# tractor: structured concurrent "actors".
# Copyright 2018-eternity Tyler Goodlet.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see .
"""
Actor primitives and helpers
"""
from __future__ import annotations
from collections import defaultdict
from functools import partial
from itertools import chain
import importlib
import importlib.util
import inspect
from pprint import pformat
import signal
import sys
from typing import (
Any,
Callable,
TYPE_CHECKING,
)
import uuid
from types import ModuleType
import os
from contextlib import ExitStack
import warnings
from async_generator import aclosing
from exceptiongroup import BaseExceptionGroup
import trio # type: ignore
from trio_typing import TaskStatus
from ._ipc import Channel
from ._context import (
mk_context,
Context,
)
from .log import get_logger
from ._exceptions import (
pack_error,
unpack_error,
ModuleNotExposed,
is_multi_cancelled,
ContextCancelled,
TransportClosed,
)
from .devx import _debug
from ._discovery import get_registry
from ._portal import Portal
from . import _state
from . import _mp_fixup_main
if TYPE_CHECKING:
from ._supervise import ActorNursery
log = get_logger('tractor')
async def _invoke(
actor: Actor,
cid: str,
chan: Channel,
func: Callable,
kwargs: dict[str, Any],
is_rpc: bool = True,
task_status: TaskStatus[
Context | BaseException
] = trio.TASK_STATUS_IGNORED,
):
'''
Schedule a `trio` task-as-func and deliver result(s) over
connected IPC channel.
This is the core "RPC" `trio.Task` scheduling machinery used to start every
remotely invoked function, normally in `Actor._service_n: trio.Nursery`.
'''
__tracebackhide__: bool = True
treat_as_gen: bool = False
failed_resp: bool = False
if _state.debug_mode():
try:
import greenback
await greenback.ensure_portal()
except ModuleNotFoundError:
log.warning(
'`greenback` is not installed.\n'
'No sync debug support!'
)
# possibly a traceback (not sure what typing is for this..)
tb = None
cancel_scope = trio.CancelScope()
# activated cancel scope ref
cs: trio.CancelScope | None = None
ctx = actor.get_context(
chan,
cid,
# We shouldn't ever need to pass this through right?
# it's up to the soon-to-be called rpc task to
# open the stream with this option.
# allow_overruns=True,
)
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!')
try:
coro = func(**kwargs)
except TypeError:
raise
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:
ctx._scope = cs
task_status.started(ctx)
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:
ctx._scope = cs
task_status.started(ctx)
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})
# TODO: every other "func type" should be implemented from
# a special case of a context eventually!
elif context:
# context func with support for bi-dir streaming
await chan.send({'functype': 'context', 'cid': cid})
try:
async with trio.open_nursery() as nurse:
ctx._scope_nursery = nurse
ctx._scope = nurse.cancel_scope
task_status.started(ctx)
res = await coro
await chan.send({
'return': res,
'cid': cid
})
# XXX: do we ever trigger this block any more?
except (
BaseExceptionGroup,
trio.Cancelled,
) as scope_error:
# always set this (callee) side's exception as the
# local error on the context
ctx._local_error: BaseException = scope_error
# if a remote error was set then likely the
# exception group was raised due to that, so
# and we instead raise that error immediately!
if re := ctx._remote_error:
ctx._maybe_raise_remote_err(re)
# maybe TODO: pack in
# ``trio.Cancelled.__traceback__`` here so they can
# be unwrapped and displayed on the caller side?
raise
finally:
# XXX: only pop the context tracking if
# a ``@tractor.context`` entrypoint was called
assert chan.uid
# don't pop the local context until we know the
# associated child isn't in debug any more
await _debug.maybe_wait_for_debugger()
ctx: Context = actor._contexts.pop((chan.uid, cid))
log.runtime(
f'Context entrypoint {func} was terminated:\n'
f'{ctx}'
)
if ctx.cancelled_caught:
# first check for and raise any remote error
# before raising any context cancelled case
# so that real remote errors don't get masked as
# ``ContextCancelled``s.
if re := ctx._remote_error:
ctx._maybe_raise_remote_err(re)
fname: str = func.__name__
cs: trio.CancelScope = ctx._scope
if cs.cancel_called:
canceller: tuple = ctx.canceller
msg: str = (
f'`{fname}()`@{actor.uid} cancelled by '
)
# NOTE / TODO: if we end up having
# ``Actor._cancel_task()`` call
# ``Context.cancel()`` directly, we're going to
# need to change this logic branch since it
# will always enter..
if ctx._cancel_called:
msg += 'itself '
