""" Actor primitives and helpers """ from collections import defaultdict from functools import partial from itertools import chain import importlib import importlib.util import inspect import uuid import typing from typing import Dict, List, Tuple, Any, Optional, Union from types import ModuleType import sys import os from contextlib import ExitStack import warnings import trio # type: ignore from trio_typing import TaskStatus from async_generator import aclosing from ._ipc import Channel from ._streaming import Context from .log import get_logger from ._exceptions import ( pack_error, unpack_error, ModuleNotExposed, is_multi_cancelled, TransportClosed, ) from . import _debug from ._discovery import get_arbiter from ._portal import Portal from . import _state from . import _mp_fixup_main log = get_logger('tractor') class ActorFailure(Exception): "General actor failure" async def _invoke( actor: 'Actor', cid: str, chan: Channel, func: typing.Callable, kwargs: Dict[str, Any], task_status: TaskStatus[ Union[trio.CancelScope, BaseException] ] = trio.TASK_STATUS_IGNORED, ): """Invoke local func and deliver result(s) over provided channel. """ treat_as_gen = False cs = None cancel_scope = trio.CancelScope() ctx = Context(chan, cid, _cancel_scope=cancel_scope) context = False if getattr(func, '_tractor_stream_function', False): # handle decorated ``@tractor.stream`` async functions sig = inspect.signature(func) params = sig.parameters # compat with old api kwargs['ctx'] = ctx if 'ctx' in params: warnings.warn( "`@tractor.stream decorated funcs should now declare " "a `stream` arg, `ctx` is now designated for use with " "@tractor.context", DeprecationWarning, stacklevel=2, ) elif 'stream' in params: assert 'stream' in params kwargs['stream'] = ctx treat_as_gen = True elif getattr(func, '_tractor_context_function', False): # handle decorated ``@tractor.context`` async function kwargs['ctx'] = ctx context = True # errors raised inside this block are propgated back to caller try: if not ( inspect.isasyncgenfunction(func) or inspect.iscoroutinefunction(func) ): raise TypeError(f'{func} must be an async function!') coro = func(**kwargs) if inspect.isasyncgen(coro): await chan.send({'functype': 'asyncgen', 'cid': cid}) # XXX: massive gotcha! If the containing scope # is cancelled and we execute the below line, # any ``ActorNursery.__aexit__()`` WON'T be # triggered in the underlying async gen! So we # have to properly handle the closing (aclosing) # of the async gen in order to be sure the cancel # is propagated! with cancel_scope as cs: task_status.started(cs) async with aclosing(coro) as agen: async for item in agen: # TODO: can we send values back in here? # it's gonna require a `while True:` and # some non-blocking way to retrieve new `asend()` # values from the channel: # to_send = await chan.recv_nowait() # if to_send is not None: # to_yield = await coro.asend(to_send) await chan.send({'yield': item, 'cid': cid}) log.debug(f"Finished iterating {coro}") # TODO: we should really support a proper # `StopAsyncIteration` system here for returning a final # value if desired await chan.send({'stop': True, 'cid': cid}) # one way @stream func that gets treated like an async gen elif treat_as_gen: await chan.send({'functype': 'asyncgen', 'cid': cid}) # XXX: the async-func may spawn further tasks which push # back values like an async-generator would but must # manualy construct the response dict-packet-responses as # above with cancel_scope as cs: task_status.started(cs) await coro if not cs.cancelled_caught: # task was not cancelled so we can instruct the # far end async gen to tear down await chan.send({'stop': True, 'cid': cid}) elif context: # context func with support for bi-dir streaming await chan.send({'functype': 'context', 'cid': cid}) with cancel_scope as cs: task_status.started(cs) await chan.send({'return': await coro, 'cid': cid}) # if cs.cancelled_caught: # # task was cancelled so relay to the cancel to caller # await chan.send({'return': await coro, 'cid': cid}) else: # regular async