perf(data): compact immutable snapshots with current execution rules

2026-09-12 16:02:24 +08:00
parent ffd23b9920
commit 828690a51e
22 changed files with 1430 additions and 1058 deletions
@@ -0,0 +1,339 @@
+use std::borrow::Cow;
+use std::collections::BTreeMap;
+use std::fmt;
+use std::ops::Index;
+
+use serde::de::{MapAccess, Visitor};
+use serde::ser::SerializeMap;
+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)>,
+}
+
+impl NumericFactorMap {
+    pub const fn new() -> Self {
+        Self {
+            entries: Vec::new(),
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        self.entries.len()
+    }
+    pub fn is_empty(&self) -> bool {
+        self.entries.is_empty()
+    }
+    pub fn clear(&mut self) {
+        self.entries.clear();
+    }
+
+    pub fn get(&self, key: &str) -> Option<&f64> {
+        self.entries
+            .binary_search_by(|(name, _)| name.as_ref().cmp(key))
+            .ok()
+            .map(|index| &self.entries[index].1)
+    }
+
+    pub fn get_mut(&mut self, key: &str) -> Option<&mut f64> {
+        self.entries
+            .binary_search_by(|(name, _)| name.as_ref().cmp(key))
+            .ok()
+            .map(|index| &mut self.entries[index].1)
+    }
+
+    pub fn contains_key(&self, key: &str) -> bool {
+        self.get(key).is_some()
+    }
+
+    pub fn insert(&mut self, key: Cow<'static, str>, value: f64) -> Option<f64> {
+        if self
+            .entries
+            .last()
+            .is_none_or(|(last, _)| last.as_ref() < key.as_ref())
+        {
+            self.entries.push((key, value));
+            return None;
+        }
+        match self
+            .entries
+            .binary_search_by(|(name, _)| name.as_ref().cmp(key.as_ref()))
+        {
+            Ok(index) => Some(std::mem::replace(&mut self.entries[index].1, value)),
+            Err(index) => {
+                self.entries.insert(index, (key, value));
+                None
+            }
+        }
+    }
+
+    pub fn remove(&mut self, key: &str) -> Option<f64> {
+        self.entries
+            .binary_search_by(|(name, _)| name.as_ref().cmp(key))
+            .ok()
+            .map(|index| self.entries.remove(index).1)
+    }
+
+    pub fn retain(&mut self, mut keep: impl FnMut(&Cow<'static, str>, &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 {
+        self.entries.iter().map(|(key, _)| key)
+    }
+    pub fn values(&self) -> impl DoubleEndedIterator<Item = &f64> + ExactSizeIterator {
+        self.entries.iter().map(|(_, value)| value)
+    }
+}
+
+impl fmt::Debug for NumericFactorMap {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_map().entries(self).finish()
+    }
+}
+
+impl Index<&str> for NumericFactorMap {
+    type Output = f64;
+    fn index(&self, key: &str) -> &Self::Output {
+        self.get(key).expect("numeric factor key not found")
+    }
+}
+
+pub struct Iter<'a>(std::slice::Iter<'a, (Cow<'static, str>, f64)>);
+impl<'a> Iterator for Iter<'a> {
+    type Item = (&'a Cow<'static, str>, &'a f64);
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next().map(|(k, v)| (k, v))
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+impl DoubleEndedIterator for Iter<'_> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.0.next_back().map(|(k, v)| (k, v))
+    }
+}
+impl ExactSizeIterator for Iter<'_> {}
+impl<'a> IntoIterator for &'a NumericFactorMap {
+    type Item = (&'a Cow<'static, str>, &'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 IntoIter = std::vec::IntoIter<Self::Item>;
+    fn into_iter(self) -> Self::IntoIter {
+        self.entries.into_iter()
+    }
+}
+
+impl FromIterator<(Cow<'static, str>, f64)> for NumericFactorMap {
+    fn from_iter<T: IntoIterator<Item = (Cow<'static, str>, 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) {
+            entries.sort_by(|left, right| left.0.cmp(&right.0));
+        }
+        entries.dedup_by(|later, earlier| {
+            if later.0 == earlier.0 {
+                earlier.1 = later.1;
+                true
+            } else {
+                false
+            }
+        });
+        Self { entries }
+    }
+}
+impl Extend<(Cow<'static, str>, f64)> for NumericFactorMap {
+    fn extend<T: IntoIterator<Item = (Cow<'static, str>, f64)>>(&mut self, iter: T) {
+        let mut incoming: Self = iter.into_iter().collect();
+        if incoming.is_empty() {
+            return;
+        }
+        if self.is_empty() {
+            *self = incoming;
+            return;
+        }
+        if self.entries.last().unwrap().0 < incoming.entries[0].0 {
+            self.entries.append(&mut incoming.entries);
+            return;
+        }
+        // Merge sorted sets in linear time; wide factor batches must not shift
+        // the existing vector once per field. Existing keys keep their identity.
