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Consider relaying context error via raised-in-scope-nursery task

context_finesse
Tyler Goodlet 2021-06-24 19:56:05 -04:00
parent a1603709ab
commit 807c1d71a2
3 changed files with 177 additions and 89 deletions
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84
tractor/_actor.py
View File

@ -46,6 +46,7 @@ class ActorFailure(Exception):
async def _invoke(
actor: 'Actor',
cid: str,
chan: Channel,
@ -58,10 +59,12 @@ async def _invoke(
"""Invoke local func and deliver result(s) over provided channel.
"""
treat_as_gen = False
cs = None
cancel_scope = trio.CancelScope()
ctx = Context(chan, cid, _cancel_scope=cancel_scope)
context = False
cs: trio.CancelScope = None
ctx = Context(chan, cid)
context: bool = False
if getattr(func, '_tractor_stream_function', False):
# handle decorated ``@tractor.stream`` async functions
@ -149,14 +152,22 @@ async def _invoke(
# context func with support for bi-dir streaming
await chan.send({'functype': 'context', 'cid': cid})
with cancel_scope as cs:
async with trio.open_nursery() as scope_nursery:
ctx._scope_nursery = scope_nursery
cs = scope_nursery.cancel_scope
task_status.started(cs)
await chan.send({'return': await coro, 'cid': cid})
if cs.cancelled_caught:
if ctx._cancel_called:
msg = f'{func.__name__} cancelled itself',
else:
msg = f'{func.__name__} was remotely cancelled',
# task-contex was cancelled so relay to the cancel to caller
raise ContextCancelled(
f'{func.__name__} cancelled itself',
msg,
suberror_type=trio.Cancelled,
)
@ -191,8 +202,10 @@ async def _invoke(
await chan.send(err_msg)
except trio.ClosedResourceError:
log.warning(
f"Failed to ship error to caller @ {chan.uid}")
# if we can't propagate the error that's a big boo boo
log.error(
f"Failed to ship error to caller @ {chan.uid} !?"
)
if cs is None:
# error is from above code not from rpc invocation
@ -372,12 +385,16 @@ class Actor:
raise mne
async def _stream_handler(
self,
stream: trio.SocketStream,
) -> None:
"""Entry point for new inbound connections to the channel server.
"""
self._no_more_peers = trio.Event() # unset
chan = Channel(stream=stream)
log.info(f"New connection to us {chan}")
@ -423,10 +440,24 @@ class Actor:
try:
await self._process_messages(chan)
finally:
# channel cleanup sequence
# for (channel, cid) in self._rpc_tasks.copy():
# if channel is chan:
# with trio.CancelScope(shield=True):
# await self._cancel_task(cid, channel)
# # close all consumer side task mem chans
# send_chan, _ = self._cids2qs[(chan.uid, cid)]
# assert send_chan.cid == cid # type: ignore
# await send_chan.aclose()
# Drop ref to channel so it can be gc-ed and disconnected
log.debug(f"Releasing channel {chan} from {chan.uid}")
chans = self._peers.get(chan.uid)
chans.remove(chan)
if not chans:
log.debug(f"No more channels for {chan.uid}")
self._peers.pop(chan.uid, None)
@ -439,14 +470,22 @@ class Actor:
# # XXX: is this necessary (GC should do it?)
if chan.connected():
# if the channel is still connected it may mean the far
# end has not closed and we may have gotten here due to
# an error and so we should at least try to terminate
# the channel from this end gracefully.
log.debug(f"Disconnecting channel {chan}")
try:
# send our msg loop terminate sentinel
# send a msg loop terminate sentinel
await chan.send(None)
# XXX: do we want this?
# causes "[104] connection reset by peer" on other end
# await chan.aclose()
except trio.BrokenResourceError:
log.exception(
f"Channel for {chan.uid} was already zonked..")
log.warning(f"Channel for {chan.uid} was already closed")
async def _push_result(
self,
@ -456,18 +495,22 @@ class Actor:
) -> None:
"""Push an RPC result to the local consumer's queue.
"""
actorid = chan.uid
assert actorid, f"`actorid` can't be {actorid}"
send_chan, recv_chan = self._cids2qs[(actorid, cid)]
# actorid = chan.uid
assert chan.uid, f"`chan.uid` can't be {chan.uid}"
send_chan, recv_chan = self._cids2qs[(chan.uid, cid)]
assert send_chan.cid == cid # type: ignore
# if 'stop' in msg:
if 'error' in msg:
ctx = getattr(recv_chan, '_ctx', None)
# if ctx:
# ctx._error_from_remote_msg(msg)
# log.debug(f"{send_chan} was terminated at remote end")
# # indicate to consumer that far end has stopped
# return await send_chan.aclose()
try:
log.debug(f"Delivering {msg} from {actorid} to caller {cid}")
log.debug(f"Delivering {msg} from {chan.uid} to caller {cid}")
# maintain backpressure
await send_chan.send(msg)
@ -486,7 +529,9 @@ class Actor:
self,
actorid: Tuple[str, str],
cid: str
) -> Tuple[trio.abc.SendChannel, trio.abc.ReceiveChannel]:
log.debug(f"Getting result queue for {actorid} cid {cid}")
try:
send_chan, recv_chan = self._cids2qs[(actorid, cid)]
@ -548,9 +593,15 @@ class Actor:
if channel is chan:
await self._cancel_task(cid, channel)
# close all consumer side task mem chans
# send_chan, _ = self._cids2qs[(chan.uid, cid)]
# assert send_chan.cid == cid # type: ignore
# await send_chan.aclose()
log.debug(
f"Msg loop signalled to terminate for"
f" {chan} from {chan.uid}")
break
log.trace( # type: ignore
@ -657,9 +708,6 @@ class Actor:
log.error(f"{chan} form {chan.uid} closed abruptly")
# raise
except trio.ClosedResourceError:
log.error(f"{chan} form {chan.uid} broke")
except (Exception, trio.MultiError) as err:
# ship any "internal" exception (i.e. one from internal machinery
# not from an rpc task) to parent

