perf(data): inline numeric factor keys and preserve borrowed static names

crates/fidc-core/src/data.rs

@@ -4411,7 +4411,7 @@ fn normalize_factor_snapshots(
                     {
                         Some((field, value))
                     } else {
-                        Some((Cow::Owned(trimmed.to_ascii_lowercase()), value))
+                        Some((CompactString::from(trimmed.to_ascii_lowercase()), value))
                     }
                 })
                 .collect();

crates/fidc-core/src/numeric_factors.rs

@@ -3,6 +3,7 @@ use std::collections::BTreeMap;
 use std::fmt;
 use std::ops::Index;
 
+use compact_str::CompactString;
 use serde::de::{MapAccess, Visitor};
 use serde::ser::SerializeMap;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
@@ -10,7 +11,14 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 /// Sorted numeric fields stored contiguously, without a tree node per snapshot.
 #[derive(Clone, Default, PartialEq)]
 pub struct NumericFactorMap {
-    entries: Vec<(Cow<'static, str>, f64)>,
+    entries: Vec<(CompactString, f64)>,
+}
+
+fn compact_key(key: Cow<'static, str>) -> CompactString {
+    match key {
+        Cow::Borrowed(value) => CompactString::const_new(value),
+        Cow::Owned(value) => CompactString::from(value),
+    }
 }
 
 impl NumericFactorMap {
@@ -49,6 +57,10 @@ impl NumericFactorMap {
     }
 
     pub fn insert(&mut self, key: Cow<'static, str>, value: f64) -> Option<f64> {
+        self.insert_compact(compact_key(key), value)
+    }
+
+    pub fn insert_compact(&mut self, key: CompactString, value: f64) -> Option<f64> {
         if self
             .entries
             .last()
@@ -76,14 +88,14 @@ impl NumericFactorMap {
             .map(|index| self.entries.remove(index).1)
     }
 
-    pub fn retain(&mut self, mut keep: impl FnMut(&Cow<'static, str>, &mut f64) -> bool) {
+    pub fn retain(&mut self, mut keep: impl FnMut(&CompactString, &mut f64) -> bool) {
         self.entries.retain_mut(|(key, value)| keep(key, value));
     }
 
     pub fn iter(&self) -> Iter<'_> {
         Iter(self.entries.iter())
     }
-    pub fn keys(&self) -> impl DoubleEndedIterator<Item = &Cow<'static, str>> + ExactSizeIterator {
+    pub fn keys(&self) -> impl DoubleEndedIterator<Item = &CompactString> + ExactSizeIterator {
         self.entries.iter().map(|(key, _)| key)
     }
     pub fn values(&self) -> impl DoubleEndedIterator<Item = &f64> + ExactSizeIterator {
@@ -104,9 +116,9 @@ impl Index<&str> for NumericFactorMap {
     }
 }
 
-pub struct Iter<'a>(std::slice::Iter<'a, (Cow<'static, str>, f64)>);
+pub struct Iter<'a>(std::slice::Iter<'a, (CompactString, f64)>);
 impl<'a> Iterator for Iter<'a> {
-    type Item = (&'a Cow<'static, str>, &'a f64);
+    type Item = (&'a CompactString, &'a f64);
     fn next(&mut self) -> Option<Self::Item> {
         self.0.next().map(|(k, v)| (k, v))
     }
@@ -121,14 +133,14 @@ impl DoubleEndedIterator for Iter<'_> {
 }
 impl ExactSizeIterator for Iter<'_> {}
 impl<'a> IntoIterator for &'a NumericFactorMap {
-    type Item = (&'a Cow<'static, str>, &'a f64);
+    type Item = (&'a CompactString, &'a f64);
     type IntoIter = Iter<'a>;
     fn into_iter(self) -> Self::IntoIter {
         self.iter()
     }
 }
 impl IntoIterator for NumericFactorMap {
-    type Item = (Cow<'static, str>, f64);
+    type Item = (CompactString, f64);
     type IntoIter = std::vec::IntoIter<Self::Item>;
     fn into_iter(self) -> Self::IntoIter {
         self.entries.into_iter()
@@ -137,6 +149,11 @@ impl IntoIterator for NumericFactorMap {
 