+        let mut merged = Vec::with_capacity(self.len() + incoming.len());
+        let mut old = std::mem::take(&mut self.entries).into_iter().peekable();
+        let mut new = incoming.entries.into_iter().peekable();
+        while let (Some(left), Some(right)) = (old.peek(), new.peek()) {
+            match left.0.cmp(&right.0) {
+                std::cmp::Ordering::Less => merged.push(old.next().unwrap()),
+                std::cmp::Ordering::Greater => merged.push(new.next().unwrap()),
+                std::cmp::Ordering::Equal => {
+                    let (key, _) = old.next().unwrap();
+                    merged.push((key, new.next().unwrap().1));
+                }
+            }
+        }
+        merged.extend(old);
+        merged.extend(new);
+        self.entries = merged;
+    }
+}
+impl<const N: usize> From<[(Cow<'static, str>, f64); N]> for NumericFactorMap {
+    fn from(entries: [(Cow<'static, str>, f64); N]) -> Self {
+        entries.into_iter().collect()
+    }
+}
+impl From<BTreeMap<Cow<'static, str>, f64>> for NumericFactorMap {
+    fn from(entries: BTreeMap<Cow<'static, str>, f64>) -> Self {
+        Self {
+            entries: entries.into_iter().collect(),
+        }
+    }
+}
+
+impl Serialize for NumericFactorMap {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        let mut map = serializer.serialize_map(Some(self.len()))?;
+        for (key, value) in self {
+            map.serialize_entry(key, value)?;
+        }
+        map.end()
+    }
+}
+impl<'de> Deserialize<'de> for NumericFactorMap {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        struct Fields;
+        impl<'de> Visitor<'de> for Fields {
+            type Value = NumericFactorMap;
+            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                f.write_str("a numeric factor map")
+            }
+            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>()? {
+                    entries.push((Cow::Owned(key), value));
+                }
+                Ok(entries.into_iter().collect())
+            }
+        }
+        deserializer.deserialize_map(Fields)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn updates_order_removal_and_values_match_tree_map() {
+        let mut flat = NumericFactorMap::new();
+        let mut tree = BTreeMap::new();
+        let mut seed = 71_u64;
+        for index in 0..10000 {
+            seed = seed.wrapping_mul(6364136223846793005).wrapping_add(1);
+            let key: Cow<'static, str> = Cow::Owned(format!("factor_{:04}", (seed >> 32) % 1000));
+            let value = (index as f64 - 5000.0) / 7.0;
+            if index % 11 == 0 {
+                assert_eq!(flat.remove(key.as_ref()), tree.remove(key.as_ref()));
+            } else {
+                assert_eq!(flat.insert(key.clone(), value), tree.insert(key, value));
+            }
+        }
+        assert_eq!(
+            flat.iter().collect::<Vec<_>>(),
+            tree.iter().collect::<Vec<_>>()
+        );
+        flat.retain(|_, value| *value > 100.0);
+        tree.retain(|_, value| *value > 100.0);
+        assert_eq!(
+            flat.iter().collect::<Vec<_>>(),
