`_root`: drop unused `typing` import

Allows forcing the opened actor to either obtain the passed registry
addrs or raise a runtime error.

tests/conftest.py

@@ -93,12 +93,18 @@ _reg_addr: tuple[str, int] = (
     '127.0.0.1',
     random.randint(1000, 9999),
 )
-_arb_addr = _reg_addr
 
 
 @pytest.fixture(scope='session')
-def arb_addr():
-    return _arb_addr
+def reg_addr() -> tuple[str, int]:
+
+    # globally override the runtime to the per-test-session-dynamic
+    # addr so that all tests never conflict with any other actor
+    # tree using the default.
+    from tractor import _root
+    _root._default_lo_addrs = [_reg_addr]
+
+    return _reg_addr
 
 
 def pytest_generate_tests(metafunc):
@@ -140,30 +146,35 @@ def sig_prog(proc, sig):
 def daemon(
     loglevel: str,
     testdir,
-    arb_addr: tuple[str, int],
+    reg_addr: tuple[str, int],
 ):
     '''
-    Run a daemon actor as a "remote arbiter".
+    Run a daemon root actor as a separate actor-process tree and
+    "remote registrar" for discovery-protocol related tests.
 
     '''
     if loglevel in ('trace', 'debug'):
-        # too much logging will lock up the subproc (smh)
-        loglevel = 'info'
+        # XXX: too much logging will lock up the subproc (smh)
+        loglevel: str = 'info'
 
-    cmdargs = [
-        sys.executable, '-c',
-        "import tractor; tractor.run_daemon([], registry_addr={}, loglevel={})"
-        .format(
-            arb_addr,
-            "'{}'".format(loglevel) if loglevel else None)
+    code: str = (
+            "import tractor; "
+            "tractor.run_daemon([], registry_addrs={reg_addrs}, loglevel={ll})"
+    ).format(
+        reg_addrs=str([reg_addr]),
+        ll="'{}'".format(loglevel) if loglevel else None,
+    )
+    cmd: list[str] = [
+        sys.executable,
+        '-c', code,
     ]
-    kwargs = dict()
+    kwargs = {}
     if platform.system() == 'Windows':
         # without this, tests hang on windows forever
         kwargs['creationflags'] = subprocess.CREATE_NEW_PROCESS_GROUP
 
     proc = testdir.popen(
-        cmdargs,
+        cmd,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         **kwargs,

tests/test_debugger.py

@@ -10,6 +10,7 @@ TODO:
     - wonder if any of it'll work on OS X?
 
 """
+from functools import partial
 import itertools
 from typing import Optional
 import platform
@@ -26,6 +27,10 @@ from pexpect.exceptions import (
 from tractor._testing import (
     examples_dir,
 )
+from tractor.devx._debug import (
+    _pause_msg,
+    _crash_msg,
+)
 from conftest import (
     _ci_env,
 )
@@ -123,20 +128,52 @@ def expect(
         raise
 
 
+def in_prompt_msg(
+    prompt: str,
+    parts: list[str],
+
+    pause_on_false: bool = False,
+    print_prompt_on_false: bool = True,
+
+) -> bool:
+    '''
+    Predicate check if (the prompt's) std-streams output has all
+    `str`-parts in it.
+
+    Can be used in test asserts for bulk matching expected
+    log/REPL output for a given `pdb` interact point.
+
+    '''
+    for part in parts:
+        if part not in prompt:
+
+            if pause_on_false:
+                import pdbp
+                pdbp.set_trace()
+
+            if print_prompt_on_false:
+                print(prompt)
+
+            return False
+
+    return True
+
 def assert_before(
     child,
     patts: list[str],
 
+    **kwargs,
+
 ) -> None:
 
-    before = str(child.before.decode())
+    # as in before the prompt end
+    before: str = str(child.before.decode())
+    assert in_prompt_msg(
+        prompt=before,
+        parts=patts,
 
-    for patt in patts:
-        try:
-            assert patt in before
-        except AssertionError:
-            print(before)
-            raise
+        **kwargs
+    )
 
 
 @pytest.fixture(
@@ -166,7 +203,7 @@ def ctlc(
         # XXX: disable pygments highlighting for auto-tests
         # since some envs (like actions CI) will struggle
         # the the added color-char encoding..
-        from tractor._debug import TractorConfig
+        from tractor.devx._debug import TractorConfig
         TractorConfig.use_pygements = False
 
     yield use_ctlc
@@ -195,7 +232,10 @@ def test_root_actor_error(spawn, user_in_out):
     before = str(child.before.decode())
 
     # make sure expected logging and error arrives
-    assert "Attaching to pdb in crashed actor: ('root'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('root'"]
+    )
     assert 'AssertionError' in before
 
     # send user command
@@ -332,7 +372,10 @@ def test_subactor_error(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
 
     if do_next:
         child.sendline('n')
@@ -353,9 +396,15 @@ def test_subactor_error(
     before = str(child.before.decode())
 
     # root actor gets debugger engaged
-    assert "Attaching to pdb in crashed actor: ('root'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('root'"]
+    )
     # error is a remote error propagated from the subactor
-    assert "RemoteActorError: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
 
     # another round
     if ctlc:
@@ -380,7 +429,10 @@ def test_subactor_breakpoint(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     # do some "next" commands to demonstrate recurrent breakpoint
     # entries
@@ -396,7 +448,10 @@ def test_subactor_breakpoint(
         child.sendline('continue')
         child.expect(PROMPT)
         before = str(child.before.decode())
-        assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+        assert in_prompt_msg(
+            before,
+            [_pause_msg, "('breakpoint_forever'"]
+        )
 
         if ctlc:
             do_ctlc(child)
@@ -441,7 +496,10 @@ def test_multi_subactors(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -461,7 +519,10 @@ def test_multi_subactors(
     # first name_error failure
     child.expect(PROMPT)
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
     assert "NameError" in before
 
     if ctlc:
@@ -487,7 +548,10 @@ def test_multi_subactors(
     child.sendline('c')
     child.expect(PROMPT)
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -527,9 +591,12 @@ def test_multi_subactors(
     child.expect(PROMPT)
     before = str(child.before.decode())
 
-    assert_before(child, [
+    assert_before(
+        child, [
             # debugger attaches to root
-        "Attaching to pdb in crashed actor: ('root'",
+            # "Attaching to pdb in crashed actor: ('root'",
+            _crash_msg,
+            "('root'",
 
             # expect a multierror with exceptions for each sub-actor
             "RemoteActorError: ('breakpoint_forever'",
@@ -537,7 +604,8 @@ def test_multi_subactors(
             "RemoteActorError: ('spawn_error'",
             "RemoteActorError: ('name_error_1'",
             'bdb.BdbQuit',
-    ])
+        ]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -574,15 +642,22 @@ def test_multi_daemon_subactors(
     # the root's tty lock first so anticipate either crash
     # message on the first entry.
 
-    bp_forever_msg = "Attaching pdb to actor: ('bp_forever'"
+    bp_forev_parts = [_pause_msg, "('bp_forever'"]
+    bp_forev_in_msg = partial(
+        in_prompt_msg,
+        parts=bp_forev_parts,
+    )
+
     name_error_msg = "NameError: name 'doggypants' is not defined"
+    name_error_parts = [name_error_msg]
 
     before = str(child.before.decode())
-    if bp_forever_msg in before:
-        next_msg = name_error_msg
+
+    if bp_forev_in_msg(prompt=before):
+        next_parts = name_error_parts
 
     elif name_error_msg in before:
-        next_msg = bp_forever_msg
+        next_parts = bp_forev_parts
 
     else:
         raise ValueError("Neither log msg was found !?")
@@ -599,7 +674,10 @@ def test_multi_daemon_subactors(
 
     child.sendline('c')
     child.expect(PROMPT)
-    assert_before(child, [next_msg])
+    assert_before(
+        child,
+        next_parts,
+    )
 
     # XXX: hooray the root clobbering the child here was fixed!
     # IMO, this demonstrates the true power of SC system design.
@@ -607,7 +685,7 @@ def test_multi_daemon_subactors(
     # now the root actor won't clobber the bp_forever child
     # during it's first access to the debug lock, but will instead
     # wait for the lock to release, by the edge triggered
-    # ``_debug.Lock.no_remote_has_tty`` event before sending cancel messages
+    # ``devx._debug.Lock.no_remote_has_tty`` event before sending cancel messages
     # (via portals) to its underlings B)
 
     # at some point here there should have been some warning msg from
@@ -623,9 +701,15 @@ def test_multi_daemon_subactors(
     child.expect(PROMPT)
 
     try:
-        assert_before(child, [bp_forever_msg])
+        assert_before(
+            child,
+            bp_forev_parts,
+        )
     except AssertionError:
-        assert_before(child, [name_error_msg])
+        assert_before(
+            child,
+            name_error_parts,
+        )
 
     else:
         if ctlc:
@@ -637,7 +721,10 @@ def test_multi_daemon_subactors(
 
         child.sendline('c')
         child.expect(PROMPT)
-        assert_before(child, [name_error_msg])
+        assert_before(
+            child,
+            name_error_parts,
+        )
 
     # wait for final error in root
     # where it crashs with boxed error
@@ -647,7 +734,7 @@ def test_multi_daemon_subactors(
             child.expect(PROMPT)
             assert_before(
                 child,
-                [bp_forever_msg]
+                bp_forev_parts
             )
         except AssertionError:
             break
@@ -656,7 +743,9 @@ def test_multi_daemon_subactors(
         child,
         [
             # boxed error raised in root task
-            "Attaching to pdb in crashed actor: ('root'",
+            # "Attaching to pdb in crashed actor: ('root'",
+            _crash_msg,
+            "('root'",
             "_exceptions.RemoteActorError: ('name_error'",
         ]
     )
@@ -770,7 +859,7 @@ def test_multi_nested_subactors_error_through_nurseries(
 
     child = spawn('multi_nested_subactors_error_up_through_nurseries')
 
-    timed_out_early: bool = False
+    # timed_out_early: bool = False
 
     for send_char in itertools.cycle(['c', 'q']):
         try:
@@ -871,11 +960,14 @@ def test_root_nursery_cancels_before_child_releases_tty_lock(
 
     if not timed_out_early:
         before = str(child.before.decode())
-        assert_before(child, [
+        assert_before(
+            child,
+            [
                 "tractor._exceptions.RemoteActorError: ('spawner0'",
                 "tractor._exceptions.RemoteActorError: ('name_error'",
                 "NameError: name 'doggypants' is not defined",
-        ])
+            ],
+        )
 
 
 def test_root_cancels_child_context_during_startup(
@@ -909,8 +1001,10 @@ def test_different_debug_mode_per_actor(
 
     # only one actor should enter the debugger
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('debugged_boi'" in before
-    assert "RuntimeError" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('debugged_boi'", "RuntimeError"],
+    )
 
     if ctlc:
         do_ctlc(child)

tests/test_docs_examples.py

@@ -20,7 +20,7 @@ from tractor._testing import (
 def run_example_in_subproc(
     loglevel: str,
     testdir,
-    arb_addr: tuple[str, int],
+    reg_addr: tuple[str, int],
 ):
 
     @contextmanager

tests/test_rpc.py

@@ -15,9 +15,19 @@ async def sleep_back_actor(
     func_name,
     func_defined,
     exposed_mods,
+    *,
+    reg_addr: tuple,
 ):
     if actor_name:
-        async with tractor.find_actor(actor_name) as portal:
+        async with tractor.find_actor(
+            actor_name,
+            # NOTE: must be set manually since
+            # the subactor doesn't have the reg_addr
+            # fixture code run in it!
+            # TODO: maybe we should just set this once in the
+            # _state mod and derive to all children?
+            registry_addrs=[reg_addr],
+        ) as portal:
             try:
                 await portal.run(__name__, func_name)
             except tractor.RemoteActorError as err:
@@ -52,11 +62,17 @@ async def short_sleep():
         'fail_on_syntax',
     ],
 )
-def test_rpc_errors(reg_addr, to_call, testdir):
-    """Test errors when making various RPC requests to an actor
+def test_rpc_errors(
+    reg_addr,
+    to_call,
+    testdir,
+):
+    '''
+    Test errors when making various RPC requests to an actor
     that either doesn't have the requested module exposed or doesn't define
     the named function.
-    """
+
+    '''
     exposed_mods, funcname, inside_err = to_call
     subactor_exposed_mods = []
     func_defined = globals().get(funcname, False)
@@ -84,8 +100,13 @@ def test_rpc_errors(reg_addr, to_call, testdir):
 
         # spawn a subactor which calls us back
         async with tractor.open_nursery(
-            arbiter_addr=reg_addr,
+            registry_addrs=[reg_addr],
             enable_modules=exposed_mods.copy(),
+
+            # NOTE: will halt test in REPL if uncommented, so only
+            # do that if actually debugging subactor but keep it
+            # disabled for the test.
+            # debug_mode=True,
         ) as n:
 
             actor = tractor.current_actor()
@@ -102,6 +123,7 @@ def test_rpc_errors(reg_addr, to_call, testdir):
                 exposed_mods=exposed_mods,
                 func_defined=True if func_defined else False,
                 enable_modules=subactor_exposed_mods,
+                reg_addr=reg_addr,
             )
 
     def run():

tests/test_spawning.py

@@ -32,8 +32,7 @@ async def spawn(
 
         if actor.is_arbiter:
 
-            async with tractor.open_nursery(
-            ) as nursery:
+            async with tractor.open_nursery() as nursery:
 
                 # forks here
                 portal = await nursery.run_in_actor(
@@ -55,7 +54,9 @@ async def spawn(
             return 10
 
 
-def test_local_arbiter_subactor_global_state(reg_addr):
+def test_local_arbiter_subactor_global_state(
+    reg_addr,
+):
     result = trio.run(
         spawn,
         True,

tractor/__init__.py

@@ -18,76 +18,49 @@
 tractor: structured concurrent ``trio``-"actors".
 
