Macro shrink_to_fit

macro_rules! shrink_to_fit {
    ($map:expr, $threshold:expr) => { ... };
}

Shrinks the map $map when it reserves more than $threshold slots for future entries.

Examples

use std::collections::HashMap;
use ckb_util::shrink_to_fit;

let mut h = HashMap::<u32, u32>::new();
// Shrink the map when it reserves more than 10 slots for future entries.
shrink_to_fit!(h, 10);