tests/test-lrucachedict.py

interfaces: introduce and use a protocol class for the `mpatch` module

See f2832de2a46c for details when this was done for the `bdiff` module.

Two things worth pointing out-

  1) The `cffi` module "inherits" the `pure` implementation of `patchedsize()`
     because of its wildcard import.
  2) It's odd that the `mpatchError` lives in both `pure` and `cext` modules.

I initially thought to move the exception into the new class, and make the
existing class name an alias to the class in the new location, but the exception
is created in C code by the `cext` module, so that won't work.  I don't think a
protocol class is approriate, because there's nothing special about the class to
distinguish from any other `Exception`.  Fortunately, nobody is catching this
exception in core, so we can kick the can down the road.

import unittest

import silenttestrunner

from mercurial import util


class testlrucachedict(unittest.TestCase):
    def testsimple(self):
        d = util.lrucachedict(4)
        self.assertEqual(d.capacity, 4)
        d.insert('a', 'va', cost=2)
        d['b'] = 'vb'
        d['c'] = 'vc'
        d.insert('d', 'vd', cost=42)

        self.assertEqual(d['a'], 'va')
        self.assertEqual(d['b'], 'vb')
        self.assertEqual(d['c'], 'vc')
        self.assertEqual(d['d'], 'vd')

        self.assertEqual(d.totalcost, 44)

        # 'a' should be dropped because it was least recently used.
        d['e'] = 've'
        self.assertNotIn('a', d)
        self.assertIsNone(d.get('a'))
        self.assertEqual(d.totalcost, 42)

        self.assertEqual(d['b'], 'vb')
        self.assertEqual(d['c'], 'vc')
        self.assertEqual(d['d'], 'vd')
        self.assertEqual(d['e'], 've')

        # Replacing item with different cost adjusts totalcost.
        d.insert('e', 've', cost=4)
        self.assertEqual(d.totalcost, 46)

        # Touch entries in some order (both get and set).
        d['e']
        d['c'] = 'vc2'
        d['d']
        d['b'] = 'vb2'

        # 'e' should be dropped now
        d['f'] = 'vf'
        self.assertNotIn('e', d)
        self.assertEqual(d['b'], 'vb2')
        self.assertEqual(d['c'], 'vc2')
        self.assertEqual(d['d'], 'vd')
        self.assertEqual(d['f'], 'vf')

        d.clear()
        for key in ('a', 'b', 'c', 'd', 'e', 'f'):
            self.assertNotIn(key, d)

    def testunfull(self):
        d = util.lrucachedict(4)
        d['a'] = 1
        d['b'] = 2
        d['a']
        d['b']

        for key in ('a', 'b'):
            self.assertIn(key, d)

    def testget(self):
        d = util.lrucachedict(4)
        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'

        self.assertIsNone(d.get('missing'))
        self.assertEqual(list(d), ['c', 'b', 'a'])

        self.assertEqual(d.get('a'), 'va')
        self.assertEqual(list(d), ['a', 'c', 'b'])

    def testpeek(self):
        d = util.lrucachedict(4)
        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'

        with self.assertRaises(KeyError):
            d.peek('missing')
        self.assertEqual(list(d), ['c', 'b', 'a'])
        self.assertIsNone(d.peek('missing', None))
        self.assertEqual(list(d), ['c', 'b', 'a'])

        self.assertEqual(d.peek('a'), 'va')
        self.assertEqual(list(d), ['c', 'b', 'a'])

    def testpop(self):
        d = util.lrucachedict(4)
        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'

        with self.assertRaises(KeyError):
            d.pop('missing')
        self.assertEqual(list(d), ['c', 'b', 'a'])
        self.assertIsNone(d.pop('missing', None))
        self.assertEqual(list(d), ['c', 'b', 'a'])

        self.assertEqual(d.pop('b'), 'vb')
        self.assertEqual(list(d), ['c', 'a'])

    def testcopypartial(self):
        d = util.lrucachedict(4)
        d.insert('a', 'va', cost=4)
        d.insert('b', 'vb', cost=2)

