tractor/tractor/_actor.py

1339 lines
50 KiB
Python

"""
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,
ContextCancelled,
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')
async def _invoke(
actor: 'Actor',
cid: str,
chan: Channel,
func: typing.Callable,
kwargs: Dict[str, Any],
is_rpc: bool = True,
task_status: TaskStatus[
Union[trio.CancelScope, BaseException]
] = trio.TASK_STATUS_IGNORED,
):
'''
Invoke local func and deliver result(s) over provided channel.
'''
__tracebackhide__ = True
treat_as_gen = False
# possible a traceback (not sure what typing is for this..)
tb = None
cancel_scope = trio.CancelScope()
cs: Optional[trio.CancelScope] = None
ctx = Context(chan, cid)
context: bool = 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.runtime(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})
async with trio.open_nursery() as scope_nursery:
ctx._scope_nursery = scope_nursery
cs = scope_nursery.cancel_scope
task_status.started(cs)
try:
await chan.send({'return': await coro, 'cid': cid})
except trio.Cancelled as err:
tb = err.__traceback__
if cs.cancelled_caught:
# TODO: pack in ``trio.Cancelled.__traceback__`` here
# so they can be unwrapped and displayed on the caller
# side!
fname = func.__name__
if ctx._cancel_called:
msg = f'{fname} cancelled itself'
elif cs.cancel_called:
msg = (
f'{fname} was remotely cancelled by its caller '
f'{ctx.chan.uid}'
)
# task-contex was cancelled so relay to the cancel to caller
raise ContextCancelled(
msg,
suberror_type=trio.Cancelled,
)
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:
if not is_multi_cancelled(err):
# TODO: maybe we'll want different "levels" of debugging
# eventualy such as ('app', 'supervisory', 'runtime') ?
# if not isinstance(err, trio.ClosedResourceError) and (
# if not is_multi_cancelled(err) and (
entered_debug: bool = False
if not isinstance(err, ContextCancelled) or (
isinstance(err, ContextCancelled) and ctx._cancel_called
):
# XXX: is there any case where we'll want to debug IPC
# disconnects as a default?
#
# 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 our transport layer itself? Going to keep this
# open ended for now.
entered_debug = await _debug._maybe_enter_pm(err)
if not entered_debug:
log.exception("Actor crashed:")
# always ship errors back to caller
err_msg = pack_error(err, tb=tb)
err_msg['cid'] = cid
try:
await chan.send(err_msg)
except trio.ClosedResourceError:
# if we can't propagate the error that's a big boo boo
log.error(
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 is_rpc:
# 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.runtime("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 process
executing a ``trio`` task tree, communicating
with other actors through "portals" which provide a native async API
around various IPC transport "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 = (
str(arbiter_addr[0]),
int(arbiter_addr[1])
) if arbiter_addr else None
# 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.runtime(f"Waiting for peer {uid} to connect")
event = self._peer_connected.setdefault(uid, trio.Event())
await event.wait()
log.runtime(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.runtime(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(<name>, 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.from_stream(stream)
log.runtime(f"New connection to us {chan}")
# send/receive initial handshake response
try:
uid = await self._do_handshake(chan)
except (
# we need this for ``msgspec`` for some reason?
# for now, it's been put in the stream backend.
# 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.runtime(f"Waking channel waiters {event.statistics()}")
# Alert any task waiting on this connection to come up
event.set()
chans = self._peers[uid]
# TODO: re-use channels for new connections instead
# of always new ones; will require changing all the
# discovery funcs
if chans:
log.runtime(
f"already have channel(s) for {uid}:{chans}?"
)
log.runtime(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:
# channel cleanup sequence
# for (channel, cid) in self._rpc_tasks.copy():
# if channel is chan:
# with trio.CancelScope(shield=True):
# await self._cancel_task(cid, channel)
# # close all consumer side task mem chans
# send_chan, _ = self._cids2qs[(chan.uid, cid)]
# assert send_chan.cid == cid # type: ignore
# await send_chan.aclose()
# Drop ref to channel so it can be gc-ed and disconnected
log.runtime(f"Releasing channel {chan} from {chan.uid}")
chans = self._peers.get(chan.uid)
chans.remove(chan)
if not chans:
log.runtime(f"No more channels for {chan.uid}")
self._peers.pop(chan.uid, None)
log.runtime(f"Peers is {self._peers}")
if not self._peers: # no more channels connected
log.runtime("Signalling no more peer channels")
self._no_more_peers.set()
# # XXX: is this necessary (GC should do it?)
if chan.connected():
# if the channel is still connected it may mean the far
# end has not closed and we may have gotten here due to
# an error and so we should at least try to terminate
# the channel from this end gracefully.
log.runtime(f"Disconnecting channel {chan}")
try:
# send a msg loop terminate sentinel
await chan.send(None)
