forked from goodboy/tractor
739 lines
27 KiB
Python
739 lines
27 KiB
Python
"""
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Actor primitives and helpers
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"""
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import inspect
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import importlib
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from collections import defaultdict
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from functools import partial
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import traceback
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import uuid
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from itertools import chain
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import trio
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from async_generator import asynccontextmanager, aclosing
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from ._ipc import Channel, _connect_chan
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from .log import get_console_log, get_logger
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from ._portal import (
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Portal,
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open_portal,
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_do_handshake,
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LocalPortal,
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maybe_open_nursery
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)
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from . import _state
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from ._state import current_actor
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log = get_logger('tractor')
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class ActorFailure(Exception):
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"General actor failure"
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class InternalActorError(RuntimeError):
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"Actor primitive internals failure"
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async def _invoke(
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actor, cid, chan, func, kwargs,
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treat_as_gen=False,
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task_status=trio.TASK_STATUS_IGNORED
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):
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"""Invoke local func and return results over provided channel.
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"""
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try:
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is_async_partial = False
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is_async_gen_partial = False
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if isinstance(func, partial):
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is_async_partial = inspect.iscoroutinefunction(func.func)
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is_async_gen_partial = inspect.isasyncgenfunction(func.func)
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if (
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not inspect.iscoroutinefunction(func) and
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not inspect.isasyncgenfunction(func) and
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not is_async_partial and
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not is_async_gen_partial
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):
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await chan.send({'functype': 'function', 'cid': cid})
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with trio.open_cancel_scope() as cs:
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task_status.started(cs)
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await chan.send({'return': func(**kwargs), 'cid': cid})
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else:
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coro = func(**kwargs)
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if inspect.isasyncgen(coro):
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await chan.send({'functype': 'asyncgen', 'cid': cid})
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# XXX: massive gotcha! If the containing scope
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# is cancelled and we execute the below line,
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# any ``ActorNursery.__aexit__()`` WON'T be
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# triggered in the underlying async gen! So we
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# have to properly handle the closing (aclosing)
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# of the async gen in order to be sure the cancel
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# is propagated!
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with trio.open_cancel_scope() as cs:
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task_status.started(cs)
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async with aclosing(coro) as agen:
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async for item in agen:
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# TODO: can we send values back in here?
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# it's gonna require a `while True:` and
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# some non-blocking way to retrieve new `asend()`
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# values from the channel:
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# to_send = await chan.recv_nowait()
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# if to_send is not None:
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# to_yield = await coro.asend(to_send)
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await chan.send({'yield': item, 'cid': cid})
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log.debug(f"Finished iterating {coro}")
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# TODO: we should really support a proper
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# `StopAsyncIteration` system here for returning a final
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# value if desired
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await chan.send({'stop': None, 'cid': cid})
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else:
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if treat_as_gen:
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await chan.send({'functype': 'asyncgen', 'cid': cid})
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# XXX: the async-func may spawn further tasks which push
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# back values like an async-generator would but must
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# manualy construct the response dict-packet-responses as
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# above
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with trio.open_cancel_scope() as cs:
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task_status.started(cs)
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await coro
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else:
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await chan.send({'functype': 'asyncfunction', 'cid': cid})
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with trio.open_cancel_scope() as cs:
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task_status.started(cs)
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await chan.send({'return': await coro, 'cid': cid})
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except Exception:
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# always ship errors back to caller
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log.exception("Actor errored:")
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await chan.send({'error': traceback.format_exc(), 'cid': cid})
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finally:
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# RPC task bookeeping
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tasks = actor._rpc_tasks.get(chan, None)
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if tasks:
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tasks.remove((cs, func))
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if not tasks:
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actor._rpc_tasks.pop(chan, None)
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if not actor._rpc_tasks:
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log.info(f"All RPC tasks have completed")
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actor._no_more_rpc_tasks.set()
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class Actor:
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"""The fundamental concurrency primitive.
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An *actor* is the combination of a regular Python or
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``multiprocessing.Process`` executing a ``trio`` task tree, communicating
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with other actors through "portals" which provide a native async API
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around "channels".