 """
-from exceptiongroup import BaseExceptionGroup
+from exceptiongroup import BaseExceptionGroup as BaseExceptionGroup
 
-from ._clustering import open_actor_cluster
+from ._clustering import (
+    open_actor_cluster as open_actor_cluster,
+)
 from ._context import (
-    Context,  # the type
-    context,  # a func-decorator
+    Context as Context,  # the type
+    context as context,  # a func-decorator
 )
 from ._streaming import (
-    MsgStream,
-    stream,
+    MsgStream as MsgStream,
+    stream as stream,
 )
 from ._discovery import (
-    get_arbiter,
-    find_actor,
-    wait_for_actor,
-    query_actor,
+    get_arbiter as get_arbiter,
+    find_actor as find_actor,
+    wait_for_actor as wait_for_actor,
+    query_actor as query_actor,
+)
+from ._supervise import (
+    open_nursery as open_nursery,
+    ActorNursery as ActorNursery,
 )
-from ._supervise import open_nursery
 from ._state import (
-    current_actor,
-    is_root_process,
+    current_actor as current_actor,
+    is_root_process as is_root_process,
 )
 from ._exceptions import (
-    RemoteActorError,
-    ModuleNotExposed,
-    ContextCancelled,
+    RemoteActorError as RemoteActorError,
+    ModuleNotExposed as ModuleNotExposed,
+    ContextCancelled as ContextCancelled,
 )
-from ._debug import (
-    breakpoint,
-    pause,
-    pause_from_sync,
-    post_mortem,
+from .devx import (
+    breakpoint as breakpoint,
+    pause as pause,
+    pause_from_sync as pause_from_sync,
+    post_mortem as post_mortem,
 )
-from . import msg
+from . import msg as msg
 from ._root import (
-    run_daemon,
-    open_root_actor,
+    run_daemon as run_daemon,
+    open_root_actor as open_root_actor,
 )
-from ._ipc import Channel
-from ._portal import Portal
-from ._runtime import Actor
-
-
-__all__ = [
-    'Actor',
-    'BaseExceptionGroup',
-    'Channel',
-    'Context',
-    'ContextCancelled',
-    'ModuleNotExposed',
-    'MsgStream',
-    'Portal',
-    'RemoteActorError',
-    'breakpoint',
-    'context',
-    'current_actor',
-    'find_actor',
-    'query_actor',
-    'get_arbiter',
-    'is_root_process',
-    'msg',
-    'open_actor_cluster',
-    'open_nursery',
-    'open_root_actor',
-    'pause',
-    'post_mortem',
-    'pause_from_sync',
-    'query_actor',
-    'run_daemon',
-    'stream',
-    'to_asyncio',
-    'wait_for_actor',
-]
+from ._ipc import Channel as Channel
+from ._portal import Portal as Portal
+from ._runtime import Actor as Actor

tractor/_context.py

@@ -868,6 +868,9 @@ class Context:
 
         # TODO: maybe we should also call `._res_scope.cancel()` if it
         # exists to support cancelling any drain loop hangs?
+        # NOTE: this usage actually works here B)
+        # from .devx._debug import breakpoint
+        # await breakpoint()
 
     # TODO: add to `Channel`?
     @property

tractor/_discovery.py

@@ -15,16 +15,20 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 """
-Actor discovery API.
+Discovery (protocols) API for automatic addressing and location
+management of (service) actors.
 
 """
+from __future__ import annotations
 from typing import (
-    Optional,
-    Union,
     AsyncGenerator,
+    AsyncContextManager,
+    TYPE_CHECKING,
 )
 from contextlib import asynccontextmanager as acm
+import warnings
 
+from .trionics import gather_contexts
 from ._ipc import _connect_chan, Channel
 from ._portal import (
     Portal,
@@ -34,13 +38,19 @@ from ._portal import (
 from ._state import current_actor, _runtime_vars
 
 
-@acm
-async def get_arbiter(
+if TYPE_CHECKING:
+    from ._runtime import Actor
 
+
+@acm
+async def get_registry(
     host: str,
     port: int,
 
-) -> AsyncGenerator[Union[Portal, LocalPortal], None]:
+) -> AsyncGenerator[
+    Portal | LocalPortal | None,
+    None,
+]:
     '''
     Return a portal instance connected to a local or remote
     arbiter.
@@ -51,16 +61,33 @@ async def get_arbiter(
     if not actor:
         raise RuntimeError("No actor instance has been defined yet?")
 
-    if actor.is_arbiter:
+    if actor.is_registrar:
         # we're already the arbiter
         # (likely a re-entrant call from the arbiter actor)
-        yield LocalPortal(actor, Channel((host, port)))
+        yield LocalPortal(
+            actor,
+            Channel((host, port))
+        )
     else:
-        async with _connect_chan(host, port) as chan:
+        async with (
+            _connect_chan(host, port) as chan,
+            open_portal(chan) as regstr_ptl,
+        ):
+            yield regstr_ptl
 
-            async with open_portal(chan) as arb_portal:
 
-                yield arb_portal
+
+# TODO: deprecate and this remove _arbiter form!
+@acm
+async def get_arbiter(*args, **kwargs):
+    warnings.warn(
+        '`tractor.get_arbiter()` is now deprecated!\n'
+        'Use `.get_registry()` instead!',
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    async with get_registry(*args, **kwargs) as to_yield:
+        yield to_yield
 
 
 @acm
@@ -68,51 +95,80 @@ async def get_root(
     **kwargs,
 ) -> AsyncGenerator[Portal, None]:
 
+    # TODO: rename mailbox to `_root_maddr` when we finally
+    # add and impl libp2p multi-addrs?
     host, port = _runtime_vars['_root_mailbox']
     assert host is not None
 
-    async with _connect_chan(host, port) as chan:
-        async with open_portal(chan, **kwargs) as portal:
+    async with (
+        _connect_chan(host, port) as chan,
+        open_portal(chan, **kwargs) as portal,
+    ):
         yield portal
 
 
 @acm
 async def query_actor(
     name: str,
-    arbiter_sockaddr: Optional[tuple[str, int]] = None,
+    arbiter_sockaddr: tuple[str, int] | None = None,
+    regaddr: tuple[str, int] | None = None,
 
-) -> AsyncGenerator[tuple[str, int], None]:
+) -> AsyncGenerator[
+    tuple[str, int] | None,
+    None,
+]:
     '''
-    Simple address lookup for a given actor name.
+    Make a transport address lookup for an actor name to a specific
+    registrar.
 
-    Returns the (socket) address or ``None``.
+    Returns the (socket) address or ``None`` if no entry under that
+    name exists for the given registrar listening @ `regaddr`.
 
     '''
-    actor = current_actor()
-    async with get_arbiter(
-        *arbiter_sockaddr or actor._arb_addr
-    ) as arb_portal:
+    actor: Actor = current_actor()
+    if (
+        name == 'registrar'
+        and actor.is_registrar
+    ):
+        raise RuntimeError(
+            'The current actor IS the registry!?'
+        )
 
-        sockaddr = await arb_portal.run_from_ns(
+    if arbiter_sockaddr is not None:
+        warnings.warn(
+            '`tractor.query_actor(regaddr=<blah>)` is deprecated.\n'
+            'Use `registry_addrs: list[tuple]` instead!',
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        regaddr: list[tuple[str, int]] = arbiter_sockaddr
+
+    reg_portal: Portal
+    regaddr: tuple[str, int] = regaddr or actor.reg_addrs[0]
+    async with get_registry(*regaddr) as reg_portal:
+        # TODO: return portals to all available actors - for now
+        # just the last one that registered
+        sockaddr: tuple[str, int] = await reg_portal.run_from_ns(
             'self',
             'find_actor',
             name=name,
         )
-
-        # TODO: return portals to all available actors - for now just
-        # the last one that registered
-        if name == 'arbiter' and actor.is_arbiter:
-            raise RuntimeError("The current actor is the arbiter")
-
-        yield sockaddr if sockaddr else None
+        yield sockaddr
 
 
 @acm
 async def find_actor(
     name: str,
-    arbiter_sockaddr: tuple[str, int] | None = None
+    arbiter_sockaddr: tuple[str, int] | None = None,
+    registry_addrs: list[tuple[str, int]] | None = None,
 
-) -> AsyncGenerator[Optional[Portal], None]:
+    only_first: bool = True,
+    raise_on_none: bool = False,
+
+) -> AsyncGenerator[
+    Portal | list[Portal] | None,
+    None,
+]:
     '''
     Ask the arbiter to find actor(s) by name.
 
@@ -120,11 +176,23 @@ async def find_actor(
     known to the arbiter.
 
     '''
+    if arbiter_sockaddr is not None:
+        warnings.warn(
+            '`tractor.find_actor(arbiter_sockaddr=<blah>)` is deprecated.\n'
+            'Use `registry_addrs: list[tuple]` instead!',
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        registry_addrs: list[tuple[str, int]] = [arbiter_sockaddr]
+
+    @acm
+    async def maybe_open_portal_from_reg_addr(
+        addr: tuple[str, int],
+    ):
         async with query_actor(
             name=name,
-        arbiter_sockaddr=arbiter_sockaddr,
+            regaddr=addr,
         ) as sockaddr:
-
             if sockaddr:
                 async with _connect_chan(*sockaddr) as chan:
                     async with open_portal(chan) as portal:
@@ -132,12 +200,55 @@ async def find_actor(
             else:
                 yield None
 
+    if not registry_addrs:
+        # XXX NOTE: make sure to dynamically read the value on
+        # every call since something may change it globally (eg.
+        # like in our discovery test suite)!
+        from . import _root
+        registry_addrs = _root._default_lo_addrs
+
+    maybe_portals: list[
+        AsyncContextManager[tuple[str, int]]
+    ] = list(
+        maybe_open_portal_from_reg_addr(addr)
+        for addr in registry_addrs
+    )
+
+    async with gather_contexts(
+        mngrs=maybe_portals,
+    ) as portals:
+        # log.runtime(
+        #     'Gathered portals:\n'
+        #     f'{portals}'
+        # )
+        # NOTE: `gather_contexts()` will return a
+        # `tuple[None, None, ..., None]` if no contact
+        # can be made with any regstrar at any of the
+        # N provided addrs!
+        if not any(portals):
+            if raise_on_none:
+                raise RuntimeError(
+                    f'No actor "{name}" found registered @ {registry_addrs}'
+                )
+            yield None
+            return
+
+        portals: list[Portal] = list(portals)
+        if only_first:
+            yield portals[0]
+
+        else:
+            # TODO: currently this may return multiple portals
+            # given there are multi-homed or multiple registrars..
+            # SO, we probably need de-duplication logic?
+            yield portals
+
 
 @acm
 async def wait_for_actor(
     name: str,
     arbiter_sockaddr: tuple[str, int] | None = None,
-    # registry_addr: tuple[str, int] | None = None,
+    registry_addr: tuple[str, int] | None = None,
 
 ) -> AsyncGenerator[Portal, None]:
     '''
@@ -146,17 +257,31 @@ async def wait_for_actor(
     A portal to the first registered actor is returned.
 
