Mask tpt-closed handling of `chan.send(return_msg)`

A partial revert of commit c05d08e426 since it seem we already
suppress tpt-closed errors lower down in `.ipc.Channel.send()`; given
that i'm pretty sure this new handler code should basically never run?

Left in a todo to remove the masked content once i'm done more
thoroughly testing under `piker`.

examples/trio/send_chan_aclose_masks_beg.py

@@ -0,0 +1,145 @@
+from contextlib import (
+    contextmanager as cm,
+    # TODO, any diff in async case(s)??
+    # asynccontextmanager as acm,
+)
+from functools import partial
+
+import tractor
+import trio
+
+
+log = tractor.log.get_logger(__name__)
+tractor.log.get_console_log('info')
+
+@cm
+def teardown_on_exc(
+    raise_from_handler: bool = False,
+):
+    '''
+    You could also have a teardown handler which catches any exc and
+    does some required teardown. In this case the problem is
+    compounded UNLESS you ensure the handler's scope is OUTSIDE the
+    `ux.aclose()`.. that is in the caller's enclosing scope.
+
+    '''
+    try:
+        yield
+    except BaseException as _berr:
+        berr = _berr
+        log.exception(
+            f'Handling termination teardown in child due to,\n'
+            f'{berr!r}\n'
+        )
+        if raise_from_handler:
+            # XXX teardown ops XXX
+            # on termination these steps say need to be run to
+            # ensure wider system consistency (like the state of
+            # remote connections/services).
+            #
+            # HOWEVER, any bug in this teardown code is also
+            # masked by the `tx.aclose()`!
+            # this is also true if `_tn.cancel_scope` is
+            # `.cancel_called` by the parent in a graceful
+            # request case..
+
+            # simulate a bug in teardown handler.
+            raise RuntimeError(
+                'woopsie teardown bug!'
+            )
+
+        raise  # no teardown bug.
+
+
+async def finite_stream_to_rent(
+    tx: trio.abc.SendChannel,
+    child_errors_mid_stream: bool,
+
+    task_status: trio.TaskStatus[
+        trio.CancelScope,
+    ] = trio.TASK_STATUS_IGNORED,
+):
+    async with (
+        # XXX without this unmasker the mid-streaming RTE is never
+        # reported since it is masked by the `tx.aclose()`
+        # call which in turn raises `Cancelled`!
+        #
+        # NOTE, this is WITHOUT doing any exception handling
+        # inside the child  task!
+        #
+        # TODO, uncomment next LoC to see the supprsessed beg[RTE]!
+        # tractor.trionics.maybe_raise_from_masking_exc(),
+
+        tx as tx,  # .aclose() is the guilty masker chkpt!
+        trio.open_nursery() as _tn,
+    ):
+        # pass our scope back to parent for supervision\
+        # control.
+        task_status.started(_tn.cancel_scope)
+
+        with teardown_on_exc(
+            raise_from_handler=not child_errors_mid_stream,
+        ):
+            for i in range(100):
+                log.info(
+                    f'Child tx {i!r}\n'
+                )
+                if (
+                    child_errors_mid_stream
+                    and
+                    i == 66
+                ):
+                    # oh wait but WOOPS there's a bug
+                    # in that teardown code!?
+                    raise RuntimeError(
+                        'woopsie, a mid-streaming bug!?'
+                    )
+
+                await tx.send(i)
+
+
+async def main(
+    # TODO! toggle this for the 2 cases!
+    # 1. child errors mid-stream while parent is also requesting
+    #   (graceful) cancel of that child streamer.
+    #
+    # 2. child contains a teardown handler which contains a
+    #   bug and raises.
+    #
+    child_errors_mid_stream: bool,
+):
+    tx, rx = trio.open_memory_channel(1)
+
+    async with (
+        trio.open_nursery() as tn,
+        rx as rx,
+    ):
+
+        _child_cs = await tn.start(
+            partial(
+                finite_stream_to_rent,
+                child_errors_mid_stream=child_errors_mid_stream,
+                tx=tx,
+            )
+        )
+        async for msg in rx:
+            log.info(
+                f'Rent rx {msg!r}\n'
+            )
+
+            # simulate some external cancellation
+            # request **JUST BEFORE** the child errors.
+            if msg == 65:
+                log.cancel(
+                    f'Cancelling parent on,\n'
+                    f'msg={msg}\n'
+                    f'\n'
+                    f'Simulates OOB cancel request!\n'
+                )
+                tn.cancel_scope.cancel()
+
+
+if __name__ == '__main__':
+
+    for case in [True, False]:
+        trio.run(main, case)

tests/test_legacy_one_way_streaming.py

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

tractor/_root.py

@@ -478,7 +478,10 @@ async def open_root_actor(
 
             # start runtime in a bg sub-task, yield to caller.
             async with (
-                collapse_eg(),
+                collapse_eg(
+                    # bp=True,
+                    hide_tb=False,
+                ),
                 trio.open_nursery() as root_tn,
 