# XXX: do we want this?
# causes "[104] connection reset by peer" on other end
# await chan.aclose()
except trio.BrokenResourceError:
log.warning(f"Channel for {chan.uid} was already closed")
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 chan.uid, f"`chan.uid` can't be {chan.uid}"
send_chan, recv_chan = self._cids2qs[(chan.uid, cid)]
assert send_chan.cid == cid # type: ignore
# if 'error' in msg:
# ctx = getattr(recv_chan, '_ctx', None)
# if ctx:
# ctx._error_from_remote_msg(msg)
# log.runtime(f"{send_chan} was terminated at remote end")
# # indicate to consumer that far end has stopped
# return await send_chan.aclose()
try:
log.runtime(f"Delivering {msg} from {chan.uid} 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.runtime(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(2**6)
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.runtime(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
nursery_cancelled_before_task: bool = False
log.runtime(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.cancel(
f"Cancelling all tasks for {chan} from {chan.uid}")
for (channel, cid) in self._rpc_tasks.copy():
if channel is chan:
await self._cancel_task(cid, channel)
log.runtime(
f"Msg loop signalled to terminate for"
f" {chan} from {chan.uid}")
break
log.transport( # 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.runtime(
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.runtime(
f"Processing request from {actorid}\n"
f"{ns}.{funcname}({kwargs})")
if ns == 'self':
func = getattr(self, funcname)
if funcname == 'cancel':
# don't start entire actor runtime cancellation if this
# actor is in debug mode
pdb_complete = _debug._local_pdb_complete
if pdb_complete:
await pdb_complete.wait()
# we immediately start the runtime machinery shutdown
with trio.CancelScope(shield=True):
# self.cancel() was called so kill this msg loop
# and break out into ``_async_main()``
log.cancel(
f"Actor {self.uid} was remotely cancelled; "
"waiting on cancellation completion..")
await _invoke(self, cid, chan, func, kwargs, is_rpc=False)
# await self._cancel_complete.wait()
loop_cs.cancel()
break
if funcname == '_cancel_task':
# we immediately start the runtime machinery shutdown
with trio.CancelScope(shield=True):
# self.cancel() was called so kill this msg loop
# and break out into ``_async_main()``
kwargs['chan'] = chan
log.cancel(
f"Actor {self.uid} was remotely cancelled; "
"waiting on cancellation completion..")
await _invoke(self, cid, chan, func, kwargs, is_rpc=False)
continue
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.runtime(f"Spawning task for {func}")
assert self._service_n
try:
cs = await self._service_n.start(
partial(_invoke, self, cid, chan, func, kwargs),
name=funcname,
)
except (RuntimeError, trio.MultiError):
# avoid reporting a benign race condition
# during actor runtime teardown.
nursery_cancelled_before_task = True
break
# 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.runtime(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())
log.runtime(
f"Waiting on next msg for {chan} from {chan.uid}")
# end of async for, channel disconnect vis ``trio.EndOfChannel``
log.runtime(
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.runtime(f'channel from {chan.uid} closed abruptly:\n{chan}')
except (Exception, trio.MultiError) as err:
if nursery_cancelled_before_task:
sn = self._service_n
assert sn and sn.cancel_scope.cancel_called
log.cancel(
f'Service nursery cancelled before it handled {funcname}'
)
else:
# 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.runtime(f"Msg loop was cancelled for {chan}")
raise
finally:
# msg debugging for when he machinery is brokey
log.runtime(
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: dict[str, Any]
parent_data = await chan.recv()
log.runtime(
"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.runtime(f"Runtime vars are: {rvs}")
rvs['_is_root'] = False
_state._runtime_vars.update(rvs)
for attr, value in parent_data.items():
if attr == '_arb_addr':
# XXX: ``msgspec`` doesn't support serializing tuples
# so just cash manually here since it's what our
# internals expect.
value = tuple(value) if value else None
self._arb_addr = value
else:
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 to 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.runtime(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.runtime("Waiting on service nursery to complete")
log.runtime("Service nursery complete")
log.runtime("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:
log.info("Closing all actor lifetime contexts")
_lifetime_stack.close()
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("Runtime nursery complete")
# tear down all lifetime contexts if not in guest mode
# XXX: should this just be in the entrypoint?
log.info("Closing all actor lifetime contexts")
# TODO: we can't actually do this bc the debugger
# uses the _service_n to spawn the lock task, BUT,
# in theory if we had the root nursery surround this finally
# block it might be actually possible to debug THIS
# machinery in the same way as user task code?
# if self.name == 'brokerd.ib':
# with trio.CancelScope(shield=True):
# await _debug.breakpoint()
_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.runtime(
f"Waiting for remaining peers {self._peers} to clear")
with trio.CancelScope(shield=True):
await self._no_more_peers.wait()
log.runtime("All peer channels are complete")
log.runtime("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.runtime(
"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's runtime.
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.cancel(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.cancel("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.cancel(f"{self.uid} called `Actor.cancel()`")
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.cancel(f"{cid} has already completed/terminated?")
return
log.cancel(
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.runtime(
f"Waiting on task to cancel:\ncid: {cid}\nfunc: {func}\n"
f"peer: {chan.uid}\n")
await is_complete.wait()
log.runtime(
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
if tasks:
log.cancel(f"Cancelling all {len(tasks)} rpc tasks:\n{tasks} ")
for (chan, cid), (scope, func, is_complete) in tasks.copy().items():
if only_chan is not None:
if only_chan != chan:
continue
# TODO: this should really done in a nursery batch
if func != self._cancel_task:
await self._cancel_task(cid, chan)
log.cancel(
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.runtime("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)
value = await chan.recv()
uid: Tuple[str, str] = (str(value[0]), str(value[1]))
if not isinstance(uid, tuple):
raise ValueError(f"{uid} is not a valid uid?!")
chan.uid = str(uid[0]), str(uid[1])
log.runtime(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: Dict[
Tuple[str, str],
Tuple[str, int],
] = {}
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[Tuple[str, str], Tuple[str, int]]:
'''Return current name registry.
This method is async to allow for cross-actor invocation.
'''
# 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:
uid = name, uuid = (str(uid[0]), str(uid[1]))
self._registry[uid] = (str(sockaddr[0]), int(sockaddr[1]))
# 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:
uid = (str(uid[0]), str(uid[1]))
self._registry.pop(uid)