constructor: ConstructionWithContainer, container: Container): |
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self.instance = None |
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self.constructor = constructor # type: ignore |
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self.container = container |
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self._lock = Lock() |
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async def get(self) -> T: |
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if not self.instance: |
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async with self._lock: |
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if not self.instance: |
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self.instance = await self.constructor.get_instance(self.container) |
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return self.instance |
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49
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def reset(self): |
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self.instance = None |
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53
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class AsyncContextContainer(Container): |
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async_exit_stack: Optional[AsyncExitStack] = None |
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_managed_singletons: List[Union[SingletonWrapper, AwaitableSingleton]] |
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def __init__( |
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self, |
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container: Container, |
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context_types: Collection[Type], |
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context_singletons: Collection[Type] = tuple(), |
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log_undefined_deps: Union[bool, logging.Logger] = False, |
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): |
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super().__init__(container, log_undefined_deps) |
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self._managed_singletons = [] |
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for dep_type in set(context_types): |
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managed_dep = self._context_type_def(dep_type) |
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key = Awaitable[dep_type] if isinstance(managed_dep, AsyncConstructionWithContainer) else dep_type # type: ignore |
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self[key] = managed_dep # type: ignore |
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for dep_type in set(context_singletons): |
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managed_singleton = self._singleton_type_def(dep_type) |
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self._managed_singletons.append(managed_singleton) |
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key = AwaitableSingleton[dep_type] if isinstance(managed_singleton, AwaitableSingleton) else dep_type # type: ignore |
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self[key] = managed_singleton # type: ignore |
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async def __aenter__(self): |
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if not self.async_exit_stack: |
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self.async_exit_stack = AsyncExitStack() |
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return self |
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async def __aexit__(self, exc_type, exc_val, exc_tb): |
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if self.async_exit_stack: |
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await self.async_exit_stack.aclose() |
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self.async_exit_stack = None |
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for managed_singleton in self._managed_singletons: |
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managed_singleton.reset() |
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def _context_type_def(self, dep_type: Type): |
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type_def = self.get_definition(ContextManager[dep_type]) or self.get_definition(Iterator[dep_type]) or self.get_definition(Generator[dep_type, None, None]) or self.get_definition(AsyncGenerator[dep_type, None]) or self.get_definition(AsyncContextManager[dep_type]) # type: ignore |
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if type_def is None: |
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raise InvalidDependencyDefinition( |
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f"A ContextManager[{dep_type}] should be defined. " |
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f"This could be an Iterator[{dep_type}] or Generator[{dep_type}, None, None] " |
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f"with the @contextmanager decorator" |
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) |
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if isinstance(type_def, Alias): |
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# Without this we create a definition that points to |
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# itself. |
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type_def = copy(type_def) |
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type_def.skip_definitions = True |
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if self.get_definition(AsyncGenerator[dep_type, None]) or self.get_definition(AsyncContextManager[dep_type]): # type: ignore |
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return AsyncConstructionWithContainer(lambda c: self._async_context_resolver(c, type_def)) # type: ignore |
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return ConstructionWithContainer(lambda c: self._context_resolver(c, type_def)) # type: ignore |
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def _context_resolver(self, c: ReadableContainer, type_def: SpecialDepDefinition): |
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""" |
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Takes an existing definition which must be a context manager. Returns |
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the value of the context manager from __enter__ and then places the |
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__exit__ in this container's exit stack |
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""" |
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assert self.async_exit_stack, "Types can only be resolved within an async with" |
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context_manager = type_def.get_instance(c) |
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return self.async_exit_stack.enter_context(context_manager) |
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115
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def _async_context_resolver( |
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self, c: ReadableContainer, type_def: SpecialDepDefinition |
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): |
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""" |
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Takes an existing definition which must be a context manager. Returns |
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the value of the context manager from __aenter__ and then places the |
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__aexit__ in this container's exit stack |
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""" |
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assert self.async_exit_stack, "Types can only be resolved within an async with" |
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context_manager = type_def.get_instance(c) |
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return self.async_exit_stack.enter_async_context(context_manager) |
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def _singleton_type_def(self, dep_type: Type): |
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""" |
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The same as context_type_def but acts as a singleton within this container |
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""" |
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type_def = self._context_type_def(dep_type) |
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if isinstance(type_def, AsyncConstructionWithContainer): |
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return AwaitableSingleton(type_def, self) |
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return SingletonWrapper(type_def) |
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meadsteve /
lagom