     '''
-    actor = current_actor()
+    actor: Actor = current_actor()
 
-    async with get_arbiter(
-        *arbiter_sockaddr or actor._arb_addr,
-    ) as arb_portal:
-        sockaddrs = await arb_portal.run_from_ns(
+    if arbiter_sockaddr is not None:
+        warnings.warn(
+            '`tractor.wait_for_actor(arbiter_sockaddr=<foo>)` is deprecated.\n'
+            'Use `registry_addr: tuple` instead!',
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        registry_addr: tuple[str, int] = arbiter_sockaddr
+
+    # TODO: use `.trionics.gather_contexts()` like
+    # above in `find_actor()` as well?
+    reg_portal: Portal
+    regaddr: tuple[str, int] = registry_addr or actor.reg_addrs[0]
+    async with get_registry(*regaddr) as reg_portal:
+        sockaddrs = await reg_portal.run_from_ns(
             'self',
             'wait_for_actor',
             name=name,
         )
-        sockaddr = sockaddrs[-1]
+
+        # get latest registered addr by default?
+        # TODO: offer multi-portal yields in multi-homed case?
+        sockaddr: tuple[str, int] = sockaddrs[-1]
 
         async with _connect_chan(*sockaddr) as chan:
             async with open_portal(chan) as portal:

tractor/_entry.py

@@ -47,8 +47,8 @@ log = get_logger(__name__)
 
 def _mp_main(
 
-    actor: Actor,  # type: ignore
-    accept_addr: tuple[str, int],
+    actor: Actor,
+    accept_addrs: list[tuple[str, int]],
     forkserver_info: tuple[Any, Any, Any, Any, Any],
     start_method: SpawnMethodKey,
     parent_addr: tuple[str, int] | None = None,
@@ -77,8 +77,8 @@ def _mp_main(
     log.debug(f"parent_addr is {parent_addr}")
     trio_main = partial(
         async_main,
-        actor,
-        accept_addr,
+        actor=actor,
+        accept_addrs=accept_addrs,
         parent_addr=parent_addr
     )
     try:
@@ -96,7 +96,7 @@ def _mp_main(
 
 def _trio_main(
 
-    actor: Actor,  # type: ignore
+    actor: Actor,
     *,
     parent_addr: tuple[str, int] | None = None,
     infect_asyncio: bool = False,

tractor/_ipc.py

@@ -517,7 +517,9 @@ class Channel:
 
 @acm
 async def _connect_chan(
-    host: str, port: int
+    host: str,
+    port: int
+
 ) -> typing.AsyncGenerator[Channel, None]:
     '''
     Create and connect a channel with disconnect on context manager

tractor/_multiaddr.py

@@ -0,0 +1,151 @@
+# tractor: structured concurrent "actors".
+# Copyright 2018-eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+'''
+Multiaddress parser and utils according the spec(s) defined by
+`libp2p` and used in dependent project such as `ipfs`:
+
+- https://docs.libp2p.io/concepts/fundamentals/addressing/
+- https://github.com/libp2p/specs/blob/master/addressing/README.md
+
+'''
+from typing import Iterator
+
+from bidict import bidict
+
+# TODO: see if we can leverage libp2p ecosys projects instead of
+# rolling our own (parser) impls of the above addressing specs:
+# - https://github.com/libp2p/py-libp2p
+# - https://docs.libp2p.io/concepts/nat/circuit-relay/#relay-addresses
+# prots: bidict[int, str] = bidict({
+prots: bidict[int, str] = {
+    'ipv4': 3,
+    'ipv6': 3,
+    'wg': 3,
+
+    'tcp': 4,
+    'udp': 4,
+
+    # TODO: support the next-gen shite Bo
+    # 'quic': 4,
+    # 'ssh': 7,  # via rsyscall bootstrapping
+}
+
+prot_params: dict[str, tuple[str]] = {
+    'ipv4': ('addr',),
+    'ipv6': ('addr',),
+    'wg': ('addr', 'port', 'pubkey'),
+
+    'tcp': ('port',),
+    'udp': ('port',),
+
+    # 'quic': ('port',),
+    # 'ssh': ('port',),
+}
+
+
+def iter_prot_layers(
+    multiaddr: str,
+) -> Iterator[
+    tuple[
+        int,
+        list[str]
+    ]
+]:
+    '''
+    Unpack a libp2p style "multiaddress" into multiple "segments"
+    for each "layer" of the protocoll stack (in OSI terms).
+
+    '''
+    tokens: list[str] = multiaddr.split('/')
+    root, tokens = tokens[0], tokens[1:]
+    assert not root  # there is a root '/' on LHS
+    itokens = iter(tokens)
+
+    prot: str | None = None
+    params: list[str] = []
+    for token in itokens:
+        # every prot path should start with a known
+        # key-str.
+        if token in prots:
+            if prot is None:
+                prot: str = token
+            else:
+                yield prot, params
+                prot = token
+
+            params = []
+
+        elif token not in prots:
+            params.append(token)
+
+    else:
+        yield prot, params
+
+
+def parse_maddr(
+    multiaddr: str,
+) -> dict[str, str | int | dict]:
+    '''
+    Parse a libp2p style "multiaddress" into its distinct protocol
+    segments where each segment is of the form:
+
+        `../<protocol>/<param0>/<param1>/../<paramN>`
+
+    and is loaded into a (order preserving) `layers: dict[str,
+    dict[str, Any]` which holds each protocol-layer-segment of the
+    original `str` path as a separate entry according to its approx
+    OSI "layer number".
+
+    Any `paramN` in the path must be distinctly defined by a str-token in the
+    (module global) `prot_params` table.
+
+    For eg. for wireguard which requires an address, port number and publickey
+    the protocol params are specified as the entry:
+
+        'wg': ('addr', 'port', 'pubkey'),
+
+    and are thus parsed from a maddr in that order:
+        `'/wg/1.1.1.1/51820/<pubkey>'`
+
+    '''
+    layers: dict[str, str | int | dict] = {}
+    for (
+        prot_key,
+        params,
+    ) in iter_prot_layers(multiaddr):
+
+        layer: int = prots[prot_key]  # OSI layer used for sorting
+        ep: dict[str, int | str] = {'layer': layer}
+        layers[prot_key] = ep
+
+        # TODO; validation and resolving of names:
+        # - each param via a validator provided as part of the
+        #   prot_params def? (also see `"port"` case below..)
+        # - do a resolv step that will check addrs against
+        #   any loaded network.resolv: dict[str, str]
+        rparams: list = list(reversed(params))
+        for key in prot_params[prot_key]:
+            val: str | int = rparams.pop()
+
+            # TODO: UGHH, dunno what we should do for validation
+            # here, put it in the params spec somehow?
+            if key == 'port':
+                val = int(val)
+
+            ep[key] = val
+
+    return layers

tractor/_portal.py

@@ -461,7 +461,12 @@ class LocalPortal:
     actor: 'Actor'  # type: ignore # noqa
     channel: Channel
 
-    async def run_from_ns(self, ns: str, func_name: str, **kwargs) -> Any:
+    async def run_from_ns(
+        self,
+        ns: str,
+        func_name: str,
+        **kwargs,
+    ) -> Any:
         '''
         Run a requested local function from a namespace path and
         return it's result.

tractor/_root.py

@@ -25,7 +25,6 @@ import logging
 import signal
 import sys
 import os
-import typing
 import warnings
 
 
@@ -38,7 +37,7 @@ from ._runtime import (
     # Arbiter as Registry,
     async_main,
 )
-from . import _debug
+from .devx import _debug
 from . import _spawn
 from . import _state
 from . import log
@@ -47,8 +46,14 @@ from ._exceptions import is_multi_cancelled
 
 
 # set at startup and after forks
-_default_arbiter_host: str = '127.0.0.1'
-_default_arbiter_port: int = 1616
+_default_host: str = '127.0.0.1'
+_default_port: int = 1616
+
+# default registry always on localhost
+_default_lo_addrs: list[tuple[str, int]] = [(
+    _default_host,
+    _default_port,
+)]
 
 
 logger = log.get_logger('tractor')
@@ -59,10 +64,10 @@ async def open_root_actor(
 
     *,
     # defaults are above
-    arbiter_addr: tuple[str, int] | None = None,
+    registry_addrs: list[tuple[str, int]] | None = None,
 
     # defaults are above
-    registry_addr: tuple[str, int] | None = None,
+    arbiter_addr: tuple[str, int] | None = None,
 
     name: str | None = 'root',
 
@@ -80,7 +85,11 @@ async def open_root_actor(
     enable_modules: list | None = None,
     rpc_module_paths: list | None = None,
 
-) -> typing.Any:
+    # NOTE: allow caller to ensure that only one registry exists
+    # and that this call creates it.
+    ensure_registry: bool = False,
+
+) -> Actor:
     '''
     Runtime init entry point for ``tractor``.
 
@@ -90,7 +99,7 @@ async def open_root_actor(
     # https://github.com/python-trio/trio/issues/1155#issuecomment-742964018
     builtin_bp_handler = sys.breakpointhook
     orig_bp_path: str | None = os.environ.get('PYTHONBREAKPOINT', None)
-    os.environ['PYTHONBREAKPOINT'] = 'tractor._debug.pause_from_sync'
+    os.environ['PYTHONBREAKPOINT'] = 'tractor.devx._debug.pause_from_sync'
 
     # attempt to retreive ``trio``'s sigint handler and stash it
     # on our debugger lock state.
@@ -116,20 +125,19 @@ async def open_root_actor(
 
     if arbiter_addr is not None:
         warnings.warn(
-            '`arbiter_addr` is now deprecated and has been renamed to'
-            '`registry_addr`.\nUse that instead..',
+            '`arbiter_addr` is now deprecated\n'
+            'Use `registry_addrs: list[tuple]` instead..',
             DeprecationWarning,
             stacklevel=2,
         )
+        registry_addrs = [arbiter_addr]
 
-    registry_addr = (host, port) = (
-        registry_addr
-        or arbiter_addr
-        or (
-            _default_arbiter_host,
-            _default_arbiter_port,
-        )
+    registry_addrs: list[tuple[str, int]] = (
+        registry_addrs
+        or
+        _default_lo_addrs
     )
+    assert registry_addrs
 
     loglevel = (loglevel or log._default_loglevel).upper()
 
@@ -138,7 +146,7 @@ async def open_root_actor(
 
         # expose internal debug module to every actor allowing
         # for use of ``await tractor.breakpoint()``
-        enable_modules.append('tractor._debug')
+        enable_modules.append('tractor.devx._debug')
 
         # if debug mode get's enabled *at least* use that level of
         # logging for some informative console prompts.
@@ -158,73 +166,131 @@ async def open_root_actor(
 
     log.get_console_log(loglevel)
 
-    try:
-        # make a temporary connection to see if an arbiter exists,
-        # if one can't be made quickly we assume none exists.
-        arbiter_found = False
+    # closed into below ping task-func
+    ponged_addrs: list[tuple[str, int]] = []
 
-        # TODO: this connect-and-bail forces us to have to carefully
-        # rewrap TCP 104-connection-reset errors as EOF so as to avoid
-        # propagating cancel-causing errors to the channel-msg loop
-        # machinery.  Likely it would be better to eventually have
-        # a "discovery" protocol with basic handshake instead.
-        with trio.move_on_after(1):
-            async with _connect_chan(host, port):
-                arbiter_found = True
+    async def ping_tpt_socket(
+        addr: tuple[str, int],
+        timeout: float = 1,
+    ) -> None:
+        '''
+        Attempt temporary connection to see if a registry is
+        listening at the requested address by a tranport layer
+        ping.
+
+        If a connection can't be made quickly we assume none no
+        server is listening at that addr.
+
+        '''
+        try:
+            # TODO: this connect-and-bail forces us to have to
+            # carefully rewrap TCP 104-connection-reset errors as
+            # EOF so as to avoid propagating cancel-causing errors
+            # to the channel-msg loop machinery. Likely it would
+            # be better to eventually have a "discovery" protocol
+            # with basic handshake instead?
+            with trio.move_on_after(timeout):
+                async with _connect_chan(*addr):
+                    ponged_addrs.append(addr)
 
         except OSError:
             # TODO: make this a "discovery" log level?
-        logger.warning(f"No actor registry found @ {host}:{port}")
+            logger.warning(f'No actor registry found @ {addr}')
 
-    # create a local actor and start up its main routine/task
-    if arbiter_found:
+    async with trio.open_nursery() as tn:
+        for addr in registry_addrs:
+            tn.start_soon(
+                ping_tpt_socket,
+                tuple(addr),  # TODO: just drop this requirement?
+            )
+
+    trans_bind_addrs: list[tuple[str, int]] = []
+
+    # Create a new local root-actor instance which IS NOT THE
+    # REGISTRAR
+    if ponged_addrs:
+
+        if ensure_registry:
+            raise RuntimeError(
+                 f'Failed to open `{name}`@{ponged_addrs}: '
+                'registry socket(s) already bound'
+            )
 
         # we were able to connect to an arbiter
-        logger.info(f"Arbiter seems to exist @ {host}:{port}")
+        logger.info(
+            f'Registry(s) seem(s) to exist @ {ponged_addrs}'
+        )
 
         actor = Actor(
-            name or 'anonymous',
-            arbiter_addr=registry_addr,
+            name=name or 'anonymous',
+            registry_addrs=ponged_addrs,
             loglevel=loglevel,
             enable_modules=enable_modules,
         )
-        host, port = (host, 0)
+        # DO NOT use the registry_addrs as the transport server
+        # addrs for this new non-registar, root-actor.
+        for host, port in ponged_addrs:
+            # NOTE: zero triggers dynamic OS port allocation
+            trans_bind_addrs.append((host, 0))
 
+    # Start this local actor as the "registrar", aka a regular
+    # actor who manages the local registry of "mailboxes" of
+    # other process-tree-local sub-actors.
     else:
-        # start this local actor as the arbiter (aka a regular actor who
-        # manages the local registry of "mailboxes")
 
-        # Note that if the current actor is the arbiter it is desirable
-        # for it to stay up indefinitely until a re-election process has
-        # taken place - which is not implemented yet FYI).
+        # NOTE that if the current actor IS THE REGISTAR, the
+        # following init steps are taken:
+        # - the tranport layer server is bound to each (host, port)
+        #   pair defined in provided registry_addrs, or the default.
+        trans_bind_addrs = registry_addrs
+
+        # - it is normally desirable for any registrar to stay up
+        #   indefinitely until either all registered (child/sub)
+        #   actors are terminated (via SC supervision) or,
+        #   a re-election process has taken place. 
+        # NOTE: all of ^ which is not implemented yet - see:
+        # https://github.com/goodboy/tractor/issues/216
+        # https://github.com/goodboy/tractor/pull/348
+        # https://github.com/goodboy/tractor/issues/296
 
         actor = Arbiter(
-            name or 'arbiter',
-            arbiter_addr=registry_addr,
+            name or 'registrar',
+            registry_addrs=registry_addrs,
             loglevel=loglevel,
             enable_modules=enable_modules,
         )
 
