First try: pack cancelled tracebacks and ship to caller

tractor/_actor.py

@@ -60,6 +60,9 @@ async def _invoke(
     """
     treat_as_gen = False
 
+    # possible a traceback (not sure what typing is for this..)
+    tb = None
+
     cancel_scope = trio.CancelScope()
     cs: trio.CancelScope = None
 
@@ -156,14 +159,26 @@ async def _invoke(
                 ctx._scope_nursery = scope_nursery
                 cs = scope_nursery.cancel_scope
                 task_status.started(cs)
-                await chan.send({'return': await coro, 'cid': cid})
+                try:
+                    await chan.send({'return': await coro, 'cid': cid})
+                except trio.Cancelled as err:
+                    tb = err.__traceback__
 
             if cs.cancelled_caught:
-                if ctx._cancel_called:
-                    msg = f'{func.__name__} cancelled itself',
 
-                else:
+                # TODO: pack in ``trio.Cancelled.__traceback__`` here
-                    msg = f'{func.__name__} was remotely cancelled',
+                # so they can be unwrapped and displayed on the caller
+                # side!
+
+                fname = func.__name__
+                if ctx._cancel_called:
+                    msg = f'{fname} cancelled itself'
+
+                elif cs.cancel_called:
+                    msg = (
+                        f'{fname} was remotely cancelled by its caller '
+                        f'{ctx.chan.uid}'
+                    )
 
                 # task-contex was cancelled so relay to the cancel to caller
                 raise ContextCancelled(
@@ -209,7 +224,7 @@ async def _invoke(
                 log.exception("Actor crashed:")
 
         # always ship errors back to caller
-        err_msg = pack_error(err)
+        err_msg = pack_error(err, tb=tb)
         err_msg['cid'] = cid
         try:
             await chan.send(err_msg)
@@ -236,7 +251,7 @@ async def _invoke(
                 f"Task {func} likely errored or cancelled before it started")
         finally:
             if not actor._rpc_tasks:
-                log.info("All RPC tasks have completed")
+                log.runtime("All RPC tasks have completed")
                 actor._ongoing_rpc_tasks.set()
 
 
@@ -251,10 +266,10 @@ _lifetime_stack: ExitStack = ExitStack()
 class Actor:
     """The fundamental concurrency primitive.
 
-    An *actor* is the combination of a regular Python or
+    An *actor* is the combination of a regular Python process
-    ``multiprocessing.Process`` executing a ``trio`` task tree, communicating
+    executing a ``trio`` task tree, communicating
     with other actors through "portals" which provide a native async API
-    around "channels".
+    around various IPC transport "channels".
     """
     is_arbiter: bool = False
 
@@ -409,7 +424,7 @@ class Actor:
         self._no_more_peers = trio.Event()  # unset
 
         chan = Channel(stream=stream)
-        log.info(f"New connection to us {chan}")
+        log.runtime(f"New connection to us {chan}")
 
         # send/receive initial handshake response
         try:
@@ -440,8 +455,12 @@ class Actor:
             event.set()
 
         chans = self._peers[uid]
+
+        # TODO: re-use channels for new connections instead 
+        # of always new ones; will require changing all the
+        # discovery funcs
         if chans:
-            log.warning(
+            log.runtime(
                 f"already have channel(s) for {uid}:{chans}?"
             )
 
@@ -686,7 +705,7 @@ class Actor:
                         else:
                             # mark that we have ongoing rpc tasks
                             self._ongoing_rpc_tasks = trio.Event()
-                            log.info(f"RPC func is {func}")
+                            log.runtime(f"RPC func is {func}")
                             # store cancel scope such that the rpc task can be
                             # cancelled gracefully if requested
                             self._rpc_tasks[(chan, cid)] = (
@@ -695,7 +714,7 @@ class Actor:
                         # self.cancel() was called so kill this msg loop
                         # and break out into ``_async_main()``
                         log.warning(
-                            f"{self.uid} was remotely cancelled; "
+                            f"Actor {self.uid} was remotely cancelled; "
                             "waiting on cancellation completion..")
                         await self._cancel_complete.wait()
                         loop_cs.cancel()
@@ -713,14 +732,13 @@ class Actor:
         except (
             TransportClosed,
             trio.BrokenResourceError,
-            trio.ClosedResourceError
+            # trio.ClosedResourceError
         ):
             # channels "breaking" is ok since we don't have a teardown
             # handshake for them (yet) and instead we simply bail out
-            # of the message loop and expect the teardown sequence
+            # of the message loop and expect the surrounding
-            # to clean up.
+            # caller's teardown sequence to clean up.
-            log.error(f"{chan} form {chan.uid} closed abruptly")
+            log.warning(f"Channel from {chan.uid} closed abruptly")
-            # raise
 
         except (Exception, trio.MultiError) as err:
             # ship any "internal" exception (i.e. one from internal machinery
@@ -1164,7 +1182,7 @@ class Actor:
             raise ValueError(f"{uid} is not a valid uid?!")
 
         chan.uid = uid
-        log.info(f"Handshake with actor {uid}@{chan.raddr} complete")
+        log.runtime(f"Handshake with actor {uid}@{chan.raddr} complete")
         return uid
 
 

tractor/_exceptions.py

@@ -56,13 +56,22 @@ class NoRuntime(RuntimeError):
     "The root actor has not been initialized yet"
 
 
-def pack_error(exc: BaseException) -> Dict[str, Any]:
+def pack_error(
+    exc: BaseException,
+    tb = None,
+
+) -> Dict[str, Any]:
     """Create an "error message" for tranmission over
     a channel (aka the wire).
     """
+    if tb:
+        tb_str = ''.join(traceback.format_tb(tb))
+    else:
+        tb_str = traceback.format_exc()
+
     return {
         'error': {
-            'tb_str': traceback.format_exc(),
+            'tb_str': tb_str,
             'type_str': type(exc).__name__,
         }
     }