WIP, "revertible" or "dynamic" multicast streams

TODO, write up the deats, prolly by distilling (todo) notes from
`tests/test_resource_cache.py::test_open_local_sub_to_stream` comments!

examples/advanced_faults/ipc_failure_during_stream.py

@@ -16,6 +16,7 @@ from tractor import (
     ContextCancelled,
     MsgStream,
     _testing,
+    trionics,
 )
 import trio
 import pytest
@@ -62,9 +63,8 @@ async def recv_and_spawn_net_killers(
     await ctx.started()
     async with (
         ctx.open_stream() as stream,
-        trio.open_nursery(
+        trionics.collapse_eg(),
-            strict_exception_groups=False,
+        trio.open_nursery() as tn,
-        ) as tn,
     ):
         async for i in stream:
             print(f'child echoing {i}')

examples/debugging/root_self_cancelled_w_error.py

@@ -0,0 +1,35 @@
+import trio
+import tractor
+
+
+async def main():
+    async with tractor.open_root_actor(
+        debug_mode=True,
+        loglevel='cancel',
+    ) as _root:
+
+        # manually trigger self-cancellation and wait
+        # for it to fully trigger.
+        _root.cancel_soon()
+        await _root._cancel_complete.wait()
+        print('root cancelled')
+
+        # now ensure we can still use the REPL
+        try:
+            await tractor.pause()
+        except trio.Cancelled as _taskc:
+            assert (root_cs := _root._root_tn.cancel_scope).cancel_called
+            # NOTE^^ above logic but inside `open_root_actor()` and
+            # passed to the `shield=` expression is effectively what
+            # we're testing here!
+            await tractor.pause(shield=root_cs.cancel_called)
+
+        # XXX, if shield logic *is wrong* inside `open_root_actor()`'s
+        # crash-handler block this should never be interacted,
+        # instead `trio.Cancelled` would be bubbled up: the original
+        # BUG.
+        assert 0
+
+
+if __name__ == '__main__':
+    trio.run(main)

examples/quick_cluster.py

@@ -23,9 +23,8 @@ async def main():
             modules=[__name__]
         ) as portal_map,
 
-        trio.open_nursery(
+        tractor.trionics.collapse_eg(),
-            strict_exception_groups=False,
+        trio.open_nursery() as tn,
-        ) as tn,
     ):
 
         for (name, portal) in portal_map.items():

tests/devx/test_debugger.py

@@ -1,13 +1,13 @@
 """
 That "native" debug mode better work!
 
-All these tests can be understood (somewhat) by running the equivalent
+All these tests can be understood (somewhat) by running the
-`examples/debugging/` scripts manually.
+equivalent `examples/debugging/` scripts manually.
 
 TODO:
-    - none of these tests have been run successfully on windows yet but
+  - none of these tests have been run successfully on windows yet but
-      there's been manual testing that verified it works.
+    there's been manual testing that verified it works.
-    - wonder if any of it'll work on OS X?
+  - wonder if any of it'll work on OS X?
 
 """
 from __future__ import annotations
@@ -925,6 +925,7 @@ def test_post_mortem_api(
             "<Task 'name_error'",
             "NameError",
             "('child'",
+            'getattr(doggypants)',  # exc-LoC
         ]
     )
     if ctlc:
@@ -941,8 +942,8 @@ def test_post_mortem_api(
             "<Task '__main__.main'",
             "('root'",
             "NameError",
-            "tractor.post_mortem()",
             "src_uid=('child'",
+            "tractor.post_mortem()",  # in `main()`-LoC
         ]
     )
     if ctlc:
@@ -960,6 +961,10 @@ def test_post_mortem_api(
             "('root'",
             "NameError",
             "src_uid=('child'",
+
+            # raising line in `main()` but from crash-handling
+            # in `tractor.open_nursery()`.
+            'async with p.open_context(name_error) as (ctx, first):',
         ]
     )
     if ctlc:
@@ -1151,6 +1156,54 @@ def test_ctxep_pauses_n_maybe_ipc_breaks(
             )
 
 
+def test_crash_handling_within_cancelled_root_actor(
+    spawn: PexpectSpawner,
+):
+    '''
+    Ensure that when only a root-actor is started via `open_root_actor()`
+    we can crash-handle in debug-mode despite self-cancellation.
+
+    More-or-less ensures we conditionally shield the pause in
+    `._root.open_root_actor()`'s `await debug._maybe_enter_pm()`
+    call.
+
+    '''
+    child = spawn('root_self_cancelled_w_error')
+    child.expect(PROMPT)
+
+    assert_before(
+        child,
+        [
+            "Actor.cancel_soon()` was called!",
+            "root cancelled",
+            _pause_msg,
+            "('root'",  # actor name
+        ]
+    )
+
+    child.sendline('c')
+    child.expect(PROMPT)
+    assert_before(
+        child,
+        [
+            _crash_msg,
+            "('root'",  # actor name
+            "AssertionError",
+            "assert 0",
+        ]
+    )
+
+    child.sendline('c')
+    child.expect(EOF)
+    assert_before(
+        child,
+        [
+            "AssertionError",
+            "assert 0",
+        ]
+    )
+
+
 # TODO: better error for "non-ideal" usage from the root actor.
 # -[ ] if called from an async scope emit a message that suggests
 #    using `await tractor.pause()` instead since it's less overhead

tests/ipc/test_each_tpt.py

@@ -0,0 +1,114 @@
+'''
+Unit-ish tests for specific IPC transport protocol backends.
+
+'''
+from __future__ import annotations
+from pathlib import Path
+
+import pytest
+import trio
+import tractor
+from tractor import (
+    Actor,
+    _state,
+    _addr,
+)
+
+
+@pytest.fixture
+def bindspace_dir_str() -> str:
+
+    rt_dir: Path = tractor._state.get_rt_dir()
+    bs_dir: Path = rt_dir / 'doggy'
+    bs_dir_str: str = str(bs_dir)
+    assert not bs_dir.is_dir()
+
+    yield bs_dir_str
+
+    # delete it on suite teardown.
+    # ?TODO? should we support this internally
+    # or is leaking it ok?
+    if bs_dir.is_dir():
+        bs_dir.rmdir()
+
+
+def test_uds_bindspace_created_implicitly(
+    debug_mode: bool,
+    bindspace_dir_str: str,
+):
+    registry_addr: tuple = (
+        f'{bindspace_dir_str}',
+        'registry@doggy.sock',
+    )
+    bs_dir_str: str = registry_addr[0]
+
+    # XXX, ensure bindspace-dir DNE beforehand!
+    assert not Path(bs_dir_str).is_dir()
+
+    async def main():
+        async with tractor.open_nursery(
+            enable_transports=['uds'],
+            registry_addrs=[registry_addr],
+            debug_mode=debug_mode,
+        ) as _an:
+
+            # XXX MUST be created implicitly by
+            # `.ipc._uds.start_listener()`!
+            assert Path(bs_dir_str).is_dir()
+
+            root: Actor = tractor.current_actor()
+            assert root.is_registrar
+
+            assert registry_addr in root.reg_addrs
+            assert (
+                registry_addr
+                in
+                _state._runtime_vars['_registry_addrs']
+            )
+            assert (
+                _addr.wrap_address(registry_addr)
+                in
+                root.registry_addrs
+            )
+
+    trio.run(main)
+
+
+def test_uds_double_listen_raises_connerr(
+    debug_mode: bool,
+    bindspace_dir_str: str,
+):
+    registry_addr: tuple = (
+        f'{bindspace_dir_str}',
+        'registry@doggy.sock',
+    )
+
+    async def main():
+        async with tractor.open_nursery(
+            enable_transports=['uds'],
+            registry_addrs=[registry_addr],
+            debug_mode=debug_mode,
+        ) as _an:
+
+            # runtime up
+            root: Actor = tractor.current_actor()
+
+            from tractor.ipc._uds import (
+                start_listener,
+                UDSAddress,
+            )
+            ya_bound_addr: UDSAddress = root.registry_addrs[0]
+            try:
+                await start_listener(
+                    addr=ya_bound_addr,
+                )
+            except ConnectionError as connerr:
+                assert type(src_exc := connerr.__context__) is OSError
+                assert 'Address already in use' in src_exc.args
+                # complete, exit test.
+
+            else:
+                pytest.fail('It dint raise a connerr !?')
+
+
+    trio.run(main)

tests/test_advanced_streaming.py

@@ -313,9 +313,8 @@ async def inf_streamer(
         # `trio.EndOfChannel` doesn't propagate directly to the above
         # .open_stream() parent, resulting in it also raising instead
         # of gracefully absorbing as normal.. so how to handle?
-        trio.open_nursery(
+        tractor.trionics.collapse_eg(),
-            strict_exception_groups=False,
+        trio.open_nursery() as tn,
-        ) as tn,
     ):
         async def close_stream_on_sentinel():
             async for msg in stream:

tests/test_cancellation.py

@@ -236,7 +236,10 @@ async def stream_forever():
 async def test_cancel_infinite_streamer(start_method):
 
     # stream for at most 1 seconds
-    with trio.move_on_after(1) as cancel_scope:
+    with (
+        trio.fail_after(4),
+        trio.move_on_after(1) as cancel_scope
+    ):
         async with tractor.open_nursery() as n:
             portal = await n.start_actor(
                 'donny',
@@ -284,20 +287,32 @@ async def test_cancel_infinite_streamer(start_method):
     ],
 )
 @tractor_test
-async def test_some_cancels_all(num_actors_and_errs, start_method, loglevel):
+async def test_some_cancels_all(
-    """Verify a subset of failed subactors causes all others in
+    num_actors_and_errs: tuple,
+    start_method: str,
+    loglevel: str,
+):
+    '''
+    Verify a subset of failed subactors causes all others in
     the nursery to be cancelled just like the strategy in trio.
 
     This is the first and only supervisory strategy at the moment.
-    """
+
-    num_actors, first_err, err_type, ria_func, da_func = num_actors_and_errs
+    '''
+    (
+        num_actors,
+        first_err,
+        err_type,
+        ria_func,
+        da_func,
+    ) = num_actors_and_errs
     try:
-        async with tractor.open_nursery() as n:
+        async with tractor.open_nursery() as an:
 
             # spawn the same number of deamon actors which should be cancelled
             dactor_portals = []
             for i in range(num_actors):
-                dactor_portals.append(await n.start_actor(
+                dactor_portals.append(await an.start_actor(
                     f'deamon_{i}',
                     enable_modules=[__name__],
                 ))
@@ -307,7 +322,7 @@ async def test_some_cancels_all(num_actors_and_errs, start_method, loglevel):
             for i in range(num_actors):
                 # start actor(s) that will fail immediately
                 riactor_portals.append(
-                    await n.run_in_actor(
+                    await an.run_in_actor(
                         func,
                         name=f'actor_{i}',
                         **kwargs
@@ -337,7 +352,8 @@ async def test_some_cancels_all(num_actors_and_errs, start_method, loglevel):
 
         # should error here with a ``RemoteActorError`` or ``MultiError``
 
-    except first_err as err:
+    except first_err as _err:
+        err = _err
         if isinstance(err, BaseExceptionGroup):
             assert len(err.exceptions) == num_actors
             for exc in err.exceptions:
@@ -348,8 +364,8 @@ async def test_some_cancels_all(num_actors_and_errs, start_method, loglevel):
         elif isinstance(err, tractor.RemoteActorError):
             assert err.boxed_type == err_type
 
-        assert n.cancelled is True
+        assert an.cancelled is True
-        assert not n._children
+        assert not an._children
     else:
         pytest.fail("Should have gotten a remote assertion error?")
 