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"""
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is_arbiter = False
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def __init__(
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self,
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name: str,
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rpc_module_paths: [str] = [],
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statespace: dict = {},
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uid: str = None,
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allow_rpc: bool = True,
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loglevel: str = None,
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arbiter_addr: (str, int) = None,
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):
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self.name = name
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self.uid = (name, uid or str(uuid.uuid1()))
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self.rpc_module_paths = rpc_module_paths
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self._mods = {}
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# TODO: consider making this a dynamically defined
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# @dataclass once we get py3.7
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self.statespace = statespace
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self._allow_rpc = allow_rpc
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self.loglevel = loglevel
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self._arb_addr = arbiter_addr
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# filled in by `_async_main` after fork
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self._root_nursery = None
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self._server_nursery = None
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self._peers = defaultdict(list)
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self._peer_connected = {}
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self._no_more_peers = trio.Event()
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self._no_more_peers.set()
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self._no_more_rpc_tasks = trio.Event()
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self._no_more_rpc_tasks.set()
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self._rpc_tasks = {}
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self._actors2calls = {} # map {uids -> {callids -> waiter queues}}
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self._listeners = []
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self._parent_chan = None
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self._accept_host = None
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self._forkserver_info = None
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async def wait_for_peer(self, uid):
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"""Wait for a connection back from a spawned actor with a given
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``uid``.
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"""
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log.debug(f"Waiting for peer {uid} to connect")
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event = self._peer_connected.setdefault(uid, trio.Event())
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await event.wait()
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log.debug(f"{uid} successfully connected back to us")
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return event, self._peers[uid][-1]
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def load_namespaces(self):
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# We load namespaces after fork since this actor may
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# be spawned on a different machine from the original nursery
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# and we need to try and load the local module code (if it
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# exists)
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for path in self.rpc_module_paths:
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self._mods[path] = importlib.import_module(path)
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async def _stream_handler(
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self,
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stream: trio.SocketStream,
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):
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"""Entry point for new inbound connections to the channel server.
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"""
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self._no_more_peers.clear()
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chan = Channel(stream=stream)
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log.info(f"New connection to us {chan}")
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# send/receive initial handshake response
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try:
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uid = await _do_handshake(self, chan)
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except StopAsyncIteration:
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log.warn(f"Channel {chan} failed to handshake")
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return
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# channel tracking
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event = self._peer_connected.pop(uid, None)
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if event:
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# Instructing connection: this is likely a new channel to
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# a recently spawned actor which we'd like to control via
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# async-rpc calls.
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log.debug(f"Waking channel waiters {event.statistics()}")
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# Alert any task waiting on this connection to come up
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event.set()
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chans = self._peers[uid]
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if chans:
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log.warn(
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f"already have channel(s) for {uid}:{chans}?"
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)
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log.debug(f"Registered {chan} for {uid}")
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# append new channel
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self._peers[uid].append(chan)
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# Begin channel management - respond to remote requests and
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# process received reponses.
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try:
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await self._process_messages(chan)
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finally:
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# Drop ref to channel so it can be gc-ed and disconnected
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log.debug(f"Releasing channel {chan} from {chan.uid}")
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chans = self._peers.get(chan.uid)
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chans.remove(chan)
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if not chans:
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log.debug(f"No more channels for {chan.uid}")
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self._peers.pop(chan.uid, None)
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log.debug(f"Peers is {self._peers}")
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if not self._peers: # no more channels connected
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self._no_more_peers.set()
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log.debug(f"Signalling no more peer channels")
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# # XXX: is this necessary (GC should do it?)
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if chan.connected():
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log.debug(f"Disconnecting channel {chan}")
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await chan.send(None)
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await chan.aclose()
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async def _push_result(self, actorid, cid, msg):
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assert actorid, f"`actorid` can't be {actorid}"
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q = self.get_waitq(actorid, cid)
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log.debug(f"Delivering {msg} from {actorid} to caller {cid}")
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# maintain backpressure
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await q.put(msg)
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def get_waitq(self, actorid, cid):
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log.debug(f"Getting result queue for {actorid} cid {cid}")
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cids2qs = self._actors2calls.setdefault(actorid, {})
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return cids2qs.setdefault(cid, trio.Queue(1000))
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async def send_cmd(self, chan, ns, func, kwargs):
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"""Send a ``'cmd'`` message to a remote actor and return a
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caller id and a ``trio.Queue`` that can be used to wait for
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responses delivered by the local message processing loop.