# if the channel which spawned the ctx is the
# one that cancelled it then we report that, vs.
# it being some other random actor that for ex.
# some actor who calls `Portal.cancel_actor()`
# and by side-effect cancels this ctx.
elif canceller == ctx.chan.uid:
msg += f'its caller {canceller} '
else:
msg += f'remote actor {canceller}'
# TODO: does this ever get set any more or can
# we remove it?
if ctx._cancel_msg:
msg += (
' with msg:\n'
f'{ctx._cancel_msg}'
)
# task-contex was either cancelled by request using
# ``Portal.cancel_actor()`` or ``Context.cancel()``
# on the far end, or it was cancelled by the local
# (callee) task, so relay this cancel signal to the
# other side.
raise ContextCancelled(
msg,
suberror_type=trio.Cancelled,
canceller=canceller,
)
# regular async function
else:
try:
await chan.send({
'functype': 'asyncfunc',
'cid': cid
})
except trio.BrokenResourceError:
failed_resp = True
if is_rpc:
raise
else:
log.warning(
f'Failed to respond to non-rpc request: {func}'
)
with cancel_scope as cs:
ctx._scope = cs
task_status.started(ctx)
result = await coro
fname: str = func.__name__
log.runtime(f'{fname}() result: {result}')
if not failed_resp:
# only send result if we know IPC isn't down
await chan.send(
{'return': result,
'cid': cid}
)
except (
Exception,
BaseExceptionGroup,
) 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
# if the root blocks the debugger lock request from a child
# we will get a remote-cancelled condition.
and ctx._enter_debugger_on_cancel
)
):
# XXX QUESTION 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)
# TODO: tests for this scenario:
# - RPC caller closes connection before getting a response
# should **not** crash this actor..
except (
trio.ClosedResourceError,
trio.BrokenResourceError,
BrokenPipeError,
):
# if we can't propagate the error that's a big boo boo
log.exception(
f"Failed to ship error to caller @ {chan.uid} !?"
)
# error is probably from above coro running code *not from the
# underlyingn rpc invocation* since a scope was never allocated
# around actual coroutine await.
if ctx._scope is None:
# we don't ever raise directly here to allow the
# msg-loop-scheduler to continue running for this
# channel.
task_status.started(err)
finally:
# RPC task bookeeping
try:
ctx, 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 start")
else:
log.cancel(f'{func.__name__}({kwargs}) failed?')
finally:
if not actor._rpc_tasks:
log.runtime("All RPC tasks have completed")
actor._ongoing_rpc_tasks.set()
def _get_mod_abspath(module: ModuleType) -> str:
return os.path.abspath(module.__file__)
async def try_ship_error_to_parent(
channel: Channel,
err: Exception | BaseExceptionGroup,
) -> None:
with trio.CancelScope(shield=True):
try:
# internal error so ship to parent without cid
await channel.send(pack_error(err))
except (
trio.ClosedResourceError,
trio.BrokenResourceError,
):
# in SC terms this is one of the worst things that can
# happen and creates the 2-general's dilemma.
log.critical(
f"Failed to ship error to parent "
f"{channel.uid}, channel was closed"
)
class Actor:
'''
The fundamental "runtime" concurrency primitive.
An *actor* is the combination of a regular Python process executing
a ``trio`` task tree, communicating with other actors through
"memory boundary portals" - which provide a native async API around
IPC transport "channels" which themselves encapsulate various
(swappable) network protocols.
Each "actor" is ``trio.run()`` scheduled "runtime" composed of
many concurrent tasks in a single thread. The "runtime" tasks
conduct a slew of low(er) level functions to make it possible
for message passing between actors as well as the ability to
create new actors (aka new "runtimes" in new processes which
are supervised via a nursery construct). Each task which sends
messages to a task in a "peer" (not necessarily a parent-child,
depth hierarchy) is able to do so via an "address", which maps
IPC connections across memory boundaries, and a task request id
which allows for per-actor tasks to send and receive messages
to specific peer-actor tasks with which there is an ongoing
RPC/IPC dialog.