@@ -519,10 +535,15 @@ def test_cancel_via_SIGINT_other_task(
     async def main():
         # should never timeout since SIGINT should cancel the current program
         with trio.fail_after(timeout):
-            async with trio.open_nursery(
+            async with (
-                strict_exception_groups=False,
+
-            ) as n:
+                # XXX ?TODO? why no work!?
-                await n.start(spawn_and_sleep_forever)
+                # tractor.trionics.collapse_eg(),
+                trio.open_nursery(
+                    strict_exception_groups=False,
+                ) as tn,
+            ):
+                await tn.start(spawn_and_sleep_forever)
                 if 'mp' in spawn_backend:
                     time.sleep(0.1)
                 os.kill(pid, signal.SIGINT)
@@ -533,38 +554,123 @@ def test_cancel_via_SIGINT_other_task(
 
 async def spin_for(period=3):
     "Sync sleep."
+    print(f'sync sleeping in sub-sub for {period}\n')
     time.sleep(period)
 
 
-async def spawn():
+async def spawn_sub_with_sync_blocking_task():
-    async with tractor.open_nursery() as tn:
+    async with tractor.open_nursery() as an:
-        await tn.run_in_actor(
+        print('starting sync blocking subactor..\n')
+        await an.run_in_actor(
             spin_for,
             name='sleeper',
         )
+        print('exiting first subactor layer..\n')
 
 
+@pytest.mark.parametrize(
+    'man_cancel_outer',
+    [
+        False,  # passes if delay != 2
+
+        # always causes an unexpected eg-w-embedded-assert-err?
+        pytest.param(True,
+             marks=pytest.mark.xfail(
+                 reason=(
+                    'always causes an unexpected eg-w-embedded-assert-err?'
+                )
+            ),
+        ),
+    ],
+)
 @no_windows
 def test_cancel_while_childs_child_in_sync_sleep(
-    loglevel,
+    loglevel: str,
-    start_method,
+    start_method: str,
-    spawn_backend,
+    spawn_backend: str,
+    debug_mode: bool,
+    reg_addr: tuple,
+    man_cancel_outer: bool,
 ):
-    """Verify that a child cancelled while executing sync code is torn
+    '''
+    Verify that a child cancelled while executing sync code is torn
     down even when that cancellation is triggered by the parent
     2 nurseries "up".
-    """
+
+    Though the grandchild should stay blocking its actor runtime, its
+    parent should issue a "zombie reaper" to hard kill it after
+    sufficient timeout.
+
+    '''
     if start_method == 'forkserver':
         pytest.skip("Forksever sux hard at resuming from sync sleep...")
 
     async def main():
-        with trio.fail_after(2):
+        #
-            async with tractor.open_nursery() as tn:
+        # XXX BIG TODO NOTE XXX
-                await tn.run_in_actor(
+        #
-                    spawn,
+        # it seems there's a strange race that can happen
-                    name='spawn',
+        # where where the fail-after will trigger outer scope
+        # .cancel() which then causes the inner scope to raise,
+        #
+        # BaseExceptionGroup('Exceptions from Trio nursery', [
+        #   BaseExceptionGroup('Exceptions from Trio nursery',
+        #   [
+        #       Cancelled(),
+        #       Cancelled(),
+        #   ]
+        #   ),
+        #   AssertionError('assert 0')
+        # ])
+        #
+        # WHY THIS DOESN'T MAKE SENSE:
+        # ---------------------------
+        # - it should raise too-slow-error when too slow..
+        #  * verified that using simple-cs and manually cancelling
+        #    you get same outcome -> indicates that the fail-after
+        #    can have its TooSlowError overriden!
+        #  |_ to check this it's easy, simplly decrease the timeout
+        #     as per the var below.
+        #
+        # - when using the manual simple-cs the outcome is different
+        #   DESPITE the `assert 0` which means regardless of the
+        #   inner scope effectively failing in the same way, the
+        #   bubbling up **is NOT the same**.
+        #
+        # delays trigger diff outcomes..
+        # ---------------------------
+        # as seen by uncommenting various lines below there is from
+        # my POV an unexpected outcome due to the delay=2 case.
+        #
+        # delay = 1  # no AssertionError in eg, TooSlowError raised.
+        # delay = 2  # is AssertionError in eg AND no TooSlowError !?
+        delay = 4  # is AssertionError in eg AND no _cs cancellation.
+
+        with trio.fail_after(delay) as _cs:
+        # with trio.CancelScope() as cs:
+        # ^XXX^ can be used instead to see same outcome.
+
+            async with (
+                # tractor.trionics.collapse_eg(),  # doesn't help
+                tractor.open_nursery(
+                    hide_tb=False,
+                    debug_mode=debug_mode,
+                    registry_addrs=[reg_addr],
+                ) as an,
+            ):
+                await an.run_in_actor(
+                    spawn_sub_with_sync_blocking_task,
+                    name='sync_blocking_sub',
                 )
                 await trio.sleep(1)
+
+                if man_cancel_outer:
+                    print('Cancelling manually in root')
+                    _cs.cancel()
+
+                # trigger exc-srced taskc down
+                # the actor tree.
+                print('RAISING IN ROOT')
                 assert 0
 
     with pytest.raises(AssertionError):

tests/test_child_manages_service_nursery.py

@@ -117,9 +117,10 @@ async def open_actor_local_nursery(
     ctx: tractor.Context,
 ):
     global _nursery
-    async with trio.open_nursery(
+    async with (
-        strict_exception_groups=False,
+        tractor.trionics.collapse_eg(),
-    ) as tn:
+        trio.open_nursery() as tn
+    ):
         _nursery = tn
         await ctx.started()
         await trio.sleep(10)

tests/test_clustering.py

@@ -13,26 +13,24 @@ MESSAGE = 'tractoring at full speed'
 def test_empty_mngrs_input_raises() -> None:
 
     async def main():
-        with trio.fail_after(1):
+        with trio.fail_after(3):
             async with (
                 open_actor_cluster(
                     modules=[__name__],
 
                     # NOTE: ensure we can passthrough runtime opts
-                    loglevel='info',
+                    loglevel='cancel',
-                    # debug_mode=True,
+                    debug_mode=False,
 
                 ) as portals,
 
-                gather_contexts(
+                gather_contexts(mngrs=()),
-                    # NOTE: it's the use of inline-generator syntax
-                    # here that causes the empty input.
-                    mngrs=(
-                        p.open_context(worker) for p in portals.values()
-                    ),
-                ),
             ):
-                assert 0
+                # should fail before this?
+                assert portals
+
+                # test should fail if we mk it here!
+                assert 0, 'Should have raised val-err !?'
 
     with pytest.raises(ValueError):
         trio.run(main)

tests/test_discovery.py

@@ -11,6 +11,7 @@ import psutil
 import pytest
 import subprocess
 import tractor
+from tractor.trionics import collapse_eg
 from tractor._testing import tractor_test
 import trio
 
@@ -193,10 +194,10 @@ async def spawn_and_check_registry(
 
             try:
                 async with tractor.open_nursery() as an:
-                    async with trio.open_nursery(
+                    async with (
-                        strict_exception_groups=False,
+                        collapse_eg(),
-                    ) as trion:
+                        trio.open_nursery() as trion,
-
+                    ):
                         portals = {}
                         for i in range(3):
                             name = f'a{i}'
@@ -338,11 +339,12 @@ async def close_chans_before_nursery(
                         async with portal2.open_stream_from(
                             stream_forever
                         ) as agen2:
-                            async with trio.open_nursery(
+                            async with (
-                                strict_exception_groups=False,
+                                collapse_eg(),
-                            ) as n:
+                                trio.open_nursery() as tn,
-                                n.start_soon(streamer, agen1)
+                            ):
-                                n.start_soon(cancel, use_signal, .5)
+                                tn.start_soon(streamer, agen1)
+                                tn.start_soon(cancel, use_signal, .5)
                                 try:
                                     await streamer(agen2)
                                 finally:

tests/test_infected_asyncio.py

@@ -234,10 +234,8 @@ async def trio_ctx(
     with trio.fail_after(1 + delay):
         try:
             async with (
-                trio.open_nursery(
+                tractor.trionics.collapse_eg(),
-                    # TODO, for new `trio` / py3.13
+                trio.open_nursery() as tn,
-                    # strict_exception_groups=False,
-                ) as tn,
                 tractor.to_asyncio.open_channel_from(
                     sleep_and_err,
                 ) as (first, chan),
@@ -573,14 +571,16 @@ def test_basic_interloop_channel_stream(
     fan_out: bool,
 ):
     async def main():
-        async with tractor.open_nursery() as an:
+        # TODO, figure out min timeout here!
-            portal = await an.run_in_actor(
+        with trio.fail_after(6):
-                stream_from_aio,
+            async with tractor.open_nursery() as an:
-                infect_asyncio=True,
+                portal = await an.run_in_actor(
-                fan_out=fan_out,
+                    stream_from_aio,
-            )
+                    infect_asyncio=True,
-            # should raise RAE diectly
+                    fan_out=fan_out,
-            await portal.result()
+                )
+                # should raise RAE diectly
+                await portal.result()
 
     trio.run(main)
 
@@ -1088,6 +1088,108 @@ def test_sigint_closes_lifetime_stack(
     trio.run(main)
 
 
+
+# ?TODO asyncio.Task fn-deco?
+# -[ ] do sig checkingat import time like @context?
+# -[ ] maybe name it @aio_task ??
+# -[ ] chan: to_asyncio.InterloopChannel ??
+async def raise_before_started(
+    # from_trio: asyncio.Queue,
+    # to_trio: trio.abc.SendChannel,
+    chan: to_asyncio.LinkedTaskChannel,
+
+) -> None:
+    '''
+    `asyncio.Task` entry point which RTEs before calling
+    `to_trio.send_nowait()`.
+
+    '''
+    await asyncio.sleep(0.2)
+    raise RuntimeError('Some shite went wrong before `.send_nowait()`!!')
+
+    # to_trio.send_nowait('Uhh we shouldve RTE-d ^^ ??')
+    chan.started_nowait('Uhh we shouldve RTE-d ^^ ??')
+    await asyncio.sleep(float('inf'))
+
+
+@tractor.context
+async def caching_ep(
+    ctx: tractor.Context,
+):
+
+    log = tractor.log.get_logger('caching_ep')
+    log.info('syncing via `ctx.started()`')
+    await ctx.started()
+
+    # XXX, allocate the `open_channel_from()` inside
+    # a `.trionics.maybe_open_context()`.
+    chan: to_asyncio.LinkedTaskChannel
+    async with (
+        tractor.trionics.maybe_open_context(
+            acm_func=tractor.to_asyncio.open_channel_from,
+            kwargs={
+                'target': raise_before_started,
+                # ^XXX, kwarg to `open_channel_from()`
+            },
+
+            # lock around current actor task access
+            key=tractor.current_actor().uid,
+
+        ) as (cache_hit, (clients, chan)),
+    ):
+        if cache_hit:
+            log.error(
+                'Re-using cached `.open_from_channel()` call!\n'
+            )
+
+        else:
+            log.info(
+                'Allocating SHOULD-FAIL `.open_from_channel()`\n'
+            )
+
+        await trio.sleep_forever()
+
+
+def test_aio_side_raises_before_started(
+    reg_addr: tuple[str, int],
+    debug_mode: bool,
+    loglevel: str,
+):
+    '''
+    Simulates connection-err from `piker.brokers.ib.api`..
+
+    Ensure any error raised by child-`asyncio.Task` BEFORE
+    `chan.started()`
+
+    '''
+    # delay = 999 if debug_mode else 1
+    async def main():
+        with trio.fail_after(3):
+            an: tractor.ActorNursery
+            async with tractor.open_nursery(
+                debug_mode=debug_mode,
+                loglevel=loglevel,
+            ) as an:
+                p: tractor.Portal = await an.start_actor(
+                    'lchan_cacher_that_raises_fast',
+                    enable_modules=[__name__],
+                    infect_asyncio=True,
+                )
+                async with p.open_context(
+                    caching_ep,
+                ) as (ctx, first):
+                    assert not first
+
+    with pytest.raises(
+        expected_exception=(RemoteActorError),
+    ) as excinfo:
+        trio.run(main)
+
+    # ensure `asyncio.Task` exception is bubbled
+    # allll the way erp!!
+    rae = excinfo.value
+    assert rae.boxed_type is RuntimeError
+
 # TODO: debug_mode tests once we get support for `asyncio`!
 #
 # -[ ] need tests to wrap both scripts:

tests/test_legacy_one_way_streaming.py

@@ -235,10 +235,16 @@ async def cancel_after(wait, reg_addr):
 
 
 @pytest.fixture(scope='module')
-def time_quad_ex(reg_addr, ci_env, spawn_backend):
+def time_quad_ex(
+    reg_addr: tuple,
+    ci_env: bool,
+    spawn_backend: str,
+):
     if spawn_backend == 'mp':
-        """no idea but the  mp *nix runs are flaking out here often...
+        '''
-        """
+        no idea but the  mp *nix runs are flaking out here often...
+
+        '''
         pytest.skip("Test is too flaky on mp in CI")
 
     timeout = 7 if platform.system() in ('Windows', 'Darwin') else 4
@@ -249,12 +255,24 @@ def time_quad_ex(reg_addr, ci_env, spawn_backend):
     return results, diff
 
 
-def test_a_quadruple_example(time_quad_ex, ci_env, spawn_backend):
+def test_a_quadruple_example(
-    """This also serves as a kind of "we'd like to be this fast test"."""
+    time_quad_ex: tuple,
+    ci_env: bool,
+    spawn_backend: str,
+):
+    '''
+    This also serves as a kind of "we'd like to be this fast test".
 
