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Eliminate unecessary extra sigil node from LruCache.

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Instead of allocating both head and tail nodes for the ends of the node
list, a single node can be allocated and linked circularly instead,
making it act as both the head and the tail of the list at the same
time.
This commit is contained in:
Yuri Kunde Schlesner 2014-04-18 07:23:36 -03:00
parent 04784540ef
commit ad4062e8af
1 changed files with 3 additions and 6 deletions
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9
src/libcollections/lru_cache.rs
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@ -59,7 +59,6 @@ pub struct LruCache<K, V> {
map: HashMap<KeyRef<K>, ~LruEntry<K, V>>,
max_size: uint,
head: *mut LruEntry<K, V>,
tail: *mut LruEntry<K, V>,
}
impl<S, K: Hash<S>> Hash<S> for KeyRef<K> {
@ -103,11 +102,10 @@ impl<K: Hash + TotalEq, V> LruCache<K, V> {
map: HashMap::new(),
max_size: capacity,
head: unsafe{ cast::transmute(~LruEntry::<K, V>::new()) },
tail: unsafe{ cast::transmute(~LruEntry::<K, V>::new()) },
};
unsafe {
(*cache.head).next = cache.tail;
(*cache.tail).prev = cache.head;
(*cache.head).next = cache.head;
(*cache.head).prev = cache.head;
}
return cache;
}
@ -191,7 +189,7 @@ impl<K: Hash + TotalEq, V> LruCache<K, V> {
#[inline]
fn remove_lru(&mut self) {
if self.len() > 0 {
let lru = unsafe { (*self.tail).prev };
let lru = unsafe { (*self.head).prev };
self.detach(lru);
unsafe {
match (*lru).key {
@ -269,7 +267,6 @@ impl<K, V> Drop for LruCache<K, V> {
fn drop(&mut self) {
unsafe {
let _: ~LruEntry<K, V> = cast::transmute(self.head);
let _: ~LruEntry<K, V> = cast::transmute(self.tail);
}
}
}