'''
# ugh, we need to get rid of this and replace with a "registry" sys
# https://github.com/goodboy/tractor/issues/216
is_arbiter: bool = False
@property
def is_registrar(self) -> bool:
return self.is_arbiter
msg_buffer_size: int = 2**6
# nursery placeholders filled in by `async_main()` after fork
_root_n: trio.Nursery | None = None
_service_n: trio.Nursery | None = None
_server_n: trio.Nursery | None = None
# Information about `__main__` from parent
_parent_main_data: dict[str, str]
_parent_chan_cs: trio.CancelScope | None = None
# syncs for setup/teardown sequences
_server_down: trio.Event | None = None
# user toggled crash handling (including monkey-patched in
# `trio.open_nursery()` via `.trionics._supervisor` B)
_debug_mode: bool = False
# if started on ``asycio`` running ``trio`` in guest mode
_infected_aio: bool = False
# Process-global stack closed at end on actor runtime teardown.
# NOTE: this is currently an undocumented public api.
lifetime_stack: ExitStack = ExitStack()
def __init__(
self,
name: str,
*,
enable_modules: list[str] = [],
uid: str | None = None,
loglevel: str | None = None,
registry_addrs: list[tuple[str, int]] | None = None,
spawn_method: str | None = None,
# TODO: remove!
arbiter_addr: tuple[str, int] | None = 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_by_remote: tuple[str, tuple] | None = None
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.devx._debug')
self.enable_modules: dict[str, str] = {}
for name in enable_modules:
mod: ModuleType = importlib.import_module(name)
self.enable_modules[name] = _get_mod_abspath(mod)
self._mods: dict[str, ModuleType] = {}
self.loglevel: str = loglevel
if arbiter_addr is not None:
warnings.warn(
'`Actor(arbiter_addr=)` is now deprecated.\n'
'Use `registry_addrs: list[tuple]` instead.',
DeprecationWarning,
stacklevel=2,
)
registry_addrs: list[tuple[str, int]] = [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: str = spawn_method
self._peers: defaultdict = defaultdict(list)
self._peer_connected: dict[tuple[str, str], trio.Event] = {}
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[Context, Callable, trio.Event]
] = {}
# map {actor uids -> Context}
self._contexts: dict[
tuple[tuple[str, str], str],
Context
] = {}
self._listeners: list[trio.abc.Listener] = []
self._parent_chan: Channel | None = None
self._forkserver_info: tuple | None = None
self._actoruid2nursery: dict[
tuple[str, str],
ActorNursery | None,
] = {} # type: ignore # noqa
# when provided, init the registry addresses property from
# input via the validator.
self._reg_addrs: list[tuple[str, int]] = []
if registry_addrs:
self.reg_addrs: list[tuple[str, int]] = registry_addrs
@property
def reg_addrs(self) -> list[tuple[str, int]]:
'''
List of (socket) addresses for all known (and contactable)
registry actors.
'''
return self._reg_addrs
@reg_addrs.setter
def reg_addrs(
self,
addrs: list[tuple[str, int]],
) -> None:
if not addrs:
log.warning(
'Empty registry address list is invalid:\n'
f'{addrs}'
)
return
# always sanity check the input list since it's critical
# that addrs are correct for discovery sys operation.
for addr in addrs:
if not isinstance(addr, tuple):
raise ValueError(
'Expected `Actor.reg_addrs: list[tuple[str, int]]`\n'
f'Got {addrs}'
)
self._reg_addrs = addrs
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__':
modpath = '__name__'
else:
modpath = f"'{ns}'"
msg = (
"\n\nMake sure you exposed the target module, `{ns}`, "
"using:\n"
"ActorNursery.start_actor(, enable_modules=[{mod}])"
).format(
ns=ns,
mod=modpath,
)
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)
their_uid: tuple[str, str] | None = chan.uid
if their_uid:
log.warning(
f'Re-connection from already known {their_uid}'
)
else:
log.runtime(f'New connection to us @{chan.raddr}')
# 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)
local_nursery: ActorNursery | None = None # noqa
disconnected: bool = False
# Begin channel management - respond to remote requests and
# process received reponses.
try:
disconnected = await process_messages(self, chan)
except (
trio.Cancelled,
):
log.cancel(f"Msg loop was cancelled for {chan}")
raise
finally:
local_nursery = self._actoruid2nursery.get(uid, local_nursery)
# This is set in ``Portal.cancel_actor()``. So if
# the peer was cancelled we try to wait for them
# to tear down their side of the connection before
# moving on with closing our own side.
if (
local_nursery
):
if chan._cancel_called:
log.cancel(f"Waiting on cancel request to peer {chan.uid}")
# XXX: this is a soft wait on the channel (and its
# underlying transport protocol) to close from the
# remote peer side since we presume that any channel
# which is mapped to a sub-actor (i.e. it's managed by
# one of our local nurseries) has a message is sent to
# the peer likely by this actor (which is now in
# a cancelled condition) when the local runtime here is
# now cancelled while (presumably) in the middle of msg
# loop processing.
with trio.move_on_after(0.5) as cs:
cs.shield = True
# Attempt to wait for the far end to close the channel
# and bail after timeout (2-generals on closure).
assert chan.msgstream
log.runtime(
f'Draining lingering msgs from stream {chan.msgstream}'
)
async for msg in chan.msgstream.drain():
# try to deliver any lingering msgs
# before we destroy the channel.
# This accomplishes deterministic
# ``Portal.cancel_actor()`` cancellation by
# making sure any RPC response to that call is
# delivered the local calling task.
# TODO: factor this into a helper?
log.runtime(f'drained {msg} for {chan.uid}')
cid = msg.get('cid')
if cid:
# deliver response to local caller/waiter
await self._push_result(chan, cid, msg)
log.runtime('Waiting on actor nursery to exit..')
await local_nursery.exited.wait()
if disconnected:
# if the transport died and this actor is still
# registered within a local nursery, we report
# that the IPC layer may have failed
# unexpectedly since it may be the cause of
# other downstream errors.
entry = local_nursery._children.get(uid)
if entry:
_, proc, _ = entry
if (
(poll := getattr(proc, 'poll', None))
and poll() is None
):
log.cancel(
f'Actor {uid} IPC broke but proc is alive?\n'
'Attempting to self cancel..'
)
# ``Channel`` teardown and closure sequence
# 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(uid, None)
log.runtime(f"Peers is {self._peers}")
# No more channels to other actors (at all) registered
# as connected.
if not self._peers:
log.runtime("Signalling no more peer channel connections")
self._no_more_peers.set()
# NOTE: block this actor from acquiring the
# debugger-TTY-lock since we have no way to know if we
# cancelled it and further there is no way to ensure the
# lock will be released if acquired due to having no
# more active IPC channels.
if _state.is_root_process():
pdb_lock = _debug.Lock
pdb_lock._blocked.add(uid)
log.runtime(f"{uid} blocked from pdb locking")
# if a now stale local task has the TTY lock still
# we cancel it to allow servicing other requests for
# the lock.
db_cs = pdb_lock._root_local_task_cs_in_debug
if (
db_cs
and not db_cs.cancel_called
):
log.critical(
f'STALE DEBUG LOCK DETECTED FOR {uid}'
)
# TODO: figure out why this breaks tests..
db_cs.cancel()
# 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.runtime(f"Channel {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.
'''
uid = chan.uid
assert uid, f"`chan.uid` can't be {uid}"
try:
ctx = self._contexts[(uid, cid)]
except KeyError:
log.warning(
f'Ignoring msg from [no-longer/un]known context {uid}:'
f'\n{msg}')
return
return await ctx._deliver_msg(msg)
def get_context(
self,
chan: Channel,
cid: str,
msg_buffer_size: int | None = None,
allow_overruns: bool = False,
) -> Context:
'''
Look up or create a new inter-actor-task-IPC-linked task
"context" which encapsulates the local task's scheduling
enviroment including a ``trio`` cancel scope, a pair of IPC
messaging "feeder" channels, and an RPC id unique to the
task-as-function invocation.
'''
log.runtime(f"Getting result queue for {chan.uid} cid {cid}")
actor_uid = chan.uid
assert actor_uid
try:
ctx = self._contexts[(actor_uid, cid)]
ctx._allow_overruns = allow_overruns
# adjust buffer size if specified
state = ctx._send_chan._state # type: ignore
if msg_buffer_size and state.max_buffer_size != msg_buffer_size:
state.max_buffer_size = msg_buffer_size
except KeyError:
ctx = mk_context(
chan,
cid,
msg_buffer_size=msg_buffer_size or self.msg_buffer_size,
_allow_overruns=allow_overruns,
)
self._contexts[(actor_uid, cid)] = ctx
return ctx
async def start_remote_task(
self,
chan: Channel,
ns: str,
func: str,
kwargs: dict,
msg_buffer_size: int | None = None,
allow_overruns: bool = False,
) -> Context:
'''
Send a ``'cmd'`` message to a remote actor, which starts
a remote task-as-function entrypoint.
