dulwich/tests/test_lru_cache.py

# Copyright (C) 2006, 2008 Canonical Ltd
#
# Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
# General Public License as public by the Free Software Foundation; version 2.0
# or (at your option) any later version. You can redistribute it and/or
# modify it under the terms of either of these two licenses.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# You should have received a copy of the licenses; if not, see
# <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
# and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
# License, Version 2.0.
#

"""Tests for the lru_cache module."""

from dulwich import lru_cache

from . import TestCase


class TestLRUCache(TestCase):
    """Test that LRU cache properly keeps track of entries."""

    def test_cache_size(self):
        cache = lru_cache.LRUCache(max_cache=10)
        self.assertEqual(10, cache.cache_size())

        cache = lru_cache.LRUCache(max_cache=256)
        self.assertEqual(256, cache.cache_size())

        cache.resize(512)
        self.assertEqual(512, cache.cache_size())

    def test_missing(self):
        cache = lru_cache.LRUCache(max_cache=10)

        self.assertNotIn("foo", cache)
        self.assertRaises(KeyError, cache.__getitem__, "foo")

        cache["foo"] = "bar"
        self.assertEqual("bar", cache["foo"])
        self.assertIn("foo", cache)
        self.assertNotIn("bar", cache)

    def test_map_None(self):
        # Make sure that we can properly map None as a key.
        cache = lru_cache.LRUCache(max_cache=10)
        self.assertNotIn(None, cache)
        cache[None] = 1
        self.assertEqual(1, cache[None])
        cache[None] = 2
        self.assertEqual(2, cache[None])
        # Test the various code paths of __getitem__, to make sure that we can
        # handle when None is the key for the LRU and the MRU
        cache[1] = 3
        cache[None] = 1
        cache[None]
        cache[1]
        cache[None]
        self.assertEqual([None, 1], [n.key for n in cache._walk_lru()])

    def test_add__null_key(self):
        cache = lru_cache.LRUCache(max_cache=10)
        self.assertRaises(ValueError, cache.add, lru_cache._null_key, 1)

    def test_overflow(self):
        """Adding extra entries will pop out old ones."""
        cache = lru_cache.LRUCache(max_cache=1, after_cleanup_count=1)

        cache["foo"] = "bar"
        # With a max cache of 1, adding 'baz' should pop out 'foo'
        cache["baz"] = "biz"

        self.assertNotIn("foo", cache)
        self.assertIn("baz", cache)

        self.assertEqual("biz", cache["baz"])

    def test_by_usage(self):
        """Accessing entries bumps them up in priority."""
        cache = lru_cache.LRUCache(max_cache=2)

        cache["baz"] = "biz"
        cache["foo"] = "bar"

        self.assertEqual("biz", cache["baz"])

        # This must kick out 'foo' because it was the last accessed
        cache["nub"] = "in"

        self.assertNotIn("foo", cache)

    def test_cleanup(self):
        """Test that we can use a cleanup function."""
        cleanup_called = []

        def cleanup_func(key, val):
            cleanup_called.append((key, val))

        cache = lru_cache.LRUCache(max_cache=2, after_cleanup_count=2)

        cache.add("baz", "1", cleanup=cleanup_func)
        cache.add("foo", "2", cleanup=cleanup_func)
        cache.add("biz", "3", cleanup=cleanup_func)

        self.assertEqual([("baz", "1")], cleanup_called)

        # 'foo' is now most recent, so final cleanup will call it last
        cache["foo"]
        cache.clear()
        self.assertEqual([("baz", "1"), ("biz", "3"), ("foo", "2")], cleanup_called)

    def test_cleanup_on_replace(self):
        """Replacing an object should cleanup the old value."""
        cleanup_called = []

        def cleanup_func(key, val):
            cleanup_called.append((key, val))

        cache = lru_cache.LRUCache(max_cache=2)
        cache.add(1, 10, cleanup=cleanup_func)
        cache.add(2, 20, cleanup=cleanup_func)
        cache.add(2, 25, cleanup=cleanup_func)

        self.assertEqual([(2, 20)], cleanup_called)
        self.assertEqual(25, cache[2])