+    '''
     results, diff = time_quad_ex
     assert results
-    this_fast = 6 if platform.system() in ('Windows', 'Darwin') else 3
+    this_fast = (
+        6 if platform.system() in (
+            'Windows',
+            'Darwin',
+        )
+        else 3
+    )
     assert diff < this_fast
 
 

tests/test_resource_cache.py

@@ -1,5 +1,6 @@
 '''
-Async context manager cache api testing: ``trionics.maybe_open_context():``
+Suites for our `.trionics.maybe_open_context()` multi-task
+shared-cached `@acm` API.
 
 '''
 from contextlib import asynccontextmanager as acm
@@ -9,6 +10,15 @@ from typing import Awaitable
 import pytest
 import trio
 import tractor
+from tractor.trionics import (
+    maybe_open_context,
+)
+from tractor.log import (
+    get_console_log,
+    get_logger,
+)
+log = get_logger(__name__)
+
 
 
 _resource: int = 0
@@ -52,7 +62,7 @@ def test_resource_only_entered_once(key_on):
                 # different task names per task will be used
                 kwargs = {'task_name': name}
 
-            async with tractor.trionics.maybe_open_context(
+            async with maybe_open_context(
                 maybe_increment_counter,
                 kwargs=kwargs,
                 key=key,
@@ -140,7 +150,7 @@ async def open_stream() -> Awaitable[
 
 @acm
 async def maybe_open_stream(taskname: str):
-    async with tractor.trionics.maybe_open_context(
+    async with maybe_open_context(
         # NOTE: all secondary tasks should cache hit on the same key
         acm_func=open_stream,
     ) as (
@@ -305,3 +315,92 @@ def test_open_local_sub_to_stream(
         print('exiting main.')
 
     trio.run(main)
+
+
+
+@acm
+async def cancel_outer_cs(
+    cs: trio.CancelScope|None = None,
+    delay: float = 0,
+):
+    # on first task delay this enough to block
+    # the 2nd task but then cancel it mid sleep
+    # so that the tn.start() inside the key-err handler block
+    # is cancelled and would previously corrupt the
+    # mutext state.
+    log.info(f'task entering sleep({delay})')
+    await trio.sleep(delay)
+    if cs:
+        log.info('task calling cs.cancel()')
+        cs.cancel()
+    trio.lowlevel.checkpoint()
+    yield
+    await trio.sleep_forever()
+
+
+def test_lock_not_corrupted_on_fast_cancel(
+    debug_mode: bool,
+    loglevel: str,
+):
+    '''
+    Verify that if the caching-task (the first to enter
+    `maybe_open_context()`) is cancelled mid-cache-miss, the embedded
+    mutex can never be left in a corrupted state.
+
+    That is, the lock is always eventually released ensuring a peer
+    (cache-hitting) task will never,
+
+    - be left to inf-block/hang on the `lock.acquire()`.
+    - try to release the lock when still owned by the caching-task
+      due to it having erronously exited without calling
+      `lock.release()`.
+
+
+    '''
+    delay: float = 1.
+
+    async def use_moc(
+        cs: trio.CancelScope|None,
+        delay: float,
+    ):
+        log.info('task entering moc')
+        async with maybe_open_context(
+            cancel_outer_cs,
+            kwargs={
+                'cs': cs,
+                'delay': delay,
+            },
+        ) as (cache_hit, _null):
+            if cache_hit:
+                log.info('2nd task entered')
+            else:
+                log.info('1st task entered')
+
+            await trio.sleep_forever()
+
+    async def main():
+        with trio.fail_after(delay + 2):
+            async with (
+                tractor.open_root_actor(
+                    debug_mode=debug_mode,
+                    loglevel=loglevel,
+                ),
+                trio.open_nursery() as tn,
+            ):
+                get_console_log('info')
+                log.info('yo starting')
+                cs = tn.cancel_scope
+                tn.start_soon(
+                    use_moc,
+                    cs,
+                    delay,
+                    name='child',
+                )
+                with trio.CancelScope() as rent_cs:
+                    await use_moc(
+                        cs=rent_cs,
+                        delay=delay,
+                    )
+
+
+    trio.run(main)

tests/test_root_infect_asyncio.py

@@ -147,8 +147,7 @@ def test_trio_prestarted_task_bubbles(
         await trio.sleep_forever()
 
     async def _trio_main():
-        # with trio.fail_after(2):
+        with trio.fail_after(2 if not debug_mode else 999):
-        with trio.fail_after(999):
             first: str
             chan: to_asyncio.LinkedTaskChannel
             aio_ev = asyncio.Event()
@@ -217,32 +216,25 @@ def test_trio_prestarted_task_bubbles(
                         ):
                             aio_ev.set()
 
-    with pytest.raises(
-        expected_exception=ExceptionGroup,
-    ) as excinfo:
-        tractor.to_asyncio.run_as_asyncio_guest(
-            trio_main=_trio_main,
-        )
-
-    eg = excinfo.value
-    rte_eg, rest_eg = eg.split(RuntimeError)
-
     # ensure the trio-task's error bubbled despite the aio-side
     # having (maybe) errored first.
     if aio_err_trigger in (
         'after_trio_task_starts',
         'after_start_point',
     ):
-        assert len(errs := rest_eg.exceptions) == 1
+        patt: str = 'trio-side'
-        typerr = errs[0]
+        expect_exc = TypeError
-        assert (
-            type(typerr) is TypeError
-            and
-            'trio-side' in typerr.args
-        )
 
     # when aio errors BEFORE (last) trio task is scheduled, we should
     # never see anythinb but the aio-side.
     else:
-        assert len(rtes := rte_eg.exceptions) == 1
+        patt: str = 'asyncio-side'
-        assert 'asyncio-side' in rtes[0].args[0]
+        expect_exc = RuntimeError
+
+    with pytest.raises(expect_exc) as excinfo:
+        tractor.to_asyncio.run_as_asyncio_guest(
+            trio_main=_trio_main,
+        )
+
+    caught_exc = excinfo.value
+    assert patt in caught_exc.args

tests/test_trioisms.py

@@ -8,6 +8,7 @@ from contextlib import (
 )
 
 import pytest
+from tractor.trionics import collapse_eg
 import trio
 from trio import TaskStatus
 
@@ -64,9 +65,8 @@ def test_stashed_child_nursery(use_start_soon):
     async def main():
 
         async with (
-            trio.open_nursery(
+            collapse_eg(),
-                strict_exception_groups=False,
+            trio.open_nursery() as pn,
-            ) as pn,
         ):
             cn = await pn.start(mk_child_nursery)
             assert cn
@@ -197,10 +197,8 @@ def test_gatherctxs_with_memchan_breaks_multicancelled(
         async with (
             # XXX should ensure ONLY the KBI
             # is relayed upward
-            trionics.collapse_eg(),
+            collapse_eg(),
-            trio.open_nursery(
+            trio.open_nursery(), # as tn,
-                # strict_exception_groups=False,
-            ), # as tn,
 
             trionics.gather_contexts([
                 open_memchan(),

tractor/_clustering.py

@@ -55,10 +55,17 @@ async def open_actor_cluster(
         raise ValueError(
             'Number of names is {len(names)} but count it {count}')
 
-    async with tractor.open_nursery(
+    async with (
-        **runtime_kwargs,
+        # tractor.trionics.collapse_eg(),
-    ) as an:
+        tractor.open_nursery(
-        async with trio.open_nursery() as n:
+            **runtime_kwargs,
+        ) as an
+    ):
+        async with (
+            # tractor.trionics.collapse_eg(),
+            trio.open_nursery() as tn,
+            tractor.trionics.maybe_raise_from_masking_exc()
+        ):
             uid = tractor.current_actor().uid
 
             async def _start(name: str) -> None:
@@ -69,9 +76,8 @@ async def open_actor_cluster(
                 )
 
             for name in names:
-                n.start_soon(_start, name)
+                tn.start_soon(_start, name)
 
         assert len(portals) == count
         yield portals
-
         await an.cancel(hard_kill=hard_kill)

tractor/_context.py

@@ -154,7 +154,7 @@ class Context:
     2 cancel-scope-linked, communicating and parallel executing
     `Task`s. Contexts are allocated on each side of any task
     RPC-linked msg dialog, i.e. for every request to a remote
-    actor from a `Portal`. On the "callee" side a context is
+    actor from a `Portal`. On the "child" side a context is
     always allocated inside `._rpc._invoke()`.
 
     TODO: more detailed writeup on cancellation, error and
@@ -222,8 +222,8 @@ class Context:
     # `._runtime.invoke()`.
     _remote_func_type: str | None = None
 
-    # NOTE: (for now) only set (a portal) on the caller side since
+    # NOTE: (for now) only set (a portal) on the parent side since
-    # the callee doesn't generally need a ref to one and should
+    # the child doesn't generally need a ref to one and should
     # normally need to explicitly ask for handle to its peer if
     # more the the `Context` is needed?
     _portal: Portal | None = None
@@ -252,12 +252,12 @@ class Context:
     _outcome_msg: Return|Error|ContextCancelled = Unresolved
 
     # on a clean exit there should be a final value
-    # delivered from the far end "callee" task, so
+    # delivered from the far end "child" task, so
     # this value is only set on one side.
     # _result: Any | int = None
     _result: PayloadT|Unresolved = Unresolved
 
-    # if the local "caller"  task errors this value is always set
+    # if the local "parent"  task errors this value is always set
     # to the error that was captured in the
     # `Portal.open_context().__aexit__()` teardown block OR, in
     # 2 special cases when an (maybe) expected remote error
@@ -293,7 +293,7 @@ class Context:
     # a `ContextCancelled` due to a call to `.cancel()` triggering
     # "graceful closure" on either side:
     # - `._runtime._invoke()` will check this flag before engaging
-    #   the crash handler REPL in such cases where the "callee"
+    #   the crash handler REPL in such cases where the "child"
     #   raises the cancellation,
     # - `.devx.debug.lock_stdio_for_peer()` will set it to `False` if
     #   the global tty-lock has been configured to filter out some
@@ -307,8 +307,8 @@ class Context:
     _stream_opened: bool = False
     _stream: MsgStream|None = None
 
-    # caller of `Portal.open_context()` for
+    # the parent-task's calling-fn's frame-info, the frame above
-    # logging purposes mostly
+    # `Portal.open_context()`, for introspection/logging.
     _caller_info: CallerInfo|None = None
 
     # overrun handling machinery
@@ -529,11 +529,11 @@ class Context:
         '''
         Exactly the value of `self._scope.cancelled_caught`
         (delegation) and should only be (able to be read as)
-        `True` for a `.side == "caller"` ctx wherein the
+        `True` for a `.side == "parent"` ctx wherein the
         `Portal.open_context()` block was exited due to a call to
         `._scope.cancel()` - which should only ocurr in 2 cases:
 
-        - a caller side calls `.cancel()`, the far side cancels
+        - a parent side calls `.cancel()`, the far side cancels
           and delivers back a `ContextCancelled` (making
           `.cancel_acked == True`) and `._scope.cancel()` is
           called by `._maybe_cancel_and_set_remote_error()` which
@@ -542,20 +542,20 @@ class Context:
           => `._scope.cancelled_caught == True` by normal `trio`
           cs semantics.
 
-        - a caller side is delivered a `._remote_error:
+        - a parent side is delivered a `._remote_error:
           RemoteActorError` via `._deliver_msg()` and a transitive
           call to `_maybe_cancel_and_set_remote_error()` calls
           `._scope.cancel()` and that cancellation eventually
           results in `trio.Cancelled`(s) caught in the
           `.open_context()` handling around the @acm's `yield`.
 
-        Only as an FYI, in the "callee" side case it can also be
+        Only as an FYI, in the "child" side case it can also be
         set but never is readable by any task outside the RPC
         machinery in `._invoke()` since,:
-        - when a callee side calls `.cancel()`, `._scope.cancel()`
+        - when a child side calls `.cancel()`, `._scope.cancel()`
           is called immediately and handled specially inside
           `._invoke()` to raise a `ContextCancelled` which is then
-          sent to the caller side.
+          sent to the parent side.
 
           However, `._scope.cancelled_caught` can NEVER be
           accessed/read as `True` by any RPC invoked task since it
@@ -666,7 +666,7 @@ class Context:
         when called/closed by actor local task(s).
 
         NOTEs: 
-          - It is expected that the caller has previously unwrapped
+          - It is expected that the parent has previously unwrapped
             the remote error using a call to `unpack_error()` and
             provides that output exception value as the input
             `error` argument *here*.
@@ -676,7 +676,7 @@ class Context:
             `Portal.open_context()` (ideally) we want to interrupt
             any ongoing local tasks operating within that
             `Context`'s cancel-scope so as to be notified ASAP of
-            the remote error and engage any caller handling (eg.
+            the remote error and engage any parent handling (eg.
             for cross-process task supervision).
 