                 # XXX, finally-footgun below?
@@ -523,6 +526,12 @@ async def open_root_actor(
                         err,
                         api_frame=inspect.currentframe(),
                         debug_filter=debug_filter,
+
+                        # XXX NOTE, required to debug root-actor
+                        # crashes under cancellation conditions; so
+                        # most of them!
+                        shield=root_tn.cancel_scope.cancel_called,
+                        # ^TODO? write a (debugger) test for this ya?
                     )
 
                     if (

tractor/_rpc.py

@@ -324,8 +324,8 @@ async def _errors_relayed_via_ipc(
                     )
                 )
                 # TODO? better then `debug_filter` below?
-                # and
-                # not isinstance(err, TransportClosed)
+                and
+                not isinstance(err, TransportClosed)
             ):
                 # XXX QUESTION XXX: is there any case where we'll
                 # want to debug IPC disconnects as a default?
@@ -693,20 +693,23 @@ async def _invoke(
                     f'\n'
                     f'{pretty_struct.pformat(return_msg)}\n'
                 )
-                try:
-                    await chan.send(return_msg)
-                except TransportClosed:
-                    log.exception(
-                        f"Failed send final result to 'parent'-side of IPC-ctx!\n"
-                        f'\n'
-                        f'{chan}\n'
-                        f'Channel already disconnected ??\n'
-                        f'\n'
-                        f'{pretty_struct.pformat(return_msg)}'
-                    )
-                    # ?TODO? will this ever be true though?
-                    if chan.connected():
-                        raise
+                await chan.send(return_msg)
+                # ?TODO, remove the below since .send() already
+                # doesn't raise on tpt-closed?
+                # try:
+                #     await chan.send(return_msg)
+                # except TransportClosed:
+                #     log.exception(
+                #         f"Failed send final result to 'parent'-side of IPC-ctx!\n"
+                #         f'\n'
+                #         f'{chan}\n'
+                #         f'Channel already disconnected ??\n'
+                #         f'\n'
+                #         f'{pretty_struct.pformat(return_msg)}'
+                #     )
+                #     # ?TODO? will this ever be true though?
+                #     if chan.connected():
+                #         raise
 
             # NOTE: this happens IFF `ctx._scope.cancel()` is
             # called by any of,

tractor/_spawn.py

@@ -297,6 +297,23 @@ async def hard_kill(
     # zombies (as a feature) we ask the OS to do send in the
     # removal swad as the last resort.
     if cs.cancelled_caught:
+
+        # TODO? attempt at intermediary-rent-sub
+        # with child in debug lock?
+        # |_https://github.com/goodboy/tractor/issues/320
+        #
+        # if not is_root_process():
+        #     log.warning(
+        #         'Attempting to acquire debug-REPL-lock before zombie reap!'
+        #     )
+        #     with trio.CancelScope(shield=True):
+        #         async with debug.acquire_debug_lock(
+        #             subactor_uid=current_actor().uid,
+        #         ) as _ctx:
+        #             log.warning(
+        #                 'Acquired debug lock, child ready to be killed ??\n'
+        #             )
+
         # TODO: toss in the skynet-logo face as ascii art?
         log.critical(
             # 'Well, the #ZOMBIE_LORD_IS_HERE# to collect\n'

tractor/ipc/_transport.py

@@ -430,6 +430,7 @@ class MsgpackTransport(MsgTransport):
                 return await self.stream.send_all(size + bytes_data)
             except (
                 trio.BrokenResourceError,
+                trio.ClosedResourceError,
             ) as _re:
                 trans_err = _re
                 tpt_name: str = f'{type(self).__name__!r}'
@@ -458,6 +459,22 @@ class MsgpackTransport(MsgTransport):
                         )
                         raise tpt_closed from trans_err
 
+                    # case trio.ClosedResourceError() if (
+                    #     'this socket was already closed'
+                    #     in
+                    #     trans_err.args[0]
+                    # ):
+                    #     tpt_closed = TransportClosed.from_src_exc(
+                    #         message=(
+                    #             f'{tpt_name} already closed by peer\n'
+                    #         ),
+                    #         body=f'{self}\n',
+                    #         src_exc=trans_err,
+                    #         raise_on_report=True,
+                    #         loglevel='transport',
+                    #     )
+                    #     raise tpt_closed from trans_err
+
                     # unless the disconnect condition falls under "a
                     # normal operation breakage" we usualy console warn
                     # about it.