Synchronously validates the endpoint type and return a caller
side task ``Context`` that can be used to wait for responses
delivered by the local runtime's message processing loop.
'''
cid = str(uuid.uuid4())
assert chan.uid
ctx = self.get_context(
chan,
cid,
msg_buffer_size=msg_buffer_size,
allow_overruns=allow_overruns,
)
log.runtime(f"Sending cmd to {chan.uid}: {ns}.{func}({kwargs})")
await chan.send(
{'cmd': (ns, func, kwargs, self.uid, cid)}
)
# Wait on first response msg and validate; this should be
# immediate.
first_msg = await ctx._recv_chan.receive()
functype = first_msg.get('functype')
if 'error' in first_msg:
raise unpack_error(first_msg, chan)
elif functype not in (
'asyncfunc',
'asyncgen',
'context',
):
raise ValueError(f"{first_msg} is an invalid response packet?")
ctx._remote_func_type = functype
return ctx
async def _from_parent(
self,
parent_addr: tuple[str, int] | None,
) -> tuple[
Channel,
list[tuple[str, int]] | None,
]:
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()
# TODO: move this into a `Channel.handshake()`?
# Initial handshake: swap names.
await self._do_handshake(chan)
accept_addrs: list[tuple[str, int]] | None = 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_addrs: list[tuple[str, int]] = parent_data.pop('bind_addrs')
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 == 'reg_addrs'
and value
):
# XXX: ``msgspec`` doesn't support serializing tuples
# so just cash manually here since it's what our
# internals expect.
# TODO: we don't really NEED these as
# tuples so we can probably drop this
# casting since apparently in python lists
# are "more efficient"?
self.reg_addrs = [tuple(val) for val in value]
else:
setattr(self, attr, value)
return chan, accept_addrs
except OSError: # failed to connect
log.warning(
f"Failed to connect to parent @ {parent_addr},"
" closing server")
await self.cancel(requesting_uid=self.uid)
raise
async def _serve_forever(
self,
handler_nursery: trio.Nursery,
*,
# (host, port) to bind for channel server
listen_sockaddrs: list[tuple[str, int]] | None = None,
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.
'''
if listen_sockaddrs is None:
listen_sockaddrs = [(None, 0)]
self._server_down = trio.Event()
try:
async with trio.open_nursery() as server_n:
for host, port in listen_sockaddrs:
listeners: list[trio.abc.Listener] = await server_n.start(
partial(
trio.serve_tcp,
handler=self._stream_handler,
port=port,
host=host,
# NOTE: configured such that new
# connections will stay alive even if
# this server is cancelled!
handler_nursery=handler_nursery,
)
)
sockets: list[trio.socket] = [
getattr(listener, 'socket', 'unknown socket')
for listener in listeners
]
log.runtime(
f'Started tcp server(s) on {sockets}'
)
self._listeners.extend(listeners)
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,
self.uid,
)
async def cancel(
self,
requesting_uid: tuple[str, str],
) -> 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} requested to cancel by:\n'
f'{requesting_uid}'
)
# TODO: what happens here when we self-cancel tho?
self._cancel_called_by_remote: tuple = requesting_uid
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.Lock._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(
requesting_uid=requesting_uid,
)
# stop channel server
self.cancel_server()
if self._server_down is not None:
await self._server_down.wait()
else:
log.warning(
f'{self.uid} was likely cancelled before it started')
# 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: str,
chan: Channel,
requesting_uid: tuple[str, str] | None = None,
) -> bool:
'''
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
ctx, func, is_complete = self._rpc_tasks[(chan, cid)]
scope: trio.CancelScope = ctx._scope
except KeyError:
log.cancel(f"{cid} has already completed/terminated?")