           - In some cases we may want to raise the remote error
@@ -886,6 +886,11 @@ class Context:
 
     @property
     def repr_caller(self) -> str:
+        '''
+        Render a "namespace-path" style representation of the calling
+        task-fn.
+
+        '''
         ci: CallerInfo|None = self._caller_info
         if ci:
             return (
@@ -899,7 +904,7 @@ class Context:
     def repr_api(self) -> str:
         return 'Portal.open_context()'
 
-        # TODO: use `.dev._frame_stack` scanning to find caller!
+        # TODO: use `.dev._frame_stack` scanning to find caller fn!
         # ci: CallerInfo|None = self._caller_info
         # if ci:
         #     return (
@@ -934,7 +939,7 @@ class Context:
         => That is, an IPC `Context` (this) **does not**
            have the same semantics as a `trio.CancelScope`.
 
-        If the caller (who entered the `Portal.open_context()`)
+        If the parent (who entered the `Portal.open_context()`)
         desires that the internal block's cancel-scope  be
         cancelled it should open its own `trio.CancelScope` and
         manage it as needed.
@@ -1006,7 +1011,6 @@ class Context:
                 else:
                     log.cancel(
                         f'Timed out on cancel request of remote task?\n'
-                        f'\n'
                         f'{reminfo}'
                     )
 
@@ -1017,7 +1021,7 @@ class Context:
         # `_invoke()` RPC task.
         #
         # NOTE: on this side we ALWAYS cancel the local scope
-        # since the caller expects a `ContextCancelled` to be sent
+        # since the parent expects a `ContextCancelled` to be sent
         # from `._runtime._invoke()` back to the other side. The
         # logic for catching the result of the below
         # `._scope.cancel()` is inside the `._runtime._invoke()`
@@ -1190,8 +1194,8 @@ class Context:
 
     ) -> Any|Exception:
         '''
-        From some (caller) side task, wait for and return the final
+        From some (parent) side task, wait for and return the final
-        result from the remote (callee) side's task.
+        result from the remote (child) side's task.
 
         This provides a mechanism for one task running in some actor to wait
         on another task at the other side, in some other actor, to terminate.
@@ -1487,6 +1491,12 @@ class Context:
                 ):
                     status = 'peer-cancelled'
 
+            case (
+                Unresolved,
+                trio.Cancelled(),  # any error-type
+            ) if self.canceller:
+                status = 'actor-cancelled'
+
             # (remote) error condition
             case (
                 Unresolved,
@@ -1600,7 +1610,7 @@ class Context:
                 raise err
 
         # TODO: maybe a flag to by-pass encode op if already done
-        # here in caller?
+        # here in parent?
         await self.chan.send(started_msg)
 
         # set msg-related internal runtime-state
@@ -1676,7 +1686,7 @@ class Context:
 
          XXX RULES XXX
         ------ - ------
-        - NEVER raise remote errors from this method; a runtime task caller.
+        - NEVER raise remote errors from this method; a calling runtime-task.
           An error "delivered" to a ctx should always be raised by
           the corresponding local task operating on the
           `Portal`/`Context` APIs.
@@ -1752,7 +1762,7 @@ class Context:
 
             else:
                 report = (
-                    'Queueing OVERRUN msg on caller task:\n\n'
+                    'Queueing OVERRUN msg on parent task:\n\n'
                     + report
                 )
                 log.debug(report)
@@ -1948,12 +1958,12 @@ async def open_context_from_portal(
     IPC protocol.
 
     The yielded `tuple` is a pair delivering a `tractor.Context`
-    and any first value "sent" by the "callee" task via a call
+    and any first value "sent" by the "child" task via a call
     to `Context.started(<value: Any>)`; this side of the
-    context does not unblock until the "callee" task calls
+    context does not unblock until the "child" task calls
     `.started()` in similar style to `trio.Nursery.start()`.
-    When the "callee" (side that is "called"/started by a call
+    When the "child" (side that is "called"/started by a call
-    to *this* method) returns, the caller side (this) unblocks
+    to *this* method) returns, the parent side (this) unblocks
     and any final value delivered from the other end can be
     retrieved using the `Contex.wait_for_result()` api.
 
@@ -1966,7 +1976,7 @@ async def open_context_from_portal(
     __tracebackhide__: bool = hide_tb
 
     # denote this frame as a "runtime frame" for stack
-    # introspection where we report the caller code in logging
+    # introspection where we report the parent code in logging
     # and error message content.
     # NOTE: 2 bc of the wrapping `@acm`
     __runtimeframe__: int = 2  # noqa
@@ -2025,7 +2035,7 @@ async def open_context_from_portal(
     # placeholder for any exception raised in the runtime
     # or by user tasks which cause this context's closure.
     scope_err: BaseException|None = None
-    ctxc_from_callee: ContextCancelled|None = None
+    ctxc_from_child: ContextCancelled|None = None
     try:
         async with (
             collapse_eg(),
@@ -2104,7 +2114,7 @@ async def open_context_from_portal(
             # that we can re-use it around the `yield` ^ here
             # or vice versa?
             #
-            # maybe TODO NOTE: between the caller exiting and
+            # maybe TODO NOTE: between the parent exiting and
             # arriving here the far end may have sent a ctxc-msg or
             # other error, so the quetion is whether we should check
             # for it here immediately and maybe raise so as to engage
@@ -2170,16 +2180,16 @@ async def open_context_from_portal(
     #   request in which case we DO let the error bubble to the
     #   opener.
     #
-    # 2-THIS "caller" task somewhere invoked `Context.cancel()`
+    # 2-THIS "parent" task somewhere invoked `Context.cancel()`
-    #   and received a `ContextCanclled` from the "callee"
+    #   and received a `ContextCanclled` from the "child"
     #   task, in which case we mask the `ContextCancelled` from
-    #   bubbling to this "caller" (much like how `trio.Nursery`
+    #   bubbling to this "parent" (much like how `trio.Nursery`
     #   swallows any `trio.Cancelled` bubbled by a call to
     #   `Nursery.cancel_scope.cancel()`)
     except ContextCancelled as ctxc:
         scope_err = ctxc
         ctx._local_error: BaseException = scope_err
-        ctxc_from_callee = ctxc
+        ctxc_from_child = ctxc
 
         # XXX TODO XXX: FIX THIS debug_mode BUGGGG!!!
         # using this code and then resuming the REPL will
@@ -2216,11 +2226,11 @@ async def open_context_from_portal(
     # the above `._scope` can be cancelled due to:
     # 1. an explicit self cancel via `Context.cancel()` or
     #    `Actor.cancel()`,
-    # 2. any "callee"-side remote error, possibly also a cancellation
+    # 2. any "child"-side remote error, possibly also a cancellation
     #    request by some peer,
-    # 3. any "caller" (aka THIS scope's) local error raised in the above `yield`
+    # 3. any "parent" (aka THIS scope's) local error raised in the above `yield`
     except (
-        # CASE 3: standard local error in this caller/yieldee
+        # CASE 3: standard local error in this parent/yieldee
         Exception,
 
         # CASES 1 & 2: can manifest as a `ctx._scope_nursery`
@@ -2234,9 +2244,9 @@ async def open_context_from_portal(
         #   any `Context._maybe_raise_remote_err()` call.
         #
         # 2.-`BaseExceptionGroup[ContextCancelled | RemoteActorError]`
-        #    from any error delivered from the "callee" side
+        #    from any error delivered from the "child" side
         #    AND a group-exc is only raised if there was > 1
-        #    tasks started *here* in the "caller" / opener
+        #    tasks started *here* in the "parent" / opener
         #    block. If any one of those tasks calls
         #    `.wait_for_result()` or `MsgStream.receive()`
         #    `._maybe_raise_remote_err()` will be transitively
@@ -2249,8 +2259,8 @@ async def open_context_from_portal(
         trio.Cancelled,  # NOTE: NOT from inside the ctx._scope
         KeyboardInterrupt,
 
-    ) as caller_err:
+    ) as rent_err:
-        scope_err = caller_err
+        scope_err = rent_err
         ctx._local_error: BaseException = scope_err
 
         # XXX: ALWAYS request the context to CANCEL ON any ERROR.
@@ -2260,7 +2270,7 @@ async def open_context_from_portal(
         # await debug.pause()
         # log.cancel(
         match scope_err:
-            case trio.Cancelled:
+            case trio.Cancelled():
                 logmeth = log.cancel
 
             # XXX explicitly report on any non-graceful-taskc cases
@@ -2268,7 +2278,7 @@ async def open_context_from_portal(
                 logmeth = log.exception
 
         logmeth(
-            f'ctx {ctx.side!r}-side exited with {ctx.repr_outcome()}\n'
+            f'ctx {ctx.side!r}-side exited with {ctx.repr_outcome()!r}\n'
         )
 
         if debug_mode():
@@ -2289,9 +2299,9 @@ async def open_context_from_portal(
                     'Calling `ctx.cancel()`!\n'
                 )
 
-        # we don't need to cancel the callee if it already
+        # we don't need to cancel the child if it already
         # told us it's cancelled ;p
-        if ctxc_from_callee is None:
+        if ctxc_from_child is None:
             try:
                 await ctx.cancel()
             except (
@@ -2322,8 +2332,8 @@ async def open_context_from_portal(
             # via a call to
             # `Context._maybe_cancel_and_set_remote_error()`.
             # As per `Context._deliver_msg()`, that error IS
-            # ALWAYS SET any time "callee" side fails and causes "caller
+            # ALWAYS SET any time "child" side fails and causes
-            # side" cancellation via a `ContextCancelled` here.
+            # "parent side" cancellation via a `ContextCancelled` here.
             try:
                 result_or_err: Exception|Any = await ctx.wait_for_result()
             except BaseException as berr:
@@ -2359,7 +2369,7 @@ async def open_context_from_portal(
                     )
                 case (None, _):
                     log.runtime(
-                        'Context returned final result from callee task:\n'
+                        'Context returned final result from child task:\n'
                         f'<= peer: {uid}\n'
                         f'  |_ {nsf}()\n\n'
 
@@ -2454,7 +2464,7 @@ async def open_context_from_portal(
                 )
 
             # TODO: should we add a `._cancel_req_received`
-            # flag to determine if the callee manually called
+            # flag to determine if the child manually called
             # `ctx.cancel()`?
             # -[ ] going to need a cid check no?
 
@@ -2510,7 +2520,7 @@ def mk_context(
     recv_chan: trio.MemoryReceiveChannel
     send_chan, recv_chan = trio.open_memory_channel(msg_buffer_size)
 
-    # TODO: only scan caller-info if log level so high!
+    # TODO: only scan parent-info if log level so high!
     from .devx._frame_stack import find_caller_info
     caller_info: CallerInfo|None = find_caller_info()
 

tractor/_root.py

@@ -481,10 +481,11 @@ async def open_root_actor(
                 collapse_eg(),
                 trio.open_nursery() as root_tn,
 
-                # XXX, finally-footgun below?
+                # ?TODO? finally-footgun below?
                 # -> see note on why shielding.
                 # maybe_raise_from_masking_exc(),
             ):
+                actor._root_tn = root_tn
                 # `_runtime.async_main()` creates an internal nursery
                 # and blocks here until any underlying actor(-process)
                 # tree has terminated thereby conducting so called
@@ -523,6 +524,11 @@ async def open_root_actor(
                         err,
                         api_frame=inspect.currentframe(),
                         debug_filter=debug_filter,
+
+                        # XXX NOTE, required to debug root-actor
+                        # crashes under cancellation conditions; so
+                        # most of them!
+                        shield=root_tn.cancel_scope.cancel_called,
                     )
 
                     if (
@@ -562,6 +568,7 @@ async def open_root_actor(
                         f'{op_nested_actor_repr}'
                     )
                     # XXX, THIS IS A *finally-footgun*!
+                    # (also mentioned in with-block above)
                     # -> though already shields iternally it can
                     # taskc here and mask underlying errors raised in
                     # the try-block above?

tractor/_rpc.py

@@ -384,7 +384,7 @@ async def _errors_relayed_via_ipc(
 
     # RPC task bookeeping.
     # since RPC tasks are scheduled inside a flat
-    # `Actor._service_n`, we add "handles" to each such that
+    # `Actor._service_tn`, we add "handles" to each such that
     # they can be individually ccancelled.
     finally:
 
@@ -462,7 +462,7 @@ async def _invoke(
     connected IPC channel.
 
