Start a very basic ipc-server unit test suite

For now it just boots a server, parametrized over all tpt-protos, sin
any actor runtime bootup. Obvi the future todo is ensuring it all works
with a client connecting via the equivalent lowlevel
`.ipc._chan._connect_chan()` API(s).

tests/conftest.py

@@ -138,11 +138,19 @@ def tpt_protos(request) -> list[str]:
     yield proto_keys
 
 
-@pytest.fixture(scope='session')
+@pytest.fixture(
+    scope='session',
+    autouse=True,
+)
 def tpt_proto(
     tpt_protos: list[str],
 ) -> str:
-    yield tpt_protos[0]
+    proto_key: str = tpt_protos[0]
+    from tractor import _state
+    if _state._def_tpt_proto != proto_key:
+        _state._def_tpt_proto = proto_key
+    # breakpoint()
+    yield proto_key
 
 
 _ci_env: bool = os.environ.get('CI', False)

tests/ipc/__init__.py

@@ -0,0 +1,4 @@
+'''
+`tractor.ipc` subsystem(s)/unit testing suites.
+
+'''

tests/ipc/test_server.py

@@ -0,0 +1,72 @@
+'''
+High-level `.ipc._server` unit tests.
+
+'''
+from __future__ import annotations
+
+import pytest
+import trio
+from tractor import (
+    devx,
+    ipc,
+    log,
+)
+from tractor._testing.addr import (
+    get_rando_addr,
+)
+# TODO, use/check-roundtripping with some of these wrapper types?
+#
+# from .._addr import Address
+# from ._chan import Channel
+# from ._transport import MsgTransport
+# from ._uds import UDSAddress
+# from ._tcp import TCPAddress
+
+
+@pytest.mark.parametrize(
+    '_tpt_proto',
+    ['uds', 'tcp']
+)
+def test_basic_ipc_server(
+    _tpt_proto: str,
+    debug_mode: bool,
+    loglevel: str,
+):
+
+    # so we see the socket-listener reporting on console
+    log.get_console_log("INFO")
+
+    rando_addr: tuple = get_rando_addr(
+        tpt_proto=_tpt_proto,
+    )
+    async def main():
+        async with ipc._server.open_ipc_server() as server:
+
+            assert (
+                server._parent_tn
+                and
+                server._parent_tn is server._stream_handler_tn
+            )
+            assert server._no_more_peers.is_set()
+
+            eps: list[ipc.IPCEndpoint] = await server.listen_on(
+                accept_addrs=[rando_addr],
+                stream_handler_nursery=None,
+            )
+            assert (
+                len(eps) == 1
+                and
+                (ep := eps[0])._listener
+                and
+                not ep.peer_tpts
+            )
+
+            server._parent_tn.cancel_scope.cancel()
+
+        # !TODO! actually make a bg-task connection from a client
+        # using `ipc._chan._connect_chan()`
+
+    with devx.maybe_open_crash_handler(
+        pdb=debug_mode,
+    ):
+        trio.run(main)

tests/test_resource_cache.py

@@ -100,16 +100,29 @@ async def streamer(
 @acm
 async def open_stream() -> Awaitable[tractor.MsgStream]:
 
-    async with tractor.open_nursery() as tn:
+    try:
-        portal = await tn.start_actor('streamer', enable_modules=[__name__])
+        async with tractor.open_nursery() as an:
+            portal = await an.start_actor(
+                'streamer',
+                enable_modules=[__name__],
+            )
             async with (
                 portal.open_context(streamer) as (ctx, first),
                 ctx.open_stream() as stream,
             ):
                 yield stream
 
+            print('Cancelling streamer')
             await portal.cancel_actor()
-    print('CANCELLED STREAMER')
+            print('Cancelled streamer')
+
+    except Exception as err:
+        print(
+            f'`open_stream()` errored?\n'
+            f'{err!r}\n'
+        )
+        await tractor.pause(shield=True)
+        raise err
 
 
 @acm
@@ -132,19 +145,28 @@ async def maybe_open_stream(taskname: str):
             yield stream
 
 
-def test_open_local_sub_to_stream():
+def test_open_local_sub_to_stream(
+    debug_mode: bool,
+):
     '''
     Verify a single inter-actor stream can can be fanned-out shared to
-    N local tasks using ``trionics.maybe_open_context():``.
+    N local tasks using `trionics.maybe_open_context()`.
 
     '''
-    timeout: float = 3.6 if platform.system() != "Windows" else 10
+    timeout: float = 3.6
+    if platform.system() == "Windows":
+        timeout: float = 10
+
+    if debug_mode:
+        timeout = 999
 
     async def main():
 
         full = list(range(1000))
 
         async def get_sub_and_pull(taskname: str):
+
+            stream: tractor.MsgStream
             async with (
                 maybe_open_stream(taskname) as stream,
             ):
@@ -165,17 +187,27 @@ def test_open_local_sub_to_stream():
                 assert set(seq).issubset(set(full))
             print(f'{taskname} finished')
 
-        with trio.fail_after(timeout):
+        with trio.fail_after(timeout) as cs:
             # TODO: turns out this isn't multi-task entrant XD
             # We probably need an indepotent entry semantic?
-            async with tractor.open_root_actor():
+            async with tractor.open_root_actor(
+                debug_mode=debug_mode,
+            ):
                 async with (
-                    trio.open_nursery() as nurse,
+                    trio.open_nursery() as tn,
                 ):
                     for i in range(10):
-                        nurse.start_soon(get_sub_and_pull, f'task_{i}')
+                        tn.start_soon(
+                            get_sub_and_pull,
+                            f'task_{i}',
+                        )
                         await trio.sleep(0.001)
 
                 print('all consumer tasks finished')
 
+        if cs.cancelled_caught:
+            pytest.fail(
+                'Should NOT time out in `open_root_actor()` ?'
+            )
+
     trio.run(main)

tests/test_spawning.py

@@ -57,7 +57,11 @@ async def spawn(
             )
 
             assert len(an._children) == 1
-            assert portal.channel.uid in tractor.current_actor()._peers
+            assert (
+                portal.channel.uid
+                in
+                tractor.current_actor().ipc_server._peers
+            )
 
             # get result from child subactor
             result = await portal.result()

tests/test_trioisms.py

@@ -180,6 +180,7 @@ def test_acm_embedded_nursery_propagates_enter_err(
         with tractor.devx.maybe_open_crash_handler(
             pdb=debug_mode,
         ) as bxerr:
+            if bxerr:
                 assert not bxerr.value
 
             async with (

tractor/_discovery.py

@@ -48,6 +48,7 @@ from ._state import (
 
 if TYPE_CHECKING:
     from ._runtime import Actor
+    from .ipc._server import IPCServer
 
 
 log = get_logger(__name__)
@@ -79,7 +80,7 @@ async def get_registry(
         )
     else:
         # TODO: try to look pre-existing connection from
-        # `Actor._peers` and use it instead?
+        # `IPCServer._peers` and use it instead?
         async with (
             _connect_chan(addr) as chan,
             open_portal(chan) as regstr_ptl,
@@ -111,7 +112,7 @@ def get_peer_by_name(
 ) -> list[Channel]|None:  # at least 1
     '''
     Scan for an existing connection (set) to a named actor
-    and return any channels from `Actor._peers`.
+    and return any channels from `IPCServer._peers: dict`.
 