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"""
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cid = str(uuid.uuid1())
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q = self.get_waitq(chan.uid, cid)
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log.debug(f"Sending cmd to {chan.uid}: {ns}.{func}({kwargs})")
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await chan.send({'cmd': (ns, func, kwargs, self.uid, cid)})
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return cid, q
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async def _process_messages(self, chan, treat_as_gen=False):
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"""Process messages async-RPC style.
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Process rpc requests and deliver retrieved responses from channels.
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"""
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# TODO: once https://github.com/python-trio/trio/issues/467 gets
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# worked out we'll likely want to use that!
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log.debug(f"Entering msg loop for {chan} from {chan.uid}")
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try:
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async for msg in chan:
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if msg is None: # terminate sentinel
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log.debug(
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f"Cancelling all tasks for {chan} from {chan.uid}")
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for scope, func in self._rpc_tasks.pop(chan, ()):
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scope.cancel()
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log.debug(
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f"Msg loop signalled to terminate for"
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f" {chan} from {chan.uid}")
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break
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log.debug(f"Received msg {msg} from {chan.uid}")
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cid = msg.get('cid')
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if cid:
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if cid == 'internal': # internal actor error
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raise InternalActorError(
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f"{chan.uid}\n" + msg['error'])
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# deliver response to local caller/waiter
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await self._push_result(chan.uid, cid, msg)
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log.debug(
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f"Waiting on next msg for {chan} from {chan.uid}")
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continue
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# process command request
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ns, funcname, kwargs, actorid, cid = msg['cmd']
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log.debug(
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f"Processing request from {actorid}\n"
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f"{ns}.{funcname}({kwargs})")
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if ns == 'self':
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func = getattr(self, funcname)
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else:
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func = getattr(self._mods[ns], funcname)
|
|
|
|
# spin up a task for the requested function
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|
sig = inspect.signature(func)
|
|
treat_as_gen = False
|
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if 'chan' in sig.parameters:
|
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assert 'cid' in sig.parameters, \
|
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f"{func} must accept a `cid` (caller id) kwarg"
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kwargs['chan'] = chan
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kwargs['cid'] = cid
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# TODO: eventually we want to be more stringent
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# about what is considered a far-end async-generator.
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|
# Right now both actual async gens and any async
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# function which declares a `chan` kwarg in its
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# signature will be treated as one.
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treat_as_gen = True
|
|
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log.debug(f"Spawning task for {func}")
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cs = await self._root_nursery.start(
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_invoke, self, cid, chan, func, kwargs, treat_as_gen,
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name=funcname
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)
|
|
# never allow cancelling cancel requests (results in
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# deadlock and other weird behaviour)
|
|
if func != self.cancel:
|
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self._no_more_rpc_tasks.clear()
|
|
log.info(f"RPC func is {func}")
|
|
self._rpc_tasks.setdefault(chan, []).append((cs, func))
|
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log.debug(
|
|
f"Waiting on next msg for {chan} from {chan.uid}")
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else: # channel disconnect
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|
log.debug(f"{chan} from {chan.uid} disconnected")
|
|
|
|
except InternalActorError:
|
|
# ship internal errors upwards
|
|
if self._parent_chan:
|
|
await self._parent_chan.send(
|
|
{'error': traceback.format_exc(), 'cid': 'internal'})
|
|
raise
|
|
except trio.ClosedResourceError:
|
|
log.error(f"{chan} form {chan.uid} broke")
|
|
except Exception:
|
|
# ship exception (from above code) to peer as an internal error
|
|
await chan.send(
|
|
{'error': traceback.format_exc(), 'cid': 'internal'})
|
|
raise
|
|
finally:
|
|
log.debug(f"Exiting msg loop for {chan} from {chan.uid}")
|
|
|
|
def _fork_main(self, accept_addr, forkserver_info, parent_addr=None):
|
|
# after fork routine which invokes a fresh ``trio.run``
|
|
# log.warn("Log level after fork is {self.loglevel}")
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|
self._forkserver_info = forkserver_info
|
|
from ._trionics import ctx
|
|
if self.loglevel is not None:
|
|
get_console_log(self.loglevel)
|
|
log.info(
|
|
f"Started new {ctx.current_process()} for {self.uid}")
|
|
_state._current_actor = self
|
|
log.debug(f"parent_addr is {parent_addr}")
|
|
try:
|
|
trio.run(partial(
|
|
self._async_main, accept_addr, parent_addr=parent_addr))
|
|
except KeyboardInterrupt:
|
|
pass # handle it the same way trio does?