        # Even __setitem__ should make sure cleanup() is called
        cache[2] = 26
        self.assertEqual([(2, 20), (2, 25)], cleanup_called)

    def test_len(self):
        cache = lru_cache.LRUCache(max_cache=10, after_cleanup_count=10)

        cache[1] = 10
        cache[2] = 20
        cache[3] = 30
        cache[4] = 40

        self.assertEqual(4, len(cache))

        cache[5] = 50
        cache[6] = 60
        cache[7] = 70
        cache[8] = 80

        self.assertEqual(8, len(cache))

        cache[1] = 15  # replacement

        self.assertEqual(8, len(cache))

        cache[9] = 90
        cache[10] = 100
        cache[11] = 110

        # We hit the max
        self.assertEqual(10, len(cache))
        self.assertEqual(
            [11, 10, 9, 1, 8, 7, 6, 5, 4, 3],
            [n.key for n in cache._walk_lru()],
        )

    def test_cleanup_shrinks_to_after_clean_count(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=3)

        cache.add(1, 10)
        cache.add(2, 20)
        cache.add(3, 25)
        cache.add(4, 30)
        cache.add(5, 35)

        self.assertEqual(5, len(cache))
        # This will bump us over the max, which causes us to shrink down to
        # after_cleanup_cache size
        cache.add(6, 40)
        self.assertEqual(3, len(cache))

    def test_after_cleanup_larger_than_max(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=10)
        self.assertEqual(5, cache._after_cleanup_count)

    def test_after_cleanup_none(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=None)
        # By default _after_cleanup_size is 80% of the normal size
        self.assertEqual(4, cache._after_cleanup_count)

    def test_cleanup_2(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=2)

        # Add these in order
        cache.add(1, 10)
        cache.add(2, 20)
        cache.add(3, 25)
        cache.add(4, 30)
        cache.add(5, 35)

        self.assertEqual(5, len(cache))
        # Force a compaction
        cache.cleanup()
        self.assertEqual(2, len(cache))

    def test_preserve_last_access_order(self):
        cache = lru_cache.LRUCache(max_cache=5)

        # Add these in order
        cache.add(1, 10)
        cache.add(2, 20)
        cache.add(3, 25)
        cache.add(4, 30)
        cache.add(5, 35)

        self.assertEqual([5, 4, 3, 2, 1], [n.key for n in cache._walk_lru()])

        # Now access some randomly
        cache[2]
        cache[5]
        cache[3]
        cache[2]
        self.assertEqual([2, 3, 5, 4, 1], [n.key for n in cache._walk_lru()])

    def test_get(self):
        cache = lru_cache.LRUCache(max_cache=5)

        cache.add(1, 10)
        cache.add(2, 20)
        self.assertEqual(20, cache.get(2))
        self.assertEqual(None, cache.get(3))
        obj = object()
        self.assertIs(obj, cache.get(3, obj))
        self.assertEqual([2, 1], [n.key for n in cache._walk_lru()])
        self.assertEqual(10, cache.get(1))
        self.assertEqual([1, 2], [n.key for n in cache._walk_lru()])

    def test_keys(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=5)

        cache[1] = 2
        cache[2] = 3
        cache[3] = 4
        self.assertEqual([1, 2, 3], sorted(cache.keys()))
        cache[4] = 5
        cache[5] = 6
        cache[6] = 7
        self.assertEqual([2, 3, 4, 5, 6], sorted(cache.keys()))

    def test_resize_smaller(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=4)
        cache[1] = 2
        cache[2] = 3
        cache[3] = 4
        cache[4] = 5
        cache[5] = 6
        self.assertEqual([1, 2, 3, 4, 5], sorted(cache.keys()))
        cache[6] = 7
        self.assertEqual([3, 4, 5, 6], sorted(cache.keys()))
        # Now resize to something smaller, which triggers a cleanup
        cache.resize(max_cache=3, after_cleanup_count=2)
        self.assertEqual([5, 6], sorted(cache.keys()))
        # Adding something will use the new size
        cache[7] = 8
        self.assertEqual([5, 6, 7], sorted(cache.keys()))
        cache[8] = 9
        self.assertEqual([7, 8], sorted(cache.keys()))

