AstralTransRocketries/mcedit2
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lru_cache: Fix key being added to queue even when user_function raises an exception

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Also change try/catch to get(key, sentinel) because exceptions are more expensive and misses are common for my use-case
This commit is contained in:
David Vierra 2015-04-01 22:14:01 -10:00
parent 694e39b0c9
commit c1d5d0befa
1 changed files with 12 additions and 4 deletions
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16
src/mceditlib/cachefunc.py
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@ -185,6 +185,8 @@ class lfu_cache_object(object):
self.cache = {} # mapping of args to results self.cache = {} # mapping of args to results
self.use_count = Counter() # times each key has been accessed self.use_count = Counter() # times each key has been accessed
self.kwd_mark = object() # separate positional and keyword args self.kwd_mark = object() # separate positional and keyword args
self.sentinel = object() # marker for cache.get
self.hits = self.misses = 0 self.hits = self.misses = 0
self.user_function = user_function self.user_function = user_function
self.maxsize = maxsize self.maxsize = maxsize
@ -196,11 +198,17 @@ class lfu_cache_object(object):
self.use_count[key] += 1 self.use_count[key] += 1
# get cache entry or compute if not found # get cache entry or compute if not found
try: result = self.cache.get(key, self.sentinel)
result = self.cache[key] if result is not self.sentinel:
self.hits += 1 self.hits += 1
except KeyError: else:
result = self.user_function(*args, **kwds) try:
# exception thrown by user_function shouldn't leave cache and use_count inconsistent
result = self.user_function(*args, **kwds)
except:
self.use_count[key] -= 1
raise
self.cache[key] = result self.cache[key] = result
self.misses += 1 self.misses += 1