serialize: preallocate VecDeque in Decodable::decode

ljedrz · ljedrz · commit 464c9da9c229 · 2018-11-21T10:07:33.000+01:00
diff --git a/src/libserialize/collection_impls.rs b/src/libserialize/collection_impls.rs
@@ -86,7 +86,7 @@ impl<T: Encodable> Encodable for VecDeque<T> {
 impl<T:Decodable> Decodable for VecDeque<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<VecDeque<T>, D::Error> {
         d.read_seq(|d, len| {
-            let mut deque: VecDeque<T> = VecDeque::new();
+            let mut deque: VecDeque<T> = VecDeque::with_capacity(len);
             for i in 0..len {
                 deque.push_back(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }

Original file line number	Diff line number	Diff line change
`@@ -86,7 +86,7 @@ impl<T: Encodable> Encodable for VecDeque<T> {`
`86`	`86`	`impl<T:Decodable> Decodable for VecDeque<T> {`
`87`	`87`	`fn decode<D: Decoder>(d: &mut D) -> Result<VecDeque<T>, D::Error> {`
`88`	`88`	`d.read_seq(\|d, len\| {`
`89`		`- let mut deque: VecDeque<T> = VecDeque::new();`
	`89`	`+ let mut deque: VecDeque<T> = VecDeque::with_capacity(len);`
`90`	`90`	`for i in 0..len {`
`91`	`91`	`deque.push_back(d.read_seq_elt(i, \|d\| Decodable::decode(d))?);`
`92`	`92`	`}`