     This is an optimization method over querying the registrar for
     the same info.

tractor/_portal.py

@@ -578,12 +578,11 @@ async def open_portal(
 
         msg_loop_cs: trio.CancelScope|None = None
         if start_msg_loop:
-            from ._runtime import process_messages
+            from . import _rpc
             msg_loop_cs = await tn.start(
                 partial(
-                    process_messages,
+                    _rpc.process_messages,
-                    actor,
+                    chan=channel,
-                    channel,
                     # if the local task is cancelled we want to keep
                     # the msg loop running until our block ends
                     shield=True,

tractor/_rpc.py

@@ -869,7 +869,6 @@ async def try_ship_error_to_remote(
 
 
 async def process_messages(
-    actor: Actor,
     chan: Channel,
     shield: bool = False,
     task_status: TaskStatus[CancelScope] = trio.TASK_STATUS_IGNORED,
@@ -907,6 +906,7 @@ async def process_messages(
       (as utilized inside `Portal.cancel_actor()` ).
 
     '''
+    actor: Actor = _state.current_actor()
     assert actor._service_n  # runtime state sanity
 
     # TODO: once `trio` get's an "obvious way" for req/resp we

tractor/_runtime.py

@@ -40,9 +40,7 @@ from __future__ import annotations
 from contextlib import (
     ExitStack,
 )
-from collections import defaultdict
 from functools import partial
-from itertools import chain
 import importlib
 import importlib.util
 import os
@@ -76,6 +74,7 @@ from tractor.msg import (
 )
 from .ipc import (
     Channel,
+    # IPCServer,  # causes cycles atm..
     _server,
 )
 from ._addr import (
@@ -96,18 +95,13 @@ from ._exceptions import (
     ModuleNotExposed,
     MsgTypeError,
     unpack_error,
-    TransportClosed,
 )
 from .devx import _debug
 from ._discovery import get_registry
 from ._portal import Portal
 from . import _state
 from . import _mp_fixup_main
-from ._rpc import (
+from . import _rpc
-    process_messages,
-    try_ship_error_to_remote,
-)
-
 
 if TYPE_CHECKING:
     from ._supervise import ActorNursery
@@ -161,7 +155,6 @@ class Actor:
     _root_n: Nursery|None = None
     _service_n: Nursery|None = None
 
-    # XXX moving to IPCServer!
     _ipc_server: _server.IPCServer|None = None
 
     @property
@@ -251,14 +244,6 @@ class Actor:
         # by the user (currently called the "arbiter")
         self._spawn_method: str = spawn_method
 
-        self._peers: defaultdict[
-            str,  # uaid
-            list[Channel],  # IPC conns from peer
-        ] = defaultdict(list)
-        self._peer_connected: dict[tuple[str, str], trio.Event] = {}
-        self._no_more_peers = trio.Event()
-        self._no_more_peers.set()
-
         # RPC state
         self._ongoing_rpc_tasks = trio.Event()
         self._ongoing_rpc_tasks.set()
@@ -343,7 +328,12 @@ class Actor:
         parent_uid: tuple|None = None
         if rent_chan := self._parent_chan:
             parent_uid = rent_chan.uid
-        peers: list[tuple] = list(self._peer_connected)
+
+        peers: list = []
+        server: _server.IPCServer = self.ipc_server
+        if server:
+            peers: list[tuple] = list(server._peer_connected)
+
         fmtstr: str = (
             f' |_id: {self.aid!r}\n'
             # f"   aid{ds}{self.aid!r}\n"
@@ -399,25 +389,6 @@ class Actor:
 
         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 sub-)actor with
-        a `uid` using a `trio.Event` for sync.
-
-        '''
-        log.debug(f'Waiting for peer {uid!r} to connect')
-        event = self._peer_connected.setdefault(uid, trio.Event())
-        await event.wait()
-        log.debug(f'{uid!r} successfully connected back to us')
-        return (
-            event,
-            self._peers[uid][-1],
-        )
-
     def load_modules(
         self,
         # debug_mode: bool = False,
@@ -493,434 +464,6 @@ class Actor:
 