|
|
log.info(f"Actor {self.uid} terminated")
|
|
|
|
async def _async_main(
|
|
self,
|
|
accept_addr,
|
|
arbiter_addr=None,
|
|
parent_addr=None,
|
|
nursery=None,
|
|
task_status=trio.TASK_STATUS_IGNORED,
|
|
):
|
|
"""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.
|
|
"""
|
|
arbiter_addr = arbiter_addr or self._arb_addr
|
|
registered_with_arbiter = False
|
|
try:
|
|
async with maybe_open_nursery(nursery) as nursery:
|
|
self._root_nursery = nursery
|
|
|
|
# Startup up channel server
|
|
host, port = accept_addr
|
|
await nursery.start(partial(
|
|
self._serve_forever, accept_host=host, accept_port=port)
|
|
)
|
|
|
|
# XXX: I wonder if a better name is maybe "requester"
|
|
# since I don't think the notion of a "parent" actor
|
|
# necessarily sticks given that eventually we want
|
|
# ``'MainProcess'`` (the actor who initially starts the
|
|
# forkserver) to eventually be the only one who is
|
|
# allowed to spawn new processes per Python program.
|
|
if parent_addr is not None:
|
|
try:
|
|
# Connect back to the parent actor and conduct initial
|
|
# handshake (From this point on if we error ship the
|
|
# exception back to the parent actor)
|
|
chan = self._parent_chan = Channel(
|
|
destaddr=parent_addr,
|
|
)
|
|
await chan.connect()
|
|
# initial handshake, report who we are, who they are
|
|
await _do_handshake(self, chan)
|
|
except OSError: # failed to connect
|
|
log.warn(
|
|
f"Failed to connect to parent @ {parent_addr},"
|
|
" closing server")
|
|
await self.cancel()
|
|
self._parent_chan = None
|
|
|
|
# register with the arbiter if we're told its addr
|
|
log.debug(f"Registering {self} for role `{self.name}`")
|
|
async with get_arbiter(*arbiter_addr) as arb_portal:
|
|
await arb_portal.run(
|
|
'self', 'register_actor',
|
|
uid=self.uid, sockaddr=self.accept_addr)
|
|
registered_with_arbiter = True
|
|
|
|
task_status.started()
|
|
# handle new connection back to parent optionally
|
|
# begin responding to RPC
|
|
if self._allow_rpc:
|
|
self.load_namespaces()
|
|
if self._parent_chan:
|
|
nursery.start_soon(
|
|
self._process_messages, self._parent_chan)
|
|
|
|
log.debug("Waiting on root nursery to complete")
|
|
# blocks here as expected if no nursery was provided until
|
|
# the channel server is killed (i.e. this actor is
|
|
# cancelled or signalled by the parent actor)
|
|
except Exception:
|
|
if self._parent_chan:
|
|
try:
|
|
await self._parent_chan.send(
|
|
{'error': traceback.format_exc(), 'cid': 'internal'})
|
|
except trio.ClosedResourceError:
|
|
log.error(
|
|
f"Failed to ship error to parent "
|
|
f"{self._parent_chan.uid}, channel was closed")
|
|
log.exception("Actor errored:")
|
|
|
|
if not registered_with_arbiter:
|
|
log.exception(
|
|
f"Failed to register with arbiter @ {arbiter_addr}")
|
|
else:
|
|
raise
|
|
finally:
|
|
await self._do_unreg(arbiter_addr)
|
|
# terminate actor once all it's peers (actors that connected
|
|
# to it as clients) have disappeared
|
|
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")
|
|
await self._no_more_peers.wait()
|
|
log.debug(f"All peer channels are complete")
|
|
|
|
# tear down channel server no matter what since we errored
|
|
# or completed
|
|
self.cancel_server()
|
|
|
|
async def _serve_forever(
|
|
self,
|
|
*,
|
|
# (host, port) to bind for channel server
|
|
accept_host=None,
|
|
accept_port=0,
|
|
task_status=trio.TASK_STATUS_IGNORED
|
|
):
|
|
"""Start the channel server, begin listening for new connections.
