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tractor
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Add a separate cancel scope for the main task 

Cancellation requires that each actor cancel it's spawned subactors
before cancelling its own root (nursery's) cancel scope to avoid breaking
channel connections before kill commands (`Actor.cancel()`) have been sent
off to peers. To solve this, ensure each main task is cancelled to
completion first (which will guarantee that all actor nurseries have
completed their cancellation steps) before cancelling the actor's "core"
tasks under the "root" scope.
asyncgen_closing_fix
Tyler Goodlet 2018-07-11 00:20:50 -04:00
parent 1854471992
commit 209a6a2096
1 changed files with 37 additions and 23 deletions
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60
tractor/__init__.py
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@ -176,6 +176,8 @@ class Actor:
self._peers = defaultdict(list)
self._peer_connected = {}
self._no_more_peers = trio.Event()
self._main_complete = trio.Event()
self._main_scope = None
self._no_more_peers.set()
self._actors2calls = {} # map {uids -> {callids -> waiter queues}}
self._listeners = []
@ -443,28 +445,32 @@ class Actor:
self._process_messages, self._parent_chan)
if self.main:
try:
if self._parent_chan:
log.debug(f"Starting main task `{self.main}`")
# spawned subactor so deliver "main" task result(s)
# back to parent
await nursery.start(
_invoke, 'main',
self._parent_chan, self.main, {},
False, True # treat_as_gen, raise_errs params
)
else:
# run directly - we are an "unspawned actor"
log.debug(f"Running `{self.main}` directly")
result = await self.main()
finally:
# tear down channel server in order to ensure
# we exit normally when the main task is done
if not self._outlive_main:
log.debug(f"Shutting down channel server")
self.cancel_server()
with trio.open_cancel_scope() as main_scope:
self._main_scope = main_scope
try:
if self._parent_chan:
log.debug(f"Starting main task `{self.main}`")
# spawned subactor so deliver "main" task result(s)
# back to parent
await nursery.start(
_invoke, 'main',
self._parent_chan, self.main, {},
False, True # treat_as_gen, raise_errs params
)
else:
# run directly - we are an "unspawned actor"
log.debug(f"Running `{self.main}` directly")
result = await self.main()
finally:
# tear down channel server in order to ensure
# we exit normally when the main task is done
if not self._outlive_main:
log.debug(f"Shutting down channel server")
self.cancel_server()
if main_scope.cancelled_caught:
log.debug("Main task was cancelled sucessfully")
self._main_complete.set()
log.debug("Waiting on root nursery to complete")
# blocks here as expected if no nursery was provided until
# the channel server is killed (i.e. this actor is
@ -550,6 +556,10 @@ class Actor:
cancelling (for all intents and purposes) this actor.
"""
self.cancel_server()
if self._main_scope:
self._main_scope.cancel()
log.debug("Waiting on main task to complete")
await self._main_complete.wait()
self._root_nursery.cancel_scope.cancel()
def cancel_server(self):
@ -684,9 +694,11 @@ class Portal:
cancel_scope.shield = True
# send cancel cmd - might not get response
await self.run('self', 'cancel')
return True
except trio.ClosedStreamError:
log.warn(
f"{self.channel} for {self.channel.uid} was alreaday closed?")
f"{self.channel} for {self.channel.uid} was already closed?")
return False
@asynccontextmanager
@ -795,7 +807,8 @@ class ActorNursery:
return portal
async def wait(self):
"""Wait for all subactors to complete.
"""
async def wait_for_proc(proc, actor, portal):
# TODO: timeout block here?
if proc.is_alive():
@ -1022,6 +1035,7 @@ async def _main(async_fn, args, kwargs, name, arbiter_addr):
actor = Actor(
name or 'anonymous',
main=main,
arbiter_addr=arbiter_addr,
**kwargs
)
host, port = (host, 0)