fix initial capacity (and typo)

Author: aneubeck

crates/hash-sorted-map/src/group_ops.rs

@@ -4,6 +4,13 @@ pub const GROUP_SIZE: usize = 16;
 #[cfg(not(target_arch = "x86_64"))]
 pub const GROUP_SIZE: usize = 8;
 
+/// Maximum safe fill ratio (keys / primary slots) that keeps overflow within
+/// the 12.5% reserve budget at p95 confidence. Derived from simulation.
+#[cfg(target_arch = "x86_64")]
+pub const MAX_FILL: f64 = 0.71;
+#[cfg(not(target_arch = "x86_64"))]
+pub const MAX_FILL: f64 = 0.67;
+
 pub const CTRL_EMPTY: u8 = 0x00;
 
 #[cfg(target_arch = "x86_64")]

crates/hash-sorted-map/src/hash_sorted_map.rs

@@ -65,8 +65,8 @@ impl<K, V, S> HashSortedMap<K, V, S> {
     }
 
     pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self {
-        let adjusted = capacity.checked_mul(8).unwrap_or(usize::MAX) / 7;
-        let min_groups = (adjusted / GROUP_SIZE).max(1).next_power_of_two();
+        let adjusted = (capacity as f64 / group_ops::MAX_FILL).ceil() as usize;
+        let min_groups = (adjusted.div_ceil(GROUP_SIZE)).max(1).next_power_of_two();
         let n_bits = min_groups.trailing_zeros().max(1);
         let (groups, num_primary) = Self::alloc_groups(n_bits);
         Self {

crates/hash-sorted-map/src/lib.rs

@@ -1,4 +1,4 @@
 mod group_ops;
 mod hash_sorted_map;
 
-pub use hash_sorted_map::{Entry, HashSortedMap, OccupiedEntry, VacandEntry};
+pub use hash_sorted_map::{Entry, HashSortedMap, OccupiedEntry, VacantEntry};