        dc = d.copy()

        self.assertEqual(len(dc), 2)
        self.assertEqual(dc.totalcost, 6)
        for key in ('a', 'b'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        self.assertEqual(len(d), 2)
        for key in ('a', 'b'):
            self.assertIn(key, d)
            self.assertEqual(d[key], 'v%s' % key)

        d['c'] = 'vc'
        del d['b']
        self.assertEqual(d.totalcost, 4)
        dc = d.copy()
        self.assertEqual(len(dc), 2)
        self.assertEqual(dc.totalcost, 4)
        for key in ('a', 'c'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

    def testcopyempty(self):
        d = util.lrucachedict(4)
        dc = d.copy()
        self.assertEqual(len(dc), 0)

    def testcopyfull(self):
        d = util.lrucachedict(4)
        d.insert('a', 'va', cost=42)
        d['b'] = 'vb'
        d['c'] = 'vc'
        d['d'] = 'vd'

        dc = d.copy()

        for key in ('a', 'b', 'c', 'd'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        self.assertEqual(d.totalcost, 42)
        self.assertEqual(dc.totalcost, 42)

        # 'a' should be dropped because it was least recently used.
        dc['e'] = 've'
        self.assertNotIn('a', dc)
        for key in ('b', 'c', 'd', 'e'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        self.assertEqual(d.totalcost, 42)
        self.assertEqual(dc.totalcost, 0)

        # Contents and order of original dict should remain unchanged.
        dc['b'] = 'vb_new'

        self.assertEqual(list(iter(d)), ['d', 'c', 'b', 'a'])
        for key in ('a', 'b', 'c', 'd'):
            self.assertEqual(d[key], 'v%s' % key)

        d = util.lrucachedict(4, maxcost=42)
        d.insert('a', 'va', cost=5)
        d.insert('b', 'vb', cost=4)
        d.insert('c', 'vc', cost=3)
        dc = d.copy()
        self.assertEqual(dc.maxcost, 42)
        self.assertEqual(len(dc), 3)

        # Max cost can be lowered as part of copy.
        dc = d.copy(maxcost=10)
        self.assertEqual(dc.maxcost, 10)
        self.assertEqual(len(dc), 2)
        self.assertEqual(dc.totalcost, 7)
        self.assertIn('b', dc)
        self.assertIn('c', dc)

    def testcopydecreasecapacity(self):
        d = util.lrucachedict(5)
        d.insert('a', 'va', cost=4)
        d.insert('b', 'vb', cost=2)
        d['c'] = 'vc'
        d['d'] = 'vd'

        dc = d.copy(2)
        self.assertEqual(dc.totalcost, 0)
        for key in ('a', 'b'):
            self.assertNotIn(key, dc)
        for key in ('c', 'd'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        dc.insert('e', 've', cost=7)
        self.assertEqual(dc.totalcost, 7)
        self.assertNotIn('c', dc)
        for key in ('d', 'e'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        # Original should remain unchanged.
        self.assertEqual(d.totalcost, 6)
        for key in ('a', 'b', 'c', 'd'):
            self.assertIn(key, d)
            self.assertEqual(d[key], 'v%s' % key)

    def testcopyincreasecapacity(self):
        d = util.lrucachedict(5)
        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'
        d['d'] = 'vd'

        dc = d.copy(6)
        for key in ('a', 'b', 'c', 'd'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        dc['e'] = 've'
        dc['f'] = 'vf'
        for key in ('a', 'b', 'c', 'd', 'e', 'f'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        dc['g'] = 'vg'
        self.assertNotIn('a', dc)
        for key in ('b', 'c', 'd', 'e', 'f', 'g'):
            self.assertIn(key, dc)
            self.assertEqual(dc[key], 'v%s' % key)

