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Provide each task's cancel scope to every `Context` 

This begins moving toward explicitly decorated "streaming functions"
instead of checking for a `ctx` arg in the signature.

- provide each context with its task's top level `trio.CancelScope`
  such that tasks can cancel themselves explictly if needed via calling
  `Context.cancel_scope()`
- make `Actor.cancel_task()` a private method (`_cancel_task()`) and
  handle remote rpc calls specially such that the caller does not need
  to provide the `chan` argument; non-primitive types can't be passed on
  the wire and we don't want the client actor be require knowledge of
  the channel instance the request is associated with. This also ties into
  how we're tracking tasks right now (`Actor._rpc_tasks` is keyed by the
  call id, a UUID, *plus* the channel).
- make `_do_handshake` a private actor method
- use UUID version 4
stream_functions
Tyler Goodlet 2019-03-23 13:50:23 -04:00
parent ac4a025aa5
commit 2aa6ffce60
3 changed files with 61 additions and 54 deletions
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73
tractor/_actor.py
View File

@ -23,7 +23,6 @@ from ._exceptions import (
from ._portal import (
Portal,
open_portal,
_do_handshake,
LocalPortal,
)
from . import _state
@ -50,7 +49,8 @@ async def _invoke(
sig = inspect.signature(func)
treat_as_gen = False
cs = None
ctx = Context(chan, cid)
cancel_scope = trio.CancelScope()
ctx = Context(chan, cid, cancel_scope)
if 'ctx' in sig.parameters:
kwargs['ctx'] = ctx
# TODO: eventually we want to be more stringent
@ -73,7 +73,7 @@ async def _invoke(
not is_async_gen_partial
):
await chan.send({'functype': 'function', 'cid': cid})
with trio.CancelScope() as cs:
with cancel_scope as cs:
task_status.started(cs)
await chan.send({'return': func(**kwargs), 'cid': cid})
else:
@ -88,7 +88,7 @@ async def _invoke(
# have to properly handle the closing (aclosing)
# of the async gen in order to be sure the cancel
# is propagated!
with trio.CancelScope() as cs:
with cancel_scope as cs:
task_status.started(cs)
async with aclosing(coro) as agen:
async for item in agen:
@ -113,7 +113,7 @@ async def _invoke(
# back values like an async-generator would but must
# manualy construct the response dict-packet-responses as
# above
with trio.CancelScope() as cs:
with cancel_scope as cs:
task_status.started(cs)
await coro
if not cs.cancelled_caught:
@ -122,7 +122,7 @@ async def _invoke(
await chan.send({'stop': True, 'cid': cid})
else:
await chan.send({'functype': 'asyncfunction', 'cid': cid})
with trio.CancelScope() as cs:
with cancel_scope as cs:
task_status.started(cs)
await chan.send({'return': await coro, 'cid': cid})
except Exception as err:
@ -174,7 +174,7 @@ class Actor:
arbiter_addr: Optional[Tuple[str, int]] = None,
) -> None:
self.name = name
self.uid = (name, uid or str(uuid.uuid1()))
self.uid = (name, uid or str(uuid.uuid4()))
self.rpc_module_paths = rpc_module_paths
self._mods: dict = {}
# TODO: consider making this a dynamically defined
@ -247,7 +247,7 @@ class Actor:
# send/receive initial handshake response
try:
uid = await _do_handshake(self, chan)
uid = await self._do_handshake(chan)
except StopAsyncIteration:
log.warning(f"Channel {chan} failed to handshake")
return
@ -351,7 +351,7 @@ class Actor:
caller id and a ``trio.Queue`` that can be used to wait for
responses delivered by the local message processing loop.
"""
cid = str(uuid.uuid1())
cid = str(uuid.uuid4())
assert chan.uid
recv_chan = self.get_memchans(chan.uid, cid)
log.debug(f"Sending cmd to {chan.uid}: {ns}.{func}({kwargs})")
@ -373,11 +373,12 @@ class Actor:
msg = None
log.debug(f"Entering msg loop for {chan} from {chan.uid}")
try:
# internal scope allows for keeping this message
# loop running despite the current task having been
# cancelled (eg. `open_portal()` may call this method from
# a locally spawned task)
with trio.CancelScope(shield=shield) as cs:
# this internal scope allows for keeping this message
# loop running despite the current task having been
# cancelled (eg. `open_portal()` may call this method from
# a locally spawned task) and recieve this scope using
# ``scope = Nursery.start()``
task_status.started(cs)
async for msg in chan:
if msg is None: # loop terminate sentinel
@ -385,7 +386,7 @@ class Actor:
f"Cancelling all tasks for {chan} from {chan.uid}")
for (channel, cid) in self._rpc_tasks:
if channel is chan:
self.cancel_task(cid, Context(channel, cid))
self._cancel_task(cid, channel)
log.debug(
f"Msg loop signalled to terminate for"
f" {chan} from {chan.uid}")
@ -419,6 +420,16 @@ class Actor:
f"{ns}.{funcname}({kwargs})")
if ns == 'self':
func = getattr(self, funcname)
if funcname == '_cancel_task':
# XXX: a special case is made here for
# remote calls since we don't want the
# remote actor have to know which channel
# the task is associated with and we can't
# pass non-primitive types between actors.
# This means you can use:
# Portal.run('self', '_cancel_task, cid=did)
# without passing the `chan` arg.
kwargs['chan'] = chan
else:
# complain to client about restricted modules
try:
@ -537,7 +548,7 @@ class Actor:
)
await chan.connect()
# initial handshake, report who we are, who they are
await _do_handshake(self, chan)
await self._do_handshake(chan)
except OSError: # failed to connect
log.warning(
f"Failed to connect to parent @ {parent_addr},"
@ -661,21 +672,20 @@ class Actor:
self.cancel_server()
self._root_nursery.cancel_scope.cancel()
async def cancel_task(self, cid, ctx):
"""Cancel a local task.
async def _cancel_task(self, cid, chan):
"""Cancel a local task by call-id / channel.
Note this method will be treated as a streaming funciton
Note this method will be treated as a streaming function
by remote actor-callers due to the declaration of ``ctx``
in the signature (for now).
"""
# right now this is only implicitly called by
# streaming IPC but it should be called
# to cancel any remotely spawned task
chan = ctx.chan
try:
# this ctx based lookup ensures the requested task to
# be cancelled was indeed spawned by a request from this channel
scope, func, is_complete = self._rpc_tasks[(ctx.chan, cid)]
scope, func, is_complete = self._rpc_tasks[(chan, cid)]
except KeyError:
log.warning(f"{cid} has already completed/terminated?")
return
@ -686,7 +696,7 @@ class Actor:
# don't allow cancelling this function mid-execution
# (is this necessary?)
if func is self.cancel_task:
if func is self._cancel_task:
return
scope.cancel()
@ -704,7 +714,7 @@ class Actor:
log.info(f"Cancelling all {len(tasks)} rpc tasks:\n{tasks} ")
for (chan, cid) in tasks.copy():
# TODO: this should really done in a nursery batch
await self.cancel_task(cid, Context(chan, cid))
await self._cancel_task(cid, chan)
# if tasks:
log.info(
f"Waiting for remaining rpc tasks to complete {tasks}")
@ -735,6 +745,25 @@ class Actor:
"""Return all channels to the actor with provided uid."""
return self._peers[uid]
async def _do_handshake(
self,
chan: Channel
) -> Tuple[str, str]:
"""Exchange (name, UUIDs) identifiers as the first communication step.
These are essentially the "mailbox addresses" found in actor model
parlance.
"""
await chan.send(self.uid)
uid: Tuple[str, str] = await chan.recv()
if not isinstance(uid, tuple):
raise ValueError(f"{uid} is not a valid uid?!")
chan.uid = uid
log.info(f"Handshake with actor {uid}@{chan.raddr} complete")
return uid
class Arbiter(Actor):
"""A special actor who knows all the other actors and always has