function await chan.send({'functype': 'asyncfunc', 'cid': cid}) with cancel_scope as cs: task_status.started(cs) await chan.send({'return': await coro, 'cid': cid}) except (Exception, trio.MultiError) as err: # TODO: maybe we'll want differnet "levels" of debugging # eventualy such as ('app', 'supervisory', 'runtime') ? if not isinstance(err, trio.ClosedResourceError) and ( not is_multi_cancelled(err) ): # XXX: is there any case where we'll want to debug IPC # disconnects? I can't think of a reason that inspecting # this type of failure will be useful for respawns or # recovery logic - the only case is some kind of strange bug # in `trio` itself? entered = await _debug._maybe_enter_pm(err) if not entered: log.exception("Actor crashed:") # always ship errors back to caller err_msg = pack_error(err) err_msg['cid'] = cid try: await chan.send(err_msg) except trio.ClosedResourceError: log.warning( f"Failed to ship error to caller @ {chan.uid}") if cs is None: # error is from above code not from rpc invocation task_status.started(err) finally: # RPC task bookeeping try: scope, func, is_complete = actor._rpc_tasks.pop((chan, cid)) is_complete.set() except KeyError: # If we're cancelled before the task returns then the # cancel scope will not have been inserted yet log.warning( f"Task {func} likely errored or cancelled before it started") finally: if not actor._rpc_tasks: log.info("All RPC tasks have completed") actor._ongoing_rpc_tasks.set() def _get_mod_abspath(module): return os.path.abspath(module.__file__) # process-global stack closed at end on actor runtime teardown _lifetime_stack: ExitStack = ExitStack() class Actor: """The fundamental concurrency primitive. An *actor* is the combination of a regular Python or ``multiprocessing.Process`` executing a ``trio`` task tree, communicating with other actors through "portals" which provide a native async API around "channels". """ is_arbiter: bool = False # nursery placeholders filled in by `_async_main()` after fork _root_n: Optional[trio.Nursery] = None _service_n: Optional[trio.Nursery] = None _server_n: Optional[trio.Nursery] = None # Information about `__main__` from parent _parent_main_data: Dict[str, str] _parent_chan_cs: Optional[trio.CancelScope] = None def __init__( self, name: str, *, enable_modules: List[str] = [], uid: str = None, loglevel: str = None, arbiter_addr: Optional[Tuple[str, int]] = None, spawn_method: Optional[str] = None ) -> None: """This constructor is called in the parent actor **before** the spawning phase (aka before a new process is executed). """ self.name = name self.uid = (name, uid or str(uuid.uuid4())) self._cancel_complete = trio.Event() self._cancel_called: bool = False # retreive and store parent `__main__` data which # will be passed to children self._parent_main_data = _mp_fixup_main._mp_figure_out_main() # always include debugging tools module enable_modules.append('tractor._debug') mods = {} for name in enable_modules: mod = importlib.import_module(name) mods[name] = _get_mod_abspath(mod) self.enable_modules = mods self._mods: Dict[str, ModuleType] = {} # TODO: consider making this a dynamically defined # @dataclass once we get py3.7 self.loglevel = loglevel self._arb_addr = arbiter_addr # marked by the process spawning backend at startup # will be None for the parent most process started manually # by the user (currently called the "arbiter") self._spawn_method = spawn_method self._peers: defaultdict = defaultdict(list) self._peer_connected: dict = {} self._no_more_peers = trio.Event() self._no_more_peers.set() self._ongoing_rpc_tasks = trio.Event() self._ongoing_rpc_tasks.set() # (chan, cid) -> (cancel_scope, func) self._rpc_tasks: Dict[ Tuple[Channel, str], Tuple[trio.CancelScope, typing.Callable, trio.Event] ] = {} # map {uids -> {callids -> waiter queues}} self._cids2qs: Dict[ Tuple[Tuple[str, str], str], Tuple[ trio.abc.SendChannel[Any], trio.abc.ReceiveChannel[Any] ] ] = {} self._listeners: List[trio.abc.Listener] = [] self._parent_chan: Optional[Channel] = None self._forkserver_info: Optional[ Tuple[Any, Any, Any, Any, Any]] = None self._actoruid2nursery: Dict[str, 'ActorNursery'] = {} # type: ignore # noqa async def wait_for_peer( self, uid: Tuple[str, str] ) -> Tuple[trio.Event, Channel]: """Wait for a connection back from a spawned actor with a given ``uid``. """ log.debug(f"Waiting for peer {uid} to connect") event = self._peer_connected.setdefault(uid, trio.Event()) await event.wait() log.debug(f"{uid} successfully connected back to us") return event, self._peers[uid][-1] def load_modules(self) -> None: """Load allowed RPC modules locally (after fork). Since this actor may be spawned on a different machine from the original nursery we need to try and load the local module code (if it exists). """ try: if self._spawn_method == 'trio': parent_data = self._parent_main_data if 'init_main_from_name' in parent_data: _mp_fixup_main._fixup_main_from_name( parent_data['init_main_from_name']) elif 'init_main_from_path' in parent_data: _mp_fixup_main._fixup_main_from_path( parent_data['init_main_from_path']) for modpath, filepath in self.enable_modules.items(): # XXX append the allowed module to the python path which # should allow for relative (at least downward) imports. sys.path.append(os.path.dirname(filepath)) log.debug(f"Attempting to import {modpath}@{filepath}") mod = importlib.import_module(modpath) self._mods[modpath] = mod if modpath == '__main__': self._mods['__mp_main__'] = mod except ModuleNotFoundError: # it is expected the corresponding `ModuleNotExposed` error # will be raised later log.error(f"Failed to import {modpath} in {self.name}") raise def _get_rpc_func(self, ns, funcname): try: return getattr(self._mods[ns], funcname) except KeyError as err: mne = ModuleNotExposed(*err.args) if ns == '__main__': msg = ( "\n\nMake sure you exposed the current module using:\n\n" "ActorNursery.start_actor(, enable_modules=" "[__name__])" ) mne.msg += msg raise mne async def _stream_handler( self, stream: trio.SocketStream, ) -> None: """Entry point for new inbound connections to the channel server. """ self._no_more_peers = trio.Event() # unset chan = Channel(stream=stream) log.info(f"New connection to us {chan}") # send/receive initial handshake response try: uid = await self._do_handshake(chan) except ( # trio.BrokenResourceError, # trio.ClosedResourceError, TransportClosed, ): # XXX: This may propagate up from ``Channel._aiter_recv()`` # and ``MsgpackStream._inter_packets()`` on a read from the # stream particularly when the runtime is first starting up # inside ``open_root_actor()`` where there is a check for # a bound listener on the "arbiter" addr. the reset will be # because the handshake was never meant took place. log.warning(f"Channel {chan} failed to handshake") return # channel tracking event = self._peer_connected.pop(uid, None) if event: # Instructing connection: this is likely a new channel to # a recently spawned actor which we'd like to control via # async-rpc calls. log.debug(f"Waking channel waiters {event.statistics()}") # Alert any task waiting on this connection to come up event.set() chans = self._peers[uid] if chans: log.warning( f"already have channel(s) for {uid}:{chans}?" ) log.trace(f"Registered {chan} for {uid}") # type: ignore # append new channel self._peers[uid].append(chan) # Begin channel management - respond to remote requests and # process received reponses. try: await self._process_messages(chan) finally: # Drop ref to channel so it can be gc-ed and disconnected log.debug(f"Releasing channel {chan} from {chan.uid}") chans = self._peers.get(chan.uid) chans.remove(chan) if not chans: log.debug(f"No more channels for {chan.uid}") self._peers.pop(chan.uid, None) log.debug(f"Peers is {self._peers}") if not self._peers: # no more channels connected self._no_more_peers.set() log.debug("Signalling no more peer channels") # # XXX: is this necessary (GC should do it?) if chan.connected(): log.debug(f"Disconnecting channel {chan}") try: # send our msg loop terminate sentinel await chan.send(None) # await chan.aclose() except trio.BrokenResourceError: log.exception( f"Channel for {chan.uid} was already zonked..") async def _push_result( self, chan: Channel, cid: str, msg: Dict[str, Any], ) -> None: """Push an RPC result to the local consumer's queue. """ actorid = chan.uid assert actorid, f"`actorid` can't be {actorid}" send_chan, recv_chan = self._cids2qs[(actorid, cid)] assert send_chan.cid == cid # type: ignore # if 'stop' in msg: # log.debug(f"{send_chan} was terminated at remote end") # # indicate to consumer that far end has stopped # return await send_chan.aclose() try: log.debug(f"Delivering {msg} from {actorid} to caller {cid}") # maintain backpressure await send_chan.send(msg) except trio.BrokenResourceError: # TODO: what is the right way to handle the case where the # local task has already sent a 'stop' / StopAsyncInteration # to the other side but and possibly has closed the local # feeder mem chan? Do we wait for some kind of ack or just # let this fail silently and bubble up (currently)? # XXX: local consumer has closed their side # so cancel the far end streaming task log.warning(f"{send_chan} consumer is already closed") def get_memchans( self, actorid: Tuple[str, str], cid: str ) -> Tuple[trio.abc.SendChannel, trio.abc.ReceiveChannel]: log.debug(f"Getting result queue for {actorid} cid {cid}") try: send_chan, recv_chan = self._cids2qs[(actorid, cid)] except KeyError: send_chan, recv_chan = trio.open_memory_channel(1000) send_chan.cid = cid # type: ignore recv_chan.cid = cid # type: ignore self._cids2qs[(actorid, cid)] = send_chan, recv_chan return send_chan, recv_chan async def send_cmd( self, chan: Channel, ns: str, func: str, kwargs: dict ) -> Tuple[str, trio.abc.ReceiveChannel]: """Send a ``'cmd'`` message to a remote actor and return a caller id and a ``trio.Queue`` that can be used to wait for responses delivered by the local message processing loop. """ cid = str(uuid.uuid4()) assert chan.uid send_chan, recv_chan = self.get_memchans(chan.uid, cid) log.debug(f"Sending cmd to {chan.uid}: {ns}.{func}({kwargs})") await chan.send({'cmd': (ns, func, kwargs, self.uid, cid)}) return cid, recv_chan async def _process_messages( self, chan: Channel, shield: bool = False, task_status: TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED, ) -> None: """Process messages for the channel async-RPC style. Receive multiplexed RPC requests and deliver responses over ``chan``. """ # TODO: once https://github.com/python-trio/trio/issues/467 gets # worked out we'll likely want to use that! msg = None log.debug(f"Entering msg loop for {chan} from {chan.uid}") try: with trio.CancelScope(shield=shield) as loop_cs: # this internal scope allows for keeping this message # loop running despite the current task having been # cancelled (eg. `open_portal()` may call this method from # a locally spawned task) and recieve this scope using # ``scope = Nursery.start()`` task_status.started(loop_cs) async for msg in chan: if msg is None: # loop terminate sentinel log.debug( f"Cancelling all tasks for {chan} from {chan.uid}") for (channel, cid) in self._rpc_tasks: if channel is chan: await self._cancel_task(cid, channel) log.debug( f"Msg loop signalled to terminate for" f" {chan} from {chan.uid}") break log.trace( # type: ignore f"Received msg {msg} from {chan.uid}") cid = msg.get('cid') if cid: # deliver response to local caller/waiter await self._push_result(chan, cid, msg) log.debug( f"Waiting on next msg for {chan} from {chan.uid}") continue # process command request try: ns, funcname, kwargs, actorid, cid = msg['cmd'] except KeyError: # This is the non-rpc error case, that is, an # error **not** raised inside a call to ``_invoke()`` # (i.e. no cid was provided in the msg - see above). # Push this error to all local channel consumers # (normally portals) by marking the channel as errored assert chan.uid exc = unpack_error(msg, chan=chan) chan._exc = exc raise exc log.debug( f"Processing request from {actorid}\n" f"{ns}.