return True
log.cancel(
f"Cancelling task:\ncid: {cid}\nfunc: {func}\n"
f"peer: {chan.uid}\n")
if (
ctx._canceller is None
and requesting_uid
):
ctx._canceller: tuple = requesting_uid
# don't allow cancelling this function mid-execution
# (is this necessary?)
if func is self._cancel_task:
return True
# TODO: shouldn't we eventually be calling ``Context.cancel()``
# directly here instead (since that method can handle both
# side's calls into it?
# await ctx.cancel()
scope.cancel()
# wait for _invoke to mark the task complete
log.runtime(
'Waiting on task to cancel:\n'
f'cid: {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")
return True
async def cancel_rpc_tasks(
self,
only_chan: Channel | None = None,
requesting_uid: tuple[str, str] | None = None,
) -> None:
'''
Cancel all existing RPC responder tasks using the cancel scope
registered for each.
'''
tasks: dict = self._rpc_tasks
if tasks:
log.cancel(
f'Cancelling all {len(tasks)} rpc tasks:\n'
f'{tasks}'
)
for (
(chan, cid),
(ctx, 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,
requesting_uid=requesting_uid,
)
log.cancel(
'Waiting for remaining rpc tasks to complete:\n'
f'{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_addrs(self) -> list[tuple[str, int]]:
'''
All addresses to which the transport-channel server binds
and listens for new connections.
'''
# throws OSError on failure
return [
listener.socket.getsockname()
for listener in self._listeners
] # type: ignore
@property
def accept_addr(self) -> tuple[str, int]:
'''
Primary address to which the channel server is bound.
'''
# throws OSError on failure
return self.accept_addrs[0]
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]
# TODO: move to `Channel.handshake(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
def is_infected_aio(self) -> bool:
return self._infected_aio
async def async_main(
actor: Actor,
accept_addrs: tuple[str, int] | None = 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: tuple[str, int] | None = None,
task_status: TaskStatus[None] = trio.TASK_STATUS_IGNORED,
) -> None:
'''
Actor runtime entrypoint; start the IPC channel server, maybe connect
back to the parent, and startup all core machinery tasks.
A "root" (or "top-level") nursery for this actor is opened here and
when cancelled/terminated effectively closes the actor's "runtime".
'''
# attempt to retreive ``trio``'s sigint handler and stash it
# on our debugger lock state.
_debug.Lock._trio_handler = signal.getsignal(signal.SIGINT)
is_registered: bool = False
try:
# establish primary connection with immediate parent
actor._parent_chan: Channel | None = None
if parent_addr is not None:
(
actor._parent_chan,
set_accept_addr_says_rent,
) = await actor._from_parent(parent_addr)
# either it's passed in because we're not a child or
# because we're running in mp mode
if (
set_accept_addr_says_rent
and set_accept_addr_says_rent is not None
):
accept_addrs = set_accept_addr_says_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
actor.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:
actor._root_n = root_nursery
assert actor._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.
actor._service_n = service_nursery
assert actor._service_n
# Startup up the transport(-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_addrs
try:
actor._server_n = await service_nursery.start(
partial(
actor._serve_forever,
service_nursery,
listen_sockaddrs=accept_addrs,
)
)
except OSError as oserr:
# NOTE: always allow runtime hackers to debug
# tranport address bind errors - normally it's
# something silly like the wrong socket-address
# passed via a config or CLI Bo
entered_debug = await _debug._maybe_enter_pm(oserr)
if entered_debug:
log.runtime('Exited debug REPL..')
raise
accept_addrs: list[tuple[str, int]] = actor.accept_addrs
# NOTE: only set the loopback addr for the
# process-tree-global "root" mailbox since
# all sub-actors should be able to speak to
# their root actor over that channel.
if _state._runtime_vars['_is_root']:
for addr in accept_addrs:
host, _ = addr
# TODO: generic 'lo' detector predicate
if '127.0.0.1' in host:
_state._runtime_vars['_root_mailbox'] = addr
# Register with the arbiter if we're told its addr
log.runtime(
f'Registering `{actor.name}` ->\n'
f'{pformat(accept_addrs)}'
)