5
tractor/_ipc.py
View File

@ -215,10 +215,7 @@ class Context:
"""
chan: Channel
cid: str
# TODO: we should probably attach the actor-task
# cancel scope here now that trio is exposing it
# as a public object
cancel_scope: trio.CancelScope
async def send_yield(self, data: Any) -> None:
await self.chan.send({'yield': data, 'cid': self.cid})

37
tractor/_portal.py
View File

@ -33,21 +33,6 @@ async def maybe_open_nursery(nursery: trio._core._run.Nursery = None):
yield nursery
async def _do_handshake(
actor: 'Actor', # type: ignore
chan: Channel
) -> Any:
await chan.send(actor.uid)
uid: Tuple[str, str] = await chan.recv()
if not isinstance(uid, tuple):
raise ValueError(f"{uid} is not a valid uid?!")
chan.uid = uid
log.info(f"Handshake with actor {uid}@{chan.raddr} complete")
return uid
class StreamReceiveChannel(trio.abc.ReceiveChannel):
"""A wrapper around a ``trio._channel.MemoryReceiveChannel`` with
special behaviour for signalling stream termination across an
@ -95,8 +80,8 @@ class StreamReceiveChannel(trio.abc.ReceiveChannel):
raise unpack_error(msg, self._portal.channel)
async def aclose(self):
"""Cancel associate remote actor task on close
as well as the local memory channel.
"""Cancel associated remote actor task and local memory channel
on close.
"""
if self._rx_chan._closed:
log.warning(f"{self} is already closed")
@ -107,15 +92,10 @@ class StreamReceiveChannel(trio.abc.ReceiveChannel):
log.warning(
f"Cancelling stream {cid} to "
f"{self._portal.channel.uid}")
# TODO: yeah.. it'd be nice if this was just an
# async func on the far end. Gotta figure out a
# better way then implicitly feeding the ctx
# to declaring functions; likely a decorator
# system.
rchan = await self._portal.run(
'self', 'cancel_task', cid=cid)
async for _ in rchan:
pass
# NOTE: we're telling the far end actor to cancel a task
# corresponding to *this actor*. The far end local channel
# instance is passed to `Actor._cancel_task()` implicitly.
await self._portal.run('self', '_cancel_task', cid=cid)
if cs.cancelled_caught:
# XXX: there's no way to know if the remote task was indeed
@ -153,6 +133,7 @@ class Portal:
Tuple[str, Any, str, Dict[str, Any]]
] = None
self._streams: Set[StreamReceiveChannel] = set()
self.actor = current_actor()
async def _submit(
self,
@ -167,7 +148,7 @@ class Portal:
This is an async call.
"""
# ship a function call request to the remote actor
cid, recv_chan = await current_actor().send_cmd(
cid, recv_chan = await self.actor.send_cmd(
self.channel, ns, func, kwargs)
# wait on first response msg and handle (this should be
@ -345,7 +326,7 @@ async def open_portal(
was_connected = True
if channel.uid is None:
await _do_handshake(actor, channel)
await actor._do_handshake(channel)
msg_loop_cs = await nursery.start(
partial(