|
|
|
|
This will cause an actor to continue living (blocking) until
|
|
``cancel_server()`` is called.
|
|
"""
|
|
async with trio.open_nursery() as nursery:
|
|
self._server_nursery = nursery
|
|
# TODO: might want to consider having a separate nursery
|
|
# for the stream handler such that the server can be cancelled
|
|
# whilst leaving existing channels up
|
|
listeners = await nursery.start(
|
|
partial(
|
|
trio.serve_tcp,
|
|
self._stream_handler,
|
|
# new connections will stay alive even if this server
|
|
# is cancelled
|
|
handler_nursery=self._root_nursery,
|
|
port=accept_port, host=accept_host,
|
|
)
|
|
)
|
|
log.debug(
|
|
f"Started tcp server(s) on {[l.socket for l in listeners]}")
|
|
self._listeners.extend(listeners)
|
|
task_status.started()
|
|
|
|
async def _do_unreg(self, arbiter_addr):
|
|
# UNregister actor from the arbiter
|
|
try:
|
|
if arbiter_addr is not None:
|
|
async with get_arbiter(*arbiter_addr) as arb_portal:
|
|
await arb_portal.run(
|
|
'self', 'unregister_actor', uid=self.uid)
|
|
except OSError:
|
|
log.warn(f"Unable to unregister {self.name} from arbiter")
|
|
|
|
async def cancel(self):
|
|
"""Cancel this actor.
|
|
|
|
The sequence in order is:
|
|
- cancelling all rpc tasks
|
|
- cancelling the channel server
|
|
- cancel the "root" nursery
|
|
"""
|
|
# cancel all ongoing rpc tasks
|
|
await self.cancel_rpc_tasks()
|
|
self.cancel_server()
|
|
self._root_nursery.cancel_scope.cancel()
|
|
|
|
async def cancel_rpc_tasks(self):
|
|
"""Cancel all existing RPC responder tasks using the cancel scope
|
|
registered for each.
|
|
"""
|
|
scopes = self._rpc_tasks
|
|
log.info(f"Cancelling all {len(scopes)} rpc tasks:\n{scopes}")
|
|
for chan, scopes in scopes.items():
|
|
log.debug(f"Cancelling all tasks for {chan.uid}")
|
|
for scope, func in scopes:
|
|
log.debug(f"Cancelling task for {func}")
|
|
scope.cancel()
|
|
if scopes:
|
|
log.info(
|
|
f"Waiting for remaining rpc tasks to complete {scopes}")
|
|
await self._no_more_rpc_tasks.wait()
|
|
|
|
def cancel_server(self):
|
|
"""Cancel the internal channel server nursery thereby
|
|
preventing any new inbound connections from being established.
|
|
"""
|
|
log.debug("Shutting down channel server")
|
|
self._server_nursery.cancel_scope.cancel()
|
|
|
|
@property
|
|
def accept_addr(self):
|
|
"""Primary address to which the channel server is bound.