     This is the core "RPC" `trio.Task` scheduling machinery used to start every
-    remotely invoked function, normally in `Actor._service_n: Nursery`.
+    remotely invoked function, normally in `Actor._service_tn: Nursery`.
 
     '''
     __tracebackhide__: bool = hide_tb
@@ -642,7 +642,7 @@ async def _invoke(
             tn: Nursery
             rpc_ctx_cs: CancelScope
             async with (
-                collapse_eg(),
+                collapse_eg(hide_tb=False),
                 trio.open_nursery() as tn,
                 msgops.maybe_limit_plds(
                     ctx=ctx,
@@ -823,24 +823,44 @@ async def _invoke(
                 f'after having {ctx.repr_state!r}\n'
             )
             if merr:
-
                 logmeth: Callable = log.error
-                if isinstance(merr, ContextCancelled):
+                if (
-                    logmeth: Callable = log.runtime
+                    # ctxc: by `Context.cancel()`
+                    isinstance(merr, ContextCancelled)
 
-                if not isinstance(merr, RemoteActorError):
+                    # out-of-layer cancellation, one of:
-                    tb_str: str = ''.join(traceback.format_exception(merr))
+                    # - actorc: by `Portal.cancel_actor()`
+                    # - OSc: by SIGINT or `Process.signal()`
+                    or (
+                        isinstance(merr, trio.Cancelled)
+                        and
+                        ctx.canceller
+                    )
+                ):
+                    logmeth: Callable = log.cancel
+                    descr_str += (
+                        f' with {merr!r}\n'
+                    )
+
+                elif (
+                    not isinstance(merr, RemoteActorError)
+                ):
+                    tb_str: str = ''.join(
+                        traceback.format_exception(merr)
+                    )
                     descr_str += (
                         f'\n{merr!r}\n'  # needed?
                         f'{tb_str}\n'
-                        f'\n'
-                        f'scope_error:\n'
-                        f'{scope_err!r}\n'
                     )
                 else:
-                    descr_str += f'\n{merr!r}\n'
+                    descr_str += (
+                        f'{merr!r}\n'
+                    )
             else:
-                descr_str += f'\nwith final result {ctx.outcome!r}\n'
+                descr_str += (
+                    f'\n'
+                    f'with final result {ctx.outcome!r}\n'
+                )
 
             logmeth(
                 f'{message}\n'
@@ -916,7 +936,7 @@ async def process_messages(
 
     Receive (multiplexed) per-`Channel` RPC requests as msgs from
     remote processes; schedule target async funcs as local
-    `trio.Task`s inside the `Actor._service_n: Nursery`.
+    `trio.Task`s inside the `Actor._service_tn: Nursery`.
 
     Depending on msg type, non-`cmd` (task spawning/starting)
     request payloads (eg. `started`, `yield`, `return`, `error`)
@@ -941,7 +961,7 @@ async def process_messages(
 
     '''
     actor: Actor = _state.current_actor()
-    assert actor._service_n  # runtime state sanity
+    assert actor._service_tn  # runtime state sanity
 
     # TODO: once `trio` get's an "obvious way" for req/resp we
     # should use it?
@@ -1152,7 +1172,7 @@ async def process_messages(
                         start_status += '->( scheduling new task..\n'
                         log.runtime(start_status)
                         try:
-                            ctx: Context = await actor._service_n.start(
+                            ctx: Context = await actor._service_tn.start(
                                 partial(
                                     _invoke,
                                     actor,
@@ -1292,7 +1312,7 @@ async def process_messages(
     ) as err:
 
         if nursery_cancelled_before_task:
-            sn: Nursery = actor._service_n
+            sn: Nursery = actor._service_tn
             assert sn and sn.cancel_scope.cancel_called  # sanity
             log.cancel(
                 f'Service nursery cancelled before it handled {funcname}'

tractor/_runtime.py

@@ -35,6 +35,15 @@ for running all lower level spawning, supervision and msging layers:
   SC-transitive RPC via scheduling of `trio` tasks.
 - registration of newly spawned actors with the discovery sys.
 
+Glossary:
+--------
+ - tn: a `trio.Nursery` or "task nursery".
+ - an: an `ActorNursery` or "actor nursery".
+ - root: top/parent-most scope/task/process/actor (or other runtime
+         primitive) in a hierarchical tree.
+ - parent-ish: "higher-up" in the runtime-primitive hierarchy.
+ - child-ish: "lower-down" in the runtime-primitive hierarchy.
+
 '''
 from __future__ import annotations
 from contextlib import (
@@ -76,6 +85,7 @@ from tractor.msg import (
 )
 from .trionics import (
     collapse_eg,
+    maybe_open_nursery,
 )
 from .ipc import (
     Channel,
@@ -173,10 +183,11 @@ class Actor:
 
     msg_buffer_size: int = 2**6
 
-    # nursery placeholders filled in by `async_main()` after fork
+    # nursery placeholders filled in by `async_main()`,
-    _root_n: Nursery|None = None
+    # - after fork for subactors.
-    _service_n: Nursery|None = None
+    # - during boot for the root actor.
-
+    _root_tn: Nursery|None = None
+    _service_tn: Nursery|None = None
     _ipc_server: _server.IPCServer|None = None
 
     @property
@@ -1010,12 +1021,48 @@ class Actor:
         the RPC service nursery.
 
         '''
-        assert self._service_n
+        actor_repr: str = _pformat.nest_from_op(
-        self._service_n.start_soon(
+            input_op='>c(',
+            text=self.pformat(),
+            nest_indent=1,
+        )
+        log.cancel(
+            'Actor.cancel_soon()` was called!\n'
+            f'>> scheduling `Actor.cancel()`\n'
+            f'{actor_repr}'
+        )
+        assert self._service_tn
+        self._service_tn.start_soon(
             self.cancel,
             None,  # self cancel all rpc tasks
         )
 
+        # schedule a "canceller task" in the `._root_tn` once the
+        # `._service_tn` is fully shutdown; task waits for child-ish
+        # scopes to fully exit then finally cancels its parent,
+        # root-most, scope.
+        async def cancel_root_tn_after_services():
+            log.runtime(
+                'Waiting on service-tn to cancel..\n'
+                f'c>)\n'
+                f'|_{self._service_tn.cancel_scope!r}\n'
+            )
+            await self._cancel_complete.wait()
+            log.cancel(
+                f'`._service_tn` cancelled\n'
+                f'>c)\n'
+                f'|_{self._service_tn.cancel_scope!r}\n'
+                f'\n'
+                f'>> cancelling `._root_tn`\n'
+                f'c>(\n'
+                f' |_{self._root_tn.cancel_scope!r}\n'
+            )
+            self._root_tn.cancel_scope.cancel()
+
+        self._root_tn.start_soon(
+            cancel_root_tn_after_services
+        )
+
     @property
     def cancel_complete(self) -> bool:
         return self._cancel_complete.is_set()
@@ -1120,8 +1167,8 @@ class Actor:
                 await ipc_server.wait_for_shutdown()
 
             # cancel all rpc tasks permanently
-            if self._service_n:
+            if self._service_tn:
-                self._service_n.cancel_scope.cancel()
+                self._service_tn.cancel_scope.cancel()
 
         log_meth(msg)
         self._cancel_complete.set()
@@ -1258,7 +1305,7 @@ class Actor:
         '''
         Cancel all ongoing RPC tasks owned/spawned for a given
         `parent_chan: Channel` or simply all tasks (inside
-        `._service_n`) when `parent_chan=None`.
+        `._service_tn`) when `parent_chan=None`.
 
         '''
         tasks: dict = self._rpc_tasks
@@ -1470,46 +1517,55 @@ async def async_main(
                     accept_addrs.append(addr.unwrap())
 
         assert accept_addrs
-        # The "root" nursery ensures the channel with the immediate
+
-        # parent is kept alive as a resilient service until
+        ya_root_tn: bool = bool(actor._root_tn)
-        # cancellation steps have (mostly) occurred in
+        ya_service_tn: bool = bool(actor._service_tn)
-        # a deterministic way.
+
+        # NOTE, a top-most "root" nursery in each actor-process
+        # enables a lifetime priority for the IPC-channel connection
+        # with a sub-actor's immediate parent. I.e. this connection
+        # is kept alive as a resilient service connection until all
+        # other machinery has exited, cancellation of all
+        # embedded/child scopes have completed. This helps ensure
+        # a deterministic (and thus "graceful")
+        # first-class-supervision style teardown where a parent actor
+        # (vs. say peers) is always the last to be contacted before
+        # disconnect.
         root_tn: trio.Nursery
         async with (
             collapse_eg(),
-            trio.open_nursery() as root_tn,
+            maybe_open_nursery(
+                nursery=actor._root_tn,
+            ) as root_tn,
         ):
-            actor._root_n = root_tn
+            if ya_root_tn:
-            assert actor._root_n
+                assert root_tn is actor._root_tn
+            else:
+                actor._root_tn = root_tn
 
             ipc_server: _server.IPCServer
             async with (
                 collapse_eg(),
-                trio.open_nursery() as service_nursery,
+                maybe_open_nursery(
+                    nursery=actor._service_tn,
+                ) as service_tn,
                 _server.open_ipc_server(
-                    parent_tn=service_nursery,
+                    parent_tn=service_tn,  # ?TODO, why can't this be the root-tn
-                    stream_handler_tn=service_nursery,
+                    stream_handler_tn=service_tn,
                 ) as ipc_server,
-                # ) as actor._ipc_server,
-                # ^TODO? prettier?
 
             ):
-                # This nursery is used to handle all inbound
+                if ya_service_tn:
-                # connections to us such that if the TCP server
+                    assert service_tn is actor._service_tn
-                # is killed, connections can continue to process
+                else:
-                # in the background until this nursery is cancelled.
+                    # This nursery is used to handle all inbound
-                actor._service_n = service_nursery
+                    # connections to us such that if the TCP server
+                    # is killed, connections can continue to process
+                    # in the background until this nursery is cancelled.
+                    actor._service_tn = service_tn
+
+                # set after allocate
                 actor._ipc_server = ipc_server
-                assert (
-                    actor._service_n
-                    and (
-                        actor._service_n
-                        is
-                        actor._ipc_server._parent_tn
-                        is
-                        ipc_server._stream_handler_tn
-                    )
-                )
 
                 # load exposed/allowed RPC modules
                 # XXX: do this **after** establishing a channel to the parent
@@ -1535,10 +1591,11 @@ async def async_main(
                 # - root actor: the ``accept_addr`` passed to this method
 
                 # TODO: why is this not with the root nursery?
+                # - see above that the `._service_tn` is what's used?
                 try:
                     eps: list = await ipc_server.listen_on(
                         accept_addrs=accept_addrs,
-                        stream_handler_nursery=service_nursery,
+                        stream_handler_nursery=service_tn,
                     )
                     log.runtime(
                         f'Booted IPC server\n'
@@ -1546,7 +1603,7 @@ async def async_main(
                     )
                     assert (
                         (eps[0].listen_tn)
-                        is not service_nursery
+                        is not service_tn
                     )
 
                 except OSError as oserr:
@@ -1708,7 +1765,7 @@ async def async_main(
 
         # XXX TODO but hard XXX
         # we can't actually do this bc the debugger uses the
-        # _service_n to spawn the lock task, BUT, in theory if we had
+        # _service_tn to spawn the lock task, BUT, in theory if we had
         # the root nursery surround this finally block it might be
         # actually possible to debug THIS machinery in the same way
         # as user task code?

tractor/_spawn.py

@@ -236,10 +236,6 @@ async def hard_kill(
     # whilst also hacking on it XD
     # terminate_after: int = 99999,
 
-    # NOTE: for mucking with `.pause()`-ing inside the runtime
-    # whilst also hacking on it XD
-    # terminate_after: int = 99999,
-
 ) -> None:
     '''
     Un-gracefully terminate an OS level `trio.Process` after timeout.
@@ -301,6 +297,23 @@ async def hard_kill(
     # zombies (as a feature) we ask the OS to do send in the
     # removal swad as the last resort.
     if cs.cancelled_caught:
+
+        # TODO? attempt at intermediary-rent-sub
+        # with child in debug lock?
+        # |_https://github.com/goodboy/tractor/issues/320
+        #
+        # if not is_root_process():
+        #     log.warning(
+        #         'Attempting to acquire debug-REPL-lock before zombie reap!'
+        #     )
+        #     with trio.CancelScope(shield=True):
+        #         async with debug.acquire_debug_lock(
+        #             subactor_uid=current_actor().uid,
+        #         ) as _ctx:
+        #             log.warning(
+        #                 'Acquired debug lock, child ready to be killed ??\n'
+        #             )
+
         # TODO: toss in the skynet-logo face as ascii art?
         log.critical(
             # 'Well, the #ZOMBIE_LORD_IS_HERE# to collect\n'

tractor/_supervise.py

@@ -643,8 +643,9 @@ _shutdown_msg: str = (
     'Actor-runtime-shutdown'
 )
 
