Avoid alloc due to vector pushes (#6632)

2019-10-30 21:55:17 -07:00
parent 83d5115a02
commit 5264fded00
3 changed files with 38 additions and 32 deletions
--- a/runtime/src/append_vec.rs
+++ b/runtime/src/append_vec.rs
@@ -292,7 +292,7 @@ impl AppendVec {
        hashes: &[Hash],
    ) -> Vec<usize> {
        let mut offset = self.append_offset.lock().unwrap();
-        let mut rv = vec![];
+        let mut rv = Vec::with_capacity(accounts.len());
        for ((stored_meta, account), hash) in accounts.iter().zip(hashes) {
            let meta_ptr = stored_meta as *const StoredMeta;
            let account_meta = AccountMeta {