Add "root mailbox" contact info passing

Every subactor in the tree now receives the socket (or whatever the
mailbox type ends up being) during startup and can call the new
`tractor._discovery.get_root()` function to get a portal to the current
root actor in their tree. The main reason for adding this atm is to
support nested child actors gaining access to the root's tty lock for
debugging.

Also, when a channel disconnects from a message loop, might as well kill
all its rpc tasks.

tractor/_actor.py

@@ -539,7 +539,9 @@ class Actor:
                         f"Waiting on next msg for {chan} from {chan.uid}")
                 else:
                     # channel disconnect
-                    log.debug(f"{chan} from {chan.uid} disconnected")
+                    log.debug(
+                        f"{chan} from {chan.uid} disconnected, cancelling all rpc tasks")
+                    self.cancel_rpc_tasks(chan)
 
         except trio.ClosedResourceError:
             log.error(f"{chan} form {chan.uid} broke")
@@ -676,6 +678,9 @@ class Actor:
                             accept_port=port
                         )
                     )
+                    accept_addr = self.accept_addr
+                    if _state._runtime_vars['_is_root']:
+                        _state._runtime_vars['_root_mailbox'] = accept_addr
 
                     # Register with the arbiter if we're told its addr
                     log.debug(f"Registering {self} for role `{self.name}`")
@@ -686,7 +691,7 @@ class Actor:
                             'self',
                             'register_actor',
                             uid=self.uid,
-                            sockaddr=self.accept_addr,
+                            sockaddr=accept_addr,
                         )
 
                     registered_with_arbiter = True
@@ -895,15 +900,23 @@ class Actor:
             f"Sucessfully cancelled task:\ncid: {cid}\nfunc: {func}\n"
             f"peer: {chan.uid}\n")
 
-    async def cancel_rpc_tasks(self) -> None:
+    async def cancel_rpc_tasks(
+        self,
+        only_chan: Optional[Channel] = None,
+    ) -> None:
         """Cancel all existing RPC responder tasks using the cancel scope
         registered for each.
         """
         tasks = self._rpc_tasks
         log.info(f"Cancelling all {len(tasks)} rpc tasks:\n{tasks} ")
         for (chan, cid) in tasks.copy():
+            if only_chan is not None:
+                if only_chan != chan:
+                    continue
+
             # TODO: this should really done in a nursery batch
             await self._cancel_task(cid, chan)
+
         log.info(
             f"Waiting for remaining rpc tasks to complete {tasks}")
         await self._ongoing_rpc_tasks.wait()
@@ -1058,10 +1071,16 @@ async def _start_actor(
         try:
             result = await main()
         except (Exception, trio.MultiError) as err:
+            try:
                 log.exception("Actor crashed:")
                 await _debug._maybe_enter_pm(err)
+
                 raise
 
+            finally:
+                actor._service_n.cancel_scope.cancel()
+                await actor.cancel()
+
         # XXX: the actor is cancelled when this context is complete
         # given that there are no more active peer channels connected
         actor.cancel_server()

tractor/_debug.py

@@ -15,6 +15,7 @@ import trio
 
 from .log import get_logger
 from . import _state
+from ._discovery import get_root
 
 try:
     # wtf: only exported when installed in dev mode?
@@ -190,11 +191,7 @@ def _breakpoint(debug_func) -> Awaitable[None]:
         with trio.CancelScope() as cs:
             _debugger_request_cs = cs
             try:
-                async with tractor._portal.open_portal(
-                    actor._parent_chan,
-                    start_msg_loop=False,
-                    # shield=True,
-                ) as portal:
+                async with get_root() as portal:
                     with trio.fail_after(.5):
                         agen = await portal.run(
                             'tractor._debug',
@@ -262,9 +259,14 @@ def _breakpoint(debug_func) -> Awaitable[None]:
             async def _lock(
                 task_status=trio.TASK_STATUS_IGNORED
             ):
+                try:
                     async with _acquire_debug_lock():
                         task_status.started()
                         await do_unlock.wait()
+                finally:
+                    global _in_debug
+                    _in_debug = False
+                    log.debug(f"{actor} released tty lock")
 
             await actor._service_n.start(_lock)
 

tractor/_discovery.py

@@ -11,7 +11,7 @@ from ._portal import (
     open_portal,
     LocalPortal,
 )
-from ._state import current_actor
+from ._state import current_actor, _runtime_vars
 
 
 @asynccontextmanager
@@ -37,6 +37,16 @@ async def get_arbiter(
                 yield arb_portal
 
 
+@asynccontextmanager
+async def get_root(
+**kwargs,
+) -> typing.AsyncGenerator[Union[Portal, LocalPortal], None]:
+    host, port = _runtime_vars['_root_mailbox']
+    async with _connect_chan(host, port) as chan:
+        async with open_portal(chan, **kwargs) as portal:
+            yield portal
+
+
 @asynccontextmanager
 async def find_actor(
     name: str,

tractor/_state.py

@@ -11,6 +11,7 @@ _current_actor: Optional['Actor'] = None  # type: ignore
 _runtime_vars = {
     '_debug_mode': False,
     '_is_root': False,
+    '_root_mailbox': (None, None)
 }