             raise mne
 
-    # TODO: maybe change to mod-func and rename for implied
-    # multi-transport semantics?
-    async def _stream_handler(
-        self,
-        stream: trio.SocketStream,
-
-    ) -> None:
-        '''
-        Entry point for new inbound IPC connections on a specific
-        transport server.
-
-        '''
-        self._no_more_peers = trio.Event()  # unset by making new
-        # with _debug.maybe_open_crash_handler(
-        #     pdb=True,
-        # ) as boxerr:
-        chan = Channel.from_stream(stream)
-        con_status: str = (
-            'New inbound IPC connection <=\n'
-            f'|_{chan}\n'
-        )
-
-        # send/receive initial handshake response
-        try:
-            peer_aid: msgtypes.Aid = await chan._do_handshake(
-                aid=self.aid,
-            )
-        except (
-            TransportClosed,
-            # ^XXX NOTE, the above wraps `trio` exc types raised
-            # during various `SocketStream.send/receive_xx()` calls
-            # under different fault conditions such as,
-            #
-            # trio.BrokenResourceError,
-            # trio.ClosedResourceError,
-            #
-            # Inside our `.ipc._transport` layer we absorb and
-            # re-raise our own `TransportClosed` exc such that this
-            # higher level runtime code can only worry one
-            # "kinda-error" that we expect to tolerate during
-            # discovery-sys related pings, queires, DoS etc.
-        ):
-            # 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.runtime(
-                con_status
-                +
-                ' -> But failed to handshake? Ignoring..\n'
-            )
-            return
-
-        uid: tuple[str, str] = (
-            peer_aid.name,
-            peer_aid.uuid,
-        )
-        # TODO, can we make this downstream peer tracking use the
-        # `peer_aid` instead?
-        familiar: str = 'new-peer'
-        if _pre_chan := self._peers.get(uid):
-            familiar: str = 'pre-existing-peer'
-        uid_short: str = f'{uid[0]}[{uid[1][-6:]}]'
-        con_status += (
-            f' -> Handshake with {familiar} `{uid_short}` complete\n'
-        )
-
-        if _pre_chan:
-            # con_status += (
-            # ^TODO^ swap once we minimize conn duplication
-            # -[ ] last thing might be reg/unreg runtime reqs?
-            # log.warning(
-            log.debug(
-                f'?Wait?\n'
-                f'We already have IPC with peer {uid_short!r}\n'
-                f'|_{_pre_chan}\n'
-            )
-
-        # IPC connection tracking for both peers and new children:
-        # - if this is a new channel to a locally spawned
-        #   sub-actor there will be a spawn wait even registered
-        #   by a call to `.wait_for_peer()`.
-        # - if a peer is connecting no such event will exit.
-        event: trio.Event|None = self._peer_connected.pop(
-            uid,
-            None,
-        )
-        if event:
-            con_status += (
-                ' -> Waking subactor spawn waiters: '
-                f'{event.statistics().tasks_waiting}\n'
-                f' -> Registered IPC chan for child actor {uid}@{chan.raddr}\n'
-                # f'    {event}\n'
-                # f'    |{event.statistics()}\n'
-            )
-            # wake tasks waiting on this IPC-transport "connect-back"
-            event.set()
-
-        else:
-            con_status += (
-                f' -> Registered IPC chan for peer actor {uid}@{chan.raddr}\n'
-            )  # type: ignore
-
-        chans: list[Channel] = self._peers[uid]
-        # if chans:
-        #     # TODO: re-use channels for new connections instead
-        #     # of always new ones?
-        #     # => will require changing all the discovery funcs..
-
-        # append new channel
-        # TODO: can we just use list-ref directly?
-        chans.append(chan)
-
-        con_status += ' -> Entering RPC msg loop..\n'
-        log.runtime(con_status)
-
-        # Begin channel management - respond to remote requests and
-        # process received reponses.
-        disconnected: bool = False
-        last_msg: MsgType
-        try:
-            (
-                disconnected,
-                last_msg,
-            ) = await process_messages(
-                self,
-                chan,
-            )
-        except trio.Cancelled:
-            log.cancel(
-                'IPC transport msg loop was cancelled\n'
-                f'c)>\n'
-                f' |_{chan}\n'
-            )
-            raise
-
-        finally:
-            local_nursery: (
-                ActorNursery|None
-            ) = self._actoruid2nursery.get(uid)
-
-            # 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
-                and (
-                    self._cancel_called
-                    or
-                    chan._cancel_called
-                )
-                #
-                # ^-TODO-^ along with this is there another condition
-                # that we should filter with to avoid entering this
-                # waiting block needlessly?
-                # -[ ] maybe `and local_nursery.cancelled` and/or
-                #     only if the `._children` table is empty or has
-                #     only `Portal`s with .chan._cancel_called ==
-                #     True` as per what we had below; the MAIN DIFF
-                #     BEING that just bc one `Portal.cancel_actor()`
-                #     was called, doesn't mean the whole actor-nurse
-                #     is gonna exit any time soon right!?
-                #
-                # or
-                # all(chan._cancel_called for chan in chans)
-
-            ):
-                log.cancel(
-                    'Waiting on cancel request to peer..\n'
-                    f'c)=>\n'
-                    f'  |_{chan.uid}\n'
-                )
-
-                # 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 local actor-nursery) has a message that is sent
-                # to the peer likely by this actor (which may be in
-                # a shutdown sequence due to cancellation) when the
-                # local runtime here is now cancelled while
-                # (presumably) in the middle of msg loop processing.
-                chan_info: str = (
-                    f'{chan.uid}\n'
-                    f'|_{chan}\n'
-                    f'  |_{chan.transport}\n\n'
-                )
-                with trio.move_on_after(0.5) as drain_cs:
-                    drain_cs.shield = True
-
-                    # attempt to wait for the far end to close the
-                    # channel and bail after timeout (a 2-generals
-                    # problem on closure).
-                    assert chan.transport
-                    async for msg in chan.transport.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.warning(
-                            'Draining msg from disconnected peer\n'
-                            f'{chan_info}'
-                            f'{pformat(msg)}\n'
-                        )
-                        # cid: str|None = msg.get('cid')
-                        cid: str|None = msg.cid
-                        if cid:
-                            # deliver response to local caller/waiter
-                            await self._deliver_ctx_payload(
-                                chan,
-                                cid,
-                                msg,
-                            )
-                if drain_cs.cancelled_caught:
-                    log.warning(
-                        'Timed out waiting on IPC transport channel to drain?\n'
-                        f'{chan_info}'
-                    )
-
-                # XXX NOTE XXX when no explicit call to
-                # `open_root_actor()` was made by the application
-                # (normally we implicitly make that call inside
-                # the first `.open_nursery()` in root-actor
-                # user/app code), we can assume that either we
-                # are NOT the root actor or are root but the
-                # runtime was started manually. and thus DO have
-                # to wait for the nursery-enterer to exit before
-                # shutting down the local runtime to avoid
-                # clobbering any ongoing subactor
-                # teardown/debugging/graceful-cancel.
-                #
-                # see matching  note inside `._supervise.open_nursery()`
-                #
-                # TODO: should we have a separate cs + timeout
-                # block here?
-                if (
-                    # XXX SO either,
-                    #  - not root OR,
-                    #  - is root but `open_root_actor()` was
-                    #    entered manually (in which case we do
-                    #    the equiv wait there using the
-                    #    `devx._debug` sub-sys APIs).
-                    not local_nursery._implicit_runtime_started
-                ):
-                    log.runtime(
-                        'Waiting on local actor nursery to exit..\n'
-                        f'|_{local_nursery}\n'
-                    )
-                    with trio.move_on_after(0.5) as an_exit_cs:
-                        an_exit_cs.shield = True
-                        await local_nursery.exited.wait()
-
-                    # TODO: currently this is always triggering for every
-                    # sub-daemon spawned from the `piker.services._mngr`?
-                    # -[ ] how do we ensure that the IPC is supposed to
-                    #      be long lived and isn't just a register?
-                    # |_ in the register case how can we signal that the
-                    #    ephemeral msg loop was intentional?
-                    if (
-                        # not local_nursery._implicit_runtime_started
-                        # and
-                        an_exit_cs.cancelled_caught
-                    ):
-                        report: str = (
-                            'Timed out waiting on local actor-nursery to exit?\n'
-                            f'c)>\n'
-                            f' |_{local_nursery}\n'
-                        )
-                        if children := local_nursery._children:
-                            # indent from above local-nurse repr
-                            report += (
-                                f'   |_{pformat(children)}\n'
-                            )
-
-                        log.warning(report)
-
-                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: tuple|None = local_nursery._children.get(uid)
-                    if entry:
-                        proc: trio.Process
-                        _, proc, _ = entry
-
-                        if (
-                            (poll := getattr(proc, 'poll', None))
-                            and
-                            poll() is None  # proc still alive
-                        ):
-                            # TODO: change log level based on
-                            # detecting whether chan was created for
-                            # ephemeral `.register_actor()` request!
-                            # -[ ] also, that should be avoidable by
-                            #   re-using any existing chan from the
-                            #   `._discovery.get_registry()` call as
-                            #   well..
-                            log.runtime(
-                                f'Peer IPC broke but subproc is alive?\n\n'
-
-                                f'<=x {chan.uid}@{chan.raddr}\n'
-                                f'   |_{proc}\n'
-                            )
-
-            # ``Channel`` teardown and closure sequence
-            # drop ref to channel so it can be gc-ed and disconnected
-            con_teardown_status: str = (
-                f'IPC channel disconnected:\n'
-                f'<=x uid: {chan.uid}\n'
-                f'   |_{pformat(chan)}\n\n'
-            )
-            chans.remove(chan)
-
-            # TODO: do we need to be this pedantic?
-            if not chans:
-                con_teardown_status += (
-                    f'-> No more channels with {chan.uid}'
-                )
-                self._peers.pop(uid, None)
-
-            peers_str: str = ''
-            for uid, chans in self._peers.items():
-                peers_str += (
-                    f'uid: {uid}\n'
-                )
-                for i, chan in enumerate(chans):
-                    peers_str += (
-                        f' |_[{i}] {pformat(chan)}\n'
-                    )
-
-            con_teardown_status += (
-                f'-> Remaining IPC {len(self._peers)} peers: {peers_str}\n'
-            )
-
-            # No more channels to other actors (at all) registered
-            # as connected.
-            if not self._peers:
-                con_teardown_status += (
-                    '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)
-
-                    # TODO: NEEEDS TO BE TESTED!
-                    # actually, no idea if this ever even enters.. XD
-                    #
-                    # XXX => YES IT DOES, when i was testing ctl-c
-                    # from broken debug TTY locking due to
-                    # msg-spec races on application using RunVar...
-                    if (
-                        (ctx_in_debug := pdb_lock.ctx_in_debug)
-                        and
-                        (pdb_user_uid := ctx_in_debug.chan.uid)
-                        and
-                        local_nursery
-                    ):
-                        entry: tuple|None = local_nursery._children.get(
-                            tuple(pdb_user_uid)
-                        )
-                        if entry:
-                            proc: trio.Process
-                            _, proc, _ = entry
-
-                            if (
-                                (poll := getattr(proc, 'poll', None))
-                                and poll() is None
-                            ):
-                                log.cancel(
-                                    'Root actor reports no-more-peers, BUT\n'
-                                    'a DISCONNECTED child still has the debug '
-                                    'lock!\n\n'
-                                    # f'root uid: {self.uid}\n'
-                                    f'last disconnected child uid: {uid}\n'
-                                    f'locking child uid: {pdb_user_uid}\n'
-                                )
-                                await _debug.maybe_wait_for_debugger(
-                                    child_in_debug=True
-                                )
-
-                    # TODO: just bc a child's transport dropped
-                    # doesn't mean it's not still using the pdb
-                    # REPL! so,
-                    # -[ ] ideally we can check out child proc
-                    #  tree to ensure that its alive (and
-                    #  actually using the REPL) before we cancel
-                    #  it's lock acquire by doing the below!
-                    # -[ ] create a way to read the tree of each actor's
-                    #  grandchildren such that when an
-                    #  intermediary parent is cancelled but their
-                    #  child has locked the tty, the grandparent
-                    #  will not allow the parent to cancel or
-                    #  zombie reap the child! see open issue:
-                    #  - https://github.com/goodboy/tractor/issues/320
-                    # ------ - ------
-                    # if a now stale local task has the TTY lock still
-                    # we cancel it to allow servicing other requests for
-                    # the lock.
-                    if (
-                        (db_cs := pdb_lock.get_locking_task_cs())
-                        and not db_cs.cancel_called
-                        and uid == pdb_user_uid
-                    ):
-                        log.critical(
-                            f'STALE DEBUG LOCK DETECTED FOR {uid}'
-                        )
-                        # TODO: figure out why this breaks tests..
-                        db_cs.cancel()
-
-            log.runtime(con_teardown_status)
-        # finally block closure
-
     # TODO: rename to `._deliver_payload()` since this handles
     # more then just `result` msgs now obvi XD
     async def _deliver_ctx_payload(
@@ -1157,7 +700,7 @@ class Actor:
             )
             assert isinstance(chan, Channel)
 
