From f4af2b9fda5b03b2964c75d7166db8d8d46f4615 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Mon, 14 Feb 2022 10:25:42 -0500
Subject: [PATCH] Run first soft wait inside a task

Theoretically we can actually concurrently soft wait the process and the
nursery exit event, the only problem at the moment is some pubsub tests
puking. You're right in guessing this isn't really changing anything but
it is meant to be a reminder. If we can add this the spawn task can
report when a process dies earlier then expected and in the longer term
once we remove the `ActorNursery.run_in_actor()` API, we can probably do
away with both the nursery exit event and the portal result fetching.
---
 tractor/_spawn.py | 71 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 50 insertions(+), 21 deletions(-)

diff --git a/tractor/_spawn.py b/tractor/_spawn.py
index 3d7e6b1..b3657b7 100644
--- a/tractor/_spawn.py
+++ b/tractor/_spawn.py
@@ -295,7 +295,7 @@ async def new_proc(
             # the OS; it otherwise can be passed via the parent channel if
             # we prefer in the future (for privacy).
             "--uid",
-            str(subactor.uid),
+            str(uid),
             # Address the child must connect to on startup
             "--parent_addr",
             str(parent_addr)
@@ -321,8 +321,7 @@ async def new_proc(
                 # wait for actor to spawn and connect back to us
                 # channel should have handshake completed by the
                 # local actor by the time we get a ref to it
-                event, chan = await actor_nursery._actor.wait_for_peer(
-                    subactor.uid)
+                event, chan = await actor_nursery._actor.wait_for_peer(uid)
 
             except trio.Cancelled:
                 cancelled_during_spawn = True
@@ -363,10 +362,54 @@ async def new_proc(
             task_status.started(portal)
 
             # wait for ActorNursery.wait() to be called
+            n_exited = actor_nursery._join_procs
             with trio.CancelScope(shield=True):
-                await actor_nursery._join_procs.wait()
+                await n_exited.wait()
 
             async with trio.open_nursery() as nursery:
+
+                async def soft_wait_and_maybe_cancel_ria_task():
+                    # This is a "soft" (cancellable) join/reap which
+                    # will remote cancel the actor on a ``trio.Cancelled``
+                    # condition.
+                    await soft_wait(
+                        proc,
+                        trio.Process.wait,
+                        portal
+                    )
+
+                    if n_exited.is_set():
+                        # cancel result waiter that may have been spawned in
+                        # tandem if not done already
+                        log.warning(
+                            "Cancelling existing result waiter task for "
+                            f"{subactor.uid}"
+                        )
+                        nursery.cancel_scope.cancel()
+
+                    else:
+                        log.warning(
+                            f'Process for actor {uid} terminated before'
+                            'nursery exit. ' 'This may mean an IPC'
+                            'connection failed!'
+                        )
+
+                nursery.start_soon(soft_wait_and_maybe_cancel_ria_task)
+
+                # TODO: when we finally remove the `.run_in_actor()` api
+                # we should be able to entirely drop these 2 blocking calls:
+                # - we don't need to wait on nursery exit to capture
+                #   process-spawn-machinery level errors (and propagate them).
+                # - we don't need to wait on final results from ria portals
+                #   since this will be done in some higher level wrapper API.
+
+                # XXX: interestingly we can't put this here bc it causes
+                # the pub-sub tests to fail? wth.. should probably drop
+                # those XD
+                # wait for ActorNursery.wait() to be called
+                # with trio.CancelScope(shield=True):
+                #     await n_exited.wait()
+
                 if portal in actor_nursery._cancel_after_result_on_exit:
                     nursery.start_soon(
                         cancel_on_completion,
@@ -375,22 +418,6 @@ async def new_proc(
                         errors
                     )
 
-                # This is a "soft" (cancellable) join/reap which
-                # will remote cancel the actor on a ``trio.Cancelled``
-                # condition.
-                await soft_wait(
-                    proc,
-                    trio.Process.wait,
-                    portal
-                )
-
-                # cancel result waiter that may have been spawned in
-                # tandem if not done already
-                log.warning(
-                    "Cancelling existing result waiter task for "
-                    f"{subactor.uid}")
-                nursery.cancel_scope.cancel()
-
         finally:
             # The "hard" reap since no actor zombies are allowed!
             # XXX: do this **after** cancellation/tearfown to avoid
@@ -407,8 +434,10 @@ async def new_proc(
                                 await proc.wait()
 
                     if is_root_process():
+
                         await maybe_wait_for_debugger(
-                            child_in_debug=_runtime_vars.get('_debug_mode', False),
+                            child_in_debug=_runtime_vars.get(
+                                '_debug_mode', False)
                         )
 
                     if proc.poll() is None: