util: make capacity a public attribute on lrucachedict

util: make capacity a public attribute on lrucachedict

So others can query it. Useful for operations that may want to verify
the cache has capacity for N items before it performs an operation that
may cause cache eviction.

Differential Revision: https://phab.mercurial-scm.org/D4499

--- a/mercurial/util.py	Thu Sep 06 11:33:40 2018 -0700
+++ b/mercurial/util.py	Thu Sep 06 11:37:27 2018 -0700
@@ -1241,7 +1241,7 @@
         head.prev = head
         head.next = head
         self._size = 1
-        self._capacity = max
+        self.capacity = max
 
     def __len__(self):
         return len(self._cache)
@@ -1269,7 +1269,7 @@
             self._movetohead(node)
             return
 
-        if self._size < self._capacity:
+        if self._size < self.capacity:
             node = self._addcapacity()
         else:
             # Grab the last/oldest item.
@@ -1312,7 +1312,7 @@
         self._cache.clear()
 
     def copy(self):
-        result = lrucachedict(self._capacity)
+        result = lrucachedict(self.capacity)
 
         # We copy entries by iterating in oldest-to-newest order so the copy
         # has the correct ordering.

--- a/tests/test-lrucachedict.py	Thu Sep 06 11:33:40 2018 -0700
+++ b/tests/test-lrucachedict.py	Thu Sep 06 11:37:27 2018 -0700
@@ -11,6 +11,7 @@
 class testlrucachedict(unittest.TestCase):
     def testsimple(self):
         d = util.lrucachedict(4)
+        self.assertEqual(d.capacity, 4)
         d['a'] = 'va'
         d['b'] = 'vb'
         d['c'] = 'vc'