{funcname}({kwargs})") if ns == 'self': func = getattr(self, funcname) if funcname == '_cancel_task': # XXX: a special case is made here for # remote calls since we don't want the # remote actor have to know which channel # the task is associated with and we can't # pass non-primitive types between actors. # This means you can use: # Portal.run('self', '_cancel_task, cid=did) # without passing the `chan` arg. kwargs['chan'] = chan else: # complain to client about restricted modules try: func = self._get_rpc_func(ns, funcname) except (ModuleNotExposed, AttributeError) as err: err_msg = pack_error(err) err_msg['cid'] = cid await chan.send(err_msg) continue # spin up a task for the requested function log.debug(f"Spawning task for {func}") assert self._service_n cs = await self._service_n.start( partial(_invoke, self, cid, chan, func, kwargs), name=funcname, ) # never allow cancelling cancel requests (results in # deadlock and other weird behaviour) if func != self.cancel: if isinstance(cs, Exception): log.warning( f"Task for RPC func {func} failed with" f"{cs}") else: # mark that we have ongoing rpc tasks self._ongoing_rpc_tasks = trio.Event() log.info(f"RPC func is {func}") # store cancel scope such that the rpc task can be # cancelled gracefully if requested self._rpc_tasks[(chan, cid)] = ( cs, func, trio.Event()) else: # self.cancel() was called so kill this msg loop # and break out into ``_async_main()`` log.warning( f"{self.uid} was remotely cancelled; " "waiting on cancellation completion..") await self._cancel_complete.wait() loop_cs.cancel() break log.debug( f"Waiting on next msg for {chan} from {chan.uid}") else: # channel disconnect log.debug( f"{chan} for {chan.uid} disconnected, cancelling tasks" ) await self.cancel_rpc_tasks(chan) except ( TransportClosed, ): # channels "breaking" (for TCP streams by EOF or 104 # connection-reset) is ok since we don't have a teardown # handshake for them (yet) and instead we simply bail out of # the message loop and expect the teardown sequence to clean # up. log.debug(f'channel from {chan.uid} closed abruptly:\n{chan}') except (Exception, trio.MultiError) as err: # ship any "internal" exception (i.e. one from internal machinery # not from an rpc task) to parent log.exception("Actor errored:") if self._parent_chan: await self._parent_chan.send(pack_error(err)) # if this is the `MainProcess` we expect the error broadcasting # above to trigger an error at consuming portal "checkpoints" raise except trio.Cancelled: # debugging only log.debug(f"Msg loop was cancelled for {chan}") raise finally: # msg debugging for when he machinery is brokey log.debug( f"Exiting msg loop for {chan} from {chan.uid} " f"with last msg:\n{msg}") async def _from_parent( self, parent_addr: Optional[Tuple[str, int]], ) -> Tuple[Channel, Optional[Tuple[str, int]]]: try: # Connect back to the parent actor and conduct initial # handshake. From this point on if we error, we # attempt to ship the exception back to the parent. chan = Channel( destaddr=parent_addr, ) await chan.connect() # Initial handshake: swap names. await self._do_handshake(chan) accept_addr: Optional[Tuple[str, int]] = None if self._spawn_method == "trio": # Receive runtime state from our parent parent_data = await chan.recv() log.debug( "Received state from parent:\n" f"{parent_data}" ) accept_addr = ( parent_data.pop('bind_host'), parent_data.pop('bind_port'), ) rvs = parent_data.pop('_runtime_vars') log.debug(f"Runtime vars are: {rvs}") rvs['_is_root'] = False _state._runtime_vars.update(rvs) for attr, value in parent_data.items(): setattr(self, attr, value) return chan, accept_addr except OSError: # failed to connect log.warning( f"Failed to connect to parent @ {parent_addr}," " closing server") await self.cancel() raise async def _async_main( self, accept_addr: Optional[Tuple[str, int]] = None, # XXX: currently ``parent_addr`` is only needed for the # ``multiprocessing`` backend (which pickles state sent to # the child instead of relaying it over the connect-back # channel). Once that backend is removed we can likely just # change this so a simple ``is_subactor: bool`` which will # be False when running as