Allow @cached-wrapped functions to have more or fewer than 1 argument; assert on the total count of them though

This commit is contained in:
Paul "LeoNerd" Evans 2015-03-17 18:38:55 +00:00
parent 532ebc4a82
commit 91cb46191d
1 changed files with 27 additions and 13 deletions

View File

@ -54,13 +54,12 @@ cache_counter = metrics.register_cache(
# TODO(paul):
# * more generic key management
# * consider other eviction strategies - LRU?
def cached(max_entries=1000):
def cached(max_entries=1000, num_args=1):
""" A method decorator that applies a memoizing cache around the function.
The function is presumed to take one additional argument, which is used as
the key for the cache. Cache hits are served directly from the cache;
The function is presumed to take zero or more arguments, which are used in
a tuple as the key for the cache. Hits are served directly from the cache;
misses use the function body to generate the value.
The wrapped function has an additional member, a callable called
@ -76,26 +75,41 @@ def cached(max_entries=1000):
caches_by_name[name] = cache
def prefill(key, value):
def prefill(*args): # because I can't *keyargs, value
keyargs = args[:-1]
value = args[-1]
if len(keyargs) != num_args:
raise ValueError("Expected a call to have %d arguments", num_args)
while len(cache) > max_entries:
cache.popitem(last=False)
cache[key] = value
cache[keyargs] = value
@functools.wraps(orig)
@defer.inlineCallbacks
def wrapped(self, key):
if key in cache:
def wrapped(self, *keyargs):
if len(keyargs) != num_args:
raise ValueError("Expected a call to have %d arguments", num_args)
if keyargs in cache:
cache_counter.inc_hits(name)
defer.returnValue(cache[key])
defer.returnValue(cache[keyargs])
cache_counter.inc_misses(name)
ret = yield orig(self, key)
prefill(key, ret)
ret = yield orig(self, *keyargs)
prefill_args = keyargs + (ret,)
prefill(*prefill_args)
defer.returnValue(ret)
def invalidate(key):
cache.pop(key, None)
def invalidate(*keyargs):
if len(keyargs) != num_args:
raise ValueError("Expected a call to have %d arguments", num_args)
cache.pop(keyargs, None)
wrapped.invalidate = invalidate
wrapped.prefill = prefill