Move maybe-raise-error-msg logic into context

A context method handling all this logic makes the most sense since it
contains all the state related to whether the error should be raised in
a nursery scope or is expected to be raised by a consumer task which
reads and processes the msg directly (via a `Portal` API call). This
also makes it easy to always process remote errors even when there is no
(stream) overrun condition.
stricter_context_starting
Tyler Goodlet 2021-12-06 15:52:23 -05:00
parent 1f8e1cccbb
commit c9132de7dc
2 changed files with 76 additions and 79 deletions

View File

@ -650,62 +650,38 @@ class Actor:
return
send_chan = ctx._send_chan
assert send_chan
error = msg.get('error')
if error:
# If this is an error message from a context opened by
# ``Portal.open_context()`` we want to interrupt any ongoing
# (child) tasks within that context to be notified of the remote
# error relayed here.
#
# The reason we may want to raise the remote error immediately
# is that there is no guarantee the associated local task(s)
# will attempt to read from any locally opened stream any time
# soon.
#
# NOTE: this only applies when
# ``Portal.open_context()`` has been called since it is assumed
# (currently) that other portal APIs (``Portal.run()``,
# ``.run_in_actor()``) do their own error checking at the point
# of the call and result processing.
log.warning(f'Remote context for {chan.uid}:{cid} errored {msg}')
ctx._maybe_error_from_remote_msg(msg)
try:
log.runtime(f"Delivering {msg} from {chan.uid} to caller {cid}")
# XXX: we do **not** maintain backpressure and instead
# opt to relay stream overrun errors to the sender.
try:
send_chan.send_nowait(msg)
except trio.WouldBlock:
# if an error is deteced we should always
# expect it to be raised by any context (stream)
# consumer task
await ctx._maybe_raise_from_remote_msg(msg)
# XXX: do we need this?
# if we're trying to push an error but we're in
# an overrun state we'll just get stuck sending
# the error that was sent to us back to it's sender
# instead of it actually being raises in the target
# task..
# if error:
# raise unpack_error(msg, chan) from None
except trio.WouldBlock:
# XXX: always push an error even if the local
# receiver is in overrun state.
await ctx._maybe_raise_from_remote_msg(msg)
uid = chan.uid
lines = [
'Task context stream was overrun',
f'local task: {cid} @ {self.uid}',
f'remote sender: {chan.uid}',
f'remote sender: {uid}',
]
if not ctx._stream_opened:
lines.insert(
1,
f'\n*** No stream open on `{self.uid[0]}` side! ***\n'
)
text = '\n'.join(lines)
log.warning(text)
if ctx._backpressure:
log.warning(text)
await send_chan.send(msg)
else:
try:
@ -713,15 +689,14 @@ class Actor:
except StreamOverrun as err:
err_msg = pack_error(err)
err_msg['cid'] = cid
await chan.send(err_msg)
except trio.BrokenResourceError:
try:
# TODO: what is the right way to handle the case where the
# local task has already sent a 'stop' / StopAsyncInteration
# to the other side but and possibly has closed the local
# feeder mem chan? Do we wait for some kind of ack or just
# let this fail silently and bubble up (currently)?
await chan.send(err_msg)
except trio.BrokenResourceError:
# XXX: local consumer has closed their side
# so cancel the far end streaming task
log.warning(f"{send_chan} consumer is already closed")

View File

@ -364,19 +364,41 @@ class Context:
async def send_stop(self) -> None:
await self.chan.send({'stop': True, 'cid': self.cid})
def _maybe_error_from_remote_msg(
async def _maybe_raise_from_remote_msg(
self,
msg: Dict[str, Any],
) -> None:
'''
Unpack and raise a msg error into the local scope
(Maybe) unpack and raise a msg error into the local scope
nursery for this context.
Acts as a form of "relay" for a remote error raised
in the corresponding remote callee task.
'''
error = msg.get('error')
if error:
# If this is an error message from a context opened by
# ``Portal.open_context()`` we want to interrupt any ongoing
# (child) tasks within that context to be notified of the remote
# error relayed here.
#
# The reason we may want to raise the remote error immediately
# is that there is no guarantee the associated local task(s)
# will attempt to read from any locally opened stream any time
# soon.
#
# NOTE: this only applies when
# ``Portal.open_context()`` has been called since it is assumed
# (currently) that other portal APIs (``Portal.run()``,
# ``.run_in_actor()``) do their own error checking at the point
# of the call and result processing.
log.error(
f'Remote context error for {self.chan.uid}:{self.cid}:\n'
f'{msg["error"]["tb_str"]}'
)
# await ctx._maybe_error_from_remote_msg(msg)
self._error = unpack_error(msg, self.chan)
# TODO: tempted to **not** do this by-reraising in a