▮ RECOMMENDED USE
Not recommended for production code. Reasonable API shape and correctly used time.monotonic(), but the module does not parse (syntax error), contains an infinite while:pass loop, and has data races. Avoid for systems/concurrency work.
▮ REFACTORED PATCH
# FIX 1 (the parse error): assign first, then assert.
val_d = await cache.get("D")
assert val_d, "D should exist"
val_a = await cache.get("A")
assert val_a, "A should exist (highest freq)"
# FIX 2: delete the broken while:pass loop. Bump min_freq incrementally:
# only when the min_freq bucket empties, and only ever UP by 1 (a key
# whose freq increased must land at min_freq+1). Never call min()/max().
if not old_bucket:
del self.freq_map[old_freq]
if self.min_freq == old_freq:
self.min_freq += 1 # next tier up; never scan
# FIX 3: do ALL lazy eviction INSIDE the lock, not before it:
async def get(self, key):
async with self._lock:
if self.ttl_map.get(key, inf) <= time.monotonic():
await self._remove_key(key) # now locked
return None
...
# FIX 4: make _remove_key a non-locking private helper, called from
# inside already-locked public methods, so background_loop doesn't try
# to re-acquire the non-reentrant asyncio.Lock.
# FIX 5: add __slots__ = ('key','value','ttl_expiry') to _Node.