Add locks to make the caches well behaved in multi-threaded code.
Store builtins in cell variables to speed-up the common path, reducing the chance of a lock needing to block at all.
This commit is contained in:
parent
d9e8cc6249
commit
cbe8813f18
|
@ -15,6 +15,10 @@ from _functools import partial, reduce
|
|||
from collections import OrderedDict, Counter
|
||||
from heapq import nsmallest
|
||||
from operator import itemgetter
|
||||
try:
|
||||
from _thread import allocate_lock as Lock
|
||||
except:
|
||||
from _dummy_thread import allocate_lock as Lock
|
||||
|
||||
# update_wrapper() and wraps() are tools to help write
|
||||
# wrapper functions that can handle naive introspection
|
||||
|
@ -115,37 +119,42 @@ def lfu_cache(maxsize=100):
|
|||
http://en.wikipedia.org/wiki/Cache_algorithms#Least-Frequently_Used
|
||||
|
||||
"""
|
||||
def decorating_function(user_function):
|
||||
def decorating_function(user_function, tuple=tuple, sorted=sorted, len=len):
|
||||
cache = {} # mapping of args to results
|
||||
use_count = Counter() # times each key has been accessed
|
||||
kwd_mark = object() # separate positional and keyword args
|
||||
lock = Lock()
|
||||
|
||||
@wraps(user_function)
|
||||
def wrapper(*args, **kwds):
|
||||
key = args
|
||||
if kwds:
|
||||
key += (kwd_mark,) + tuple(sorted(kwds.items()))
|
||||
use_count[key] += 1 # count a use of this key
|
||||
try:
|
||||
result = cache[key]
|
||||
wrapper.hits += 1
|
||||
with lock:
|
||||
use_count[key] += 1 # count a use of this key
|
||||
result = cache[key]
|
||||
wrapper.hits += 1
|
||||
except KeyError:
|
||||
result = user_function(*args, **kwds)
|
||||
cache[key] = result
|
||||
wrapper.misses += 1
|
||||
if len(cache) > maxsize:
|
||||
# purge the 10% least frequently used entries
|
||||
for key, _ in nsmallest(maxsize // 10,
|
||||
use_count.items(),
|
||||
key=itemgetter(1)):
|
||||
del cache[key], use_count[key]
|
||||
with lock:
|
||||
use_count[key] += 1 # count a use of this key
|
||||
cache[key] = result
|
||||
wrapper.misses += 1
|
||||
if len(cache) > maxsize:
|
||||
# purge the 10% least frequently used entries
|
||||
for key, _ in nsmallest(maxsize // 10,
|
||||
use_count.items(),
|
||||
key=itemgetter(1)):
|
||||
del cache[key], use_count[key]
|
||||
return result
|
||||
|
||||
def clear():
|
||||
"""Clear the cache and cache statistics"""
|
||||
cache.clear()
|
||||
use_count.clear()
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
with lock:
|
||||
cache.clear()
|
||||
use_count.clear()
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
wrapper.clear = clear
|
||||
|
@ -161,9 +170,10 @@ def lru_cache(maxsize=100):
|
|||
http://en.wikipedia.org/wiki/Cache_algorithms#Least_Recently_Used
|
||||
|
||||
"""
|
||||
def decorating_function(user_function):
|
||||
def decorating_function(user_function, tuple=tuple, sorted=sorted, len=len):
|
||||
cache = OrderedDict() # ordered least recent to most recent
|
||||
kwd_mark = object() # separate positional and keyword args
|
||||
lock = Lock()
|
||||
|
||||
@wraps(user_function)
|
||||
def wrapper(*args, **kwds):
|
||||
|
@ -171,20 +181,25 @@ def lru_cache(maxsize=100):
|
|||
if kwds:
|
||||
key += (kwd_mark,) + tuple(sorted(kwds.items()))
|
||||
try:
|
||||
result = cache.pop(key)
|
||||
wrapper.hits += 1
|
||||
with lock:
|
||||
result = cache[key]
|
||||
del cache[key]
|
||||
cache[key] = result # record recent use of this key
|
||||
wrapper.hits += 1
|
||||
except KeyError:
|
||||
result = user_function(*args, **kwds)
|
||||
wrapper.misses += 1
|
||||
if len(cache) >= maxsize:
|
||||
cache.popitem(0) # purge least recently used cache entry
|
||||
cache[key] = result # record recent use of this key
|
||||
with lock:
|
||||
cache[key] = result # record recent use of this key
|
||||
wrapper.misses += 1
|
||||
if len(cache) > maxsize:
|
||||
cache.popitem(0) # purge least recently used cache entry
|
||||
return result
|
||||
|
||||
def clear():
|
||||
"""Clear the cache and cache statistics"""
|
||||
cache.clear()
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
with lock:
|
||||
cache.clear()
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
|
||||
wrapper.hits = wrapper.misses = 0
|
||||
wrapper.clear = clear
|
||||
|
|
Loading…
Reference in New Issue