-            # Initial handshake: swap names.
+            # init handshake: swap actor-IDs.
             await chan._do_handshake(aid=self.aid)
 
             accept_addrs: list[UnwrappedAddress]|None = None
@@ -1719,6 +1262,10 @@ async def async_main(
     the actor's "runtime" and all thus all ongoing RPC tasks.
 
     '''
+    # XXX NOTE, `_state._current_actor` **must** be set prior to
+    # calling this core runtime entrypoint!
+    assert actor is _state.current_actor()
+
     actor._task: trio.Task = trio.lowlevel.current_task()
 
     # attempt to retreive ``trio``'s sigint handler and stash it
@@ -1778,7 +1325,6 @@ async def async_main(
                 ) as service_nursery,
 
                 _server.open_ipc_server(
-                    actor=actor,
                     parent_tn=service_nursery,
                     stream_handler_tn=service_nursery,
                 ) as ipc_server,
@@ -1832,7 +1378,6 @@ async def async_main(
                         'Booting IPC server'
                     )
                     eps: list = await ipc_server.listen_on(
-                        actor=actor,
                         accept_addrs=accept_addrs,
                         stream_handler_nursery=service_nursery,
                     )
@@ -1916,9 +1461,8 @@ async def async_main(
                 if actor._parent_chan:
                     await root_nursery.start(
                         partial(
-                            process_messages,
+                            _rpc.process_messages,
-                            actor,
+                            chan=actor._parent_chan,
-                            actor._parent_chan,
                             shield=True,
                         )
                     )
@@ -1959,7 +1503,7 @@ async def async_main(
             log.exception(err_report)
 
         if actor._parent_chan:
-            await try_ship_error_to_remote(
+            await _rpc.try_ship_error_to_remote(
                 actor._parent_chan,
                 internal_err,
             )
@@ -2053,16 +1597,18 @@ async def async_main(
                     )
 
         # Ensure all peers (actors connected to us as clients) are finished
-        if not actor._no_more_peers.is_set():
+        if (
-            if any(
+            (ipc_server := actor.ipc_server)
-                chan.connected() for chan in chain(*actor._peers.values())
+            and
+            ipc_server.has_peers(check_chans=True)
         ):
             teardown_report += (
-                    f'-> Waiting for remaining peers {actor._peers} to clear..\n'
+                f'-> Waiting for remaining peers {ipc_server._peers} to clear..\n'
             )
             log.runtime(teardown_report)
-                with CancelScope(shield=True):
+            await ipc_server.wait_for_no_more_peers(
-                    await actor._no_more_peers.wait()
+                shield=True,
+            )
 
         teardown_report += (
             '-> All peer channels are complete\n'

tractor/_spawn.py

@@ -58,9 +58,11 @@ from tractor.msg.types import (
 
 
 if TYPE_CHECKING:
+    from ipc import IPCServer
     from ._supervise import ActorNursery
     ProcessType = TypeVar('ProcessType', mp.Process, trio.Process)
 
+
 log = get_logger('tractor')
 
 # placeholder for an mp start context if so using that backend
@@ -481,6 +483,7 @@ async def trio_proc(
 
     cancelled_during_spawn: bool = False
     proc: trio.Process|None = None
+    ipc_server: IPCServer = actor_nursery._actor.ipc_server
     try:
         try:
             proc: trio.Process = await trio.lowlevel.open_process(spawn_cmd, **proc_kwargs)
@@ -492,7 +495,7 @@ async def trio_proc(
             # wait for actor to spawn and connect back to us
             # channel should have handshake completed by the
             # local actor by the time we get a ref to it
-            event, chan = await actor_nursery._actor.wait_for_peer(
+            event, chan = await ipc_server.wait_for_peer(
                 subactor.uid
             )
 
@@ -724,11 +727,12 @@ async def mp_proc(
 
     log.runtime(f"Started {proc}")
 
+    ipc_server: IPCServer = actor_nursery._actor.ipc_server
     try:
         # wait for actor to spawn and connect back to us
         # channel should have handshake completed by the
         # local actor by the time we get a ref to it
-        event, chan = await actor_nursery._actor.wait_for_peer(
+        event, chan = await ipc_server.wait_for_peer(
             subactor.uid,
         )
 

tractor/_supervise.py

@@ -53,6 +53,9 @@ from . import _spawn
 
 if TYPE_CHECKING:
     import multiprocessing as mp
+    # from .ipc._server import IPCServer
+    from .ipc import IPCServer
+
 
 log = get_logger(__name__)
 
