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#!/usr/bin/python -tt
import random
import unittest
class LRUCacheTests(unittest.TestCase):
def _getTargetClass(self):
from repoze.lru import LRUCache
return LRUCache
def check_cache_is_consistent(self, cache):
"""Return if cache is consistent, else raise fail test case."""
# cache.hand/maxpos/size
self.assertLess(cache.hand, len(cache.clock_keys))
self.assertGreaterEqual(cache.hand, 0)
self.assertEqual(cache.maxpos, cache.size - 1)
self.assertEqual(len(cache.clock_keys), cache.size)
# lengths of data structures
self.assertEqual(len(cache.clock_keys), len(cache.clock_refs))
self.assertLessEqual(len(cache.data), len(cache.clock_refs))
# For each item in cache.data
# 1. pos must be a valid index
# 2. clock_keys must point back to the entry
for key, value in cache.data.iteritems():
pos, val = value
self.assert_(isinstance(pos, int) or isinstance(pos, long))
self.assert_(pos >= 0)
self.assert_(pos <= cache.maxpos)
clock_key = cache.clock_keys[pos]
self.assert_(clock_key is key)
clock_ref = cache.clock_refs[pos]
# All clock_refs must be True or False, nothing else.
for clock_ref in cache.clock_refs:
self.assert_(clock_ref is True or clock_ref is False)
def _makeOne(self, size):
return self._getTargetClass()(size)
def test_size_lessthan_1(self):
self.assertRaises(ValueError, self._makeOne, 0)
def test_get(self):
cache = self._makeOne(1)
# Must support different types of keys
self.assertEqual(cache.get("foo"), None)
self.assertEqual(cache.get(42), None)
self.assertEqual(cache.get(("foo", 42)), None)
self.assertEqual(cache.get(None), None)
self.assertEqual(cache.get(""), None)
self.assertEqual(cache.get(object()), None)
# Check if default value is used
self.assertEqual(cache.get("foo", "bar"), "bar")
self.assertEqual(cache.get("foo", default="bar"), "bar")
self.check_cache_is_consistent(cache)
def test_put(self):
cache = self._makeOne(8)
self.check_cache_is_consistent(cache)
# Must support different types of keys
cache.put("foo", "FOO")
cache.put(42, "fortytwo")
cache.put( ("foo", 42), "tuple_as_key")
cache.put(None, "None_as_key")
cache.put("", "empty_string_as_key")
cache.put(3.141, "float_as_key")
my_object = object()
cache.put(my_object, "object_as_key")
self.check_cache_is_consistent(cache)
self.assertEqual(cache.get("foo"), "FOO")
self.assertEqual(cache.get(42), "fortytwo")
self.assertEqual(cache.get(("foo", 42), "fortytwo"), "tuple_as_key")
self.assertEqual(cache.get(None), "None_as_key")
self.assertEqual(cache.get(""), "empty_string_as_key")
self.assertEqual(cache.get(3.141), "float_as_key")
self.assertEqual(cache.get(my_object), "object_as_key")
# put()ing again must overwrite
cache.put(42, "fortytwo again")
self.assertEqual(cache.get(42), "fortytwo again")
self.check_cache_is_consistent(cache)
def test_invalidate(self):
cache = self._makeOne(3)
cache.put("foo", "bar")
cache.put("FOO", "BAR")
cache.invalidate("foo")
self.assertEqual(cache.get("foo"), None)
self.assertEqual(cache.get("FOO"), "BAR")
self.check_cache_is_consistent(cache)
cache.invalidate("FOO")
self.assertEqual(cache.get("foo"), None)
self.assertEqual(cache.get("FOO"), None)
self.assertEqual(cache.data, {})
self.check_cache_is_consistent(cache)
cache.put("foo", "bar")
cache.invalidate("nonexistingkey")
self.assertEqual(cache.get("foo"), "bar")
self.assertEqual(cache.get("FOO"), None)
self.check_cache_is_consistent(cache)
def test_small_cache(self):
"""Cache of size 1 must work"""
cache = self._makeOne(1)
cache.put("foo", "bar")
self.assertEqual(cache.get("foo"), "bar")
self.check_cache_is_consistent(cache)
cache.put("FOO", "BAR")
self.assertEqual(cache.get("FOO"), "BAR")
self.assertEqual(cache.get("foo"), None)
self.check_cache_is_consistent(cache)
# put() again
cache.put("FOO", "BAR")
self.assertEqual(cache.get("FOO"), "BAR")
self.assertEqual(cache.get("foo"), None)
self.check_cache_is_consistent(cache)
# invalidate()
cache.invalidate("FOO")
self.check_cache_is_consistent(cache)
self.assertEqual(cache.get("FOO"), None)
self.assertEqual(cache.get("foo"), None)
# clear()
cache.put("foo", "bar")
self.assertEqual(cache.get("foo"), "bar")
cache.clear()
self.check_cache_is_consistent(cache)
self.assertEqual(cache.get("FOO"), None)
self.assertEqual(cache.get("foo"), None)
def test_equal_but_not_identical(self):
"""equal but not identical keys must be treated the same"""
cache = self._makeOne(1)
tuple_one = (1, 1)
