| hg-reviewers |
This allows consumers to prune the oldest item from the cache. This
could be useful for e.g. a consumer that wishes for the size of
items tracked by the cache to remain under a high water mark.
| Lint Skipped |
| Unit Tests Skipped |
| Path | Packages | |||
|---|---|---|---|---|
| M | mercurial/util.py (22 lines) | |||
| M | tests/test-lrucachedict.py (25 lines) |
| Commit | Parents | Author | Summary | Date |
|---|---|---|---|---|
| Gregory Szorc | Sep 6 2018, 2:15 AM |
| # We could potentially skip the first N items when decreasing capacity. | # We could potentially skip the first N items when decreasing capacity. | ||||
| # But let's keep it simple unless it is a performance problem. | # But let's keep it simple unless it is a performance problem. | ||||
| for i in range(len(self._cache)): | for i in range(len(self._cache)): | ||||
| result[n.key] = n.value | result[n.key] = n.value | ||||
| n = n.prev | n = n.prev | ||||
| return result | return result | ||||
| def popoldest(self): | |||||
| """Remove the oldest item from the cache. | |||||
| Returns the (key, value) describing the removed cache entry. | |||||
| """ | |||||
| if not self._cache: | |||||
| return | |||||
| # Walk the linked list backwards starting at tail node until we hit | |||||
| # a non-empty node. | |||||
| n = self._head.prev | |||||
| while n.key is _notset: | |||||
| n = n.prev | |||||
| key, value = n.key, n.value | |||||
| # And remove it from the cache and mark it as empty. | |||||
| del self._cache[n.key] | |||||
| n.markempty() | |||||
| return key, value | |||||
| def _movetohead(self, node): | def _movetohead(self, node): | ||||
| """Mark a node as the newest, making it the new head. | """Mark a node as the newest, making it the new head. | ||||
| When a node is accessed, it becomes the freshest entry in the LRU | When a node is accessed, it becomes the freshest entry in the LRU | ||||
| list, which is denoted by self._head. | list, which is denoted by self._head. | ||||
| Visually, let's make ``N`` the new head node (* denotes head): | Visually, let's make ``N`` the new head node (* denotes head): | ||||
| self.assertIn(key, dc) | self.assertIn(key, dc) | ||||
| self.assertEqual(dc[key], 'v%s' % key) | self.assertEqual(dc[key], 'v%s' % key) | ||||
| # Original should remain unchanged. | # Original should remain unchanged. | ||||
| for key in ('a', 'b', 'c', 'd'): | for key in ('a', 'b', 'c', 'd'): | ||||
| self.assertIn(key, d) | self.assertIn(key, d) | ||||
| self.assertEqual(d[key], 'v%s' % key) | self.assertEqual(d[key], 'v%s' % key) | ||||
| def testpopoldest(self): | |||||
| d = util.lrucachedict(4) | |||||
| d['a'] = 'va' | |||||
| d['b'] = 'vb' | |||||
| self.assertEqual(len(d), 2) | |||||
| self.assertEqual(d.popoldest(), ('a', 'va')) | |||||
| self.assertEqual(len(d), 1) | |||||
| self.assertEqual(d.popoldest(), ('b', 'vb')) | |||||
| self.assertEqual(len(d), 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')) | |||||
| if __name__ == '__main__': | if __name__ == '__main__': | ||||
| silenttestrunner.main(__name__) | silenttestrunner.main(__name__) | ||||