root actor and True when as # a subactor. parent_addr: Optional[Tuple[str, int]] = None, task_status: TaskStatus[None] = trio.TASK_STATUS_IGNORED, ) -> None: """Start the channel server, maybe connect back to the parent, and start the main task. A "root-most" (or "top-level") nursery for this actor is opened here and when cancelled effectively cancels the actor. """ registered_with_arbiter = False try: # establish primary connection with immediate parent self._parent_chan = None if parent_addr is not None: self._parent_chan, accept_addr_rent = await self._from_parent( parent_addr) # either it's passed in because we're not a child # or because we're running in mp mode if accept_addr_rent is not None: accept_addr = accept_addr_rent # load exposed/allowed RPC modules # XXX: do this **after** establishing a channel to the parent # but **before** starting the message loop for that channel # such that import errors are properly propagated upwards self.load_modules() # The "root" nursery ensures the channel with the immediate # parent is kept alive as a resilient service until # cancellation steps have (mostly) occurred in # a deterministic way. async with trio.open_nursery() as root_nursery: self._root_n = root_nursery assert self._root_n async with trio.open_nursery() as service_nursery: # This nursery is used to handle all inbound # connections to us such that if the TCP server # is killed, connections can continue to process # in the background until this nursery is cancelled. self._service_n = service_nursery assert self._service_n # Startup up the channel server with, # - subactor: the bind address is sent by our parent # over our established channel # - root actor: the ``accept_addr`` passed to this method assert accept_addr host, port = accept_addr self._server_n = await service_nursery.start( partial( self._serve_forever, service_nursery, accept_host=host, accept_port=port ) ) accept_addr = self.accept_addr if _state._runtime_vars['_is_root']: _state._runtime_vars['_root_mailbox'] = accept_addr # Register with the arbiter if we're told its addr log.debug(f"Registering {self} for role `{self.name}`") assert isinstance(self._arb_addr, tuple) async with get_arbiter(*self._arb_addr) as arb_portal: await arb_portal.run_from_ns( 'self', 'register_actor', uid=self.uid, sockaddr=accept_addr, ) registered_with_arbiter = True # init steps complete task_status.started() # Begin handling our new connection back to our # parent. This is done last since we don't want to # start processing parent requests until our channel # server is 100% up and running. if self._parent_chan: await root_nursery.start( partial( self._process_messages, self._parent_chan, shield=True, ) ) log.info("Waiting on service nursery to complete") log.info("Service nursery complete") log.info("Waiting on root nursery to complete") # Blocks here as expected until the root nursery is # killed (i.e. this actor is cancelled or signalled by the parent) except Exception as err: if not registered_with_arbiter: # TODO: I guess we could try to connect back # to the parent through a channel and engage a debugger # once we have that all working with std streams locking? log.exception( f"Actor errored and failed to register with arbiter " f"@ {self._arb_addr}?") log.error( "\n\n\t^^^ THIS IS PROBABLY A TRACTOR BUGGGGG!!! ^^^\n" "\tCALMLY CALL THE AUTHORITIES AND HIDE YOUR CHILDREN.\n\n" "\tYOUR PARENT CODE IS GOING TO KEEP WORKING FINE!!!\n" "\tTHIS IS HOW RELIABlE SYSTEMS ARE SUPPOSED TO WORK!?!?