 impl FromIterator<(Cow<'static, str>, f64)> for NumericFactorMap {
     fn from_iter<T: IntoIterator<Item = (Cow<'static, str>, f64)>>(iter: T) -> Self {
+        iter.into_iter().map(|(key, value)| (compact_key(key), value)).collect()
+    }
+}
+impl FromIterator<(CompactString, f64)> for NumericFactorMap {
+    fn from_iter<T: IntoIterator<Item = (CompactString, f64)>>(iter: T) -> Self {
         let mut entries: Vec<_> = iter.into_iter().collect();
         // Stable sorting preserves last-value-wins for repeated input keys.
         if !entries.windows(2).all(|pair| pair[0].0 <= pair[1].0) {
@@ -155,6 +172,11 @@ impl FromIterator<(Cow<'static, str>, f64)> for NumericFactorMap {
 }
 impl Extend<(Cow<'static, str>, f64)> for NumericFactorMap {
     fn extend<T: IntoIterator<Item = (Cow<'static, str>, f64)>>(&mut self, iter: T) {
+        self.extend(iter.into_iter().map(|(key, value)| (compact_key(key), value)));
+    }
+}
+impl Extend<(CompactString, f64)> for NumericFactorMap {
+    fn extend<T: IntoIterator<Item = (CompactString, f64)>>(&mut self, iter: T) {
         let mut incoming: Self = iter.into_iter().collect();
         if incoming.is_empty() {
             return;
@@ -194,9 +216,7 @@ impl<const N: usize> From<[(Cow<'static, str>, f64); N]> for NumericFactorMap {
 }
 impl From<BTreeMap<Cow<'static, str>, f64>> for NumericFactorMap {
     fn from(entries: BTreeMap<Cow<'static, str>, f64>) -> Self {
-        Self {
+        entries.into_iter().collect()
-            entries: entries.into_iter().collect(),
-        }
     }
 }
 
@@ -219,8 +239,8 @@ impl<'de> Deserialize<'de> for NumericFactorMap {
             }
             fn visit_map<A: MapAccess<'de>>(self, mut map: A) -> Result<Self::Value, A::Error> {
                 let mut entries = Vec::new();
-                while let Some((key, value)) = map.next_entry::<String, f64>()? {
+                while let Some((key, value)) = map.next_entry::<CompactString, f64>()? {
-                    entries.push((Cow::Owned(key), value));
+                    entries.push((key, value));
                 }
                 Ok(entries.into_iter().collect())
             }
@@ -233,6 +253,34 @@ impl<'de> Deserialize<'de> for NumericFactorMap {
 mod tests {
     use super::*;
 
+    #[test]
+    fn compact_keys_inline_dynamic_names_and_keep_long_static_storage() {
+        const LONG: &str = "a_long_static_factor_identifier_that_must_remain_borrowed";
+        let map = NumericFactorMap::from([
+            (Cow::Owned("dynamic_factor_20".to_owned()), -0.0),
+            (Cow::Borrowed(LONG), 1.0),
+        ]);
+        let cloned = map.clone();
+        let short = cloned.keys().find(|key| key.as_str() == "dynamic_factor_20").unwrap();
+        assert!(!short.is_heap_allocated());
+        let long = cloned.keys().find(|key| key.as_str() == LONG).unwrap();
+        assert_eq!(long.as_static_str(), Some(LONG));
+        assert_eq!(cloned["dynamic_factor_20"].to_bits(), (-0.0_f64).to_bits());
+        assert_eq!(std::mem::size_of::<(CompactString, f64)>(), std::mem::size_of::<(Cow<'static, str>, f64)>());
+    }
+
+    #[test]
+    fn long_dynamic_unicode_and_short_keys_keep_the_same_json_map() {
+        let entries = ["", "a", "a_field_longer_than_the_inline_string_capacity", "价格因子", "ths_up_days_stock"]
+            .into_iter().enumerate().map(|(index, key)| (Cow::Owned(key.to_string()), index as f64 + 0.25))
+            .collect::<BTreeMap<_, _>>();
+        let map = NumericFactorMap::from(entries.clone());
+        assert_eq!(serde_json::to_string(&map).unwrap(), serde_json::to_string(&entries).unwrap());
+        let decoded: NumericFactorMap = serde_json::from_str(&serde_json::to_string(&map).unwrap()).unwrap();
+        assert_eq!(decoded, map);
+        assert!(!decoded.keys().find(|key| key.as_str() == "ths_up_days_stock").unwrap().is_heap_allocated());
+    }
+
     #[test]
     fn updates_order_removal_and_values_match_tree_map() {
         let mut flat = NumericFactorMap::new();
@@ -330,10 +378,11 @@ mod tests {
             flat.iter().collect::<Vec<_>>(),
             tree.iter().collect::<Vec<_>>()
         );
-        assert!(matches!(flat.keys().last(), Some(Cow::Borrowed("shared"))));
+        assert_eq!(flat.keys().last().map(CompactString::as_str), Some("shared"));
+        assert!(!flat.keys().last().unwrap().is_heap_allocated());
         flat.extend([(Cow::Borrowed("zz"), f64::NAN)]);
         assert!(flat["zz"].is_nan());
-        flat.extend(std::iter::empty());
+        flat.extend(std::iter::empty::<(CompactString, f64)>());
         assert_eq!(flat.len(), tree.len() + 1);
     }
 }