+            tree.iter().collect::<Vec<_>>()
+        );
+        assert_eq!(
+            std::mem::size_of::<NumericFactorMap>(),
+            std::mem::size_of_val(&tree)
+        );
+    }
+
+    #[test]
+    fn bulk_load_is_sorted_and_keeps_last_value_for_each_field() {
+        let input = vec![
+            (Cow::Borrowed("z"), 2.0),
+            (Cow::Borrowed("a"), 1.0),
+            (Cow::Borrowed("z"), 3.0),
+            (Cow::Borrowed("z"), 4.0),
+        ];
+        let flat: NumericFactorMap = input.clone().into_iter().collect();
+        let tree: BTreeMap<_, _> = input.into_iter().collect();
+        assert_eq!(
+            flat.iter().collect::<Vec<_>>(),
+            tree.iter().collect::<Vec<_>>()
+        );
+        assert_eq!(flat["z"], 4.0);
+    }
+
+    #[test]
+    fn serialization_keeps_the_map_contract_and_precise_numbers() {
+        let input = [
+            (Cow::Borrowed("zero"), -0.0),
+            (Cow::Borrowed("tiny"), 1.0000000000000002),
+            (Cow::Borrowed("large"), 9.123456789123456e20),
+        ];
+        let flat = NumericFactorMap::from(input.clone());
+        let tree = BTreeMap::from(input);
+        let json = serde_json::to_string(&flat).unwrap();
+        assert_eq!(json, serde_json::to_string(&tree).unwrap());
+        let decoded: NumericFactorMap = serde_json::from_str(&json).unwrap();
+        for (key, value) in &flat {
+            assert_eq!(value.to_bits(), decoded[key.as_ref()].to_bits());
+        }
+        let duplicate: NumericFactorMap = serde_json::from_str(r#"{"x":1,"x":2}"#).unwrap();
+        assert_eq!(duplicate["x"], 2.0);
+    }
+
+    #[test]
+    fn clone_does_not_share_mutable_values() {
+        let original = NumericFactorMap::from([(Cow::Borrowed("signal"), 1.0)]);
+        let mut copy = original.clone();
+        *copy.get_mut("signal").unwrap() = 0.0;
+        copy.insert(Cow::Borrowed("other"), 2.0);
+        assert_eq!(original["signal"], 1.0);
+        assert!(!original.contains_key("other"));
+    }
+
+    #[test]
+    fn wide_batch_merge_matches_tree_and_preserves_old_key_ownership() {
+        let entries = (0..4096)
+            .map(|index| (Cow::Owned(format!("f_{index:05}")), index as f64))
+            .collect::<Vec<_>>();
+        let mut flat: NumericFactorMap = entries.clone().into_iter().collect();
+        let mut tree = BTreeMap::from_iter(entries);
+        flat.insert(Cow::Borrowed("shared"), -0.0);
+        tree.insert(Cow::Borrowed("shared"), -0.0);
+        let incoming = (2048..8192)
+            .rev()
+            .map(|index| (Cow::Owned(format!("f_{index:05}")), -(index as f64)))
+            .chain([(Cow::Owned("shared".to_owned()), 1.0)])
+            .collect::<Vec<_>>();
+        flat.extend(incoming.clone());
+        tree.extend(incoming);
+        assert_eq!(
+            flat.iter().collect::<Vec<_>>(),
+            tree.iter().collect::<Vec<_>>()
+        );
+        assert!(matches!(flat.keys().last(), Some(Cow::Borrowed("shared"))));
+        flat.extend([(Cow::Borrowed("zz"), f64::NAN)]);
+        assert!(flat["zz"].is_nan());
+        flat.extend(std::iter::empty());
+        assert_eq!(flat.len(), tree.len() + 1);
+    }
+}