|
|
"""
|
|
try:
|
|
return self._listeners[0].socket.getsockname()
|
|
except OSError:
|
|
return
|
|
|
|
def get_parent(self):
|
|
return Portal(self._parent_chan)
|
|
|
|
def get_chans(self, actorid):
|
|
return self._peers[actorid]
|
|
|
|
|
|
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)
|
|
|
|
def find_actor(self, name):
|
|
for uid, sockaddr in self._registry.items():
|
|
if name in uid:
|
|
return sockaddr
|
|
|
|
async def wait_for_actor(self, name):
|
|
"""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
|
|
|
|
def register_actor(self, uid, sockaddr):
|
|
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:
|
|
event.set()
|
|
|
|
def unregister_actor(self, uid):
|
|
self._registry.pop(uid, None)
|
|
|
|
|
|
async def _start_actor(actor, main, host, port, arbiter_addr, nursery=None):
|
|
"""Spawn a local actor by starting a task to execute it's main
|
|
async function.
|
|
|
|
Blocks if no nursery is provided, in which case it is expected the nursery
|
|
provider is responsible for waiting on the task to complete.
|
|
"""
|
|
# assign process-local actor
|
|
_state._current_actor = actor
|
|
|
|
# start local channel-server and fake the portal API
|
|
# NOTE: this won't block since we provide the nursery
|
|
log.info(f"Starting local {actor} @ {host}:{port}")
|
|
|
|
async with trio.open_nursery() as nursery:
|
|
await nursery.start(
|
|
partial(
|
|
actor._async_main,
|
|
accept_addr=(host, port),
|
|
parent_addr=None,
|
|
arbiter_addr=arbiter_addr,
|
|
)
|
|
)
|
|
if main is not None:
|
|
result = await main()
|
|
# XXX: If spawned with a dedicated "main function",
|
|
# the actor is cancelled when this context is complete
|
|
# given that there are no more active peer channels connected
|
|
actor.cancel_server()
|
|
|
|
# block on actor to complete
|
|
|
|
# unset module state
|
|
_state._current_actor = None
|
|
log.info("Completed async main")
|
|
|
|
return result
|
|
|
|
|
|
@asynccontextmanager
|
|
async def get_arbiter(host, port):
|
|
"""Return a portal instance connected to a local or remote
|
|
arbiter.
|
|
"""
|
|
actor = current_actor()
|
|
if not actor:
|
|
raise RuntimeError("No actor instance has been defined yet?")
|
|
|
|
if actor.is_arbiter:
|
|
# we're already the arbiter
|
|
# (likely a re-entrant call from the arbiter actor)
|
|
yield LocalPortal(actor)
|
|
else:
|
|
async with _connect_chan(host, port) as chan:
|
|
async with open_portal(chan) as arb_portal:
|
|
yield arb_portal
|
|
|
|
|
|
@asynccontextmanager
|
|
async def find_actor(
|
|
name,
|
|
arbiter_sockaddr=None,
|
|
):
|
|
"""Ask the arbiter to find actor(s) by name.
|
|
|
|
Returns a connected portal to the last registered matching actor
|
|
known to the arbiter.
|
|
"""
|
|
actor = current_actor()
|
|
async with get_arbiter(*arbiter_sockaddr or actor._arb_addr) as arb_portal:
|
|
sockaddr = await arb_portal.run('self', 'find_actor', name=name)
|
|
# TODO: return portals to all available actors - for now just
|
|
# the last one that registered
|
|
if sockaddr:
|
|
async with _connect_chan(*sockaddr) as chan:
|
|
async with open_portal(chan) as portal:
|
|
yield portal
|
|
else:
|
|
yield None
|
|
|
|
|
|
@asynccontextmanager
|
|
async def wait_for_actor(
|
|
name,
|
|
arbiter_sockaddr=None,
|
|
):
|
|
"""Wait on an actor to register with the arbiter.
|
|
|
|
A portal to the first actor which registered is be returned.
|
|
"""
|
|
actor = current_actor()
|
|
async with get_arbiter(*arbiter_sockaddr or actor._arb_addr) as arb_portal:
|
|
sockaddrs = await arb_portal.run('self', 'wait_for_actor', name=name)
|
|
sockaddr = sockaddrs[-1]
|
|
async with _connect_chan(*sockaddr) as chan:
|
|
async with open_portal(chan) as portal:
|
|
yield portal
|