        # Original should remain unchanged.
        for key in ('a', 'b', 'c', 'd'):
            self.assertIn(key, d)
            self.assertEqual(d[key], 'v%s' % key)

    def testpopoldest(self):
        d = util.lrucachedict(4)
        d.insert('a', 'va', cost=10)
        d.insert('b', 'vb', cost=5)

        self.assertEqual(len(d), 2)
        self.assertEqual(d.popoldest(), ('a', 'va'))
        self.assertEqual(len(d), 1)
        self.assertEqual(d.totalcost, 5)
        self.assertEqual(d.popoldest(), ('b', 'vb'))
        self.assertEqual(len(d), 0)
        self.assertEqual(d.totalcost, 0)
        self.assertIsNone(d.popoldest())

        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'
        d['d'] = 'vd'

        self.assertEqual(d.popoldest(), ('a', 'va'))
        self.assertEqual(len(d), 3)
        for key in ('b', 'c', 'd'):
            self.assertEqual(d[key], 'v%s' % key)

        d['a'] = 'va'
        self.assertEqual(d.popoldest(), ('b', 'vb'))

    def testmaxcost(self):
        # Item cost is zero by default.
        d = util.lrucachedict(6, maxcost=10)
        d['a'] = 'va'
        d['b'] = 'vb'
        d['c'] = 'vc'
        d['d'] = 'vd'
        self.assertEqual(len(d), 4)
        self.assertEqual(d.totalcost, 0)

        d.clear()

        # Insertion to exact cost threshold works without eviction.
        d.insert('a', 'va', cost=6)
        d.insert('b', 'vb', cost=4)

        self.assertEqual(len(d), 2)
        self.assertEqual(d['a'], 'va')
        self.assertEqual(d['b'], 'vb')

        # Inserting a new element with 0 cost works.
        d['c'] = 'vc'
        self.assertEqual(len(d), 3)

        # Inserting a new element with cost putting us above high
        # water mark evicts oldest single item.
        d.insert('d', 'vd', cost=1)
        self.assertEqual(len(d), 3)
        self.assertEqual(d.totalcost, 5)
        self.assertNotIn('a', d)
        for key in ('b', 'c', 'd'):
            self.assertEqual(d[key], 'v%s' % key)

        # Inserting a new element with enough room for just itself
        # evicts all items before.
        d.insert('e', 've', cost=10)
        self.assertEqual(len(d), 1)
        self.assertEqual(d.totalcost, 10)
        self.assertIn('e', d)

        # Inserting a new element with cost greater than threshold
        # still retains that item.
        d.insert('f', 'vf', cost=11)
        self.assertEqual(len(d), 1)
        self.assertEqual(d.totalcost, 11)
        self.assertIn('f', d)

        # Inserting a new element will evict the last item since it is
        # too large.
        d['g'] = 'vg'
        self.assertEqual(len(d), 1)
        self.assertEqual(d.totalcost, 0)
        self.assertIn('g', d)

        d.clear()

        d.insert('a', 'va', cost=7)
        d.insert('b', 'vb', cost=3)
        self.assertEqual(len(d), 2)

        # Replacing a value with smaller cost won't result in eviction.
        d.insert('b', 'vb2', cost=2)
        self.assertEqual(len(d), 2)

        # Replacing a value with a higher cost will evict when threshold
        # exceeded.
        d.insert('b', 'vb3', cost=4)
        self.assertEqual(len(d), 1)
        self.assertNotIn('a', d)

    def testmaxcostcomplex(self):
        d = util.lrucachedict(100, maxcost=100)
        d.insert('a', 'va', cost=9)
        d.insert('b', 'vb', cost=21)
        d.insert('c', 'vc', cost=7)
        d.insert('d', 'vc', cost=50)
        self.assertEqual(d.totalcost, 87)

        # Inserting new element should free multiple elements so we hit
        # low water mark.
        d.insert('e', 'vd', cost=25)
        self.assertEqual(len(d), 2)
        self.assertNotIn('a', d)
        self.assertNotIn('b', d)
        self.assertNotIn('c', d)
        self.assertIn('d', d)
        self.assertIn('e', d)


if __name__ == '__main__':
    silenttestrunner.main(__name__)