+    # Start up main task set via core actor-runtime nurseries.
     try:
         # assign process-local actor
         _state._current_actor = actor
 
         # start local channel-server and fake the portal API
         # NOTE: this won't block since we provide the nursery
-        logger.info(f"Starting local {actor} @ {host}:{port}")
+        ml_addrs_str: str = '\n'.join(
+            f'@{addr}' for addr in trans_bind_addrs
+        )
+        logger.info(
+            f'Starting local {actor.uid} on the following transport addrs:\n'
+            f'{ml_addrs_str}'
+        )
 
         # start the actor runtime in a new task
         async with trio.open_nursery() as nursery:
 
-            # ``_runtime.async_main()`` creates an internal nursery and
-            # thus blocks here until the entire underlying actor tree has
-            # terminated thereby conducting structured concurrency.
-
+            # ``_runtime.async_main()`` creates an internal nursery
+            # and blocks here until any underlying actor(-process)
+            # tree has terminated thereby conducting so called
+            # "end-to-end" structured concurrency throughout an
+            # entire hierarchical python sub-process set; all
+            # "actor runtime" primitives are SC-compat and thus all
+            # transitively spawned actors/processes must be as
+            # well.
             await nursery.start(
                 partial(
                     async_main,
                     actor,
-                    accept_addr=(host, port),
+                    accept_addrs=trans_bind_addrs,
                     parent_addr=None
                 )
             )
@@ -236,7 +302,7 @@ async def open_root_actor(
                 BaseExceptionGroup,
             ) as err:
 
-                entered = await _debug._maybe_enter_pm(err)
+                entered: bool = await _debug._maybe_enter_pm(err)
                 if (
                     not entered
                     and
@@ -244,7 +310,8 @@ async def open_root_actor(
                 ):
                     logger.exception('Root actor crashed:\n')
 
-                # always re-raise
+                # ALWAYS re-raise any error bubbled up from the
+                # runtime!
                 raise
 
             finally:
@@ -265,7 +332,7 @@ async def open_root_actor(
         _state._current_actor = None
         _state._last_actor_terminated = actor
 
-        # restore breakpoint hook state
+        # restore built-in `breakpoint()` hook state
         sys.breakpointhook = builtin_bp_handler
         if orig_bp_path is not None:
             os.environ['PYTHONBREAKPOINT'] = orig_bp_path
@@ -281,10 +348,7 @@ def run_daemon(
 
     # runtime kwargs
     name: str | None = 'root',
-    registry_addr: tuple[str, int] = (
-        _default_arbiter_host,
-        _default_arbiter_port,
-    ),
+    registry_addrs: list[tuple[str, int]] = _default_lo_addrs,
 
     start_method: str | None = None,
     debug_mode: bool = False,
@@ -308,7 +372,7 @@ def run_daemon(
     async def _main():
 
         async with open_root_actor(
-            registry_addr=registry_addr,
+            registry_addrs=registry_addrs,
             name=name,
             start_method=start_method,
             debug_mode=debug_mode,

tractor/_runtime.py

@@ -45,6 +45,7 @@ from functools import partial
 from itertools import chain
 import importlib
 import importlib.util
+import os
 from pprint import pformat
 import signal
 import sys
@@ -55,7 +56,7 @@ from typing import (
 )
 import uuid
 from types import ModuleType
-import os
+import warnings
 
 import trio
 from trio import (
@@ -77,8 +78,8 @@ from ._exceptions import (
     ContextCancelled,
     TransportClosed,
 )
-from ._discovery import get_arbiter
-from . import _debug
+from .devx import _debug
+from ._discovery import get_registry
 from ._portal import Portal
 from . import _state
 from . import _mp_fixup_main
@@ -127,6 +128,11 @@ class Actor:
     # ugh, we need to get rid of this and replace with a "registry" sys
     # https://github.com/goodboy/tractor/issues/216
     is_arbiter: bool = False
+
+    @property
+    def is_registrar(self) -> bool:
+        return self.is_arbiter
+
     msg_buffer_size: int = 2**6
 
     # nursery placeholders filled in by `async_main()` after fork
@@ -164,8 +170,12 @@ class Actor:
         enable_modules: list[str] = [],
         uid: str | None = None,
         loglevel: str | None = None,
+        registry_addrs: list[tuple[str, int]] | None = None,
+        spawn_method: str | None = None,
+
+        # TODO: remove!
         arbiter_addr: tuple[str, int] | None = None,
-        spawn_method: str | None = None
+
     ) -> None:
         '''
         This constructor is called in the parent actor **before** the spawning
@@ -187,29 +197,32 @@ class Actor:
         self._parent_main_data = _mp_fixup_main._mp_figure_out_main()
 
         # always include debugging tools module
-        enable_modules.append('tractor._debug')
+        enable_modules.append('tractor.devx._debug')
 
-        mods = {}
+        self.enable_modules: dict[str, str] = {}
         for name in enable_modules:
-            mod = importlib.import_module(name)
-            mods[name] = _get_mod_abspath(mod)
+            mod: ModuleType = importlib.import_module(name)
+            self.enable_modules[name] = _get_mod_abspath(mod)
 
-        self.enable_modules = mods
         self._mods: dict[str, ModuleType] = {}
-        self.loglevel = loglevel
+        self.loglevel: str = loglevel
 
-        self._arb_addr: tuple[str, int] | None = (
-            str(arbiter_addr[0]),
-            int(arbiter_addr[1])
-        ) if arbiter_addr else None
+        if arbiter_addr is not None:
+            warnings.warn(
+                '`Actor(arbiter_addr=<blah>)` is now deprecated.\n'
+                'Use `registry_addrs: list[tuple]` instead.',
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            registry_addrs: list[tuple[str, int]] = [arbiter_addr]
 
         # marked by the process spawning backend at startup
         # will be None for the parent most process started manually
         # by the user (currently called the "arbiter")
-        self._spawn_method = spawn_method
+        self._spawn_method: str = spawn_method
 
         self._peers: defaultdict = defaultdict(list)
-        self._peer_connected: dict = {}
+        self._peer_connected: dict[tuple[str, str], trio.Event] = {}
         self._no_more_peers = trio.Event()
         self._no_more_peers.set()
         self._ongoing_rpc_tasks = trio.Event()
@@ -239,6 +252,44 @@ class Actor:
             ActorNursery | None,
         ] = {}  # type: ignore  # noqa
 
+        # when provided, init the registry addresses property from
+        # input via the validator.
+        self._reg_addrs: list[tuple[str, int]] = []
+        if registry_addrs:
+            self.reg_addrs: list[tuple[str, int]] = registry_addrs
+
+    @property
+    def reg_addrs(self) -> list[tuple[str, int]]:
+        '''
+        List of (socket) addresses for all known (and contactable)
+        registry actors.
+
+        '''
+        return self._reg_addrs
+
+    @reg_addrs.setter
+    def reg_addrs(
+        self,
+        addrs: list[tuple[str, int]],
+    ) -> None:
+        if not addrs:
+            log.warning(
+                'Empty registry address list is invalid:\n'
+                f'{addrs}'
+            )
+            return
+
+        # always sanity check the input list since it's critical
+        # that addrs are correct for discovery sys operation.
+        for addr in addrs:
+            if not isinstance(addr, tuple):
+                raise ValueError(
+                    'Expected `Actor.reg_addrs: list[tuple[str, int]]`\n'
+                    f'Got {addrs}'
+                )
+
+            self._reg_addrs = addrs
+
     async def wait_for_peer(
         self, uid: tuple[str, str]
     ) -> tuple[trio.Event, Channel]:
@@ -336,6 +387,12 @@ class Actor:
         self._no_more_peers = trio.Event()  # unset by making new
         chan = Channel.from_stream(stream)
         their_uid: tuple[str, str]|None = chan.uid
+        if their_uid:
+            log.warning(
+                f'Re-connection from already known {their_uid}'
+            )
+        else:
+           log.runtime(f'New connection to us @{chan.raddr}')
 
         con_msg: str = ''
         if their_uid:
@@ -517,16 +574,19 @@ class Actor:
 
                 if disconnected:
                     # if the transport died and this actor is still
-                    # registered within a local nursery, we report that the
-                    # IPC layer may have failed unexpectedly since it may be
-                    # the cause of other downstream errors.
+                    # registered within a local nursery, we report
+                    # that the IPC layer may have failed
+                    # unexpectedly since it may be the cause of
+                    # other downstream errors.
                     entry = local_nursery._children.get(uid)
                     if entry:
                         proc: trio.Process
                         _, proc, _ = entry
 
-                        poll = getattr(proc, 'poll', None)
-                        if poll and poll() is None:
+                        if (
+                            (poll := getattr(proc, 'poll', None))
+                            and poll() is None
+                        ):
                             log.cancel(
                                 f'Peer IPC broke but subproc is alive?\n\n'
 
@@ -880,11 +940,11 @@ class Actor:
             )
             await chan.connect()
 
+            # TODO: move this into a `Channel.handshake()`?
             # Initial handshake: swap names.
             await self._do_handshake(chan)
 
-            accept_addr: tuple[str, int] | None = None
-
+            accept_addrs: list[tuple[str, int]] | None = None
             if self._spawn_method == "trio":
                 # Receive runtime state from our parent
                 parent_data: dict[str, Any]
@@ -897,10 +957,7 @@ class Actor:
                     # if "trace"/"util" mode is enabled?
                     f'{pformat(parent_data)}\n'
                 )
-                accept_addr = (
-                    parent_data.pop('bind_host'),
-                    parent_data.pop('bind_port'),
-                )
+                accept_addrs: list[tuple[str, int]] = parent_data.pop('bind_addrs')
                 rvs = parent_data.pop('_runtime_vars')
 
                 if rvs['_debug_mode']:
@@ -918,18 +975,23 @@ class Actor:
                 _state._runtime_vars.update(rvs)
 
                 for attr, value in parent_data.items():
-
-                    if attr == '_arb_addr':
+                    if (
+                        attr == 'reg_addrs'
+                        and value
+                    ):
                         # XXX: ``msgspec`` doesn't support serializing tuples
                         # so just cash manually here since it's what our
                         # internals expect.
-                        value = tuple(value) if value else None
-                        self._arb_addr = value
+                        # TODO: we don't really NEED these as
+                        # tuples so we can probably drop this
+                        # casting since apparently in python lists
+                        # are "more efficient"?
+                        self.reg_addrs = [tuple(val) for val in value]
 
                     else:
                         setattr(self, attr, value)
 
-            return chan, accept_addr
+            return chan, accept_addrs
 
         except OSError:  # failed to connect
             log.warning(
@@ -946,9 +1008,9 @@ class Actor:
         handler_nursery: Nursery,
         *,
         # (host, port) to bind for channel server
-        accept_host: tuple[str, int] | None = None,
-        accept_port: int = 0,
-        task_status: TaskStatus[trio.Nursery] = trio.TASK_STATUS_IGNORED,
+        listen_sockaddrs: list[tuple[str, int]] | None = None,
+
+        task_status: TaskStatus[Nursery] = trio.TASK_STATUS_IGNORED,
     ) -> None:
         '''
         Start the IPC transport server, begin listening for new connections.
@@ -958,18 +1020,26 @@ class Actor:
         `.cancel_server()` is called.
 
         '''
+        if listen_sockaddrs is None:
+            listen_sockaddrs = [(None, 0)]
+
         self._server_down = trio.Event()
         try:
             async with trio.open_nursery() as server_n:
+
+                for host, port in listen_sockaddrs:
                     listeners: list[trio.abc.Listener] = await server_n.start(
                         partial(
                             trio.serve_tcp,
-                        self._stream_handler,
-                        # new connections will stay alive even if this server
-                        # is cancelled
+
+                            handler=self._stream_handler,
+                            port=port,
+                            host=host,
+
+                            # NOTE: configured such that new
+                            # connections will stay alive even if
+                            # this server is cancelled!
                             handler_nursery=handler_nursery,
-                        port=accept_port,
-                        host=accept_host,
                         )
                     )
                     sockets: list[trio.socket] = [
@@ -981,7 +1051,9 @@ class Actor:
                         f'|_{sockets}\n'
                     )
                     self._listeners.extend(listeners)
+
                 task_status.started(server_n)
+
         finally:
             # signal the server is down since nursery above terminated
             self._server_down.set()
@@ -1319,6 +1391,18 @@ class Actor:
             self._server_n.cancel_scope.cancel()
 
     @property
+    def accept_addrs(self) -> list[tuple[str, int]]:
+        '''
+        All addresses to which the transport-channel server binds
+        and listens for new connections.
+
+        '''
+        # throws OSError on failure
+        return [
+            listener.socket.getsockname() 
+            for listener in self._listeners
+        ]  # type: ignore
+
     @property
     def accept_addr(self) -> tuple[str, int]:
         '''
@@ -1327,7 +1411,7 @@ class Actor:
 
         '''
         # throws OSError on failure
-        return self._listeners[0].socket.getsockname()  # type: ignore
+        return self.accept_addrs[0]
 
     def get_parent(self) -> Portal:
         '''
@@ -1344,6 +1428,7 @@ class Actor:
         '''
         return self._peers[uid]
 