@@ -315,6 +318,9 @@ class ActorNursery:
         children: dict = self._children
         child_count: int = len(children)
         msg: str = f'Cancelling actor nursery with {child_count} children\n'
+
+        server: IPCServer = self._actor.ipc_server
+
         with trio.move_on_after(3) as cs:
             async with trio.open_nursery(
                 strict_exception_groups=False,
@@ -337,7 +343,7 @@ class ActorNursery:
 
                     else:
                         if portal is None:  # actor hasn't fully spawned yet
-                            event = self._actor._peer_connected[subactor.uid]
+                            event: trio.Event = server._peer_connected[subactor.uid]
                             log.warning(
                                 f"{subactor.uid} never 't finished spawning?"
                             )
@@ -353,7 +359,7 @@ class ActorNursery:
                             if portal is None:
                                 # cancelled while waiting on the event
                                 # to arrive
-                                chan = self._actor._peers[subactor.uid][-1]
+                                chan = server._peers[subactor.uid][-1]
                                 if chan:
                                     portal = Portal(chan)
                                 else:  # there's no other choice left

tractor/devx/_debug.py

@@ -92,7 +92,11 @@ from tractor._state import (
 if TYPE_CHECKING:
     from trio.lowlevel import Task
     from threading import Thread
-    from tractor.ipc import Channel
+    from tractor.ipc import (
+        Channel,
+        IPCServer,
+        # _server,  # TODO? export at top level?
+    )
     from tractor._runtime import (
         Actor,
     )
@@ -1434,6 +1438,7 @@ def any_connected_locker_child() -> bool:
 
     '''
     actor: Actor = current_actor()
+    server: IPCServer = actor.ipc_server
 
     if not is_root_process():
         raise InternalError('This is a root-actor only API!')
@@ -1443,7 +1448,7 @@ def any_connected_locker_child() -> bool:
         and
         (uid_in_debug := ctx.chan.uid)
     ):
-        chans: list[tractor.Channel] = actor._peers.get(
+        chans: list[tractor.Channel] = server._peers.get(
             tuple(uid_in_debug)
         )
         if chans:
@@ -3003,6 +3008,7 @@ async def _maybe_enter_pm(
         [BaseException|BaseExceptionGroup],
         bool,
     ] = lambda err: not is_multi_cancelled(err),
+    **_pause_kws,
 
 ):
     if (
@@ -3029,6 +3035,7 @@ async def _maybe_enter_pm(
         await post_mortem(
             api_frame=api_frame,
             tb=tb,
+            **_pause_kws,
         )
         return True
 

tractor/ipc/_chan.py

@@ -49,6 +49,7 @@ from tractor.log import get_logger
 from tractor._exceptions import (
     MsgTypeError,
     pack_from_raise,
+    TransportClosed,
 )
 from tractor.msg import (
     Aid,
@@ -256,7 +257,7 @@ class Channel:
         self,
         payload: Any,
 
-        hide_tb: bool = False,
+        hide_tb: bool = True,
 
     ) -> None:
         '''
@@ -274,18 +275,27 @@ class Channel:
                 payload,
                 hide_tb=hide_tb,
             )
-        except BaseException as _err:
+        except (
+            BaseException,
+            MsgTypeError,
+            TransportClosed,
+        )as _err:
             err = _err  # bind for introspection
-            if not isinstance(_err, MsgTypeError):
+            match err:
-                # assert err
+                case MsgTypeError():
-                __tracebackhide__: bool = False
-            else:
                     try:
                         assert err.cid
-
                     except KeyError:
                         raise err
+                case TransportClosed():
+                    log.transport(
+                        f'Transport stream closed due to\n'
+                        f'{err.repr_src_exc()}\n'
+                    )
 
+                case _:
+                    # never suppress non-tpt sources
+                    __tracebackhide__: bool = False
             raise
 
     async def recv(self) -> Any:

tractor/ipc/_server.py

@@ -19,11 +19,14 @@ multi-transport-protcol needs!
 
 '''
 from __future__ import annotations
+from collections import defaultdict
 from contextlib import (
     asynccontextmanager as acm,
 )
 from functools import partial
+from itertools import chain
 import inspect
+from pprint import pformat
 from types import (
     ModuleType,
 )
@@ -40,24 +43,540 @@ from trio import (
     SocketListener,
 )
 
-from ..msg import Struct
+# from ..devx import _debug
+from .._exceptions import (
+    TransportClosed,
+)
+from .. import _rpc
+from ..msg import (
+    MsgType,
+    Struct,
+    types as msgtypes,
+)
 from ..trionics import maybe_open_nursery
 from .. import (
     _state,
     log,
 )
 from .._addr import Address
+from ._chan import Channel
 from ._transport import MsgTransport
 from ._uds import UDSAddress
 from ._tcp import TCPAddress
 
 if TYPE_CHECKING:
     from .._runtime import Actor
+    from .._supervise import ActorNursery
 
 
 log = log.get_logger(__name__)
 
