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Re-implement client caching using `maybe_open_ctx`

pause_feeds_on_sym_switch
Tyler Goodlet 2021-09-01 09:01:25 -04:00
parent c3682348fe
commit 2df16e11ed
1 changed files with 17 additions and 53 deletions
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70
piker/_cacheables.py
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@ -79,59 +79,6 @@ def async_lifo_cache(maxsize=128):
_cache: dict[str, 'Client'] = {} # noqa _cache: dict[str, 'Client'] = {} # noqa
# XXX: this mis mostly an alt-implementation of
# maybe_open_ctx() below except it uses an async exit statck.
# ideally wer pick one or the other.
@asynccontextmanager
async def open_cached_client(
brokername: str,
) -> 'Client': # noqa
'''Get a cached broker client from the current actor's local vars.
If one has not been setup do it and cache it.
'''
global _cache
clients = _cache.setdefault('clients', {'_lock': trio.Lock()})
# global cache task lock
lock = clients['_lock']
client = None
try:
log.info(f"Loading existing `{brokername}` client")
async with lock:
client = clients[brokername]
client._consumers += 1
yield client
except KeyError:
log.info(f"Creating new client for broker {brokername}")
async with lock:
brokermod = get_brokermod(brokername)
exit_stack = AsyncExitStack()
client = await exit_stack.enter_async_context(
brokermod.get_client()
)
client._consumers = 0
client._exit_stack = exit_stack
clients[brokername] = client
yield client
finally:
if client is not None:
# if no more consumers, teardown the client
client._consumers -= 1
if client._consumers <= 0:
await client._exit_stack.aclose()
class cache: class cache:
'''Globally (processs wide) cached, task access to a '''Globally (processs wide) cached, task access to a
kept-alive-while-in-use async resource. kept-alive-while-in-use async resource.
@ -227,3 +174,20 @@ async def maybe_open_ctx(
# terminate mngr nursery # terminate mngr nursery
cache.no_more_users.set() cache.no_more_users.set()
@asynccontextmanager
async def open_cached_client(
brokername: str,
) -> 'Client': # noqa
'''Get a cached broker client from the current actor's local vars.
If one has not been setup do it and cache it.
'''
brokermod = get_brokermod(brokername)
async with maybe_open_ctx(
key=brokername,
mngr=brokermod.get_client(),
) as (cache_hit, client):
yield client