+    # TODO: move to `Channel.handshake(uid)`
     async def _do_handshake(
         self,
         chan: Channel
@@ -1380,7 +1465,7 @@ class Actor:
 
 async def async_main(
     actor: Actor,
-    accept_addr: tuple[str, int] | None = None,
+    accept_addrs: tuple[str, int] | None = None,
 
     # XXX: currently ``parent_addr`` is only needed for the
     # ``multiprocessing`` backend (which pickles state sent to
@@ -1408,20 +1493,25 @@ async def async_main(
     # on our debugger lock state.
     _debug.Lock._trio_handler = signal.getsignal(signal.SIGINT)
 
-    registered_with_arbiter = False
+    is_registered: bool = False
     try:
 
         # establish primary connection with immediate parent
-        actor._parent_chan = None
+        actor._parent_chan: Channel | None = None
         if parent_addr is not None:
 
-            actor._parent_chan, accept_addr_rent = await actor._from_parent(
-                parent_addr)
+            (
+                actor._parent_chan,
+                set_accept_addr_says_rent,
+            ) = await actor._from_parent(parent_addr)
 
-            # either it's passed in because we're not a child
-            # or because we're running in mp mode
-            if accept_addr_rent is not None:
-                accept_addr = accept_addr_rent
+            # either it's passed in because we're not a child or
+            # because we're running in mp mode
+            if (
+                set_accept_addr_says_rent
+                and set_accept_addr_says_rent is not None
+            ):
+                accept_addrs = set_accept_addr_says_rent
 
         # The "root" nursery ensures the channel with the immediate
         # parent is kept alive as a resilient service until
@@ -1461,34 +1551,72 @@ async def async_main(
                 # - subactor: the bind address is sent by our parent
                 #   over our established channel
                 # - root actor: the ``accept_addr`` passed to this method
-                assert accept_addr
-                host, port = accept_addr
+                assert accept_addrs
 
+                try:
                     actor._server_n = await service_nursery.start(
                         partial(
                             actor._serve_forever,
                             service_nursery,
-                        accept_host=host,
-                        accept_port=port
+                            listen_sockaddrs=accept_addrs,
                         )
                     )
-                accept_addr = actor.accept_addr
+                except OSError as oserr:
+                    # NOTE: always allow runtime hackers to debug
+                    # tranport address bind errors - normally it's
+                    # something silly like the wrong socket-address
+                    # passed via a config or CLI Bo
+                    entered_debug: bool = await _debug._maybe_enter_pm(oserr)
+                    if not entered_debug:
+                        log.exception('Failed to init IPC channel server !?\n')
+                    raise
+
+                accept_addrs: list[tuple[str, int]] = actor.accept_addrs
+
+                # NOTE: only set the loopback addr for the 
+                # process-tree-global "root" mailbox since
+                # all sub-actors should be able to speak to
+                # their root actor over that channel.
                 if _state._runtime_vars['_is_root']:
-                    _state._runtime_vars['_root_mailbox'] = accept_addr
+                    for addr in accept_addrs:
+                        host, _ = addr
+                        # TODO: generic 'lo' detector predicate
+                        if '127.0.0.1' in host:
+                            _state._runtime_vars['_root_mailbox'] = addr
 
                 # Register with the arbiter if we're told its addr
-                log.runtime(f"Registering {actor} for role `{actor.name}`")
-                assert isinstance(actor._arb_addr, tuple)
+                log.runtime(
+                    f'Registering `{actor.name}` ->\n'
+                    f'{pformat(accept_addrs)}'
+                )
 
-                async with get_arbiter(*actor._arb_addr) as arb_portal:
-                    await arb_portal.run_from_ns(
+                # TODO: ideally we don't fan out to all registrars
+                # if addresses point to the same actor..
+                # So we need a way to detect that? maybe iterate
+                # only on unique actor uids?
+                for addr in actor.reg_addrs:
+                    try:
+                        assert isinstance(addr, tuple)
+                        assert addr[1]  # non-zero after bind
+                    except AssertionError:
+                        await _debug.pause()
+
+                    async with get_registry(*addr) as reg_portal:
+                        for accept_addr in accept_addrs:
+
+                            if not accept_addr[1]:
+                                await _debug.pause()
+
+                            assert accept_addr[1]
+
+                            await reg_portal.run_from_ns(
                                 'self',
                                 'register_actor',
                                 uid=actor.uid,
                                 sockaddr=accept_addr,
                             )
 
-                registered_with_arbiter = True
+                    is_registered: bool = True
 
                 # init steps complete
                 task_status.started()
@@ -1521,18 +1649,20 @@ async def async_main(
         log.runtime("Closing all actor lifetime contexts")
         actor.lifetime_stack.close()
 
-        if not registered_with_arbiter:
+        if not is_registered:
             # TODO: I guess we could try to connect back
             # to the parent through a channel and engage a debugger
             # once we have that all working with std streams locking?
             log.exception(
                 f"Actor errored and failed to register with arbiter "
-                f"@ {actor._arb_addr}?")
+                f"@ {actor.reg_addrs[0]}?")
             log.error(
-                "\n\n\t^^^ THIS IS PROBABLY A TRACTOR BUGGGGG!!! ^^^\n"
-                "\tCALMLY CALL THE AUTHORITIES AND HIDE YOUR CHILDREN.\n\n"
-                "\tYOUR PARENT CODE IS GOING TO KEEP WORKING FINE!!!\n"
-                "\tTHIS IS HOW RELIABlE SYSTEMS ARE SUPPOSED TO WORK!?!?\n"
+                "\n\n\t^^^ THIS IS PROBABLY AN INTERNAL `tractor` BUG! ^^^\n\n"
+                "\t>> CALMLY CALL THE AUTHORITIES AND HIDE YOUR CHILDREN <<\n\n"
+                "\tIf this is a sub-actor hopefully its parent will keep running "
+                "correctly presuming this error was safely ignored..\n\n"
+                "\tPLEASE REPORT THIS TRACEBACK IN A BUG REPORT: "
+                "https://github.com/goodboy/tractor/issues\n"
             )
 
         if actor._parent_chan:
@@ -1572,16 +1702,19 @@ async def async_main(
 
         # Unregister actor from the registry-sys / registrar.
         if (
-            registered_with_arbiter
-            and not actor.is_arbiter
+            is_registered
+            and not actor.is_registrar
         ):
-            failed = False
-            assert isinstance(actor._arb_addr, tuple)
+            failed: bool = False
+            for addr in actor.reg_addrs:
+                assert isinstance(addr, tuple)
                 with trio.move_on_after(0.5) as cs:
                     cs.shield = True
                     try:
-                    async with get_arbiter(*actor._arb_addr) as arb_portal:
-                        await arb_portal.run_from_ns(
+                        async with get_registry(
+                            *addr,
+                        ) as reg_portal:
+                            await reg_portal.run_from_ns(
                                 'self',
                                 'unregister_actor',
                                 uid=actor.uid
@@ -1590,9 +1723,12 @@ async def async_main(
                         failed = True
                 if cs.cancelled_caught:
                     failed = True
+
                 if failed:
                     log.warning(
-                    f"Failed to unregister {actor.name} from arbiter")
+                        f'Failed to unregister {actor.name} from '
+                        f'registar @ {addr}'
+                    )
 
         # Ensure all peers (actors connected to us as clients) are finished
         if not actor._no_more_peers.is_set():
@@ -1611,18 +1747,36 @@ async def async_main(
 # TODO: rename to `Registry` and move to `._discovery`!
 class Arbiter(Actor):
     '''
-    A special actor who knows all the other actors and always has
-    access to a top level nursery.
+    A special registrar actor who can contact all other actors
+    within its immediate process tree and possibly keeps a registry
+    of others meant to be discoverable in a distributed
+    application. Normally the registrar is also the "root actor"
+    and thus always has access to the top-most-level actor
+    (process) nursery.
 
-    The arbiter is by default the first actor spawned on each host
-    and is responsible for keeping track of all other actors for
-    coordination purposes. If a new main process is launched and an
-    arbiter is already running that arbiter will be used.
+    By default, the registrar is always initialized when and if no
+    other registrar socket addrs have been specified to runtime
+    init entry-points (such as `open_root_actor()` or
+    `open_nursery()`). Any time a new main process is launched (and
+    thus thus a new root actor created) and, no existing registrar
+    can be contacted at the provided `registry_addr`, then a new
+    one is always created; however, if one can be reached it is
+    used.
+
+    Normally a distributed app requires at least registrar per
+    logical host where for that given "host space" (aka localhost
+    IPC domain of addresses) it is responsible for making all other
+    host (local address) bound actors *discoverable* to external
+    actor trees running on remote hosts.
 
     '''
     is_arbiter = True
 
-    def __init__(self, *args, **kwargs) -> None:
+    def __init__(
+        self,
+        *args,
+        **kwargs,
+    ) -> None:
 
         self._registry: dict[
             tuple[str, str],
@@ -1664,7 +1818,10 @@ class Arbiter(Actor):
         # unpacker since we have tuples as keys (not this makes the
         # arbiter suscetible to hashdos):
         # https://github.com/msgpack/msgpack-python#major-breaking-changes-in-msgpack-10
-        return {'.'.join(key): val for key, val in self._registry.items()}
+        return {
+            '.'.join(key): val
+            for key, val in self._registry.items()
+        }
 
     async def wait_for_actor(
         self,
@@ -1707,8 +1864,15 @@ class Arbiter(Actor):
         sockaddr: tuple[str, int]
 
     ) -> None:
-        uid = name, _ = (str(uid[0]), str(uid[1]))
-        self._registry[uid] = (str(sockaddr[0]), int(sockaddr[1]))
+        uid = name, hash = (str(uid[0]), str(uid[1]))
+        addr = (host, port) = (
+            str(sockaddr[0]),
+            int(sockaddr[1]),
+        )
+        if port == 0:
+            await _debug.pause()
+        assert port  # should never be 0-dynamic-os-alloc
+        self._registry[uid] = addr
 
         # pop and signal all waiter events
         events = self._waiters.pop(name, [])

tractor/_spawn.py

@@ -34,7 +34,7 @@ from typing import (
 import trio
 from trio import TaskStatus
 
-from ._debug import (
+from .devx._debug import (
     maybe_wait_for_debugger,
     acquire_debug_lock,
 )
@@ -220,6 +220,10 @@ 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.
@@ -365,7 +369,7 @@ async def new_proc(
     errors: dict[tuple[str, str], Exception],
 
     # passed through to actor main
-    bind_addr: tuple[str, int],
+    bind_addrs: list[tuple[str, int]],
     parent_addr: tuple[str, int],
     _runtime_vars: dict[str, Any],  # serialized and sent to _child
 
@@ -387,7 +391,7 @@ async def new_proc(
         actor_nursery,
         subactor,
         errors,
-        bind_addr,
+        bind_addrs,
         parent_addr,
         _runtime_vars,  # run time vars
         infect_asyncio=infect_asyncio,
@@ -402,7 +406,7 @@ async def trio_proc(
     errors: dict[tuple[str, str], Exception],
 
     # passed through to actor main
-    bind_addr: tuple[str, int],
+    bind_addrs: list[tuple[str, int]],
     parent_addr: tuple[str, int],
     _runtime_vars: dict[str, Any],  # serialized and sent to _child
     *,
@@ -491,12 +495,11 @@ async def trio_proc(
 
         # send additional init params
         await chan.send({
-            "_parent_main_data": subactor._parent_main_data,
-            "enable_modules": subactor.enable_modules,
-            "_arb_addr": subactor._arb_addr,
-            "bind_host": bind_addr[0],
-            "bind_port": bind_addr[1],
-            "_runtime_vars": _runtime_vars,
+            '_parent_main_data': subactor._parent_main_data,
+            'enable_modules': subactor.enable_modules,
+            'reg_addrs': subactor.reg_addrs,
+            'bind_addrs': bind_addrs,
+            '_runtime_vars': _runtime_vars,
         })
 
         # track subactor in current nursery
@@ -551,13 +554,14 @@ async def trio_proc(
                         with trio.move_on_after(0.5):
                             await proc.wait()
 