    def test_resize_larger(self):
        cache = lru_cache.LRUCache(max_cache=5, after_cleanup_count=4)
        cache[1] = 2
        cache[2] = 3
        cache[3] = 4
        cache[4] = 5
        cache[5] = 6
        self.assertEqual([1, 2, 3, 4, 5], sorted(cache.keys()))
        cache[6] = 7
        self.assertEqual([3, 4, 5, 6], sorted(cache.keys()))
        cache.resize(max_cache=8, after_cleanup_count=6)
        self.assertEqual([3, 4, 5, 6], sorted(cache.keys()))
        cache[7] = 8
        cache[8] = 9
        cache[9] = 10
        cache[10] = 11
        self.assertEqual([3, 4, 5, 6, 7, 8, 9, 10], sorted(cache.keys()))
        cache[11] = 12  # triggers cleanup back to new after_cleanup_count
        self.assertEqual([6, 7, 8, 9, 10, 11], sorted(cache.keys()))


class TestLRUSizeCache(TestCase):
    def test_basic_init(self):
        cache = lru_cache.LRUSizeCache()
        self.assertEqual(2048, cache._max_cache)
        self.assertEqual(int(cache._max_size * 0.8), cache._after_cleanup_size)
        self.assertEqual(0, cache._value_size)

    def test_add__null_key(self):
        cache = lru_cache.LRUSizeCache()
        self.assertRaises(ValueError, cache.add, lru_cache._null_key, 1)

    def test_add_tracks_size(self):
        cache = lru_cache.LRUSizeCache()
        self.assertEqual(0, cache._value_size)
        cache.add("my key", "my value text")
        self.assertEqual(13, cache._value_size)

    def test_remove_tracks_size(self):
        cache = lru_cache.LRUSizeCache()
        self.assertEqual(0, cache._value_size)
        cache.add("my key", "my value text")
        self.assertEqual(13, cache._value_size)
        node = cache._cache["my key"]
        cache._remove_node(node)
        self.assertEqual(0, cache._value_size)

    def test_no_add_over_size(self):
        """Adding a large value may not be cached at all."""
        cache = lru_cache.LRUSizeCache(max_size=10, after_cleanup_size=5)
        self.assertEqual(0, cache._value_size)
        self.assertEqual({}, cache.items())
        cache.add("test", "key")
        self.assertEqual(3, cache._value_size)
        self.assertEqual({"test": "key"}, cache.items())
        cache.add("test2", "key that is too big")
        self.assertEqual(3, cache._value_size)
        self.assertEqual({"test": "key"}, cache.items())
        # If we would add a key, only to cleanup and remove all cached entries,
        # then obviously that value should not be stored
        cache.add("test3", "bigkey")
        self.assertEqual(3, cache._value_size)
        self.assertEqual({"test": "key"}, cache.items())

        cache.add("test4", "bikey")
        self.assertEqual(3, cache._value_size)
        self.assertEqual({"test": "key"}, cache.items())

    def test_no_add_over_size_cleanup(self):
        """If a large value is not cached, we will call cleanup right away."""
        cleanup_calls = []

        def cleanup(key, value):
            cleanup_calls.append((key, value))

        cache = lru_cache.LRUSizeCache(max_size=10, after_cleanup_size=5)
        self.assertEqual(0, cache._value_size)
        self.assertEqual({}, cache.items())
        cache.add("test", "key that is too big", cleanup=cleanup)
        # key was not added
        self.assertEqual(0, cache._value_size)
        self.assertEqual({}, cache.items())
        # and cleanup was called
        self.assertEqual([("test", "key that is too big")], cleanup_calls)

