Mercurial > public > mercurial-scm > hg-stable
comparison mercurial/util.py @ 39582:bd9d3a89f07b
util: add a popoldest() method to lrucachedict
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.
Differential Revision: https://phab.mercurial-scm.org/D4501
| author | Gregory Szorc <gregory.szorc@gmail.com> |
|---|---|
| date | Wed, 05 Sep 2018 23:15:20 -0700 |
| parents | 2dcc68c7d25b |
| children | ee087f0d7db5 |
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| 39581:2dcc68c7d25b | 39582:bd9d3a89f07b |
|---|---|
| 1338 for i in range(len(self._cache)): | 1338 for i in range(len(self._cache)): |
| 1339 result[n.key] = n.value | 1339 result[n.key] = n.value |
| 1340 n = n.prev | 1340 n = n.prev |
| 1341 | 1341 |
| 1342 return result | 1342 return result |
| 1343 | |
| 1344 def popoldest(self): | |
| 1345 """Remove the oldest item from the cache. | |
| 1346 | |
| 1347 Returns the (key, value) describing the removed cache entry. | |
| 1348 """ | |
| 1349 if not self._cache: | |
| 1350 return | |
| 1351 | |
| 1352 # Walk the linked list backwards starting at tail node until we hit | |
| 1353 # a non-empty node. | |
| 1354 n = self._head.prev | |
| 1355 while n.key is _notset: | |
| 1356 n = n.prev | |
| 1357 | |
| 1358 key, value = n.key, n.value | |
| 1359 | |
| 1360 # And remove it from the cache and mark it as empty. | |
| 1361 del self._cache[n.key] | |
| 1362 n.markempty() | |
| 1363 | |
| 1364 return key, value | |
| 1343 | 1365 |
| 1344 def _movetohead(self, node): | 1366 def _movetohead(self, node): |
| 1345 """Mark a node as the newest, making it the new head. | 1367 """Mark a node as the newest, making it the new head. |
| 1346 | 1368 |
| 1347 When a node is accessed, it becomes the freshest entry in the LRU | 1369 When a node is accessed, it becomes the freshest entry in the LRU |