-                log.pdb(
-                    'Delaying subproc reaper while debugger locked..'
-                )
                 await maybe_wait_for_debugger(
                     child_in_debug=_runtime_vars.get(
                         '_debug_mode', False
                     ),
+                    header_msg=(
+                        'Delaying subproc reaper while debugger locked..\n'
+                    ),
+
                     # TODO: need a diff value then default?
                     # poll_steps=9999999,
                 )
@@ -601,7 +605,7 @@ async def mp_proc(
     subactor: Actor,
     errors: dict[tuple[str, str], Exception],
     # passed through to actor main
-    bind_addr: tuple[str, int],
+    bind_addrs: list[tuple[str, int]],
     parent_addr: tuple[str, int],
     _runtime_vars: dict[str, Any],  # serialized and sent to _child
     *,
@@ -659,7 +663,7 @@ async def mp_proc(
         target=_mp_main,
         args=(
             subactor,
-            bind_addr,
+            bind_addrs,
             fs_info,
             _spawn_method,
             parent_addr,

tractor/_supervise.py

@@ -22,16 +22,13 @@ from contextlib import asynccontextmanager as acm
 from functools import partial
 import inspect
 from pprint import pformat
-from typing import (
-    Optional,
-    TYPE_CHECKING,
-)
+from typing import TYPE_CHECKING
 import typing
 import warnings
 
 import trio
 
-from ._debug import maybe_wait_for_debugger
+from .devx._debug import maybe_wait_for_debugger
 from ._state import current_actor, is_main_process
 from .log import get_logger, get_loglevel
 from ._runtime import Actor
@@ -97,7 +94,7 @@ class ActorNursery:
             tuple[
                 Actor,
                 trio.Process | mp.Process,
-                Optional[Portal],
+                Portal | None,
             ]
         ] = {}
         # portals spawned with ``run_in_actor()`` are
@@ -121,12 +118,12 @@ class ActorNursery:
         self,
         name: str,
         *,
-        bind_addr: tuple[str, int] = _default_bind_addr,
+        bind_addrs: list[tuple[str, int]] = [_default_bind_addr],
         rpc_module_paths: list[str] | None = None,
         enable_modules: list[str] | None = None,
         loglevel: str | None = None,  # set log level per subactor
         nursery: trio.Nursery | None = None,
-        debug_mode: Optional[bool] | None = None,
+        debug_mode: bool | None = None,
         infect_asyncio: bool = False,
     ) -> Portal:
         '''
@@ -161,7 +158,9 @@ class ActorNursery:
             # modules allowed to invoked funcs from
             enable_modules=enable_modules,
             loglevel=loglevel,
-            arbiter_addr=current_actor()._arb_addr,
+
+            # verbatim relay this actor's registrar addresses
+            registry_addrs=current_actor().reg_addrs,
         )
         parent_addr = self._actor.accept_addr
         assert parent_addr
@@ -178,7 +177,7 @@ class ActorNursery:
                 self,
                 subactor,
                 self.errors,
-                bind_addr,
+                bind_addrs,
                 parent_addr,
                 _rtv,  # run time vars
                 infect_asyncio=infect_asyncio,
@@ -191,8 +190,8 @@ class ActorNursery:
         fn: typing.Callable,
         *,
 
-        name: Optional[str] = None,
-        bind_addr: tuple[str, int] = _default_bind_addr,
+        name: str | None = None,
+        bind_addrs: tuple[str, int] = [_default_bind_addr],
         rpc_module_paths: list[str] | None = None,
         enable_modules: list[str] | None = None,
         loglevel: str | None = None,  # set log level per subactor
@@ -221,7 +220,7 @@ class ActorNursery:
             enable_modules=[mod_path] + (
                 enable_modules or rpc_module_paths or []
             ),
-            bind_addr=bind_addr,
+            bind_addrs=bind_addrs,
             loglevel=loglevel,
             # use the run_in_actor nursery
             nursery=self._ria_nursery,

tractor/devx/__init__.py

@@ -0,0 +1,37 @@
+# tractor: structured concurrent "actors".
+# Copyright 2018-eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+Runtime "developer experience" utils and addons to aid our
+(advanced) users and core devs in building distributed applications
+and working with/on the actor runtime.
+
+"""
+from ._debug import (
+    maybe_wait_for_debugger as maybe_wait_for_debugger,
+    acquire_debug_lock as acquire_debug_lock,
+    breakpoint as breakpoint,
+    pause as pause,
+    pause_from_sync as pause_from_sync,
+    shield_sigint_handler as shield_sigint_handler,
+    MultiActorPdb as MultiActorPdb,
+    open_crash_handler as open_crash_handler,
+    maybe_open_crash_handler as maybe_open_crash_handler,
+    post_mortem as post_mortem,
+)
+from ._stackscope import (
+    enable_stack_on_sig as enable_stack_on_sig,
+)

tractor/devx/_debug.py

@@ -1,18 +1,19 @@
 # tractor: structured concurrent "actors".
 # Copyright 2018-eternity Tyler Goodlet.
 
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Affero General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# This program is free software: you can redistribute it and/or
+# modify it under the terms of the GNU Affero General Public License
+# as published by the Free Software Foundation, either version 3 of
+# the License, or (at your option) any later version.
 
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Affero General Public License for more details.
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Affero General Public License for more details.
 
-# You should have received a copy of the GNU Affero General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+# You should have received a copy of the GNU Affero General Public
+# License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
 
 """
 Multi-core debugging for da peeps!
@@ -20,14 +21,19 @@ Multi-core debugging for da peeps!
 """
 from __future__ import annotations
 import bdb
-import os
-import sys
-import signal
+from contextlib import (
+    asynccontextmanager as acm,
+    contextmanager as cm,
+    nullcontext,
+)
 from functools import (
     partial,
     cached_property,
 )
-from contextlib import asynccontextmanager as acm
+import os
+import signal
+import sys
+import traceback
 from typing import (
     Any,
     Callable,
@@ -39,27 +45,31 @@ from types import FrameType
 import pdbp
 import tractor
 import trio
+from trio.lowlevel import current_task
 from trio_typing import (
     TaskStatus,
     # Task,
 )
 
-from .log import get_logger
-from ._discovery import get_root
-from ._state import (
+from ..log import get_logger
+from .._state import (
+    current_actor,
     is_root_process,
     debug_mode,
 )
-from ._exceptions import (
+from .._exceptions import (
     is_multi_cancelled,
     ContextCancelled,
 )
-from ._ipc import Channel
+from .._ipc import Channel
 
 log = get_logger(__name__)
 
 
-__all__ = ['breakpoint', 'post_mortem']
+__all__ = [
+    'breakpoint',
+    'post_mortem',
+]
 
 
 class Lock:
@@ -85,12 +95,12 @@ class Lock:
     # and must be cancelled if this actor is cancelled via IPC
     # request-message otherwise deadlocks with the parent actor may
     # ensure
-    _debugger_request_cs: trio.CancelScope | None = None
+    _debugger_request_cs: trio.CancelScope|None = None
 
     # NOTE: set only in the root actor for the **local** root spawned task
     # which has acquired the lock (i.e. this is on the callee side of
     # the `lock_tty_for_child()` context entry).
-    _root_local_task_cs_in_debug: trio.CancelScope | None = None
+    _root_local_task_cs_in_debug: trio.CancelScope|None = None
 
     # actor tree-wide actor uid that supposedly has the tty lock
     global_actor_in_debug: tuple[str, str] = None
@@ -232,7 +242,7 @@ async def _acquire_debug_lock_from_root_task(
     to the ``pdb`` repl.
 
     '''
-    task_name: str = trio.lowlevel.current_task().name
+    task_name: str = current_task().name
     we_acquired: bool = False
 
     log.runtime(
@@ -317,14 +327,13 @@ async def lock_tty_for_child(
     highly reliable at releasing the mutex complete!
 
     '''
-    task_name = trio.lowlevel.current_task().name
-
+    task_name: str = current_task().name
     if tuple(subactor_uid) in Lock._blocked:
         log.warning(
             f'Actor {subactor_uid} is blocked from acquiring debug lock\n'
             f"remote task: {task_name}:{subactor_uid}"
         )
-        ctx._enter_debugger_on_cancel = False
+        ctx._enter_debugger_on_cancel: bool = False
         await ctx.cancel(f'Debug lock blocked for {subactor_uid}')
         return 'pdb_lock_blocked'
 
@@ -375,12 +384,14 @@ async def wait_for_parent_stdin_hijack(
 
     This function is used by any sub-actor to acquire mutex access to
     the ``pdb`` REPL and thus the root's TTY for interactive debugging
-    (see below inside ``_pause()``). It can be used to ensure that
+    (see below inside ``pause()``). It can be used to ensure that
     an intermediate nursery-owning actor does not clobber its children
     if they are in debug (see below inside
     ``maybe_wait_for_debugger()``).
 
     '''
+    from .._discovery import get_root
+
     with trio.CancelScope(shield=True) as cs:
         Lock._debugger_request_cs = cs
 
@@ -390,7 +401,7 @@ async def wait_for_parent_stdin_hijack(
                 # this syncs to child's ``Context.started()`` call.
                 async with portal.open_context(
 
-                    tractor._debug.lock_tty_for_child,
+                    lock_tty_for_child,
                     subactor_uid=actor_uid,
 
                 ) as (ctx, val):
@@ -399,11 +410,13 @@ async def wait_for_parent_stdin_hijack(
                     assert val == 'Locked'
 
                     async with ctx.open_stream() as stream:
-                        # unblock local caller
-
                         try:
+                            # unblock local caller
                             assert Lock.local_pdb_complete
                             task_status.started(cs)
+
+                            # wait for local task to exit and
+                            # release the REPL
                             await Lock.local_pdb_complete.wait()
 
                         finally:
@@ -441,171 +454,6 @@ def mk_mpdb() -> tuple[MultiActorPdb, Callable]:
     return pdb, Lock.unshield_sigint
 
 
-async def _pause(
-
-    debug_func: Callable | None = None,
-    release_lock_signal: trio.Event | None = None,
-
-    # TODO:
-    # shield: bool = False
-    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
-
-) -> None:
-    '''
-    A pause point (more commonly known as a "breakpoint") interrupt
-    instruction for engaging a blocking debugger instance to
-    conduct manual console-based-REPL-interaction from within
-    `tractor`'s async runtime, normally from some single-threaded
-    and currently executing actor-hosted-`trio`-task in some
-    (remote) process.
-
-    NOTE: we use the semantics "pause" since it better encompasses
-    the entirety of the necessary global-runtime-state-mutation any
-    actor-task must access and lock in order to get full isolated
-    control over the process tree's root TTY:
-    https://en.wikipedia.org/wiki/Breakpoint
-
-    '''
-    __tracebackhide__ = True
-    actor = tractor.current_actor()
-    pdb, undo_sigint = mk_mpdb()
-    task_name = trio.lowlevel.current_task().name
-
-    # TODO: is it possible to debug a trio.Cancelled except block?
-    # right now it seems like we can kinda do with by shielding
-    # around ``tractor.breakpoint()`` but not if we move the shielded
-    # scope here???
-    # with trio.CancelScope(shield=shield):
-    #     await trio.lowlevel.checkpoint()
-
-    if (
-        not Lock.local_pdb_complete
-        or Lock.local_pdb_complete.is_set()
-    ):
-        Lock.local_pdb_complete = trio.Event()
-
-    # TODO: need a more robust check for the "root" actor
-    if (
-        not is_root_process()
-        and actor._parent_chan  # a connected child
-    ):
-
-        if Lock.local_task_in_debug:
-
-            # Recurrence entry case: this task already has the lock and
-            # is likely recurrently entering a breakpoint
-            if Lock.local_task_in_debug == task_name:
-                # noop on recurrent entry case but we want to trigger
-                # a checkpoint to allow other actors error-propagate and
-                # potetially avoid infinite re-entries in some subactor.
-                await trio.lowlevel.checkpoint()
-                return
-
-            # if **this** actor is already in debug mode block here
-            # waiting for the control to be released - this allows
-            # support for recursive entries to `tractor.breakpoint()`
-            log.warning(f"{actor.uid} already has a debug lock, waiting...")
-
-            await Lock.local_pdb_complete.wait()
-            await trio.sleep(0.1)
-
-        # mark local actor as "in debug mode" to avoid recurrent
-        # entries/requests to the root process
-        Lock.local_task_in_debug = task_name
-
-        # this **must** be awaited by the caller and is done using the
-        # root nursery so that the debugger can continue to run without
-        # being restricted by the scope of a new task nursery.
-
-        # TODO: if we want to debug a trio.Cancelled triggered exception
-        # 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
-        # ```
-        # but not entirely sure if that's a sane way to implement it?
-        try:
-            with trio.CancelScope(shield=True):
-                await actor._service_n.start(
-                    wait_for_parent_stdin_hijack,
-                    actor.uid,
-                )
-                Lock.repl = pdb
-        except RuntimeError:
-            Lock.release()
-
-            if actor._cancel_called:
-                # service nursery won't be usable and we
-                # don't want to lock up the root either way since
-                # we're in (the midst of) cancellation.
-                return
-
-            raise
-
-    elif is_root_process():
-
-        # we also wait in the root-parent for any child that
-        # may have the tty locked prior
-        # TODO: wait, what about multiple root tasks acquiring it though?
-        if Lock.global_actor_in_debug == actor.uid:
-            # re-entrant root process already has it: noop.
-            return
-
-        # XXX: since we need to enter pdb synchronously below,
-        # we have to release the lock manually from pdb completion
-        # callbacks. Can't think of a nicer way then this atm.
-        if Lock._debug_lock.locked():
-            log.warning(
-                'Root actor attempting to shield-acquire active tty lock'
-                f' owned by {Lock.global_actor_in_debug}')
-
-            # must shield here to avoid hitting a ``Cancelled`` and
-            # a child getting stuck bc we clobbered the tty
-            with trio.CancelScope(shield=True):
-                await Lock._debug_lock.acquire()
-        else:
-            # may be cancelled
-            await Lock._debug_lock.acquire()
-
-        Lock.global_actor_in_debug = actor.uid
-        Lock.local_task_in_debug = task_name
-        Lock.repl = pdb
-
-    try:
-        # breakpoint()
-        if debug_func is None:
-            # assert release_lock_signal, (
-            #     'Must pass `release_lock_signal: trio.Event` if no '
-            #     'trace func provided!'
-            # )
-            print(f"{actor.uid} ENTERING WAIT")
-            task_status.started()
-
-            # with trio.CancelScope(shield=True):
-            #     await release_lock_signal.wait()
-
-        else:
-            # block here one (at the appropriate frame *up*) where
-            # ``breakpoint()`` was awaited and begin handling stdio.
-            log.debug("Entering the synchronous world of pdb")
-            debug_func(actor, pdb)
-
-    except bdb.BdbQuit:
-        Lock.release()
-        raise
-
-    # XXX: apparently we can't do this without showing this frame
-    # in the backtrace on first entry to the REPL? Seems like an odd
-    # behaviour that should have been fixed by now. This is also why
-    # we scrapped all the @cm approaches that were tried previously.
-    # finally:
-    #     __tracebackhide__ = True
-    #     # frame = sys._getframe()
-    #     # last_f = frame.f_back
-    #     # last_f.f_globals['__tracebackhide__'] = True
-    #     # signal.signal = pdbp.hideframe(signal.signal)
-
-
 def shield_sigint_handler(
     signum: int,
     frame: 'frame',  # type: ignore # noqa
@@ -625,7 +473,7 @@ def shield_sigint_handler(
 
     uid_in_debug: tuple[str, str] | None = Lock.global_actor_in_debug
 
-    actor = tractor.current_actor()
+    actor = current_actor()
     # print(f'{actor.uid} in HANDLER with ')
 
     def do_cancel():
@@ -764,27 +612,62 @@ def shield_sigint_handler(
         # https://github.com/prompt-toolkit/python-prompt-toolkit/blob/c2c6af8a0308f9e5d7c0e28cb8a02963fe0ce07a/prompt_toolkit/patch_stdout.py
 
