Virtual container¶

class RedSunConfig(TypedDict, total=False):
    """Base configuration schema of a ``redsun`` application."""

    schema_version: Required[float]
    """Plugin schema version."""

    frontend: Required[str]
    """Frontend toolkit identifier (e.g. `"pyqt"`, `"pyside"`)."""

    session: NotRequired[str]
    """Session display name, `"redsun"` if not given."""

    metadata: NotRequired[dict[str, Any]]
    """Session metadata."""

class VirtualContainer(dic.DynamicContainer, Loggable):
    """Signal bus, shared data and dependency injection of an application.

    A [`DynamicContainer`][dependency_injector.containers.DynamicContainer] that
    is also the application's signal bus and data exchange.
    """

    def __init__(self) -> None:
        super().__init__()
        # instance-scoped providers: class-level providers would be shared
        # across every container in the process, leaking config, signal,
        # and callback registrations between containers
        self._signals = dip.Factory(dict[str, SignalCache])
        self._callbacks = dip.Factory(dict[str, CallbackType])
        self._config = dip.Singleton(_FrozenConfig)
        self._components: dict[str, object] = {}
        self._links: list[tuple[SignalInstance, Callable[..., Any]]] = []
        self._connections: list[Connection] = []
        # the forwarding function is held because ophyd-async releases a
        # subscription by identity: clear_sub needs the object back
        self._subscriptions: list[
            tuple[SignalR[Any], Callable[[Any], None], SignalInstance]
        ] = []
        self._subscription_records: list[Subscription] = []
        # bindings are held here rather than through Dependency.override, which
        # mutates the key itself and would leak between containers in one process
        self._provided: dict[dip.Dependency[Any], Any] = {}

    @property
    def schema_version(self) -> float:
        """The configuration's plugin schema version."""
        return self._config().schema_version

    @property
    def frontend(self) -> str:
        """The configuration's frontend toolkit."""
        return self._config().frontend

    @property
    def session(self) -> str:
        """The configuration's session display name."""
        return self._config().session

    @property
    def metadata(self) -> dict[str, object]:
        """The configuration's session metadata."""
        return self._config().metadata

    def _set_configuration(self, config: RedSunConfig) -> None:
        """Set the application configuration, at build time.

        Parameters
        ----------
        config : RedSunConfig
            The application configuration to set.
        """
        self._config.set_kwargs(
            schema_version=config["schema_version"],
            frontend=config["frontend"],
            session=config.get("session", "redsun"),
            metadata=config.get("metadata", {}),
        )

    def provide(self, key: ProviderKey[T], value: T) -> None:
        """Bind *value* to *key* for this container.

        Parameters
        ----------
        key : ProviderKey[T]
            The key consumers resolve.
        value : T
            The object to share. Rebinding an already bound key replaces it.

        Raises
        ------
        TypeError
            If *value* is not an instance of the key's ``instance_of``.
        """
        if not isinstance(value, key.instance_of):
            raise TypeError(
                f"{value!r} is not an instance of "
                f"{key.instance_of.__name__}, required by {key!r}"
            )
        self._provided[key] = value

    def require(self, key: ProviderKey[T]) -> T:
        """Resolve *key*, which must be bound.

        Parameters
        ----------
        key : ProviderKey[T]
            The key to resolve.

        Returns
        -------
        T
            The bound value.

        Raises
        ------
        KeyError
            If nothing bound *key*. Keys are bound in ``register_providers``,
            so one read earlier is unbound even if its component exists.
        """
        try:
            return cast("T", self._provided[key])
        except KeyError:
            raise KeyError(
                f"nothing provided {key!r}; the component that owns it is "
                "either absent from this application or has not run "
                "'register_providers' yet"
            ) from None

    def try_require(self, key: ProviderKey[T]) -> T | None:
        """Resolve *key*, or return ``None`` if nothing bound it.

        Parameters
        ----------
        key : ProviderKey[T]
            The key to resolve.

        Returns
        -------
        T | None
            The bound value, or ``None`` if the application lacks this optional
            collaborator.
        """
        return cast("T | None", self._provided.get(key))

    def register_signals(
        self, owner: HasName, name: str | None = None, only: Iterable[str] | None = None
    ) -> None:
        """Cache the signals *owner* declares.

        Parameters
        ----------
        owner : HasName
            The component whose class signals are cached.
        name : str | None
            Registry key. Defaults to ``owner.name``.
        only : Iterable[str] | None
            Signal names to cache. Defaults to every
            [`Signal`][psygnal.Signal] declared on the class.
        """
        owner_class = type(owner)
        if name is not None:
            cache_entry = name
        else:
            cache_entry = owner.name

        if only is None:
            only = [
                attr
                for attr in dir(owner_class)
                if isinstance(getattr(owner_class, attr, None), Signal)
            ]

        batch: dict[str, SignalInstance] = {}
        for signal_name in only:
            signal_descriptor = getattr(owner_class, signal_name, None)
            if isinstance(signal_descriptor, Signal):
                signal_instance = getattr(owner, signal_name)
                batch[signal_name] = signal_instance
        if batch:
            self._signals.add_kwargs(**{cache_entry: batch})

    @staticmethod
    def _validate_callback(callback: object) -> CallbackType:
        """Return *callback* unchanged if it can be called as ``(name, doc)``.