    def test_adding_clears_cache_based_on_size(self):
        """The cache is cleared in LRU order until small enough."""
        cache = lru_cache.LRUSizeCache(max_size=20)
        cache.add("key1", "value")  # 5 chars
        cache.add("key2", "value2")  # 6 chars
        cache.add("key3", "value23")  # 7 chars
        self.assertEqual(5 + 6 + 7, cache._value_size)
        cache["key2"]  # reference key2 so it gets a newer reference time
        cache.add("key4", "value234")  # 8 chars, over limit
        # We have to remove 2 keys to get back under limit
        self.assertEqual(6 + 8, cache._value_size)
        self.assertEqual({"key2": "value2", "key4": "value234"}, cache.items())

    def test_adding_clears_to_after_cleanup_size(self):
        cache = lru_cache.LRUSizeCache(max_size=20, after_cleanup_size=10)
        cache.add("key1", "value")  # 5 chars
        cache.add("key2", "value2")  # 6 chars
        cache.add("key3", "value23")  # 7 chars
        self.assertEqual(5 + 6 + 7, cache._value_size)
        cache["key2"]  # reference key2 so it gets a newer reference time
        cache.add("key4", "value234")  # 8 chars, over limit
        # We have to remove 3 keys to get back under limit
        self.assertEqual(8, cache._value_size)
        self.assertEqual({"key4": "value234"}, cache.items())

    def test_custom_sizes(self):
        def size_of_list(lst):
            return sum(len(x) for x in lst)

        cache = lru_cache.LRUSizeCache(
            max_size=20, after_cleanup_size=10, compute_size=size_of_list
        )

        cache.add("key1", ["val", "ue"])  # 5 chars
        cache.add("key2", ["val", "ue2"])  # 6 chars
        cache.add("key3", ["val", "ue23"])  # 7 chars
        self.assertEqual(5 + 6 + 7, cache._value_size)
        cache["key2"]  # reference key2 so it gets a newer reference time
        cache.add("key4", ["value", "234"])  # 8 chars, over limit
        # We have to remove 3 keys to get back under limit
        self.assertEqual(8, cache._value_size)
        self.assertEqual({"key4": ["value", "234"]}, cache.items())

    def test_cleanup(self):
        cache = lru_cache.LRUSizeCache(max_size=20, after_cleanup_size=10)

        # Add these in order
        cache.add("key1", "value")  # 5 chars
        cache.add("key2", "value2")  # 6 chars
        cache.add("key3", "value23")  # 7 chars
        self.assertEqual(5 + 6 + 7, cache._value_size)

        cache.cleanup()
        # Only the most recent fits after cleaning up
        self.assertEqual(7, cache._value_size)

    def test_keys(self):
        cache = lru_cache.LRUSizeCache(max_size=10)

        cache[1] = "a"
        cache[2] = "b"
        cache[3] = "cdef"
        self.assertEqual([1, 2, 3], sorted(cache.keys()))

    def test_resize_smaller(self):
        cache = lru_cache.LRUSizeCache(max_size=10, after_cleanup_size=9)
        cache[1] = "abc"
        cache[2] = "def"
        cache[3] = "ghi"
        cache[4] = "jkl"
        # Triggers a cleanup
        self.assertEqual([2, 3, 4], sorted(cache.keys()))
        # Resize should also cleanup again
        cache.resize(max_size=6, after_cleanup_size=4)
        self.assertEqual([4], sorted(cache.keys()))
        # Adding should use the new max size
        cache[5] = "mno"
        self.assertEqual([4, 5], sorted(cache.keys()))
        cache[6] = "pqr"
        self.assertEqual([6], sorted(cache.keys()))

    def test_resize_larger(self):
        cache = lru_cache.LRUSizeCache(max_size=10, after_cleanup_size=9)
        cache[1] = "abc"
        cache[2] = "def"
        cache[3] = "ghi"
        cache[4] = "jkl"
        # Triggers a cleanup
        self.assertEqual([2, 3, 4], sorted(cache.keys()))
        cache.resize(max_size=15, after_cleanup_size=12)
        self.assertEqual([2, 3, 4], sorted(cache.keys()))
        cache[5] = "mno"
        cache[6] = "pqr"
        self.assertEqual([2, 3, 4, 5, 6], sorted(cache.keys()))
        cache[7] = "stu"
        self.assertEqual([4, 5, 6, 7], sorted(cache.keys()))