tuple_two = (1, 1)
cache.put(tuple_one, 42)
self.assertEqual(cache.get(tuple_one), 42)
self.assertEqual(cache.get(tuple_two), 42)
self.check_cache_is_consistent(cache)
cache = self._makeOne(1)
cache.put(tuple_one, 42)
cache.invalidate(tuple_two)
self.assertEqual(cache.get(tuple_one), None)
self.assertEqual(cache.get(tuple_two), None)
def test_perfect_hitrate(self):
"""If cache size equals number of items, expect 100% cache hits"""
size = 1000
cache = self._makeOne(size)
for count in xrange(size):
cache.put(count, "item%s" % count)
for cache_op in xrange(10000):
item = random.randrange(0, size - 1)
if random.getrandbits(1):
self.assertEqual(cache.get(item), "item%s" % item)
else:
cache.put(item, "item%s" % item)
self.check_cache_is_consistent(cache)
def test_imperfect_hitrate(self):
"""If cache size == half the number of items -> hit rate ~50%"""
size = 1000
cache = self._makeOne(size / 2)
for count in xrange(size):
cache.put(count, "item%s" % count)
hits = 0
misses = 0
total_gets = 0
for cache_op in xrange(10000):
item = random.randrange(0, size - 1)
if random.getrandbits(1):
entry = cache.get(item)
total_gets += 1
self.assert_(
(entry == "item%s" % item) or
entry is None)
if entry is None:
misses += 1
else:
hits += 1
else:
cache.put(item, "item%s" % item)
# Cache hit rate should be roughly 50%
hit_ratio = hits / float(total_gets) * 100
self.assertGreater(hit_ratio, 45)
self.assertLess(hit_ratio, 55)
self.check_cache_is_consistent(cache)
def test_it(self):
cache = self._makeOne(3)
self.assertEqual(cache.get('a'), None)
cache.put('a', '1')
pos, value = cache.data.get('a')
self.assertEqual(cache.clock_refs[pos], True)
self.assertEqual(cache.clock_keys[pos], 'a')
self.assertEqual(value, '1')
self.assertEqual(cache.get('a'), '1')
self.assertEqual(cache.hand, pos + 1)
pos, value = cache.data.get('a')
self.assertEqual(cache.clock_refs[pos], True)
self.assertEqual(cache.hand, pos + 1)
self.assertEqual(len(cache.data), 1)
cache.put('b', '2')
pos, value = cache.data.get('b')
self.assertEqual(cache.clock_refs[pos], True)
self.assertEqual(cache.clock_keys[pos], 'b')
self.assertEqual(len(cache.data), 2)
cache.put('c', '3')
pos, value = cache.data.get('c')
self.assertEqual(cache.clock_refs[pos], True)
self.assertEqual(cache.clock_keys[pos], 'c')
self.assertEqual(len(cache.data), 3)
pos, value = cache.data.get('a')
self.assertEqual(cache.clock_refs[pos], True)
cache.get('a')
# All items have ref==True. cache.hand points to "a". Putting
# "d" will set ref=False on all items and then replace "a",
# because "a" is the first item with ref==False that is found.
cache.put('d', '4')
self.assertEqual(len(cache.data), 3)
self.assertEqual(cache.data.get('a'), None)
# Only item "d" has ref==True. cache.hand points at "b", so "b"
# will be evicted when "e" is inserted. "c" will be left alone.
cache.put('e', '5')
self.assertEqual(len(cache.data), 3)
self.assertEqual(cache.data.get('b'), None)
self.assertEqual(cache.get('d'), '4')
self.assertEqual(cache.get('e'), '5')
self.assertEqual(cache.get('a'), None)
self.assertEqual(cache.get('b'), None)
self.assertEqual(cache.get('c'), '3')
self.check_cache_is_consistent(cache)
class DecoratorTests(unittest.TestCase):
def _getTargetClass(self):
from repoze.lru import lru_cache
return lru_cache
def _makeOne(self, maxsize, cache):
return self._getTargetClass()(maxsize, cache)
def test_ctor_nocache(self):
decorator = self._makeOne(10, None)
self.assertEqual(decorator.cache.size, 10)
def test_singlearg(self):
cache = DummyLRUCache()
decorator = self._makeOne(0, cache)
def wrapped(key):
return key
decorated = decorator(wrapped)
result = decorated(1)
self.assertEqual(cache[(1,)], 1)
self.assertEqual(result, 1)
self.assertEqual(len(cache), 1)
result = decorated(2)
self.assertEqual(cache[(2,)], 2)
self.assertEqual(result, 2)
self.assertEqual(len(cache), 2)
result = decorated(2)
self.assertEqual(cache[(2,)], 2)
self.assertEqual(result, 2)
self.assertEqual(len(cache), 2)
def test_multiargs(self):
cache = DummyLRUCache()
decorator = self._makeOne(0, cache)
def moreargs(*args):
return args
decorated = decorator(moreargs)
result = decorated(3, 4, 5)
self.assertEqual(cache[(3,4,5)], (3,4,5))
self.assertEqual(result, (3,4,5))
self.assertEqual(len(cache), 1)
class DummyLRUCache(dict):
def put(self, k, v):
return self.__setitem__(k, v)
if __name__ == "__main__":
unittest.main()
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