        Parameters
        ----------
        callback : object
            The object to validate.

        Returns
        -------
        CallbackType
            The validated callback.

        Raises
        ------
        TypeError
            If *callback* is not callable as ``(str, Document)``.
        """
        if isinstance(callback, DocumentRouter):
            return callback

        if not callable(callback):
            raise TypeError(
                f"{callback!r} is not callable. "
                "A callback must be a DocumentRouter subclass instance or a "
                "callable accepting (str, Document) arguments."
            )

        try:
            inspect.signature(callback.__call__).bind(None, None)
        except TypeError as e:
            raise TypeError(
                f"{callback!r} is callable but its signature is not compatible "
                "with the expected (str, Document) callback interface."
            ) from e

        return callback

    def register_callbacks(
        self,
        owner: HasName,
        name: str | None = None,
        callback_map: dict[str, CallbackType] | None = None,
    ) -> None:
        """Register one or more document callbacks.

        A callback is an ``event_model.DocumentRouter`` or any object callable
        as ``(name, doc)``.

        Parameters
        ----------
        owner : HasName
            The component registering callbacks, and the callback itself when
            *callback_map* is ``None``.
        name : str | None
            Registry key for *owner*. Defaults to ``owner.name``; ignored when
            *callback_map* is given.
        callback_map : dict[str, CallbackType] | None
            Several callbacks from one owner, each registered under its own
            key. *owner* is then not registered itself.

        Raises
        ------
        TypeError
            If a callback is not callable as ``(str, Document)``.
        """
        if callback_map is not None:
            for key, callback in callback_map.items():
                self._callbacks.add_kwargs(**{key: self._validate_callback(callback)})
            return

        cache_entry = name if name is not None else owner.name
        self._callbacks.add_kwargs(**{cache_entry: self._validate_callback(owner)})

    @property
    def callbacks(self) -> dict[str, CallbackType]:
        """The registered document callbacks."""
        return self._callbacks()

    @property
    def signals(self) -> dict[str, SignalCache]:
        """The registered signals."""
        return self._signals()

    def _set_components(self, components: Mapping[str, object]) -> None:
        """Record the built components' names, for the wiring report."""
        self._components = dict(components)

    def _label(self, component: object | None) -> str:
        # searched by identity rather than read from an id-keyed index: an id
        # identifies an object only while it is alive, and CPython hands a
        # released component's id to the next object of that size
        if component is None:
            return "<unknown>"
        for name, candidate in self._components.items():
            if candidate is component:
                return name
        return type(component).__name__

    def connect(
        self,
        signal: SignalInstance,
        slot: Callable[..., Any],
        *,
        thread: SlotThread = None,
    ) -> Connection:
        """Connect a signal to a slot and record the link.

        Parameters
        ----------
        signal : SignalInstance
            The emitting signal.
        slot : Callable[..., Any]
            A bound method marked with [`slot`][redsun.virtual.slot]. May be a
            coroutine function.
        thread : SlotThread
            Thread the slot runs on. Defaults to the slot's affinity, then its
            class's.

        Returns
        -------
        Connection
            The recorded link.

        Raises
        ------
        WiringError
            If *slot* is not marked, or ``psygnal`` rejects the signatures.
        """
        consumer, thread = _resolve_slot(slot, thread)

        link = Connection(
            publisher=self._label(_owner_of(signal)),
            publisher_port=signal.name or "<anonymous>",
            consumer=self._label(consumer),
            consumer_port=port_name(slot),
            thread=thread,
        )
        try:
            signal.connect(slot, thread=thread)
        except (TypeError, ValueError) as e:
            raise WiringError(f"cannot connect {link}: {e}") from e

        self._links.append((signal, slot))
        self._connections.append(link)
        self.logger.debug(f"Connected {link}")
        return link

    def subscribe(
        self,
        signal: SignalR[Any],
        slot: Callable[..., Any],
        *,
        thread: SlotThread = None,
    ) -> Subscription:
        """Subscribe a slot to an ``ophyd-async`` device signal and record it.

        Readings pass through a ``psygnal`` signal, so *thread* works as in
        `connect`. It is the only way a device signal reaches a slot with a
        thread affinity: ``ophyd-async`` calls subscribers on whichever thread
        produced the reading.

        Parameters
        ----------
        signal : SignalR[Any]
            The device signal to observe.
        slot : Callable[..., Any]
            A bound method marked with [`slot`][redsun.virtual.slot], called
            with the reading dictionary.
        thread : SlotThread
            Thread the slot runs on. Defaults to the slot's affinity, then its
            class's.

        Returns
        -------
        Subscription
            The recorded subscription.