 
+async def maybe_wait_on_canced_subs(
+    uid: tuple[str, str],
+    chan: Channel,
+    disconnected: bool,
+
+    actor: Actor|None = None,
+    chan_drain_timeout: float = 0.5,
+    an_exit_timeout: float = 0.5,
+
+) -> ActorNursery|None:
+    '''
+    When a process-local actor-nursery is found for the given actor
+    `uid` (i.e. that peer is **also** a subactor of this parent), we
+    attempt to (with timeouts) wait on,
+
+    - all IPC msgs to drain on the (common) `Channel` such that all
+      local `Context`-parent-tasks can also gracefully collect
+      `ContextCancelled` msgs from their respective remote children
+      vs. a `chan_drain_timeout`.
+
+    - the actor-nursery to cancel-n-join all its supervised children
+      (processes) *gracefully* vs. a `an_exit_timeout` and thus also
+      detect cases where the IPC transport connection broke but
+      a sub-process is detected as still alive (a case that happens
+      when the subactor is still in an active debugger REPL session).
+
+    If the timeout expires in either case we ofc report with warning.
+
+    '''
+    actor = actor or _state.current_actor()
+
+    # XXX running outside actor-runtime usage,
+    # - unit testing
+    # - possibly manual usage (eventually) ?
+    if not actor:
+        return None
+
+    local_nursery: (
+        ActorNursery|None
+    ) = actor._actoruid2nursery.get(uid)
+
+    # 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
+        and (
+            actor._cancel_called
+            or
+            chan._cancel_called
+        )
+        #
+        # ^-TODO-^ along with this is there another condition
+        # that we should filter with to avoid entering this
+        # waiting block needlessly?
+        # -[ ] maybe `and local_nursery.cancelled` and/or
+        #     only if the `._children` table is empty or has
+        #     only `Portal`s with .chan._cancel_called ==
+        #     True` as per what we had below; the MAIN DIFF
+        #     BEING that just bc one `Portal.cancel_actor()`
+        #     was called, doesn't mean the whole actor-nurse
+        #     is gonna exit any time soon right!?
+        #
+        # or
+        # all(chan._cancel_called for chan in chans)
+
+    ):
+        log.cancel(
+            'Waiting on cancel request to peer..\n'
+            f'c)=>\n'
+            f'  |_{chan.uid}\n'
+        )
+
+        # 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 local actor-nursery) has a message that is sent
+        # to the peer likely by this actor (which may be in
+        # a shutdown sequence due to cancellation) when the
+        # local runtime here is now cancelled while
+        # (presumably) in the middle of msg loop processing.
+        chan_info: str = (
+            f'{chan.uid}\n'
+            f'|_{chan}\n'
+            f'  |_{chan.transport}\n\n'
+        )
+        with trio.move_on_after(chan_drain_timeout) as drain_cs:
+            drain_cs.shield = True
+
+            # attempt to wait for the far end to close the
+            # channel and bail after timeout (a 2-generals
+            # problem on closure).
+            assert chan.transport
+            async for msg in chan.transport.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.warning(
+                    'Draining msg from disconnected peer\n'
+                    f'{chan_info}'
+                    f'{pformat(msg)}\n'
+                )
+                # cid: str|None = msg.get('cid')
+                cid: str|None = msg.cid
+                if cid:
+                    # deliver response to local caller/waiter
+                    await actor._deliver_ctx_payload(
+                        chan,
+                        cid,
+                        msg,
+                    )
+        if drain_cs.cancelled_caught:
+            log.warning(
+                'Timed out waiting on IPC transport channel to drain?\n'
+                f'{chan_info}'
+            )
+
+        # XXX NOTE XXX when no explicit call to
+        # `open_root_actor()` was made by the application
+        # (normally we implicitly make that call inside
+        # the first `.open_nursery()` in root-actor
+        # user/app code), we can assume that either we
+        # are NOT the root actor or are root but the
+        # runtime was started manually. and thus DO have
+        # to wait for the nursery-enterer to exit before
+        # shutting down the local runtime to avoid
+        # clobbering any ongoing subactor
+        # teardown/debugging/graceful-cancel.
+        #
+        # see matching  note inside `._supervise.open_nursery()`
+        #
+        # TODO: should we have a separate cs + timeout
+        # block here?
+        if (
+            # XXX SO either,
+            #  - not root OR,
+            #  - is root but `open_root_actor()` was
+            #    entered manually (in which case we do
+            #    the equiv wait there using the
+            #    `devx.debug` sub-sys APIs).
+            not local_nursery._implicit_runtime_started
+        ):
+            log.runtime(
+                'Waiting on local actor nursery to exit..\n'
+                f'|_{local_nursery}\n'
+            )
+            with trio.move_on_after(an_exit_timeout) as an_exit_cs:
+                an_exit_cs.shield = True
+                await local_nursery.exited.wait()
+
+            # TODO: currently this is always triggering for every
+            # sub-daemon spawned from the `piker.services._mngr`?
+            # -[ ] how do we ensure that the IPC is supposed to
+            #      be long lived and isn't just a register?
+            # |_ in the register case how can we signal that the
+            #    ephemeral msg loop was intentional?
+            if (
+                # not local_nursery._implicit_runtime_started
+                # and
+                an_exit_cs.cancelled_caught
+            ):
+                report: str = (
+                    'Timed out waiting on local actor-nursery to exit?\n'
+                    f'c)>\n'
+                    f' |_{local_nursery}\n'
+                )
+                if children := local_nursery._children:
+                    # indent from above local-nurse repr
+                    report += (
+                        f'   |_{pformat(children)}\n'
+                    )
+
+                log.warning(report)
+
+        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: tuple|None = local_nursery._children.get(uid)
+            if entry:
+                proc: trio.Process
+                _, proc, _ = entry
+
+                if (
+                    (poll := getattr(proc, 'poll', None))
+                    and
+                    poll() is None  # proc still alive
+                ):
+                    # TODO: change log level based on
+                    # detecting whether chan was created for
+                    # ephemeral `.register_actor()` request!
+                    # -[ ] also, that should be avoidable by
+                    #   re-using any existing chan from the
+                    #   `._discovery.get_registry()` call as
+                    #   well..
+                    log.runtime(
+                        f'Peer IPC broke but subproc is alive?\n\n'
+
+                        f'<=x {chan.uid}@{chan.raddr}\n'
+                        f'   |_{proc}\n'
+                    )
+
+    return local_nursery
+
+# TODO multi-tpt support with per-proto peer tracking?
+#
+# -[x] maybe change to mod-func and rename for implied
+#    multi-transport semantics?
+# -[ ] register each stream/tpt/chan with the owning `IPCEndpoint`
+#     so that we can query per tpt all peer contact infos?
+#  |_[ ] possibly provide a global viewing via a
+#        `collections.ChainMap`?
+#
+async def handle_stream_from_peer(
+    stream: trio.SocketStream,
+
+    *,
+    server: IPCServer,
+
+) -> None:
+    '''
+    Top-level `trio.abc.Stream` (i.e. normally `trio.SocketStream`)
+    handler-callback as spawn-invoked by `trio.serve_listeners()`.
+
+    Note that each call to this handler is as a spawned task inside
+    any `IPCServer.listen_on()` passed `stream_handler_tn: Nursery`
+    such that it is invoked as,
+
+      IPCEndpoint.stream_handler_tn.start_soon(
+          handle_stream,
+          stream,
+      )
+
+    '''
+    server._no_more_peers = trio.Event()  # unset by making new
+
+    # TODO, debug_mode tooling for when hackin this lower layer?
+    # with _debug.maybe_open_crash_handler(
+    #     pdb=True,
+    # ) as boxerr:
+
+    chan = Channel.from_stream(stream)
+    con_status: str = (
+        'New inbound IPC connection <=\n'
+        f'|_{chan}\n'
+    )
+
+    # initial handshake with peer phase
+    try:
+        if actor := _state.current_actor():
+            peer_aid: msgtypes.Aid = await chan._do_handshake(
+                aid=actor.aid,
+            )
+    except (
+        TransportClosed,