123
tractor/_portal.py
View File

@ -177,6 +177,7 @@ class Portal:
f"Cancelling all streams with {self.channel.uid}")
for stream in self._streams.copy():
try:
# with trio.CancelScope(shield=True):
await stream.aclose()
except trio.ClosedResourceError:
# don't error the stream having already been closed
@ -369,64 +370,78 @@ class Portal:
recv_chan: Optional[trio.MemoryReceiveChannel] = None
cid, recv_chan, functype, first_msg = await self._submit(
fn_mod_path, fn_name, kwargs)
assert functype == 'context'
msg = await recv_chan.receive()
try:
cid, recv_chan, functype, first_msg = await self._submit(
fn_mod_path, fn_name, kwargs)
# the "first" value here is delivered by the callee's
# ``Context.started()`` call.
first = msg['started']
assert functype == 'context'
msg = await recv_chan.receive()
except KeyError:
assert msg.get('cid'), ("Received internal error at context?")
try:
# the "first" value here is delivered by the callee's
# ``Context.started()`` call.
first = msg['started']
except KeyError:
assert msg.get('cid'), ("Received internal error at context?")
if msg.get('error'):
# raise the error message
raise unpack_error(msg, self.channel)
else:
raise
# deliver context instance and .started() msg value in open
# tuple.
ctx = Context(
self.channel,
cid,
_portal=self,
_recv_chan=recv_chan,
)
try:
yield ctx, first
if cancel_on_exit:
await ctx.cancel()
else:
if not ctx._cancel_called:
await ctx.result()
except ContextCancelled:
# if the context was cancelled by client code
# then we don't need to raise since user code
# is expecting this.
if not ctx._cancel_called:
raise
except BaseException:
# the context cancels itself on any deviation
await ctx.cancel()
if msg.get('error'):
# raise the error message
raise unpack_error(msg, self.channel)
else:
raise
finally:
log.info(f'Context for {func.__name__} completed')
# deliver context instance and .started() msg value in open
# tuple.
try:
async with trio.open_nursery() as scope_nursery:
ctx = Context(
self.channel,
cid,
_portal=self,
_recv_chan=recv_chan,
_scope_nursery=scope_nursery,
)
recv_chan._ctx = ctx
yield ctx, first
log.info(f'Context for {func.__name__} completed')
if cancel_on_exit:
await ctx.cancel()
else:
if not ctx._cancel_called:
await ctx.result()
await recv_chan.aclose()
# except TypeError:
# # if fn_name == '_emsd_main':
# import tractor
# await tractor.breakpoint()
except ContextCancelled:
if not ctx._cancel_called:
raise
# if the context was cancelled by client code
# then we don't need to raise since user code
# is expecting this and the block should exit.
else:
log.debug(f'Context {ctx} cancelled gracefully')
except trio.Cancelled:
# the context cancels itself on any deviation
await ctx.cancel()
raise
# finally:
# log.info(f'Context for {func.__name__} completed')
# finally:
# if recv_chan is not None:
finally:
if recv_chan is not None:
await recv_chan.aclose()
@dataclass
class LocalPortal:
@ -464,6 +479,7 @@ async def open_portal(
was_connected = False
async with maybe_open_nursery(nursery, shield=shield) as nursery:
if not channel.connected():
await channel.connect()
was_connected = True
@ -485,11 +501,12 @@ async def open_portal(
portal = Portal(channel)
try:
yield portal
finally:
await portal.aclose()
if was_connected:
# cancel remote channel-msg loop
# gracefully signal remote channel-msg loop
await channel.send(None)
# cancel background msg loop task