 
+_pause_msg: str = 'Attaching to pdb REPL in actor'
+
+
 def _set_trace(
     actor: tractor.Actor | None = None,
     pdb: MultiActorPdb | None = None,
-):
-    __tracebackhide__ = True
-    actor: tractor.Actor = actor or tractor.current_actor()
+    shield: bool = False,
 
-    # start 2 levels up in user code
-    frame: FrameType | None = sys._getframe()
-    if frame:
+    extra_frames_up_when_async: int = 1,
+):
+    __tracebackhide__: bool = True
+    actor: tractor.Actor = actor or current_actor()
+
+    # always start 1 level up from THIS in user code.
+    frame: FrameType|None
+    if frame := sys._getframe():
         frame: FrameType = frame.f_back  # type: ignore
 
     if (
         frame
-        and pdb
+        and (
+            pdb
             and actor is not None
+        )
+        # or shield
     ):
-        log.pdb(f"\nAttaching pdb to actor: {actor.uid}\n")
+        msg: str = _pause_msg
+        if shield:
+            # log.warning(
+            msg = (
+                '\n\n'
+                '            ------ - ------\n'
+                'Debugger invoked with `shield=True` so an extra\n'
+                '`trio.CancelScope.__exit__()` frame is shown..\n'
+                '\n'
+                'Try going up one frame to see your pause point!\n'
+                '\n'
+                '          SORRY we need to fix this!\n'
+                '            ------ - ------\n\n'
+            ) + msg
+
+        # pdbp.set_trace()
+        # TODO: maybe print the actor supervion tree up to the
+        # root here? Bo
+        log.pdb(
+            f'{msg}\n'
+            '|\n'
+            f'|_ {actor.uid}\n'
+        )
         # no f!#$&* idea, but when we're in async land
         # we need 2x frames up?
-        frame = frame.f_back
+        for i in range(extra_frames_up_when_async):
+            frame: FrameType = frame.f_back
+            log.debug(
+                f'Going up frame {i} -> {frame}\n'
+            )
 
     else:
         pdb, undo_sigint = mk_mpdb()
@@ -794,17 +677,278 @@ def _set_trace(
         Lock.local_task_in_debug = 'sync'
 
     pdb.set_trace(frame=frame)
-    # undo_
 
 
-# TODO: allow pausing from sync code, normally by remapping
-# python's builtin breakpoint() hook to this runtime aware version.
+async def _pause(
+
+    debug_func: Callable = _set_trace,
+    release_lock_signal: trio.Event | None = None,
+
+    # TODO: allow caller to pause despite task cancellation,
+    # exactly the same as wrapping with:
+    # with CancelScope(shield=True):
+    #     await pause()
+    # => the REMAINING ISSUE is that the scope's .__exit__() frame
+    # is always show in the debugger on entry.. and there seems to
+    # be no way to override it?..
+    # shield: bool = False,
+
+    shield: bool = False,
+    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
+
+) -> None:
+    '''
+    Inner impl for `pause()` to avoid the `trio.CancelScope.__exit__()`
+    stack frame when not shielded (since apparently i can't figure out
+    how to hide it using the normal mechanisms..)
+
+    Hopefully we won't need this in the long run.
+
+    '''
+    __tracebackhide__: bool = True
+    actor = current_actor()
+    pdb, undo_sigint = mk_mpdb()
+    task_name: str = trio.lowlevel.current_task().name
+
+    if (
+        not Lock.local_pdb_complete
+        or Lock.local_pdb_complete.is_set()
+    ):
+        Lock.local_pdb_complete = trio.Event()
+
+    debug_func = partial(
+        debug_func,
+    )
+
+    # TODO: need a more robust check for the "root" actor
+    if (
+        not is_root_process()
+        and actor._parent_chan  # a connected child
+    ):
+
+        if Lock.local_task_in_debug:
+
+            # Recurrence entry case: this task already has the lock and
+            # is likely recurrently entering a breakpoint
+            if Lock.local_task_in_debug == task_name:
+                # noop on recurrent entry case but we want to trigger
+                # a checkpoint to allow other actors error-propagate and
+                # potetially avoid infinite re-entries in some subactor.
+                await trio.lowlevel.checkpoint()
+                return
+
+            # if **this** actor is already in debug mode block here
+            # waiting for the control to be released - this allows
+            # support for recursive entries to `tractor.breakpoint()`
+            log.warning(f"{actor.uid} already has a debug lock, waiting...")
+
+            await Lock.local_pdb_complete.wait()
+            await trio.sleep(0.1)
+
+        # mark local actor as "in debug mode" to avoid recurrent
+        # entries/requests to the root process
+        Lock.local_task_in_debug = task_name
+
+        # this **must** be awaited by the caller and is done using the
+        # root nursery so that the debugger can continue to run without
+        # being restricted by the scope of a new task nursery.
+
+        # TODO: if we want to debug a trio.Cancelled triggered exception
+        # 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
+        # ```
+        # but not entirely sure if that's a sane way to implement it?
+        try:
+            with trio.CancelScope(shield=True):
+                await actor._service_n.start(
+                    wait_for_parent_stdin_hijack,
+                    actor.uid,
+                )
+                Lock.repl = pdb
+        except RuntimeError:
+            Lock.release()
+
+            if actor._cancel_called:
+                # service nursery won't be usable and we
+                # don't want to lock up the root either way since
+                # we're in (the midst of) cancellation.
+                return
+
+            raise
+
+    elif is_root_process():
+
+        # we also wait in the root-parent for any child that
+        # may have the tty locked prior
+        # TODO: wait, what about multiple root tasks acquiring it though?
+        if Lock.global_actor_in_debug == actor.uid:
+            # re-entrant root process already has it: noop.
+            return
+
+        # XXX: since we need to enter pdb synchronously below,
+        # we have to release the lock manually from pdb completion
+        # callbacks. Can't think of a nicer way then this atm.
+        if Lock._debug_lock.locked():
+            log.warning(
+                'Root actor attempting to shield-acquire active tty lock'
+                f' owned by {Lock.global_actor_in_debug}')
+
+            # must shield here to avoid hitting a ``Cancelled`` and
+            # a child getting stuck bc we clobbered the tty
+            with trio.CancelScope(shield=True):
+                await Lock._debug_lock.acquire()
+        else:
+            # may be cancelled
+            await Lock._debug_lock.acquire()
+
+        Lock.global_actor_in_debug = actor.uid
+        Lock.local_task_in_debug = task_name
+        Lock.repl = pdb
+
+    try:
+        # TODO: do we want to support using this **just** for the
+        # locking / common code (prolly to help address #320)?
+        #
+        # if debug_func is None:
+            # assert release_lock_signal, (
+            #     'Must pass `release_lock_signal: trio.Event` if no '
+            #     'trace func provided!'
+            # )
+            # print(f"{actor.uid} ENTERING WAIT")
+            # with trio.CancelScope(shield=True):
+            #     await release_lock_signal.wait()
+
+        # else:
+            # block here one (at the appropriate frame *up*) where
+            # ``breakpoint()`` was awaited and begin handling stdio.
+        log.debug('Entering sync world of the `pdb` REPL..')
+        try:
+            debug_func(
+                actor,
+                pdb,
+                extra_frames_up_when_async=2,
+                shield=shield,
+            )
+        except BaseException:
+            log.exception(
+                'Failed to invoke internal `debug_func = '
+                f'{debug_func.func.__name__}`\n'
+            )
+            raise
+
+    except bdb.BdbQuit:
+        Lock.release()
+        raise
+
+    except BaseException:
+        log.exception(
+            'Failed to engage debugger via `_pause()` ??\n'
+        )
+        raise
+
+# XXX: apparently we can't do this without showing this frame
+# in the backtrace on first entry to the REPL? Seems like an odd
+# behaviour that should have been fixed by now. This is also why
+# we scrapped all the @cm approaches that were tried previously.
+# finally:
+#     __tracebackhide__ = True
+#     # frame = sys._getframe()
+#     # last_f = frame.f_back
+#     # last_f.f_globals['__tracebackhide__'] = True
+#     # signal.signal = pdbp.hideframe(signal.signal)
+
+
+async def pause(
+
+    debug_func: Callable = _set_trace,
+    release_lock_signal: trio.Event | None = None,
+
+    # TODO: allow caller to pause despite task cancellation,
+    # exactly the same as wrapping with:
+    # with CancelScope(shield=True):
+    #     await pause()
+    # => the REMAINING ISSUE is that the scope's .__exit__() frame
+    # is always show in the debugger on entry.. and there seems to
+    # be no way to override it?..
+    # shield: bool = False,
+
+    shield: bool = False,
+    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
+
+) -> None:
+    '''
+    A pause point (more commonly known as a "breakpoint") interrupt
+    instruction for engaging a blocking debugger instance to
+    conduct manual console-based-REPL-interaction from within
+    `tractor`'s async runtime, normally from some single-threaded
+    and currently executing actor-hosted-`trio`-task in some
+    (remote) process.
+
+    NOTE: we use the semantics "pause" since it better encompasses
+    the entirety of the necessary global-runtime-state-mutation any
+    actor-task must access and lock in order to get full isolated
+    control over the process tree's root TTY:
+    https://en.wikipedia.org/wiki/Breakpoint
+
+    '''
+    __tracebackhide__: bool = True
+
+    if shield:
+        # NOTE XXX: even hard coding this inside the `class CancelScope:`
+        # doesn't seem to work for me!?
+        # ^ XXX ^
+
+        # def _exit(self, *args, **kwargs):
+        #     __tracebackhide__: bool = True
+        #     super().__exit__(*args, **kwargs)
+
+        trio.CancelScope.__enter__.__tracebackhide__ = True
+        trio.CancelScope.__exit__.__tracebackhide__ = True
+
+        # import types
+        # with trio.CancelScope(shield=shield) as cs:
+            # cs.__exit__ = types.MethodType(_exit, cs)
+            # cs.__exit__.__tracebackhide__ = True
+
+        with trio.CancelScope(shield=shield) as cs:
+            # setattr(cs.__exit__.__func__, '__tracebackhide__', True)
+            # setattr(cs.__enter__.__func__, '__tracebackhide__', True)
+
+            # NOTE: so the caller can always cancel even if shielded
+            task_status.started(cs)
+            return await _pause(
+                debug_func=debug_func,
+                release_lock_signal=release_lock_signal,
+                shield=True,
+                task_status=task_status,
+            )
+    else:
+        return await _pause(
+            debug_func=debug_func,
+            release_lock_signal=release_lock_signal,
+            shield=False,
+            task_status=task_status,
+        )
+
+
+
+
+# TODO: allow pausing from sync code.
+# normally by remapping python's builtin breakpoint() hook to this
+# runtime aware version which takes care of all .
 def pause_from_sync() -> None:
     print("ENTER SYNC PAUSE")
+    actor: tractor.Actor = current_actor(
+        err_on_no_runtime=False,
+    )
+    if actor:
+        try:
             import greenback
-    __tracebackhide__ = True
+            # __tracebackhide__ = True
+
 
-    actor: tractor.Actor = tractor.current_actor()
             # task_can_release_tty_lock = trio.Event()
 
             # spawn bg task which will lock out the TTY, we poll
@@ -812,12 +956,17 @@ def pause_from_sync() -> None:
             # waiting.. not the most ideal but works for now ;)
             greenback.await_(
                 actor._service_n.start(partial(
-            _pause,
+                    pause,
                     debug_func=None,
                     # release_lock_signal=task_can_release_tty_lock,
                 ))
             )
 
+        except ModuleNotFoundError:
+            log.warning('NO GREENBACK FOUND')
+    else:
+        log.warning('Not inside actor-runtime')
+
     db, undo_sigint = mk_mpdb()
     Lock.local_task_in_debug = 'sync'
     # db.config.enable_hidden_frames = True
@@ -851,11 +1000,7 @@ def pause_from_sync() -> None:
 # using the "pause" semantics instead since
 # that better covers actually somewhat "pausing the runtime"
 # for this particular paralell task to do debugging B)
-pause = partial(
-    _pause,
-    _set_trace,
-)
-pp = pause  # short-hand for "pause point"
+# pp = pause  # short-hand for "pause point"
 
 
 async def breakpoint(**kwargs):
@@ -866,9 +1011,18 @@ async def breakpoint(**kwargs):
     await pause(**kwargs)
 
 
+_crash_msg: str = (
+    'Attaching to pdb REPL in crashed actor'
+)
+
+
 def _post_mortem(
     actor: tractor.Actor,
     pdb: MultiActorPdb,
+    shield: bool = False,
+
+    # only for compat with `._set_trace()`..
+    extra_frames_up_when_async=0,
 
 ) -> None:
     '''
@@ -876,20 +1030,28 @@ def _post_mortem(
     debugger instance.
 
