def test_queue_compaction(self):
from wesgi import LRUCache
cache = LRUCache(maxsize=10)
[cache.get(1) for i in range(100)] # fill up to maxqueue
self.assertEquals(list(cache._queue), [1 for i in xrange(100)]) # our queue is full
self.assertEquals(cache._refcount, {1: 100})
cache.get(1) #push us over the limit
self.assertEquals(list(cache._queue), [1])
self.assertEquals(cache._refcount, {1: 1})
self.assertInvariants(cache)
def test_repeated_set_without_get_does_not_flushe_cache(self):
from wesgi import LRUCache
cache = LRUCache(maxsize=3)
cache.get('a')
cache.set('a', 'a')
cache.get('b')
cache.set('b', 'b')
for i in range(100):
cache.set(str(i), str(i))
self.assertEquals(cache._cache, {'99': '99', 'a': 'a', 'b': 'b'})
self.assertInvariants(cache)
def test_queue_emptying(self):
# the queue is emptied when it gets too big and we cannot compact
from wesgi import LRUCache
cache = LRUCache(maxsize=10)
[cache.get(i) for i in range(100)] # fill up to maxqueue
self.assertEquals(list(cache._queue), range(100)) # all elements are in the queue
self.assertEquals(len(cache._queue), 100)
self.assertEquals(cache._refcount, dict([(i, 1) for i in range(100)]))
cache.get(100) #push us over the limit
self.assertEquals(len(cache._queue), 80)
self.assertEquals(list(cache._queue), range(21, 101))
self.assertEquals(cache._refcount, dict([(i, 1) for i in range(21, 101)]))
self.assertInvariants(cache)
def test_queue_emptying_memory_leak(self):
# When we empty the queue, we need to make sure that elements in our cache stay in the queue
from wesgi import LRUCache
cache = LRUCache(maxsize=10)
cache.set('x', 'y')
[cache.get(i) for i in range(100)] # fill queue over maxsize
self.assertEquals(cache._cache, {'x': 'y'})
self.assertEquals(len(cache._queue), 80)
self.assertEquals(list(cache._queue), ['x'] + range(21, 100))
expected_refcount = dict([(i, 1) for i in range(21, 100)])
expected_refcount['x'] = 1
self.assertEquals(cache._refcount, expected_refcount)
self.assertInvariants(cache)
def test_hit_miss(self):
# an LRU's biggest weakness is the sequential scan
# this is what happens
from wesgi import LRUCache
cache = LRUCache(maxsize=3)
cache.get('a')
cache.set('a', 'a')
self.assertEquals(cache.hits, 0)
self.assertEquals(cache.misses, 1)
cache.get('a')
self.assertEquals(cache.hits, 1)
self.assertEquals(cache.misses, 1)
cache.get('b')
self.assertEquals(cache.hits, 1)
self.assertEquals(cache.misses, 2)
cache.get('a')
self.assertEquals(cache.hits, 2)
self.assertEquals(cache.misses, 2)
self.assertInvariants(cache)
def test_repeated_get_and_set_flushes_cache(self):
# an LRU's biggest weakness is the sequential scan
# this is what happens
from wesgi import LRUCache
cache = LRUCache(maxsize=3)
cache.get('a')
cache.set('a', 'a')
cache.get('b')
cache.set('b', 'b')
for i in range(100):
cache.get(str(i))
cache.set(str(i), str(i))
self.assertEquals(cache._cache, {'99': '99', '98': '98', '97': '97'})
self.assertEquals(cache.hits, 0)
self.assertEquals(cache.misses, 102)
self.assertInvariants(cache)
def test_basic(self):
from wesgi import LRUCache
cache = LRUCache()
self.assertEquals(cache.get('a'), None)
self.assertEquals(cache.get('b'), None)
self.assertEquals(cache._refcount, {'a': 1, 'b': 1})
self.assertEquals(cache._cache, {})
cache.set('a', 'x')
self.assertInvariants(cache)
self.assertEquals(cache.get('a'), 'x')
self.assertEquals(cache.get('b'), None)
self.assertEquals(cache._refcount, {'a': 3, 'b': 2})
self.assertEquals(cache._cache, {'a': 'x'})
cache.set('b', 'y')
self.assertInvariants(cache)
self.assertEquals(cache.get('a'), 'x')
self.assertEquals(cache.get('b'), 'y')
self.assertEquals(cache._refcount, {'a': 4, 'b': 4})
self.assertEquals(cache._cache, {'a': 'x', 'b': 'y'})
cache.set('b', 'z')
self.assertInvariants(cache)
self.assertEquals(cache.get('a'), 'x')
self.assertEquals(cache.get('b'), 'z')
self.assertEquals(cache._refcount, {'a': 5, 'b': 6})
self.assertEquals(cache._cache, {'a': 'x', 'b': 'z'})
cache.delete('b')
self.assertInvariants(cache)
self.assertEquals(cache._refcount, {'a': 5, 'b': 6})
self.assertEquals(cache.get('a'), 'x')
self.assertEquals(cache.get('b'), None)
self.assertEquals(cache._cache, {'a': 'x'})
cache.delete('a')
self.assertInvariants(cache)
self.assertEquals(cache._refcount, {'a': 6, 'b': 7})
self.assertEquals(cache.get('a'), None)
self.assertEquals(cache.get('b'), None)
self.assertEquals(cache._cache, {})
def test_queue_comaction_different_values(self):
from wesgi import LRUCache
# test compaction with a different value first
cache = LRUCache(maxsize=10)
cache.get(2)
[cache.get(1) for i in range(49)]
cache.get(2)
[cache.get(1) for i in range(50)] # Push us one over the limit
self.assertEquals(list(cache._queue), [2, 1])
self.assertEquals(cache._refcount, {1: 1, 2: 1})
# and after
cache = LRUCache(maxsize=10)
[cache.get(1) for i in range(49)]
cache.get(2)
[cache.get(1) for i in range(50)]
cache.get(2) # Push us one over the limit
self.assertEquals(list(cache._queue), [1, 2])
self.assertEquals(cache._refcount, {1: 1, 2: 1})
self.assertInvariants(cache)