\n" ) if self._parent_chan: with trio.CancelScope(shield=True): try: # internal error so ship to parent without cid await self._parent_chan.send(pack_error(err)) except trio.ClosedResourceError: log.error( f"Failed to ship error to parent " f"{self._parent_chan.uid}, channel was closed") # always! log.exception("Actor errored:") raise finally: log.info("Root nursery complete") # tear down all lifetime contexts if not in guest mode # XXX: should this just be in the entrypoint? log.warning("Closing all actor lifetime contexts") _lifetime_stack.close() # Unregister actor from the arbiter if registered_with_arbiter and ( self._arb_addr is not None ): failed = False with trio.move_on_after(0.5) as cs: cs.shield = True try: async with get_arbiter(*self._arb_addr) as arb_portal: await arb_portal.run_from_ns( 'self', 'unregister_actor', uid=self.uid ) except OSError: failed = True if cs.cancelled_caught: failed = True if failed: log.warning( f"Failed to unregister {self.name} from arbiter") # Ensure all peers (actors connected to us as clients) are finished if not self._no_more_peers.is_set(): if any( chan.connected() for chan in chain(*self._peers.values()) ): log.debug( f"Waiting for remaining peers {self._peers} to clear") with trio.CancelScope(shield=True): await self._no_more_peers.wait() log.debug("All peer channels are complete") log.debug("Runtime completed") async def _serve_forever( self, handler_nursery: trio.Nursery, *, # (host, port) to bind for channel server accept_host: Tuple[str, int] = None, accept_port: int = 0, task_status: TaskStatus[trio.Nursery] = trio.TASK_STATUS_IGNORED, ) -> None: """Start the channel server, begin listening for new connections. This will cause an actor to continue living (blocking) until ``cancel_server()`` is called. """ self._server_down = trio.Event() try: async with trio.open_nursery() as server_n: l: List[trio.abc.Listener] = await server_n.start( partial( trio.serve_tcp, self._stream_handler, # new connections will stay alive even if this server # is cancelled handler_nursery=handler_nursery, port=accept_port, host=accept_host, ) ) log.debug( "Started tcp server(s) on" f" {[getattr(l, 'socket', 'unknown socket') for l in l]}") self._listeners.extend(l) task_status.started(server_n) finally: # signal the server is down since nursery above terminated self._server_down.set() def cancel_soon(self) -> None: """Cancel this actor asap; can be called from a sync context. Schedules `.cancel()` to be run immediately just like when cancelled by the parent. """ assert self._service_n self._service_n.start_soon(self.cancel) async def cancel(self) -> bool: """Cancel this actor. The "deterministic" teardown sequence in order is: - cancel all ongoing rpc tasks by cancel scope - cancel the channel server to prevent new inbound connections - cancel the "service" nursery reponsible for spawning new rpc tasks - return control the parent channel message loop """ log.warning(f"{self.uid} is trying to cancel") self._cancel_called = True # cancel all ongoing rpc tasks with trio.CancelScope(shield=True): # kill any debugger request task to avoid deadlock # with the root actor in this tree dbcs = _debug._debugger_request_cs if dbcs is not None: log.debug("Cancelling active debugger request") dbcs.cancel() # kill all ongoing tasks await self.cancel_rpc_tasks() # stop channel server self.cancel_server() await self._server_down.wait() # cancel all rpc tasks permanently if self._service_n: self._service_n.cancel_scope.cancel() log.warning(f"{self.uid} was sucessfullly cancelled") self._cancel_complete.set() return True # XXX: hard kill logic if needed? # def _hard_mofo_kill(self): # # If we're the root actor or zombied kill everything # if self._parent_chan is None: # TODO: more robust check # root = trio.lowlevel.current_root_task() # for n in root.child_nurseries: # n.cancel_scope.cancel() async def _cancel_task(self, cid, chan): """Cancel a local task by call-id / channel. Note this method will be treated as a streaming function by remote actor-callers due to the declaration of ``ctx`` in the signature (for now). """ # right now this is only implicitly called by # streaming IPC but it should be called # to cancel any remotely spawned task try: # this ctx based lookup ensures the requested task to # be cancelled was indeed spawned by a request from this channel scope, func, is_complete = self._rpc_tasks[(chan, cid)] except KeyError: log.warning(f"{cid} has already completed/terminated?") return log.debug( f"Cancelling task:\ncid: {cid}\nfunc: {func}\n" f"peer: {chan.uid}\n") # don't allow cancelling this