[Python-checkins] cpython: Use a flag to indicate when the circular queue is fully populated and stable.
raymond.hettinger
python-checkins at python.org
Tue May 1 05:49:05 CEST 2012
http://hg.python.org/cpython/rev/f5bb290c751a
changeset: 76680:f5bb290c751a
parent: 76678:ab63e874265e
user: Raymond Hettinger <python at rcn.com>
date: Mon Apr 30 20:48:55 2012 -0700
summary:
Use a flag to indicate when the circular queue is fully populated and stable.
files:
Lib/functools.py | 21 ++++++++++++---------
1 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/Lib/functools.py b/Lib/functools.py
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -176,6 +176,7 @@
cache = {}
hits = misses = currsize = 0
+ full = False
cache_get = cache.get # bound method to lookup a key or return None
lock = Lock() # because linkedlist updates aren't threadsafe
root = [] # root of the circular doubly linked list
@@ -224,7 +225,7 @@
def wrapper(*args, **kwds):
# size limited caching that tracks accesses by recency
- nonlocal root, hits, misses, currsize
+ nonlocal root, hits, misses, currsize, full
key = make_key(args, kwds, typed) if kwds or typed else args
with lock:
link = cache_get(key)
@@ -247,13 +248,7 @@
# update is already done, we need only return the
# computed result and update the count of misses.
pass
- if currsize < maxsize:
- # put result in a new link at the front of the queue
- last = root[PREV]
- link = [last, root, key, result]
- cache[key] = last[NEXT] = root[PREV] = link
- currsize += 1
- else:
+ elif full:
# use root to store the new key and result
root[KEY] = key
root[RESULT] = result
@@ -262,6 +257,13 @@
root = root[NEXT]
del cache[root[KEY]]
root[KEY] = root[RESULT] = None
+ else:
+ # put result in a new link at the front of the queue
+ last = root[PREV]
+ link = [last, root, key, result]
+ cache[key] = last[NEXT] = root[PREV] = link
+ currsize += 1
+ full = (currsize == maxsize)
misses += 1
return result
@@ -272,11 +274,12 @@
def cache_clear():
"""Clear the cache and cache statistics"""
- nonlocal hits, misses, currsize
+ nonlocal hits, misses, currsize, full
with lock:
cache.clear()
root[:] = [root, root, None, None]
hits = misses = currsize = 0
+ full = False
wrapper.cache_info = cache_info
wrapper.cache_clear = cache_clear
--
Repository URL: http://hg.python.org/cpython
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