-# @api_frame
+
 @acm
+# @api_frame
 async def open_nursery(
     *,  # named params only!
     hide_tb: bool = True,

tractor/devx/_stackscope.py

@@ -237,9 +237,9 @@ def enable_stack_on_sig(
     try:
         import stackscope
     except ImportError:
-        log.error(
+        log.warning(
-            '`stackscope` not installed for use in debug mode!\n'
+            'The `stackscope` lib is not installed!\n'
-            '`Ignoring {enable_stack_on_sig!r} call!\n'
+            '`Ignoring enable_stack_on_sig() call!\n'
         )
         return None
 

tractor/devx/debug/_post_mortem.py

@@ -250,7 +250,7 @@ async def _maybe_enter_pm(
     *,
     tb: TracebackType|None = None,
     api_frame: FrameType|None = None,
-    hide_tb: bool = False,
+    hide_tb: bool = True,
 
     # only enter debugger REPL when returns `True`
     debug_filter: Callable[

tractor/devx/debug/_trace.py

@@ -58,6 +58,7 @@ from tractor._context import Context
 from tractor import _state
 from tractor._exceptions import (
     NoRuntime,
+    InternalError,
 )
 from tractor._state import (
     current_actor,
@@ -79,6 +80,9 @@ from ._sigint import (
     sigint_shield as sigint_shield,
     _ctlc_ignore_header as _ctlc_ignore_header
 )
+from ..pformat import (
+    ppfmt,
+)
 
 if TYPE_CHECKING:
     from trio.lowlevel import Task
@@ -477,12 +481,12 @@ async def _pause(
             # we have to figure out how to avoid having the service nursery
             # cancel on this task start? I *think* this works below:
             # ```python
-            #   actor._service_n.cancel_scope.shield = shield
+            #   actor._service_tn.cancel_scope.shield = shield
             # ```
             # but not entirely sure if that's a sane way to implement it?
 
             # NOTE currently we spawn the lock request task inside this
-            # subactor's global `Actor._service_n` so that the
+            # subactor's global `Actor._service_tn` so that the
             # lifetime of the lock-request can outlive the current
             # `._pause()` scope while the user steps through their
             # application code and when they finally exit the
@@ -506,7 +510,7 @@ async def _pause(
                 f'|_{task}\n'
             )
             with trio.CancelScope(shield=shield):
-                req_ctx: Context = await actor._service_n.start(
+                req_ctx: Context = await actor._service_tn.start(
                     partial(
                         request_root_stdio_lock,
                         actor_uid=actor.uid,
@@ -540,7 +544,7 @@ async def _pause(
             _repl_fail_report = None
 
         # when the actor is mid-runtime cancellation the
-        # `Actor._service_n` might get closed before we can spawn
+        # `Actor._service_tn` might get closed before we can spawn
         # the request task, so just ignore expected RTE.
         elif (
             isinstance(pause_err, RuntimeError)
@@ -985,7 +989,7 @@ def pause_from_sync(
                 # that output and assign the `repl` created above!
                 bg_task, _ = trio.from_thread.run(
                     afn=partial(
-                        actor._service_n.start,
+                        actor._service_tn.start,
                         partial(
                             _pause_from_bg_root_thread,
                             behalf_of_thread=thread,
@@ -1153,9 +1157,10 @@ def pause_from_sync(
                         'use_greenback',
                         False,
                 ):
-                    raise RuntimeError(
+                    raise InternalError(
-                        '`greenback` was never initialized in this actor!?\n\n'
+                        f'`greenback` was never initialized in this actor?\n'
-                        f'{_state._runtime_vars}\n'
+                        f'\n'
+                        f'{ppfmt(_state._runtime_vars)}\n'
                     ) from rte
 
                 raise

tractor/ipc/_chan.py

@@ -185,7 +185,9 @@ class Channel:
             addr,
             **kwargs,
         )
-        assert transport.raddr == addr
+        # XXX, for UDS *no!* since we recv the peer-pid and build out
+        # a new addr..
+        # assert transport.raddr == addr
         chan = Channel(transport=transport)
 
         # ?TODO, compact this into adapter level-methods?
@@ -301,7 +303,7 @@ class Channel:
         self,
         payload: Any,
 
-        hide_tb: bool = True,
+        hide_tb: bool = False,
 
     ) -> None:
         '''

tractor/ipc/_mp_bs.py

@@ -17,36 +17,59 @@
 Utils to tame mp non-SC madeness
 
 '''
+import platform
+
 
-# !TODO! in 3.13 this can be disabled (the-same/similarly) using
-# a flag,
-# - [ ] soo if it works like this, drop this module entirely for
-#   3.13+ B)
-#  |_https://docs.python.org/3/library/multiprocessing.shared_memory.html
-#
 def disable_mantracker():
     '''
     Disable all `multiprocessing` "resource tracking" machinery since
     it's an absolute multi-threaded mess of non-SC madness.
 
     '''
-    from multiprocessing import resource_tracker as mantracker
+    from multiprocessing.shared_memory import SharedMemory
 
-    # Tell the "resource tracker" thing to fuck off.
-    class ManTracker(mantracker.ResourceTracker):
-        def register(self, name, rtype):
-            pass
 
-        def unregister(self, name, rtype):
+    # 3.13+ only.. can pass `track=False` to disable
-            pass
+    # all the resource tracker bs.
+    # https://docs.python.org/3/library/multiprocessing.shared_memory.html
+    if (_py_313 := (
+            platform.python_version_tuple()[:-1]
+            >=
+            ('3', '13')
+        )
+    ):
+        from functools import partial
+        return partial(
+            SharedMemory,
+            track=False,
+        )
 
-        def ensure_running(self):
+    # !TODO, once we drop 3.12- we can obvi remove all this!
-            pass
+    else:
+        from multiprocessing import (
+            resource_tracker as mantracker,
+        )
 
-    # "know your land and know your prey"
+        # Tell the "resource tracker" thing to fuck off.
-    # https://www.dailymotion.com/video/x6ozzco
+        class ManTracker(mantracker.ResourceTracker):
-    mantracker._resource_tracker = ManTracker()
+            def register(self, name, rtype):
-    mantracker.register = mantracker._resource_tracker.register
+                pass
-    mantracker.ensure_running = mantracker._resource_tracker.ensure_running
+
-    mantracker.unregister = mantracker._resource_tracker.unregister
+            def unregister(self, name, rtype):
-    mantracker.getfd = mantracker._resource_tracker.getfd
+                pass
+
+            def ensure_running(self):
+                pass
+
+        # "know your land and know your prey"
+        # https://www.dailymotion.com/video/x6ozzco
+        mantracker._resource_tracker = ManTracker()
+        mantracker.register = mantracker._resource_tracker.register
+        mantracker.ensure_running = mantracker._resource_tracker.ensure_running
+        mantracker.unregister = mantracker._resource_tracker.unregister
+        mantracker.getfd = mantracker._resource_tracker.getfd
+
+        # use std type verbatim
+        shmT = SharedMemory
+
+    return shmT

tractor/ipc/_server.py

@@ -1001,7 +1001,11 @@ class Server(Struct):
             partial(
                 _serve_ipc_eps,
                 server=self,
-                stream_handler_tn=stream_handler_nursery,
+                stream_handler_tn=(
+                    stream_handler_nursery
+                    or
+                    self._stream_handler_tn
+                ),
                 listen_addrs=accept_addrs,
             )
         )
@@ -1145,13 +1149,17 @@ async def open_ipc_server(
 
     async with maybe_open_nursery(
         nursery=parent_tn,
-    ) as rent_tn:
+    ) as parent_tn:
         no_more_peers = trio.Event()
         no_more_peers.set()
 
         ipc_server = IPCServer(
-            _parent_tn=rent_tn,
+            _parent_tn=parent_tn,
-            _stream_handler_tn=stream_handler_tn or rent_tn,
+            _stream_handler_tn=(
+                stream_handler_tn
+                or
+                parent_tn
+            ),
             _no_more_peers=no_more_peers,
         )
         try:

tractor/ipc/_shm.py

@@ -23,14 +23,15 @@ considered optional within the context of this runtime-library.
 
 """
 from __future__ import annotations
+from multiprocessing import shared_memory as shm
+from multiprocessing.shared_memory import (
+    # SharedMemory,
+    ShareableList,
+)
+import platform
 from sys import byteorder
 import time
 from typing import Optional
-from multiprocessing import shared_memory as shm
-from multiprocessing.shared_memory import (
-    SharedMemory,
-    ShareableList,
-)
 
 from msgspec import (
     Struct,
@@ -61,7 +62,7 @@ except ImportError:
 log = get_logger(__name__)
 
 
-disable_mantracker()
+SharedMemory = disable_mantracker()
 
 
 class SharedInt:
@@ -797,8 +798,15 @@ def open_shm_list(
     # "close" attached shm on actor teardown
     try:
         actor = tractor.current_actor()
+
         actor.lifetime_stack.callback(shml.shm.close)
-        actor.lifetime_stack.callback(shml.shm.unlink)
+
+        # XXX on 3.13+ we don't need to call this?
+        # -> bc we pass `track=False` for `SharedMemeory` orr?
+        if (
+            platform.python_version_tuple()[:-1] < ('3', '13')
+        ):
+            actor.lifetime_stack.callback(shml.shm.unlink)
     except RuntimeError:
         log.warning('tractor runtime not active, skipping teardown steps')
 

tractor/ipc/_transport.py

@@ -430,20 +430,25 @@ class MsgpackTransport(MsgTransport):
                 return await self.stream.send_all(size + bytes_data)
             except (
                 trio.BrokenResourceError,
-            ) as bre:
+                trio.ClosedResourceError,
-                trans_err = bre
+            ) as _re:
+                trans_err = _re
                 tpt_name: str = f'{type(self).__name__!r}'
+
                 match trans_err:
+
+                    # XXX, specifc to UDS transport and its,
+                    # well, "speediness".. XD
+                    # |_ likely todo with races related to how fast
+                    #    the socket is setup/torn-down on linux
+                    #    as it pertains to rando pings from the
+                    #    `.discovery` subsys and protos.
                     case trio.BrokenResourceError() if (
-                        '[Errno 32] Broken pipe' in trans_err.args[0]
+                        '[Errno 32] Broken pipe'
-                        # ^XXX, specifc to UDS transport and its,
+                        in
-                        # well, "speediness".. XD
+                        trans_err.args[0]
-                        # |_ likely todo with races related to how fast
-                        #    the socket is setup/torn-down on linux
-                        #    as it pertains to rando pings from the
-                        #    `.discovery` subsys and protos.
                     ):
-                        raise TransportClosed.from_src_exc(
+                        tpt_closed = TransportClosed.from_src_exc(
                             message=(
                                 f'{tpt_name} already closed by peer\n'
                             ),
@@ -451,14 +456,31 @@ class MsgpackTransport(MsgTransport):
                             src_exc=trans_err,
                             raise_on_report=True,
                             loglevel='transport',
-                        ) from bre
+                        )
+                        raise tpt_closed from trans_err
+
+                    # case trio.ClosedResourceError() if (
+                    #     'this socket was already closed'
+                    #     in
+                    #     trans_err.args[0]
+                    # ):
+                    #     tpt_closed = TransportClosed.from_src_exc(
+                    #         message=(
+                    #             f'{tpt_name} already closed by peer\n'
+                    #         ),
+                    #         body=f'{self}\n',
+                    #         src_exc=trans_err,
+                    #         raise_on_report=True,
+                    #         loglevel='transport',
+                    #     )
+                    #     raise tpt_closed from trans_err
 
                     # unless the disconnect condition falls under "a
                     # normal operation breakage" we usualy console warn
                     # about it.
                     case _:
                         log.exception(
-                            '{tpt_name} layer failed pre-send ??\n'
+                            f'{tpt_name} layer failed pre-send ??\n'
                         )
                         raise trans_err
 
@@ -503,7 +525,7 @@ class MsgpackTransport(MsgTransport):
     def pformat(self) -> str:
         return (
             f'<{type(self).__name__}(\n'
-            f' |_peers: 2\n'
+            f' |_peers: 1\n'
             f'   laddr: {self._laddr}\n'
             f'   raddr: {self._raddr}\n'
             # f'\n'

tractor/ipc/_uds.py

@@ -18,6 +18,9 @@ Unix Domain Socket implementation of tractor.ipc._transport.MsgTransport protoco
 