+        # ^XXX NOTE, the above wraps `trio` exc types raised
+        # during various `SocketStream.send/receive_xx()` calls
+        # under different fault conditions such as,
+        #
+        # trio.BrokenResourceError,
+        # trio.ClosedResourceError,
+        #
+        # Inside our `.ipc._transport` layer we absorb and
+        # re-raise our own `TransportClosed` exc such that this
+        # higher level runtime code can only worry one
+        # "kinda-error" that we expect to tolerate during
+        # discovery-sys related pings, queires, DoS etc.
+    ):
+        # 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.runtime(
+            con_status
+            +
+            ' -> But failed to handshake? Ignoring..\n'
+        )
+        return
+
+    uid: tuple[str, str] = (
+        peer_aid.name,
+        peer_aid.uuid,
+    )
+    # TODO, can we make this downstream peer tracking use the
+    # `peer_aid` instead?
+    familiar: str = 'new-peer'
+    if _pre_chan := server._peers.get(uid):
+        familiar: str = 'pre-existing-peer'
+    uid_short: str = f'{uid[0]}[{uid[1][-6:]}]'
+    con_status += (
+        f' -> Handshake with {familiar} `{uid_short}` complete\n'
+    )
+
+    if _pre_chan:
+        # con_status += (
+        # ^TODO^ swap once we minimize conn duplication
+        # -[ ] last thing might be reg/unreg runtime reqs?
+        # log.warning(
+        log.debug(
+            f'?Wait?\n'
+            f'We already have IPC with peer {uid_short!r}\n'
+            f'|_{_pre_chan}\n'
+        )
+
+    # IPC connection tracking for both peers and new children:
+    # - if this is a new channel to a locally spawned
+    #   sub-actor there will be a spawn wait even registered
+    #   by a call to `.wait_for_peer()`.
+    # - if a peer is connecting no such event will exit.
+    event: trio.Event|None = server._peer_connected.pop(
+        uid,
+        None,
+    )
+    if event:
+        con_status += (
+            ' -> Waking subactor spawn waiters: '
+            f'{event.statistics().tasks_waiting}\n'
+            f' -> Registered IPC chan for child actor {uid}@{chan.raddr}\n'
+            # f'    {event}\n'
+            # f'    |{event.statistics()}\n'
+        )
+        # wake tasks waiting on this IPC-transport "connect-back"
+        event.set()
+
+    else:
+        con_status += (
+            f' -> Registered IPC chan for peer actor {uid}@{chan.raddr}\n'
+        )  # type: ignore
+
+    chans: list[Channel] = server._peers[uid]
+    # if chans:
+    #     # TODO: re-use channels for new connections instead
+    #     # of always new ones?
+    #     # => will require changing all the discovery funcs..
+
+    # append new channel
+    # TODO: can we just use list-ref directly?
+    chans.append(chan)
+
+    con_status += ' -> Entering RPC msg loop..\n'
+    log.runtime(con_status)
+
+    # Begin channel management - respond to remote requests and
+    # process received reponses.
+    disconnected: bool = False
+    last_msg: MsgType
+    try:
+        (
+            disconnected,
+            last_msg,
+        ) = await _rpc.process_messages(
+            chan=chan,
+        )
+    except trio.Cancelled:
+        log.cancel(
+            'IPC transport msg loop was cancelled\n'
+            f'c)>\n'
+            f' |_{chan}\n'
+        )
+        raise
+
+    finally:
+
+        # check if there are subs which we should gracefully join at
+        # both the inter-actor-task and subprocess levels to
+        # gracefully remote cancel and later disconnect (particularly
+        # for permitting subs engaged in active debug-REPL sessions).
+        local_nursery: ActorNursery|None = await maybe_wait_on_canced_subs(
+            uid=uid,
+            chan=chan,
+            disconnected=disconnected,
+        )
+
+        # ``Channel`` teardown and closure sequence
+        # drop ref to channel so it can be gc-ed and disconnected
+        con_teardown_status: str = (
+            f'IPC channel disconnected:\n'
+            f'<=x uid: {chan.uid}\n'
+            f'   |_{pformat(chan)}\n\n'
+        )
+        chans.remove(chan)
+
+        # TODO: do we need to be this pedantic?
+        if not chans:
+            con_teardown_status += (
+                f'-> No more channels with {chan.uid}'
+            )
+            server._peers.pop(uid, None)
+
+        peers_str: str = ''
+        for uid, chans in server._peers.items():
+            peers_str += (
+                f'uid: {uid}\n'
+            )
+            for i, chan in enumerate(chans):
+                peers_str += (
+                    f' |_[{i}] {pformat(chan)}\n'
+                )
+
+        con_teardown_status += (
+            f'-> Remaining IPC {len(server._peers)} peers: {peers_str}\n'
+        )
+
+        # No more channels to other actors (at all) registered
+        # as connected.
+        if not server._peers:
+            con_teardown_status += (
+                'Signalling no more peer channel connections'
+            )
+            server._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()
+                and
+                _state.is_debug_mode()
+            ):
+                from ..devx import _debug
+                pdb_lock = _debug.Lock
+                pdb_lock._blocked.add(uid)
+
+                # TODO: NEEEDS TO BE TESTED!
+                # actually, no idea if this ever even enters.. XD
+                #
+                # XXX => YES IT DOES, when i was testing ctl-c
+                # from broken debug TTY locking due to
+                # msg-spec races on application using RunVar...
+                if (
+                    local_nursery
+                    and
+                    (ctx_in_debug := pdb_lock.ctx_in_debug)
+                    and
+                    (pdb_user_uid := ctx_in_debug.chan.uid)
+                ):
+                    entry: tuple|None = local_nursery._children.get(
+                        tuple(pdb_user_uid)
+                    )
+                    if entry:
+                        proc: trio.Process
+                        _, proc, _ = entry
+
+                        if (
+                            (poll := getattr(proc, 'poll', None))
+                            and poll() is None
+                        ):
+                            log.cancel(
+                                'Root actor reports no-more-peers, BUT\n'
+                                'a DISCONNECTED child still has the debug '
+                                'lock!\n\n'
+                                # f'root uid: {actor.uid}\n'
+                                f'last disconnected child uid: {uid}\n'
+                                f'locking child uid: {pdb_user_uid}\n'
+                            )
+                            await _debug.maybe_wait_for_debugger(
+                                child_in_debug=True
+                            )
+
+                # TODO: just bc a child's transport dropped
+                # doesn't mean it's not still using the pdb
+                # REPL! so,
+                # -[ ] ideally we can check out child proc
+                #  tree to ensure that its alive (and
+                #  actually using the REPL) before we cancel
+                #  it's lock acquire by doing the below!
+                # -[ ] create a way to read the tree of each actor's
+                #  grandchildren such that when an
+                #  intermediary parent is cancelled but their
+                #  child has locked the tty, the grandparent
+                #  will not allow the parent to cancel or
+                #  zombie reap the child! see open issue:
+                #  - https://github.com/goodboy/tractor/issues/320
+                # ------ - ------
+                # if a now stale local task has the TTY lock still
+                # we cancel it to allow servicing other requests for
+                # the lock.
+                if (
+                    (db_cs := pdb_lock.get_locking_task_cs())
+                    and not db_cs.cancel_called
+                    and uid == pdb_user_uid
+                ):
+                    log.critical(
+                        f'STALE DEBUG LOCK DETECTED FOR {uid}'
+                    )
+                    # TODO: figure out why this breaks tests..
+                    db_cs.cancel()
+
+        log.runtime(con_teardown_status)
+    # finally block closure
+
+
 class IPCEndpoint(Struct):
     '''
     An instance of an IPC "bound" address where the lifetime of the
@@ -120,8 +639,23 @@ class IPCEndpoint(Struct):
 class IPCServer(Struct):
     _parent_tn: Nursery
     _stream_handler_tn: Nursery
+    # level-triggered sig for whether "no peers are currently
+    # connected"; field is **always** set to an instance but
+    # initialized with `.is_set() == True`.
+    _no_more_peers: trio.Event
+
     _endpoints: list[IPCEndpoint] = []
 
