Fix bad tail state in LRU map on removal of last entry #386
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On removal of the last entry from an LRU map, the entry is both _head and _tail. The existing remove() implementation matched it against _head, which was then updated to _head.next (null), but _tail was left unmodified in a bad state. Since _tail is not null, the next insertion into the newly-empty map don't reset it. When the map size eventually exceeds the maximum size, _removeLru() is called to evict _tail, resulting in a null-pointer exception as _removeLru() attempts to get _tail.previous (null) and then set .next on that.
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Fixes #385. |
a14n
approved these changes
Nov 16, 2017
tvolkert
approved these changes
Nov 16, 2017
| @@ -1,3 +1,9 @@ | |||
| #### 0.27.0-dev | |||
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If you plan on releasing this now, then bump the pubspec version as well
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I'm actually planning to do a trick here and release v0.26.1 since all changes since 0.26.0 are backwards-compatible. Keeping this as-is though since the current pubspec version is 0.27.0-dev and I've got one more update to land since we set the dev version.
Typically we update this value in a release commit that updates the pubspec, the readme and the changelog atomically.
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Released in v0.26.1 |
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On removal of the last entry from an LRU map, the entry is both _head
and _tail. The existing remove() implementation matched it against
_head, which was then updated to _head.next (null), but _tail was left
unmodified in a bad state.
Since _tail is not null, the next insertion into the newly-empty map
don't reset it. When the map size eventually exceeds the maximum size,
_removeLru() is called to evict _tail, resulting in a null-pointer
exception as _removeLru() attempts to get _tail.previous (null) and then
set .next on that.