        Raises
        ------
        WiringError
            If *slot* is not marked.
        """
        consumer, thread = _resolve_slot(slot, thread)

        relay = SignalInstance((object,), name=signal.name)
        relay.connect(slot, thread=thread)

        def forward(reading: Any) -> None:
            relay.emit(reading)

        record = Subscription(
            source=signal.name,
            consumer=self._label(consumer),
            consumer_port=port_name(slot),
            thread=thread,
        )

        async def attach() -> None:
            signal.subscribe_reading(forward)

        # ophyd-async requires a running loop to subscribe, and callers run on
        # the main thread during the build
        run_coro(attach())
        self._subscriptions.append((signal, forward, relay))
        self._subscription_records.append(record)
        self.logger.debug(f"Subscribed {record}")
        return record

    @property
    def subscriptions(self) -> list[Subscription]:
        """The device-signal subscriptions made through this container."""
        return list(self._subscription_records)

    def connect_paths(
        self, source: str, target: str, *, thread: SlotThread = None
    ) -> Connection:
        """Connect two ports addressed as ``component.port``.

        The string form of `connect`, used by a configuration file's ``wiring``
        section. A signal port is the signal's attribute name, or its member
        name in a signal group; a slot port is the name the slot declares.

        Parameters
        ----------
        source : str
            Path of the emitting signal.
        target : str
            Path of the consuming slot.
        thread : SlotThread
            Thread the slot runs on, overriding the slot and its class.

        Returns
        -------
        Connection
            The recorded link.

        Raises
        ------
        WiringError
            If a path is malformed or names a port the component lacks; the
            message lists the existing ones.
        ComponentNotBuilt
            If a path names a component that is not there.
        """
        signal = self._resolve_port(source, "signal")
        slot = self._resolve_port(target, "slot")
        return self.connect(
            cast("SignalInstance", signal),
            cast("Callable[..., Any]", slot),
            thread=thread,
        )

    def _resolve_port(self, path: str, kind: str) -> object:
        """Look up the signal or slot a ``component.port`` path names."""
        component_name, _, port = path.partition(".")
        if not component_name or not port or "." in port:
            raise WiringError(f"{path!r} is not a port path; expected 'component.port'")
        component = self._components.get(component_name)
        if component is None:
            known = ", ".join(sorted(self._components)) or "none"
            raise ComponentNotBuilt(
                component_name,
                f"{path!r} names component {component_name!r}, which was not "
                f"built. Built: {known}",
            )
        surface = ports(component)
        available = surface.signals if kind == "signal" else surface.slots
        if port not in available:
            known = ", ".join(sorted(available)) or "none"
            raise WiringError(
                f"{component_name!r} exposes no {kind} named {port!r}. "
                f"Its {kind} ports: {known}"
            )
        return available[port]

    @property
    def connections(self) -> list[Connection]:
        """The links established so far."""
        return list(self._connections)

    @property
    def unconnected(self) -> Unconnected:
        """Ports of the built components that no connection reaches.

        What components offer minus `connections` and `subscriptions`. A
        forgotten connection shows nowhere else, since an unnamed port cannot
        fail.

        Returns
        -------
        Unconnected
            The unreached signal and slot paths, as ``component.port``.

        Raises
        ------
        WiringError
            If a component exposes two signals under one port name.
        """
        used_signals = {(c.publisher, c.publisher_port) for c in self._connections}
        used_slots = {(c.consumer, c.consumer_port) for c in self._connections}
        used_slots |= {
            (s.consumer, s.consumer_port) for s in self._subscription_records
        }

        signals: list[str] = []
        slots: list[str] = []
        for name, component in self._components.items():
            surface = ports(component)
            signals += [
                f"{name}.{port}"
                for port in surface.signals
                if (name, port) not in used_signals
            ]
            slots += [
                f"{name}.{port}"
                for port in surface.slots
                if (name, port) not in used_slots
            ]
        return Unconnected(signals=signals, slots=slots)

    def disconnect_all(self) -> None:
        """Undo every connection and subscription made through this container."""
        for signal, slot in self._links:
            signal.disconnect(slot, missing_ok=True)
        self._links.clear()
        self._connections.clear()

        async def release(signal: SignalR[Any], forward: Callable[[Any], None]) -> None:
            signal.clear_sub(forward)

        for device_signal, forward, relay in self._subscriptions:
            run_coro(release(device_signal, forward))
            relay.disconnect()
        self._subscriptions.clear()
        self._subscription_records.clear()

    def _clear_components(self) -> None:
        """Forget the built components, after disconnecting them."""
        self._components = {}

@runtime_checkable
class HasShutdown(Protocol):  # pragma: no cover
    """A class that shuts down synchronously."""

    @abstractmethod
    def shutdown(self) -> None:
        """Clean up. Called on presenters and container hooks."""
        ...

@runtime_checkable
class IsInjectable(Protocol):  # pragma: no cover
    """A class receiving dependencies from the virtual container."""

    @abstractmethod
    def inject_dependencies(self, container: VirtualContainer) -> None:
        """Inject dependencies from the container."""
        ...