 '''
 from __future__ import annotations
+from contextlib import (
+    contextmanager as cm,
+)
 from pathlib import Path
 import os
 from socket import (
@@ -29,6 +32,7 @@ from socket import (
 )
 import struct
 from typing import (
+    Type,
     TYPE_CHECKING,
     ClassVar,
 )
@@ -99,8 +103,6 @@ class UDSAddress(
             self.filedir
             or
             self.def_bindspace
-            # or
-            # get_rt_dir()
         )
 
     @property
@@ -205,12 +207,35 @@ class UDSAddress(
             f']'
         )
 
+@cm
+def _reraise_as_connerr(
+    src_excs: tuple[Type[Exception]],
+    addr: UDSAddress,
+):
+    try:
+        yield
+    except src_excs as src_exc:
+        raise ConnectionError(
+            f'Bad UDS socket-filepath-as-address ??\n'
+            f'{addr}\n'
+            f' |_sockpath: {addr.sockpath}\n'
+            f'\n'
+            f'from src: {src_exc!r}\n'
+        ) from src_exc
+
 
 async def start_listener(
     addr: UDSAddress,
     **kwargs,
 ) -> SocketListener:
-    # sock = addr._sock = socket.socket(
+    '''
+    Start listening for inbound connections via
+    a `trio.SocketListener` (task) which `socket.bind()`s on `addr`.
+
+    Note, if the `UDSAddress.bindspace: Path` directory dne it is
+    implicitly created.
+
+    '''
     sock = socket.socket(
         socket.AF_UNIX,
         socket.SOCK_STREAM
@@ -221,17 +246,25 @@ async def start_listener(
         f'|_{addr}\n'
     )
 
+    # ?TODO? should we use the `actor.lifetime_stack`
+    # to rm on shutdown?
     bindpath: Path = addr.sockpath
-    try:
+    if not (bs := addr.bindspace).is_dir():
+        log.info(
+            'Creating bindspace dir in file-sys\n'
+            f'>{{\n'
+            f'|_{bs!r}\n'
+        )
+        bs.mkdir()
+
+    with _reraise_as_connerr(
+        src_excs=(
+            FileNotFoundError,
+            OSError,
+        ),
+        addr=addr
+    ):
         await sock.bind(str(bindpath))
-    except (
-        FileNotFoundError,
-    ) as fdne:
-        raise ConnectionError(
-            f'Bad UDS socket-filepath-as-address ??\n'
-            f'{addr}\n'
-            f' |_sockpath: {addr.sockpath}\n'
-        ) from fdne
 
     sock.listen(1)
     log.info(
@@ -356,27 +389,30 @@ class MsgpackUDSStream(MsgpackTransport):
         # `.setsockopt()` call tells the OS provide it; the client
         # pid can then be read on server/listen() side via
         # `get_peer_info()` above.
-        try:
+
+        with _reraise_as_connerr(
+            src_excs=(
+                FileNotFoundError,
+            ),
+            addr=addr
+        ):
             stream = await open_unix_socket_w_passcred(
                 str(sockpath),
                 **kwargs
             )
-        except (
-            FileNotFoundError,
-        ) as fdne:
-            raise ConnectionError(
-                f'Bad UDS socket-filepath-as-address ??\n'
-                f'{addr}\n'
-                f' |_sockpath: {sockpath}\n'
-            ) from fdne
 
-        stream = MsgpackUDSStream(
+        tpt_stream = MsgpackUDSStream(
             stream,
             prefix_size=prefix_size,
             codec=codec
         )
-        stream._raddr = addr
+        # XXX assign from new addrs after peer-PID extract!
-        return stream
+        (
+            tpt_stream._laddr,
+            tpt_stream._raddr,
+        ) = cls.get_stream_addrs(stream)
+
+        return tpt_stream
 
     @classmethod
     def get_stream_addrs(

tractor/to_asyncio.py

@@ -130,6 +130,7 @@ class LinkedTaskChannel(
     _trio_task: trio.Task
     _aio_task_complete: trio.Event
 
+    _closed_by_aio_task: bool = False
     _suppress_graceful_exits: bool = True
 
     _trio_err: BaseException|None = None
@@ -208,10 +209,15 @@ class LinkedTaskChannel(
     async def aclose(self) -> None:
         await self._from_aio.aclose()
 
-    def started(
+    # ?TODO? async version of this?
+    def started_nowait(
         self,
         val: Any = None,
     ) -> None:
+        '''
+        Synchronize aio-side with its trio-parent.
+
+        '''
         self._aio_started_val = val
         return self._to_trio.send_nowait(val)
 
@@ -242,6 +248,7 @@ class LinkedTaskChannel(
             # cycle on the trio side?
             # await trio.lowlevel.checkpoint()
             return await self._from_aio.receive()
+
         except BaseException as err:
             async with translate_aio_errors(
                 chan=self,
@@ -319,7 +326,7 @@ def _run_asyncio_task(
     qsize: int = 1,
     provide_channels: bool = False,
     suppress_graceful_exits: bool = True,
-    hide_tb: bool = False,
+    hide_tb: bool = True,
     **kwargs,
 
 ) -> LinkedTaskChannel:
@@ -347,18 +354,6 @@ def _run_asyncio_task(
         # value otherwise it would just return ;P
         assert qsize > 1
 
-    if provide_channels:
-        assert 'to_trio' in args
-
-    # allow target func to accept/stream results manually by name
-    if 'to_trio' in args:
-        kwargs['to_trio'] = to_trio
-
-    if 'from_trio' in args:
-        kwargs['from_trio'] = from_trio
-
-    coro = func(**kwargs)
-
     trio_task: trio.Task = trio.lowlevel.current_task()
     trio_cs = trio.CancelScope()
     aio_task_complete = trio.Event()
@@ -373,6 +368,25 @@ def _run_asyncio_task(
         _suppress_graceful_exits=suppress_graceful_exits,
     )
 
+    # allow target func to accept/stream results manually by name
+    if 'to_trio' in args:
+        kwargs['to_trio'] = to_trio
+
+    if 'from_trio' in args:
+        kwargs['from_trio'] = from_trio
+
+    if 'chan' in args:
+        kwargs['chan'] = chan
+
+    if provide_channels:
+        assert (
+            'to_trio' in args
+            or
+            'chan' in args
+        )
+
+    coro = func(**kwargs)
+
     async def wait_on_coro_final_result(
         to_trio: trio.MemorySendChannel,
         coro: Awaitable,
@@ -445,9 +459,23 @@ def _run_asyncio_task(
                         f'Task exited with final result: {result!r}\n'
                     )
 
-                # only close the sender side which will relay
+                # XXX ALWAYS close the child-`asyncio`-task-side's
-                # a `trio.EndOfChannel` to the trio (consumer) side.
+                # `to_trio` handle which will in turn relay
+                # a `trio.EndOfChannel` to the `trio`-parent.
+                # Consequently the parent `trio` task MUST ALWAYS
+                # check for any `chan._aio_err` to be raised when it
+                # receives an EoC.
+                #
+                # NOTE, there are 2 EoC cases,
+                # - normal/graceful EoC due to the aio-side actually
+                #   terminating its "streaming", but the task did not
+                #   error and is not yet complete.
+                #
+                # - the aio-task terminated and we specially mark the
+                #   closure as due to the `asyncio.Task`'s exit.
+                #
                 to_trio.close()
+                chan._closed_by_aio_task = True
 
             aio_task_complete.set()
             log.runtime(
@@ -645,8 +673,9 @@ def _run_asyncio_task(
                 not trio_cs.cancel_called
             ):
                 log.cancel(
-                    f'Cancelling `trio` side due to aio-side src exc\n'
+                    f'Cancelling trio-side due to aio-side src exc\n'
-                    f'{curr_aio_err}\n'
+                    f'\n'
+                    f'{curr_aio_err!r}\n'
                     f'\n'
                     f'(c>\n'
                     f'  |_{trio_task}\n'
@@ -758,6 +787,7 @@ async def translate_aio_errors(
     aio_done_before_trio: bool = aio_task.done()
     assert aio_task
     trio_err: BaseException|None = None
+    eoc: trio.EndOfChannel|None = None
     try:
         yield  # back to one of the cross-loop apis
     except trio.Cancelled as taskc:
@@ -789,12 +819,48 @@ async def translate_aio_errors(
         # )
         # raise
 
-    # XXX always passthrough EoC since this translator is often
+    # XXX EoC is a special SIGNAL from the aio-side here!
-    # called from `LinkedTaskChannel.receive()` which we want
+    # There are 2 cases to handle:
-    # passthrough and further we have no special meaning for it in
+    # 1. the "EoC passthrough" case.
-    # terms of relaying errors or signals from the aio side!
+    #   - the aio-task actually closed the channel "gracefully" and
-    except trio.EndOfChannel as eoc:
+    #     the trio-task should unwind any ongoing channel
-        trio_err = chan._trio_err = eoc
+    #     iteration/receiving,
+    #  |_this exc-translator wraps calls to `LinkedTaskChannel.receive()`
+    #    in which case we want to relay the actual "end-of-chan" for
+    #    iteration purposes.
+    #
+    # 2. relaying the "asyncio.Task termination" case.
+    #   - if the aio-task terminates, maybe with an error, AND the
+    #    `open_channel_from()` API was used, it will always signal
+    #    that termination.
+    #  |_`wait_on_coro_final_result()` always calls
+    #    `to_trio.close()` when `provide_channels=True` so we need to
+    #    always check if there is an aio-side exc which needs to be
+    #    relayed to the parent trio side!
+    #  |_in this case the special `chan._closed_by_aio_task` is
+    #    ALWAYS set.
+    #
+    except trio.EndOfChannel as _eoc:
+        eoc = _eoc
+        if (
+            chan._closed_by_aio_task
+            and
+            aio_err
+        ):
+            log.cancel(
+                f'The asyncio-child task terminated due to error\n'
+                f'{aio_err!r}\n'
+            )
+            chan._trio_to_raise = aio_err
+            trio_err = chan._trio_err = eoc
+            #
+            # ?TODO?, raise something like a,
+            # chan._trio_to_raise = AsyncioErrored()
+            # BUT, with the tb rewritten to reflect the underlying
+            # call stack?
+        else:
+            trio_err = chan._trio_err = eoc
+
         raise eoc
 
     # NOTE ALSO SEE the matching note in the `cancel_trio()` asyncio
@@ -1047,7 +1113,7 @@ async def translate_aio_errors(
         #
         if wait_on_aio_task:
             await chan._aio_task_complete.wait()
-            log.info(
+            log.debug(
                 'asyncio-task is done and unblocked trio-side!\n'
             )
 
@@ -1064,11 +1130,17 @@ async def translate_aio_errors(
         trio_to_raise: (
             AsyncioCancelled|
             AsyncioTaskExited|
+            Exception|  # relayed from aio-task
             None
         ) = chan._trio_to_raise
 
+        raise_from: Exception = (
+            trio_err if (aio_err is trio_to_raise)
+            else aio_err
+        )
+
         if not suppress_graceful_exits:
-            raise trio_to_raise from (aio_err or trio_err)
+            raise trio_to_raise from raise_from
 
         if trio_to_raise:
             match (
@@ -1101,7 +1173,7 @@ async def translate_aio_errors(
                         )
                         return
                 case _:
-                    raise trio_to_raise from (aio_err or trio_err)
+                    raise trio_to_raise from raise_from
 
         # Check if the asyncio-side is the cause of the trio-side
         # error.
@@ -1167,7 +1239,6 @@ async def run_task(
 
 @acm
 async def open_channel_from(
-
     target: Callable[..., Any],
     suppress_graceful_exits: bool = True,
     **target_kwargs,
@@ -1201,7 +1272,6 @@ async def open_channel_from(
                     # deliver stream handle upward
                     yield first, chan
             except trio.Cancelled as taskc:
-                # await tractor.pause(shield=True)  # ya it worx ;)
                 if cs.cancel_called:
                     if isinstance(chan._trio_to_raise, AsyncioCancelled):
                         log.cancel(

tractor/trionics/__init__.py

@@ -31,7 +31,7 @@ from ._broadcast import (
 )
 from ._beg import (
     collapse_eg as collapse_eg,
-    maybe_collapse_eg as maybe_collapse_eg,
+    get_collapsed_eg as get_collapsed_eg,
     is_multi_cancelled as is_multi_cancelled,
 )
 from ._taskc import (

tractor/trionics/_beg.py

@@ -15,8 +15,9 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 '''
-`BaseExceptionGroup` related utils and helpers pertaining to
+`BaseExceptionGroup` utils and helpers pertaining to
-first-class-`trio` from a historical perspective B)
+first-class-`trio` from a "historical" perspective, like "loose
+exception group" task-nurseries.
 
