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docs, tests and bugfixes for squeeze

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debris 2015-12-16 17:12:20 +01:00
parent 56de081381
commit 926efb6fc8
1 changed files with 38 additions and 4 deletions
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42
src/squeeze.rs
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@ -1,3 +1,35 @@
//! Helper module that should be used to randomly squeeze
//! caches to a given size in bytes
//!
//! ```
//! extern crate heapsize;
//! extern crate ethcore_util as util;
//! use std::collections::HashMap;
//! use std::mem::size_of;
//! use heapsize::HeapSizeOf;
//! use util::squeeze::Squeeze;
//!
//! fn main() {
//! let initial_size = 60;
//! let mut map: HashMap<u8, u8> = HashMap::with_capacity(initial_size);
//! assert!(map.capacity() >= initial_size);
//! for i in 0..initial_size {
//! map.insert(i as u8, i as u8);
//! }
//!
//! assert_eq!(map.heap_size_of_children(), map.capacity() * 2 * size_of::<u8>());
//! assert_eq!(map.len(), initial_size);
//! let initial_heap_size = map.heap_size_of_children();
//!
//! // squeeze it to size of key and value
//! map.squeeze(2 * size_of::<u8>());
//! assert_eq!(map.len(), 1);
//!
//! // its likely that heap size was reduced, but we can't be 100% sure
//! assert!(initial_heap_size >= map.heap_size_of_children());
//! }
//! ```
use std::collections::HashMap; use std::collections::HashMap;
use std::hash::Hash; use std::hash::Hash;
use heapsize::HeapSizeOf; use heapsize::HeapSizeOf;
@ -14,9 +46,10 @@ impl<K, T> Squeeze for HashMap<K, T> where K: Eq + Hash + Clone + HeapSizeOf, T:
} }
let size_of_entry = self.heap_size_of_children() / self.capacity(); let size_of_entry = self.heap_size_of_children() / self.capacity();
let mut shrinked_size = size_of_entry * self.len(); let all_entries = size_of_entry * self.len();
let mut shrinked_size = all_entries;
while self.len() > 0 || shrinked_size > size { while self.len() > 0 && shrinked_size > size {
// could be optimized // could be optimized
let key = self.keys().next().unwrap().clone(); let key = self.keys().next().unwrap().clone();
self.remove(&key); self.remove(&key);
@ -25,9 +58,10 @@ impl<K, T> Squeeze for HashMap<K, T> where K: Eq + Hash + Clone + HeapSizeOf, T:
self.shrink_to_fit(); self.shrink_to_fit();
// if we havent shrinked enough, squeeze again // if we squeezed something, but not enough, squeeze again
if self.heap_size_of_children() > size { if all_entries != shrinked_size && self.heap_size_of_children() > size {
self.squeeze(size); self.squeeze(size);
} }
} }
} }