59
tractor/_streaming.py
View File

@ -7,7 +7,7 @@ from contextlib import contextmanager, asynccontextmanager
from dataclasses import dataclass
from typing import (
Any, Iterator, Optional, Callable,
AsyncGenerator,
AsyncGenerator, Dict,
)
import warnings
@ -67,6 +67,9 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
raise trio.EndOfChannel
try:
# if self._ctx.chan.uid[0] == 'brokerd.ib':
# breakpoint()
msg = await self._rx_chan.receive()
return msg['yield']
@ -134,6 +137,11 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
raise # propagate
# except trio.Cancelled:
# if not self._shielded:
# # if shielded we don't propagate a cancelled
# raise
# except trio.Cancelled:
# # relay cancels to the remote task
# await self.aclose()
@ -165,7 +173,7 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
# https://trio.readthedocs.io/en/stable/reference-io.html#trio.abc.AsyncResource.aclose
rx_chan = self._rx_chan
if rx_chan._closed:
if rx_chan._closed: # or self._eoc:
log.warning(f"{self} is already closed")
# this stream has already been closed so silently succeed as
@ -212,7 +220,10 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
# stop from the caller side
await self._ctx.send_stop()
except trio.BrokenResourceError:
except (
trio.BrokenResourceError,
trio.ClosedResourceError
):
# the underlying channel may already have been pulled
# in which case our stop message is meaningless since
# it can't traverse the transport.
@ -254,18 +265,6 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
# still need to consume msgs that are "in transit" from the far
# end (eg. for ``Context.result()``).
# TODO: but make it broadcasting to consumers
# def clone(self):
# """Clone this receive channel allowing for multi-task
# consumption from the same channel.
# """
# return ReceiveStream(
# self._cid,
# self._rx_chan.clone(),
# self._portal,
# )
class MsgStream(ReceiveMsgStream, trio.abc.Channel):
"""
@ -282,6 +281,17 @@ class MsgStream(ReceiveMsgStream, trio.abc.Channel):
'''
await self._ctx.chan.send({'yield': data, 'cid': self._ctx.cid})
# TODO: but make it broadcasting to consumers
def clone(self):
"""Clone this receive channel allowing for multi-task
consumption from the same channel.
"""
return MsgStream(
self._ctx,
self._rx_chan.clone(),
)
@dataclass
class Context:
@ -308,7 +318,7 @@ class Context:
_cancel_called: bool = False
# only set on the callee side
_cancel_scope: Optional[trio.CancelScope] = None
_scope_nursery: Optional[trio.Nursery] = None
async def send_yield(self, data: Any) -> None:
@ -323,6 +333,16 @@ class Context:
async def send_stop(self) -> None:
await self.chan.send({'stop': True, 'cid': self.cid})
def _error_from_remote_msg(
self,
msg: Dict[str, Any],
) -> None:
async def raiser():
raise unpack_error(msg, self.chan)
self._scope_nursery.start_soon(raiser)
async def cancel(self) -> None:
'''Cancel this inter-actor-task context.
@ -361,13 +381,16 @@ class Context:
f"{cid} for {self._portal.channel.uid}")
else:
# ensure callee side
assert self._cancel_scope
assert self._scope_nursery
# TODO: should we have an explicit cancel message
# or is relaying the local `trio.Cancelled` as an
# {'error': trio.Cancelled, cid: "blah"} enough?
# This probably gets into the discussion in
# https://github.com/goodboy/tractor/issues/36
self._cancel_scope.cancel()
self._scope_nursery.cancel_scope.cancel()
if self._recv_chan:
await self._recv_chan.aclose()
@asynccontextmanager
async def open_stream(