     '''
-    log.pdb(f"\nAttaching to pdb in crashed actor: {actor.uid}\n")
+    # TODO: print the actor supervion tree up to the root
+    # here! Bo
+    log.pdb(
+        f'{_crash_msg}\n'
+        '|\n'
+        f'|_ {actor.uid}\n'
+    )
 
-    # TODO: you need ``pdbpp`` master (at least this commit
-    # https://github.com/pdbpp/pdbpp/commit/b757794857f98d53e3ebbe70879663d7d843a6c2)
-    # to fix this and avoid the hang it causes. See issue:
-    # https://github.com/pdbpp/pdbpp/issues/480
-    # TODO: help with a 3.10+ major release if/when it arrives.
-
-    pdbp.xpm(Pdb=lambda: pdb)
+    # TODO: only replacing this to add the
+    # `end=''` to the print XD
+    # pdbp.xpm(Pdb=lambda: pdb)
+    info = sys.exc_info()
+    print(traceback.format_exc(), end='')
+    pdbp.post_mortem(
+        t=info[2],
+        Pdb=lambda: pdb,
+    )
 
 
 post_mortem = partial(
-    _pause,
-    _post_mortem,
+    pause,
+    debug_func=_post_mortem,
 )
 
 
@@ -930,9 +1092,10 @@ async def acquire_debug_lock(
     '''
     Grab root's debug lock on entry, release on exit.
 
-    This helper is for actor's who don't actually need
-    to acquired the debugger but want to wait until the
-    lock is free in the process-tree root.
+    This helper is for actor's who don't actually need to acquired
+    the debugger but want to wait until the lock is free in the
+    process-tree root such that they don't clobber an ongoing pdb
+    REPL session in some peer or child!
 
     '''
     if not debug_mode():
@@ -953,14 +1116,18 @@ async def maybe_wait_for_debugger(
     poll_delay: float = 0.1,
     child_in_debug: bool = False,
 
-) -> None:
+    header_msg: str = '',
+
+) -> bool:  # was locked and we polled?
 
     if (
         not debug_mode()
         and not child_in_debug
     ):
-        return
+        return False
 
+
+    msg: str = header_msg
     if (
         is_root_process()
     ):
@@ -970,41 +1137,147 @@ async def maybe_wait_for_debugger(
         # will make the pdb repl unusable.
         # Instead try to wait for pdb to be released before
         # tearing down.
-        sub_in_debug: tuple[str, str] | None = None
+        in_debug: tuple[str, str]|None = Lock.global_actor_in_debug
+        debug_complete: trio.Event|None = Lock.no_remote_has_tty
 
-        for _ in range(poll_steps):
-
-            if Lock.global_actor_in_debug:
-                sub_in_debug = tuple(Lock.global_actor_in_debug)
-
-            log.debug('Root polling for debug')
-
-            with trio.CancelScope(shield=True):
-                await trio.sleep(poll_delay)
-
-                # TODO: could this make things more deterministic?  wait
-                # to see if a sub-actor task will be scheduled and grab
-                # the tty lock on the next tick?
-                # XXX: doesn't seem to work
-                # await trio.testing.wait_all_tasks_blocked(cushion=0)
-
-                debug_complete = Lock.no_remote_has_tty
-                if (
-                    debug_complete
-                    and sub_in_debug is not None
-                    and not debug_complete.is_set()
-                ):
-                    log.pdb(
-                        'Root has errored but pdb is in use by '
-                        f'child {sub_in_debug}\n'
-                        'Waiting on tty lock to release..'
+        if in_debug == current_actor().uid:
+            log.debug(
+                msg
+                +
+                'Root already owns the TTY LOCK'
             )
+            return True
 
-                    await debug_complete.wait()
-
-                await trio.sleep(poll_delay)
-                continue
+        elif in_debug:
+            msg += (
+                f'Debug `Lock` in use by subactor: {in_debug}\n'
+            )
+            # TODO: could this make things more deterministic?
+            # wait to see if a sub-actor task will be
+            # scheduled and grab the tty lock on the next
+            # tick?
+            # XXX => but it doesn't seem to work..
+            # await trio.testing.wait_all_tasks_blocked(cushion=0)
         else:
             log.debug(
-                    'Root acquired TTY LOCK'
+                msg
+                +
+                'Root immediately acquired debug TTY LOCK'
             )
+            return False
+
+        for istep in range(poll_steps):
+            if (
+                debug_complete
+                and not debug_complete.is_set()
+                and in_debug is not None
+            ):
+                log.pdb(
+                    msg
+                    +
+                    'Root is waiting on tty lock to release..\n'
+                )
+                with trio.CancelScope(shield=True):
+                    await debug_complete.wait()
+                log.pdb(
+                    f'Child subactor released debug lock\n'
+                    f'|_{in_debug}\n'
+                )
+
+            # is no subactor locking debugger currently?
+            if (
+                in_debug is None
+                and (
+                    debug_complete is None
+                    or debug_complete.is_set()
+                )
+            ):
+                log.pdb(
+                    msg
+                    +
+                    'Root acquired tty lock!'
+                )
+                break
+
+            else:
+                # TODO: don't need this right?
+                # await trio.lowlevel.checkpoint()
+
+                log.debug(
+                    'Root polling for debug:\n'
+                    f'poll step: {istep}\n'
+                    f'poll delya: {poll_delay}'
+                )
+                with trio.CancelScope(shield=True):
+                    await trio.sleep(poll_delay)
+                    continue
+
+        # fallthrough on failure to acquire..
+        # else:
+        #     raise RuntimeError(
+        #         msg
+        #         +
+        #         'Root actor failed to acquire debug lock?'
+        #     )
+        return True
+
+    # else:
+    #     # TODO: non-root call for #320?
+    #     this_uid: tuple[str, str] = current_actor().uid
+    #     async with acquire_debug_lock(
+    #         subactor_uid=this_uid,
+    #     ):
+    #         pass
+    return False
+
+# TODO: better naming and what additionals?
+# - [ ] optional runtime plugging?
+# - [ ] detection for sync vs. async code?
+# - [ ] specialized REPL entry when in distributed mode?
+# - [x] allow ignoring kbi Bo
+@cm
+def open_crash_handler(
+    catch: set[BaseException] = {
+        Exception,
+        BaseException,
+    },
+    ignore: set[BaseException] = {
+        KeyboardInterrupt,
+    },
+):
+    '''
+    Generic "post mortem" crash handler using `pdbp` REPL debugger.
+
+    We expose this as a CLI framework addon to both `click` and
+    `typer` users so they can quickly wrap cmd endpoints which get
+    automatically wrapped to use the runtime's `debug_mode: bool`
+    AND `pdbp.pm()` around any code that is PRE-runtime entry
+    - any sync code which runs BEFORE the main call to
+      `trio.run()`.
+
+    '''
+    try:
+        yield
+    except tuple(catch) as err:
+
+        if type(err) not in ignore:
+            pdbp.xpm()
+
+        raise
+
+
+@cm
+def maybe_open_crash_handler(pdb: bool = False):
+    '''
+    Same as `open_crash_handler()` but with bool input flag
+    to allow conditional handling.
+
+    Normally this is used with CLI endpoints such that if the --pdb
+    flag is passed the pdb REPL is engaed on any crashes B)
+    '''
+    rtctx = nullcontext
+    if pdb:
+        rtctx = open_crash_handler
+
+    with rtctx():
+        yield

tractor/devx/_stackscope.py

@@ -0,0 +1,84 @@
+# tractor: structured concurrent "actors".
+# Copyright eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+'''
+The fundamental cross process SC abstraction: an inter-actor,
+cancel-scope linked task "context".
+
+A ``Context`` is very similar to the ``trio.Nursery.cancel_scope`` built
+into each ``trio.Nursery`` except it links the lifetimes of memory space
+disjoint, parallel executing tasks in separate actors.
+
+'''
+from signal import (
+    signal,
+    SIGUSR1,
+)
+
+import trio
+
+@trio.lowlevel.disable_ki_protection
+def dump_task_tree() -> None:
+    import stackscope
+    from tractor.log import get_console_log
+
+    tree_str: str = str(
+        stackscope.extract(
+            trio.lowlevel.current_root_task(),
+            recurse_child_tasks=True
+        )
+    )
+    log = get_console_log('cancel')
+    log.pdb(
+        f'Dumping `stackscope` tree:\n\n'
+        f'{tree_str}\n'
+    )
+    # import logging
+    # try:
+    #     with open("/dev/tty", "w") as tty:
+    #         tty.write(tree_str)
+    # except BaseException:
+    #     logging.getLogger(
+    #         "task_tree"
+    #     ).exception("Error printing task tree")
+
+
+def signal_handler(sig: int, frame: object) -> None:
+    import traceback
+    try:
+        trio.lowlevel.current_trio_token(
+        ).run_sync_soon(dump_task_tree)
+    except RuntimeError:
+        # not in async context -- print a normal traceback
+        traceback.print_stack()
+
+
+
+def enable_stack_on_sig(
+    sig: int = SIGUSR1
+) -> None:
+    '''
+    Enable `stackscope` tracing on reception of a signal; by
+    default this is SIGUSR1.
+
+    '''
+    signal(
+        sig,
+        signal_handler,
+    )
+    # NOTE: not the above can be triggered from
+    # a (xonsh) shell using:
+    # kill -SIGUSR1 @$(pgrep -f '<cmd>')

tractor/devx/cli.py

@@ -0,0 +1,129 @@
+# tractor: structured concurrent "actors".
+# Copyright 2018-eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+CLI framework extensions for hacking on the actor runtime.
+
+Currently popular frameworks supported are:
+
+  - `typer` via the `@callback` API
+
+"""
+from __future__ import annotations
+from typing import (
+    Any,
+    Callable,
+)
+from typing_extensions import Annotated
+
+import typer
+
+
+_runtime_vars: dict[str, Any] = {}
+
+
+def load_runtime_vars(
+    ctx: typer.Context,
+    callback: Callable,
+    pdb: bool = False,  # --pdb
+    ll: Annotated[
+        str,
+        typer.Option(
+            '--loglevel',
+            '-l',
+            help='BigD logging level',
+        ),
+    ] = 'cancel',  # -l info
+):
+    '''
+    Maybe engage crash handling with `pdbp` when code inside
+    a `typer` CLI endpoint cmd raises.
+
+    To use this callback simply take your `app = typer.Typer()` instance
+    and decorate this function with it like so:
+
+    .. code:: python
+
+        from tractor.devx import cli
+
+        app = typer.Typer()
+
+        # manual decoration to hook into `click`'s context system!
+        cli.load_runtime_vars = app.callback(
+            invoke_without_command=True,
+        )
+
+    And then you can use the now augmented `click` CLI context as so,
+
+    .. code:: python
+
+        @app.command(
+            context_settings={
+                "allow_extra_args": True,
+                "ignore_unknown_options": True,
+            }
+        )
+        def my_cli_cmd(
+            ctx: typer.Context,
+        ):
+            rtvars: dict = ctx.runtime_vars
+            pdb: bool = rtvars['pdb']
+
+            with tractor.devx.cli.maybe_open_crash_handler(pdb=pdb):
+                trio.run(
+                    partial(
+                        my_tractor_main_task_func,
+                        debug_mode=pdb,
+                        loglevel=rtvars['ll'],
+                    )
+                )
+
+    which will enable log level and debug mode globally for the entire
+    `tractor` + `trio` runtime thereafter!
+
+    Bo
+
+    '''
+    global _runtime_vars
+    _runtime_vars |= {
+        'pdb': pdb,
+        'll': ll,
+    }
+
+    ctx.runtime_vars: dict[str, Any] = _runtime_vars
+    print(
+        f'`typer` sub-cmd: {ctx.invoked_subcommand}\n'
+        f'`tractor` runtime vars: {_runtime_vars}'
+    )
+
+    # XXX NOTE XXX: hackzone.. if no sub-cmd is specified (the
+    # default if the user just invokes `bigd`) then we simply
+    # invoke the sole `_bigd()` cmd passing in the "parent"
+    # typer.Context directly to that call since we're treating it
+    # as a "non sub-command" or wtv..
+    # TODO: ideally typer would have some kinda built-in way to get
+    # this behaviour without having to construct and manually
+    # invoke our own cmd..
+    if (
+        ctx.invoked_subcommand is None
+        or ctx.invoked_subcommand == callback.__name__
+    ):
+        cmd: typer.core.TyperCommand = typer.core.TyperCommand(
+            name='bigd',
+            callback=callback,
+        )
+        ctx.params = {'ctx': ctx}
+        cmd.invoke(ctx)