# TODO: ideally we don't fan out to all registrars
# if addresses point to the same actor..
# So we need a way to detect that? maybe iterate
# only on unique actor uids?
for addr in actor.reg_addrs:
try:
assert isinstance(addr, tuple)
assert addr[1] # non-zero after bind
except AssertionError:
await _debug.pause()
async with get_registry(*addr) as reg_portal:
for accept_addr in accept_addrs:
if not accept_addr[1]:
await _debug.pause()
assert accept_addr[1]
await reg_portal.run_from_ns(
'self',
'register_actor',
uid=actor.uid,
sockaddr=accept_addr,
)
is_registered: bool = 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 actor._parent_chan:
await root_nursery.start(
partial(
process_messages,
actor,
actor._parent_chan,
shield=True,
)
)
log.runtime("Waiting on service nursery to complete")
log.runtime(
"Service nursery complete\n"
"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.runtime("Closing all actor lifetime contexts")
actor.lifetime_stack.close()
if not is_registered:
# 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"@ {actor.reg_addrs[0]}?")
log.error(
"\n\n\t^^^ THIS IS PROBABLY AN INTERNAL `tractor` BUG! ^^^\n\n"
"\t>> CALMLY CALL THE AUTHORITIES AND HIDE YOUR CHILDREN <<\n\n"
"\tIf this is a sub-actor hopefully its parent will keep running "
"correctly presuming this error was safely ignored..\n\n"
"\tPLEASE REPORT THIS TRACEBACK IN A BUG REPORT: "
"https://github.com/goodboy/tractor/issues\n"
)
if actor._parent_chan:
await try_ship_error_to_parent(actor._parent_chan, err)
# always!
match err:
case ContextCancelled():
log.cancel(
f'Actor: {actor.uid} was task-context-cancelled with,\n'
f'str(err)'
)
case _:
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 actor.name == 'brokerd.ib':
# with trio.CancelScope(shield=True):
# await _debug.breakpoint()
actor.lifetime_stack.close()
# Unregister actor from the registry
if (
is_registered
and not actor.is_registrar
):
failed: bool = False
for addr in actor.reg_addrs:
assert isinstance(addr, tuple)
with trio.move_on_after(0.5) as cs:
cs.shield = True
try:
async with get_registry(
*addr,
) as reg_portal:
await reg_portal.run_from_ns(
'self',
'unregister_actor',
uid=actor.uid
)
except OSError:
failed = True
if cs.cancelled_caught:
failed = True
if failed:
log.warning(
f'Failed to unregister {actor.name} from '
f'registar @ {addr}'
)
# Ensure all peers (actors connected to us as clients) are finished
if not actor._no_more_peers.is_set():
if any(
chan.connected() for chan in chain(*actor._peers.values())
):
log.runtime(
f"Waiting for remaining peers {actor._peers} to clear")
with trio.CancelScope(shield=True):
await actor._no_more_peers.wait()
log.runtime("All peer channels are complete")
log.runtime("Runtime completed")
async def process_messages(
actor: Actor,
chan: Channel,
shield: bool = False,
task_status: TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED,
) -> bool:
'''
This is the per-channel, low level RPC task scheduler loop.
Receive multiplexed RPC request messages from some remote process,
spawn handler tasks depending on request type and deliver responses
or boxed errors back to the remote caller (task).
'''
# TODO: once https://github.com/python-trio/trio/issues/467 gets
# worked out we'll likely want to use that!
msg: dict | None = 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"Channel to {chan.uid} terminated?\n"
"Cancelling all associated tasks..")
for (channel, cid) in actor._rpc_tasks.copy():
if channel is chan:
await actor._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
# via its per-remote-context memory channel.
await actor._push_result(chan, cid, msg)
log.runtime(
f"Waiting on next msg for {chan} from {chan.uid}")
continue
# TODO: implement with ``match:`` syntax?
# 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':
if funcname == 'cancel':
func = actor.cancel
kwargs['requesting_uid'] = chan.uid
# don't start entire actor runtime cancellation
# if this actor is currently in debug mode!
pdb_complete = _debug.Lock.local_pdb_complete
if pdb_complete:
await pdb_complete.wait()
# we immediately start the runtime machinery
# shutdown
with trio.CancelScope(shield=True):
# actor.cancel() was called so kill this
# msg loop and break out into
# ``async_main()``
log.cancel(
"Actor runtime for was remotely cancelled "
f"by {chan.uid}"
)
await _invoke(
actor,
cid,
chan,
func,
kwargs,
is_rpc=False,
)
log.cancel(
f'Cancelling msg loop for {chan.uid}'
)
loop_cs.cancel()
break
if funcname == '_cancel_task':
func = actor._cancel_task
# we immediately start the runtime machinery
# shutdown
# with trio.CancelScope(shield=True):
kwargs['chan'] = chan
target_cid = kwargs['cid']
kwargs['requesting_uid'] = chan.uid
log.cancel(
f'Remote request to cancel task\n'
f'remote actor: {chan.uid}\n'
f'task: {target_cid}'
)
try:
await _invoke(
actor,
cid,
chan,
func,
kwargs,
is_rpc=False,
)
except BaseException:
log.exception("failed to cancel task?")