+    # connection tracking & mgmt
+    _peers: defaultdict[
+        str,  # uaid
+        list[Channel],  # IPC conns from peer
+    ] = defaultdict(list)
+    _peer_connected: dict[
+        tuple[str, str],
+        trio.Event,
+    ] = {}
+
     # syncs for setup/teardown sequences
     _shutdown: trio.Event|None = None
 
@@ -183,6 +717,65 @@ class IPCServer(Struct):
                 f'protos: {tpt_protos!r}\n'
             )
 
+    def has_peers(
+        self,
+        check_chans: bool = False,
+    ) -> bool:
+        '''
+        Predicate for "are there any active peer IPC `Channel`s at the moment?"
+
+        '''
+        has_peers: bool = not self._no_more_peers.is_set()
+        if (
+            has_peers
+            and
+            check_chans
+        ):
+            has_peers: bool = (
+                any(chan.connected()
+                    for chan in chain(
+                        *self._peers.values()
+                    )
+                )
+                and
+                has_peers
+            )
+
+        return has_peers
+
+    async def wait_for_no_more_peers(
+        self,
+        shield: bool = False,
+    ) -> None:
+        with trio.CancelScope(shield=shield):
+            await self._no_more_peers.wait()
+
+    async def wait_for_peer(
+        self,
+        uid: tuple[str, str],
+
+    ) -> tuple[trio.Event, Channel]:
+        '''
+        Wait for a connection back from a (spawned sub-)actor with
+        a `uid` using a `trio.Event`.
+
+        Returns a pair of the event and the "last" registered IPC
+        `Channel` for the peer with `uid`.
+
+        '''
+        log.debug(f'Waiting for peer {uid!r} to connect')
+        event: trio.Event = self._peer_connected.setdefault(
+            uid,
+            trio.Event(),
+        )
+        await event.wait()
+        log.debug(f'{uid!r} successfully connected back to us')
+        mru_chan: Channel = self._peers[uid][-1]
+        return (
+            event,
+            mru_chan,
+        )
+
     @property
     def addrs(self) -> list[Address]:
         return [ep.addr for ep in self._endpoints]
@@ -211,15 +804,25 @@ class IPCServer(Struct):
         return ev.is_set()
 
     def pformat(self) -> str:
+        eps: list[IPCEndpoint] = self._endpoints
 
-        fmtstr: str = (
+        state_repr: str = (
-            f' |_endpoints: {self._endpoints}\n'
+            f'{len(eps)!r} IPC-endpoints active'
+        )
+        fmtstr = (
+            f' |_state: {state_repr}\n'
+            f'   no_more_peers: {self.has_peers()}\n'
         )
         if self._shutdown is not None:
             shutdown_stats: EventStatistics = self._shutdown.statistics()
             fmtstr += (
-                f'\n'
+                f'   task_waiting_on_shutdown: {shutdown_stats}\n'
-                f' |_shutdown: {shutdown_stats}\n'
+            )
+
+        fmtstr += (
+            # TODO, use the `ppfmt()` helper from `modden`!
+            f' |_endpoints: {pformat(self._endpoints)}\n'
+            f' |_peers: {len(self._peers)} connected\n'
         )
 
         return (
@@ -249,7 +852,6 @@ class IPCServer(Struct):
     async def listen_on(
         self,
         *,
-        actor: Actor,
         accept_addrs: list[tuple[str, int|str]]|None = None,
         stream_handler_nursery: Nursery|None = None,
     ) -> list[IPCEndpoint]:
@@ -282,20 +884,19 @@ class IPCServer(Struct):
                 f'{self}\n'
             )
 
-        log.info(
+        log.runtime(
             f'Binding to endpoints for,\n'
             f'{accept_addrs}\n'
         )
         eps: list[IPCEndpoint] = await self._parent_tn.start(
             partial(
                 _serve_ipc_eps,
-                actor=actor,
                 server=self,
                 stream_handler_tn=stream_handler_nursery,
                 listen_addrs=accept_addrs,
             )
         )
-        log.info(
+        log.runtime(
             f'Started IPC endpoints\n'
             f'{eps}\n'
         )
@@ -318,7 +919,6 @@ class IPCServer(Struct):
 
 async def _serve_ipc_eps(
     *,
-    actor: Actor,
     server: IPCServer,
     stream_handler_tn: Nursery,
     listen_addrs: list[tuple[str, int|str]],
@@ -352,12 +952,13 @@ async def _serve_ipc_eps(
                     stream_handler_tn=stream_handler_tn,
                 )
                 try:
-                    log.info(
+                    log.runtime(
                         f'Starting new endpoint listener\n'
                         f'{ep}\n'
                     )
                     listener: trio.abc.Listener = await ep.start_listener()
                     assert listener is ep._listener
+                    # actor = _state.current_actor()
                     # if actor.is_registry:
                     #     import pdbp; pdbp.set_trace()
 
@@ -379,7 +980,10 @@ async def _serve_ipc_eps(
             _listeners: list[SocketListener] = await listen_tn.start(
                 partial(
                     trio.serve_listeners,
-                    handler=actor._stream_handler,
+                    handler=partial(
+                        handle_stream_from_peer,
+                        server=server,
+                    ),
                     listeners=listeners,
 
                     # NOTE: configured such that new
@@ -389,13 +993,13 @@ async def _serve_ipc_eps(
                 )
             )
             # TODO, wow make this message better! XD
-            log.info(
+            log.runtime(
                 'Started server(s)\n'
                 +
                 '\n'.join([f'|_{addr}' for addr in listen_addrs])
             )
 
-            log.info(
+            log.runtime(
                 f'Started IPC endpoints\n'
                 f'{eps}\n'
             )
@@ -411,6 +1015,7 @@ async def _serve_ipc_eps(
                 ep.close_listener()
                 server._endpoints.remove(ep)
 
+        # actor = _state.current_actor()
         # if actor.is_arbiter:
         #     import pdbp; pdbp.set_trace()
 
@@ -421,7 +1026,6 @@ async def _serve_ipc_eps(
 
 @acm
 async def open_ipc_server(
-    actor: Actor,
     parent_tn: Nursery|None = None,
     stream_handler_tn: Nursery|None = None,
 
@@ -430,20 +1034,28 @@ async def open_ipc_server(
     async with maybe_open_nursery(
         nursery=parent_tn,
     ) as rent_tn:
+        no_more_peers = trio.Event()
+        no_more_peers.set()
+
         ipc_server = IPCServer(
             _parent_tn=rent_tn,
             _stream_handler_tn=stream_handler_tn or rent_tn,
+            _no_more_peers=no_more_peers,
         )
         try:
             yield ipc_server
+            log.runtime(
+                f'Waiting on server to shutdown or be cancelled..\n'
+                f'{ipc_server}'
+            )
+            # TODO? when if ever would we want/need this?
+            # with trio.CancelScope(shield=True):
+            #     await ipc_server.wait_for_shutdown()
 
-        # except BaseException as berr:
+        except BaseException as berr:
-        #     log.exception(
+            log.exception(
-        #         'IPC server crashed on exit ?'
+                'IPC server caller crashed ??'
-        #     )
+            )
-        #     raise berr
-
-        finally:
             # ?TODO, maybe we can ensure the endpoints are torndown
             # (and thus their managed listeners) beforehand to ensure
             # super graceful RPC mechanics?
@@ -451,17 +1063,5 @@ async def open_ipc_server(
             # -[ ] but aren't we doing that already per-`listen_tn`
             #      inside `_serve_ipc_eps()` above?
             #
-            # if not ipc_server.is_shutdown():
             # ipc_server.cancel()
-            #     await ipc_server.wait_for_shutdown()
+            raise berr
-            # assert ipc_server.is_shutdown()
-            pass
-
-            # !XXX TODO! lol so classic, the below code is rekt!
-            #
-            # XXX here is a perfect example of suppressing errors with
-            # `trio.Cancelled` as per our demonstrating example,
-            # `test_trioisms::test_acm_embedded_nursery_propagates_enter_err
-            #
-            # with trio.CancelScope(shield=True):
-            #     await ipc_server.wait_for_shutdown()

tractor/ipc/_tcp.py

@@ -127,6 +127,11 @@ async def start_listener(
     Start a TCP socket listener on the given `TCPAddress`.
 
     '''
+    log.info(
+        f'Attempting to bind TCP socket\n'
+        f'>[\n'
+        f'|_{addr}\n'
+    )
     # ?TODO, maybe we should just change the lower-level call this is
     # using internall per-listener?
     listeners: list[SocketListener] = await open_tcp_listeners(
@@ -140,6 +145,12 @@ async def start_listener(
     assert len(listeners) == 1
     listener = listeners[0]
     host, port = listener.socket.getsockname()[:2]
+
+    log.info(
+        f'Listening on TCP socket\n'
+        f'[>\n'
+        f' |_{addr}\n'
+    )
     return listener