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Allocate an event per context

pause_feeds_on_sym_switch
Tyler Goodlet 2021-09-01 09:45:14 -04:00
parent 26cb7aa660
commit 4527d4a677
1 changed files with 17 additions and 15 deletions
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32
piker/_cacheables.py
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@ -31,13 +31,11 @@ from typing import (
)
from contextlib import (
asynccontextmanager,
AsyncExitStack,
)
import trio
from trio_typing import TaskStatus
import tractor
from tractor._portal import maybe_open_nursery
from .brokers import get_brokermod
from .log import get_logger
@ -86,8 +84,11 @@ class cache:
'''
lock = trio.Lock()
users: int = 0
values: dict[tuple[str, str], tuple[AsyncExitStack, Any]] = {}
nurseries: dict[int, Optional[trio.Nursery]] = {}
values: dict[Any, Any] = {}
resources: dict[
int,
Optional[tuple[trio.Nursery, trio.Event]]
] = {}
no_more_users: Optional[trio.Event] = None
@classmethod
@ -100,15 +101,15 @@ class cache:
) -> None:
async with mng as value:
cls.no_more_users = trio.Event()
_, no_more_users = cls.resources[id(mng)]
cls.values[key] = value
task_status.started(value)
try:
await cls.no_more_users.wait()
await no_more_users.wait()
finally:
value = cls.values.pop(key)
# discard nursery ref so it won't be re-used (an error)
cls.nurseries.pop(id(mng))
cls.resources.pop(id(mng))
@asynccontextmanager
@ -128,13 +129,12 @@ async def maybe_open_ctx(
ctx_key = id(mngr)
value = None
try:
# lock feed acquisition around task racing / ``trio``'s
# scheduler protocol
value = cache.values[key]
log.info(f'Reusing cached feed for {key}')
log.info(f'Reusing cached resource for {key}')
cache.users += 1
cache.lock.release()
yield True, value
@ -146,14 +146,15 @@ async def maybe_open_ctx(
# checking the cache until complete otherwise the scheduler
# may switch and by accident we create more then one feed.
# TODO: vaoid pulling from ``tractor`` internals and
# instead offer a "root nursery" in
# TODO: avoid pulling from ``tractor`` internals and
# instead offer a "root nursery" in piker actors?
service_n = tractor.current_actor()._service_n
# TODO: does this need to be a tractor "root nursery"?
ln = cache.nurseries.get(ctx_key)
ln = cache.resources.get(ctx_key)
assert not ln
ln = cache.nurseries[ctx_key] = service_n
ln, _ = cache.resources[ctx_key] = (service_n, trio.Event())
value = await ln.start(cache.run_ctx, mngr, key)
cache.users += 1
@ -170,10 +171,11 @@ async def maybe_open_ctx(
if value is not None:
# if no more consumers, teardown the client
if cache.users <= 0:
log.warning(f'De-allocating feed for {key}')
log.warning(f'De-allocating resource for {key}')
# terminate mngr nursery
cache.no_more_users.set()
_, no_more_users = cache.resources[ctx_key]
no_more_users.set()
@asynccontextmanager