function mid-execution # (is this necessary?) if func is self._cancel_task: return scope.cancel() # wait for _invoke to mark the task complete log.debug( f"Waiting on task to cancel:\ncid: {cid}\nfunc: {func}\n" f"peer: {chan.uid}\n") await is_complete.wait() log.debug( f"Sucessfully cancelled task:\ncid: {cid}\nfunc: {func}\n" f"peer: {chan.uid}\n") async def cancel_rpc_tasks( self, only_chan: Optional[Channel] = None, ) -> None: """Cancel all existing RPC responder tasks using the cancel scope registered for each. """ tasks = self._rpc_tasks log.info(f"Cancelling all {len(tasks)} rpc tasks:\n{tasks} ") for (chan, cid) in tasks.copy(): if only_chan is not None: if only_chan != chan: continue # TODO: this should really done in a nursery batch await self._cancel_task(cid, chan) log.info( f"Waiting for remaining rpc tasks to complete {tasks}") await self._ongoing_rpc_tasks.wait() def cancel_server(self) -> None: """Cancel the internal channel server nursery thereby preventing any new inbound connections from being established. """ if self._server_n: log.debug("Shutting down channel server") self._server_n.cancel_scope.cancel() @property def accept_addr(self) -> Optional[Tuple[str, int]]: """Primary address to which the channel server is bound. """ # throws OSError on failure return self._listeners[0].socket.getsockname() # type: ignore def get_parent(self) -> Portal: """Return a portal to our parent actor.""" assert self._parent_chan, "No parent channel for this actor?" return Portal(self._parent_chan) def get_chans(self, uid: Tuple[str, str]) -> List[Channel]: """Return all channels to the actor with provided uid.""" return self._peers[uid] async def _do_handshake( self, chan: Channel ) -> Tuple[str, str]: """Exchange (name, UUIDs) identifiers as the first communication step. These are essentially the "mailbox addresses" found in actor model parlance. """ await chan.send(self.uid) uid: Tuple[str, str] = await chan.recv() if not isinstance(uid, tuple): raise ValueError(f"{uid} is not a valid uid?!") chan.uid = uid log.info(f"Handshake with actor {uid}@{chan.raddr} complete") return uid class Arbiter(Actor): """A special actor who knows all the other actors and always has access to a top level nursery. The arbiter is by default the first actor spawned on each host and is responsible for keeping track of all other actors for coordination purposes. If a new main process is launched and an arbiter is already running that arbiter will be used. """ is_arbiter = True def __init__(self, *args, **kwargs): self._registry = defaultdict(list) self._waiters = {} super().__init__(*args, **kwargs) async def find_actor(self, name: str) -> Optional[Tuple[str, int]]: for uid, sockaddr in self._registry.items(): if name in uid: return sockaddr return None async def get_registry( self ) -> Dict[str, Tuple[str, str]]: """Return current name registry. """ # NOTE: requires ``strict_map_key=False`` to the msgpack # unpacker since we have tuples as keys (not this makes the # arbiter suscetible to hashdos): # https://github.com/msgpack/msgpack-python#major-breaking-changes-in-msgpack-10 return self._registry async def wait_for_actor( self, name: str ) -> List[Tuple[str, int]]: """Wait for a particular actor to register. This is a blocking call if no actor by the provided name is currently registered. """ sockaddrs = [] for (aname, _), sockaddr in self._registry.items(): if name == aname: sockaddrs.append(sockaddr) if not sockaddrs: waiter = trio.Event() self._waiters.setdefault(name, []).append(waiter) await waiter.wait() for uid in self._waiters[name]: sockaddrs.append(self._registry[uid]) return sockaddrs async def register_actor( self, uid: Tuple[str, str], sockaddr: Tuple[str, int] ) -> None: name, uuid = uid self._registry[uid] = sockaddr # pop and signal all waiter events events = self._waiters.pop(name, ()) self._waiters.setdefault(name, []).append(uid) for event in events: if isinstance(event, trio.Event): event.set() async def unregister_actor(self, uid: Tuple[str, str]) -> None: self._registry.pop(uid)