 '''
 from contextlib import (
@@ -24,28 +25,83 @@ from contextlib import (
 )
 from typing import (
     Literal,
+    Type,
 )
 
 import trio
+# from trio._core._concat_tb import (
+#     concat_tb,
+# )
 
 
-def maybe_collapse_eg(
+# XXX NOTE
+# taken verbatim from `trio._core._run` except,
+# - remove the NONSTRICT_EXCEPTIONGROUP_NOTE deprecation-note
+#   guard-check; we know we want an explicit collapse.
+# - mask out tb rewriting in collapse case, i don't think it really
+#   matters?
+#
+def collapse_exception_group(
+    excgroup: BaseExceptionGroup[BaseException],
+) -> BaseException:
+    """Recursively collapse any single-exception groups into that single contained
+    exception.
+
+    """
+    exceptions = list(excgroup.exceptions)
+    modified = False
+    for i, exc in enumerate(exceptions):
+        if isinstance(exc, BaseExceptionGroup):
+            new_exc = collapse_exception_group(exc)
+            if new_exc is not exc:
+                modified = True
+                exceptions[i] = new_exc
+
+    if (
+        len(exceptions) == 1
+        and isinstance(excgroup, BaseExceptionGroup)
+
+        # XXX trio's loose-setting condition..
+        # and NONSTRICT_EXCEPTIONGROUP_NOTE in getattr(excgroup, "__notes__", ())
+    ):
+        # exceptions[0].__traceback__ = concat_tb(
+        #     excgroup.__traceback__,
+        #     exceptions[0].__traceback__,
+        # )
+        return exceptions[0]
+    elif modified:
+        return excgroup.derive(exceptions)
+    else:
+        return excgroup
+
+
+def get_collapsed_eg(
     beg: BaseExceptionGroup,
-) -> BaseException|bool:
+
+) -> BaseException|None:
     '''
-    If the input beg can collapse to a single non-eg sub-exception,
+    If the input beg can collapse to a single sub-exception which is
-    return it instead.
+    itself **not** an eg, return it.
 
     '''
-    if len(excs := beg.exceptions) == 1:
+    maybe_exc = collapse_exception_group(beg)
-        return excs[0]
+    if maybe_exc is beg:
+        return None
 
-    return False
+    return maybe_exc
 
 
 @acm
 async def collapse_eg(
     hide_tb: bool = True,
+
+    # XXX, for ex. will always show begs containing single taskc
+    ignore: set[Type[BaseException]] = {
+        # trio.Cancelled,
+    },
+    add_notes: bool = True,
+
+    bp: bool = False,
 ):
     '''
     If `BaseExceptionGroup` raised in the body scope is
@@ -57,16 +113,55 @@ async def collapse_eg(
     __tracebackhide__: bool = hide_tb
     try:
         yield
-    except* BaseException as beg:
+    except BaseExceptionGroup as _beg:
+        beg = _beg
+
         if (
-            exc := maybe_collapse_eg(beg)
+            bp
+            and
+            len(beg.exceptions) > 1
         ):
+            import tractor
+            if tractor.current_actor(
+                err_on_no_runtime=False,
+            ):
+                await tractor.pause(shield=True)
+            else:
+                breakpoint()
+
+        if (
+            (exc := get_collapsed_eg(beg))
+            and
+            type(exc) not in ignore
+        ):
+
+            # TODO? report number of nested groups it was collapsed
+            # *from*?
+            if add_notes:
+                from_group_note: str = (
+                    '( ^^^ this exc was collapsed from a group ^^^ )\n'
+                )
+                if (
+                    from_group_note
+                    not in
+                    getattr(exc, "__notes__", ())
+                ):
+                    exc.add_note(from_group_note)
+
+            # raise exc
+            # ^^ this will leave the orig beg tb above with the
+            # "during the handling of <beg> the following.."
+            # So, instead do..
+            #
             if cause := exc.__cause__:
                 raise exc from cause
+            else:
+                # suppress "during handling of <the beg>"
+                # output in tb/console.
+                raise exc from None
 
-            raise exc
+        # keep original
-
+        raise # beg
-        raise beg
 
 
 def is_multi_cancelled(

tractor/trionics/_mngrs.py

@@ -40,7 +40,10 @@ from typing import (
 import trio
 from tractor._state import current_actor
 from tractor.log import get_logger
-from ._beg import collapse_eg
+# from ._beg import collapse_eg
+# from ._taskc import (
+#     maybe_raise_from_masking_exc,
+# )
 
 
 if TYPE_CHECKING:
@@ -106,6 +109,9 @@ async def _enter_and_wait(
 async def gather_contexts(
     mngrs: Sequence[AsyncContextManager[T]],
 
+    # caller can provide their own scope
+    tn: trio.Nursery|None = None,
+
 ) -> AsyncGenerator[
     tuple[
         T | None,
@@ -148,34 +154,45 @@ async def gather_contexts(
             '`.trionics.gather_contexts()` input mngrs is empty?\n'
             '\n'
             'Did try to use inline generator syntax?\n'
-            'Use a non-lazy iterator or sequence-type intead!\n'
+            'Check that list({mngrs}) works!\n'
+            # 'or sequence-type intead!\n'
+            # 'Use a non-lazy iterator or sequence-type intead!\n'
         )
 
-    async with (
+    try:
-        collapse_eg(),
+        async with (
-        trio.open_nursery() as tn,
+            #
-    ):
+            # ?TODO, does including these (eg-collapsing,
-        for mngr in mngrs:
+            # taskc-unmasking) improve tb noise-reduction/legibility?
-            tn.start_soon(
+            #
-                _enter_and_wait,
+            # collapse_eg(),
-                mngr,
+            maybe_open_nursery(
-                unwrapped,
+                nursery=tn,
-                all_entered,
+            ) as tn,
-                parent_exit,
+            # maybe_raise_from_masking_exc(),
-                seed,
+        ):
-            )
+            for mngr in mngrs:
+                tn.start_soon(
+                    _enter_and_wait,
+                    mngr,
+                    unwrapped,
+                    all_entered,
+                    parent_exit,
+                    seed,
+                )
 
-        # deliver control once all managers have started up
+            # deliver control to caller once all ctx-managers have
-        await all_entered.wait()
+            # started (yielded back to us).
-
+            await all_entered.wait()
-        try:
             yield tuple(unwrapped.values())
-        finally:
-            # XXX NOTE: this is ABSOLUTELY REQUIRED to avoid
-            # the following wacky bug:
-            # <tractorbugurlhere>
             parent_exit.set()
 
+    finally:
+        # XXX NOTE: this is ABSOLUTELY REQUIRED to avoid
+        # the following wacky bug:
+        # <tractorbugurlhere>
+        parent_exit.set()
+
 
 # Per actor task caching helpers.
 # Further potential examples of interest:
@@ -187,7 +204,7 @@ class _Cache:
     a kept-alive-while-in-use async resource.
 
     '''
-    service_n: Optional[trio.Nursery] = None
+    service_tn: Optional[trio.Nursery] = None
     locks: dict[Hashable, trio.Lock] = {}
     users: int = 0
     values: dict[Any,  Any] = {}
@@ -228,6 +245,9 @@ async def maybe_open_context(
     kwargs: dict = {},
     key: Hashable | Callable[..., Hashable] = None,
 
+    # caller can provide their own scope
+    tn: trio.Nursery|None = None,
+
 ) -> AsyncIterator[tuple[bool, T]]:
     '''
     Maybe open an async-context-manager (acm) if there is not already
@@ -260,43 +280,94 @@ async def maybe_open_context(
     # have it not be closed until all consumers have exited (which is
     # currently difficult to implement any other way besides using our
     # pre-allocated runtime instance..)
-    service_n: trio.Nursery = current_actor()._service_n
+    if tn:
+        # TODO, assert tn is eventual parent of this task!
+        task: trio.Task = trio.lowlevel.current_task()
+        task_tn: trio.Nursery = task.parent_nursery
+        if not tn._cancel_status.encloses(
+            task_tn._cancel_status
+        ):
+            raise RuntimeError(
+                f'Mis-nesting of task under provided {tn} !?\n'
+                f'Current task is NOT a child(-ish)!!\n'
+                f'\n'
+                f'task: {task}\n'
+                f'task_tn: {task_tn}\n'
+            )
+        service_tn = tn
+    else:
+        service_tn: trio.Nursery = current_actor()._service_tn
 
     # TODO: is there any way to allocate
     # a 'stays-open-till-last-task-finshed nursery?
-    # service_n: trio.Nursery
+    # service_tn: trio.Nursery
-    # async with maybe_open_nursery(_Cache.service_n) as service_n:
+    # async with maybe_open_nursery(_Cache.service_tn) as service_tn:
-    #     _Cache.service_n = service_n
+    #     _Cache.service_tn = service_tn
 
+    cache_miss_ke: KeyError|None = None
+    maybe_taskc: trio.Cancelled|None = None
     try:
         # **critical section** that should prevent other tasks from
         # checking the _Cache until complete otherwise the scheduler
         # may switch and by accident we create more then one resource.
         yielded = _Cache.values[ctx_key]
 
-    except KeyError:
+    except KeyError as _ke:
-        log.debug(f'Allocating new {acm_func} for {ctx_key}')
+        # XXX, stay mutexed up to cache-miss yield
-        mngr = acm_func(**kwargs)
+        try:
-        resources = _Cache.resources
+            cache_miss_ke = _ke
-        assert not resources.get(ctx_key), f'Resource exists? {ctx_key}'
+            log.debug(
-        resources[ctx_key] = (service_n, trio.Event())
+                f'Allocating new @acm-func entry\n'
+                f'ctx_key={ctx_key}\n'
+                f'acm_func={acm_func}\n'
+            )
+            mngr = acm_func(**kwargs)
+            resources = _Cache.resources
+            assert not resources.get(ctx_key), f'Resource exists? {ctx_key}'
+            resources[ctx_key] = (service_tn, trio.Event())
+            yielded: Any = await service_tn.start(
+                _Cache.run_ctx,
+                mngr,
+                ctx_key,
+            )
+            _Cache.users += 1
+        finally:
+            # XXX, since this runs from an `except` it's a checkpoint
+            # whih can be `trio.Cancelled`-masked.
+            #
+            # NOTE, in that case the mutex is never released by the
+            # (first and) caching task and **we can't** simply shield
+            # bc that will inf-block on the `await
+            # no_more_users.wait()`.
+            #
+            # SO just always unlock!
+            lock.release()
 
-        # sync up to the mngr's yielded value
+        try:
-        yielded = await service_n.start(
+            yield (
-            _Cache.run_ctx,
+                False,  # cache_hit = "no"
-            mngr,
+                yielded,
-            ctx_key,
+            )
-        )
+        except trio.Cancelled as taskc:
-        _Cache.users += 1
+            maybe_taskc = taskc
-        lock.release()
+            log.cancel(
-        yield (
+                f'Cancelled from cache-miss entry\n'
-            False,  # cache_hit = "no"
+                f'\n'
-            yielded,
+                f'ctx_key: {ctx_key!r}\n'
-        )
+                f'mngr: {mngr!r}\n'
+            )
+            # XXX, always unset ke from cancelled context
+            # since we never consider it a masked exc case!
+            # - bc this can be called directly ty `._rpc._invoke()`?
+            #
+            if maybe_taskc.__context__ is cache_miss_ke:
+                maybe_taskc.__context__ = None
+
+            raise taskc
 
     else:
         _Cache.users += 1
-        log.runtime(
+        log.debug(
             f'Re-using cached resource for user {_Cache.users}\n\n'
             f'{ctx_key!r} -> {type(yielded)}\n'
 
@@ -312,6 +383,13 @@ async def maybe_open_context(
         )
 
     finally:
+        if lock.locked():
+            stats: trio.LockStatistics = lock.statistics()
+            log.error(
+                f'Lock left locked by last owner !?\n'
+                f'{stats}\n'
+            )
+
         _Cache.users -= 1
 
         if yielded is not None:

tractor/trionics/_taskc.py

@@ -60,8 +60,8 @@ def find_masked_excs(
     return None
 
 
-# XXX, relevant ish discussion @ `trio`-core,
+# XXX, relevant discussion @ `trio`-core,
-# https://github.com/python-trio/trio/issues/455#issuecomment-2785122216
+# https://github.com/python-trio/trio/issues/455
 #
 @acm
 async def maybe_raise_from_masking_exc(
@@ -113,7 +113,6 @@ async def maybe_raise_from_masking_exc(
     )
     matching: list[BaseException]|None = None
     maybe_eg: ExceptionGroup|None
-    maybe_eg: ExceptionGroup|None
 
     if tn:
         try:  # handle egs