Issue 10586: change the new functools.lru_cache implementation to expose the maximum and current cache sizes through the public statistics API. This API is now a single function that returns a named tuple.
diff --git a/Lib/functools.py b/Lib/functools.py
index c1fa170..c223a62 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -12,7 +12,7 @@
'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial']
from _functools import partial, reduce
-from collections import OrderedDict
+from collections import OrderedDict, namedtuple
try:
from _thread import allocate_lock as Lock
except:
@@ -114,12 +114,15 @@
raise TypeError('hash not implemented')
return K
+_CacheInfo = namedtuple("CacheInfo", "maxsize, size, hits, misses")
+
def lru_cache(maxsize=100):
"""Least-recently-used cache decorator.
Arguments to the cached function must be hashable.
- Performance statistics stored in f.cache_hits and f.cache_misses.
+ Significant statistics (maxsize, size, hits, misses) are
+ available through the f.cache_info() named tuple.
Clear the cache and statistics using f.cache_clear().
The underlying function is stored in f.__wrapped__.
@@ -127,7 +130,7 @@
"""
# Users should only access the lru_cache through its public API:
- # cache_hits, cache_misses, cache_clear(), and __wrapped__
+ # cache_info, cache_clear, and f.__wrapped__
# The internals of the lru_cache are encapsulated for thread safety and
# to allow the implementation to change (including a possible C version).
@@ -137,11 +140,13 @@
cache = OrderedDict() # ordered least recent to most recent
cache_popitem = cache.popitem
cache_renew = cache.move_to_end
+ hits = misses = 0
kwd_mark = object() # separate positional and keyword args
lock = Lock()
@wraps(user_function)
def wrapper(*args, **kwds):
+ nonlocal hits, misses
key = args
if kwds:
key += (kwd_mark,) + tuple(sorted(kwds.items()))
@@ -149,23 +154,29 @@
with lock:
result = cache[key]
cache_renew(key) # record recent use of this key
- wrapper.cache_hits += 1
+ hits += 1
except KeyError:
result = user_function(*args, **kwds)
with lock:
cache[key] = result # record recent use of this key
- wrapper.cache_misses += 1
+ misses += 1
if len(cache) > maxsize:
cache_popitem(0) # purge least recently used cache entry
return result
+ def cache_info():
+ """Report significant cache statistics"""
+ with lock:
+ return _CacheInfo(maxsize, len(cache), hits, misses)
+
def cache_clear():
"""Clear the cache and cache statistics"""
+ nonlocal hits, misses
with lock:
cache.clear()
- wrapper.cache_hits = wrapper.cache_misses = 0
+ hits = misses = 0
- wrapper.cache_hits = wrapper.cache_misses = 0
+ wrapper.cache_info = cache_info
wrapper.cache_clear = cache_clear
return wrapper