continue
else:
# normally registry methods, eg.
# ``.register_actor()`` etc.
func = getattr(actor, funcname)
else:
# complain to client about restricted modules
try:
func = actor._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 actor._service_n
try:
ctx: Context = await actor._service_n.start(
partial(
_invoke,
actor,
cid,
chan,
func,
kwargs,
),
name=funcname,
)
except (
RuntimeError,
BaseExceptionGroup,
):
# avoid reporting a benign race condition
# during actor runtime teardown.
nursery_cancelled_before_task: bool = True
break
# in the lone case where a ``Context`` is not
# delivered, it's likely going to be a locally
# scoped exception from ``_invoke()`` itself.
if isinstance(ctx, Exception):
log.warning(
f"Task for RPC func {func} failed with"
f"{ctx}"
)
continue
else:
# mark that we have ongoing rpc tasks
actor._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
actor._rpc_tasks[(chan, cid)] = (
ctx,
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 actor.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'
f'-> {chan.raddr}\n'
)
# transport **was** disconnected
return True
except (
Exception,
BaseExceptionGroup,
) as err:
if nursery_cancelled_before_task:
sn = actor._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
match err:
case ContextCancelled():
log.cancel(
f'Actor: {actor.uid} was context-cancelled with,\n'
f'str(err)'
)
case _:
log.exception("Actor errored:")
if actor._parent_chan:
await try_ship_error_to_parent(actor._parent_chan, err)
# if this is the `MainProcess` we expect the error broadcasting
# above to trigger an error at consuming portal "checkpoints"
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}"
)
# transport **was not** disconnected
return False
class Arbiter(Actor):
'''
A special registrar actor who can contact all other actors
within its immediate process tree and possibly keeps a registry
of others meant to be discoverable in a distributed
application. Normally the registrar is also the "root actor"
and thus always has access to the top-most-level actor
(process) nursery.
By default, the registrar is always initialized when and if no
other registrar socket addrs have been specified to runtime
init entry-points (such as `open_root_actor()` or
`open_nursery()`). Any time a new main process is launched (and
thus thus a new root actor created) and, no existing registrar
can be contacted at the provided `registry_addr`, then a new
one is always created; however, if one can be reached it is
used.
Normally a distributed app requires at least registrar per
logical host where for that given "host space" (aka localhost
IPC domain of addresses) it is responsible for making all other
host (local address) bound actors *discoverable* to external
actor trees running on remote hosts.
'''
is_arbiter = True
def __init__(
self,
*args,
**kwargs,
) -> None:
self._registry: dict[
tuple[str, str],
tuple[str, int],
] = {}
self._waiters: dict[
str,
# either an event to sync to receiving an actor uid (which
# is filled in once the actor has sucessfully registered),
# or that uid after registry is complete.
list[trio.Event | tuple[str, str]]
] = {}
super().__init__(*args, **kwargs)
async def find_actor(
self,
name: str,
) -> tuple[str, int] | None:
for uid, sockaddr in self._registry.items():
if name in uid:
return sockaddr
return None
async def get_registry(
self
) -> dict[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 {
'.'.join(key): val
for key, val in self._registry.items()
}
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: list[tuple[str, int]] = []
sockaddr: tuple[str, int]
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]:
if not isinstance(uid, trio.Event):
sockaddrs.append(self._registry[uid])
return sockaddrs
async def register_actor(
self,
uid: tuple[str, str],
sockaddr: tuple[str, int]
) -> None:
uid = name, hash = (str(uid[0]), str(uid[1]))
addr = (host, port) = (
str(sockaddr[0]),
int(sockaddr[1]),
)
if port == 0:
await _debug.pause()
assert port # should never be 0-dynamic-os-alloc
self._registry[uid] = addr
# 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]))
entry: tuple = self._registry.pop(uid, None)
if entry is None:
log.warning(f'Request to de-register {uid} failed?')