make error "duplicate" cheaper (#950)

Author: davidhewitt

src/errors/line_error.rs

@@ -62,10 +62,10 @@ impl<'a> ValError<'a> {
     }
 
     /// a bit like clone but change the lifetime to match py
-    pub fn duplicate<'py>(&self, py: Python<'py>) -> ValError<'py> {
+    pub fn into_owned(self, py: Python<'_>) -> ValError<'_> {
         match self {
-            ValError::LineErrors(errors) => errors.iter().map(|e| e.duplicate(py)).collect::<Vec<_>>().into(),
-            ValError::InternalErr(err) => ValError::InternalErr(err.clone_ref(py)),
+            ValError::LineErrors(errors) => errors.into_iter().map(|e| e.into_owned(py)).collect::<Vec<_>>().into(),
+            ValError::InternalErr(err) => ValError::InternalErr(err),
             ValError::Omit => ValError::Omit,
             ValError::UseDefault => ValError::UseDefault,
         }
@@ -129,28 +129,26 @@ impl<'a> ValLineError<'a> {
         self
     }
 
-    /// a bit like clone but change the lifetime to match py, used by ValError.duplicate above
-    pub fn duplicate<'py>(&'a self, py: Python<'py>) -> ValLineError<'py> {
+    /// a bit like clone but change the lifetime to match py, used by ValError.into_owned above
+    pub fn into_owned(self, py: Python<'_>) -> ValLineError<'_> {
         ValLineError {
-            error_type: self.error_type.clone(),
-            input_value: InputValue::<'py>::from(self.input_value.to_object(py)),
-            location: self.location.clone(),
+            error_type: self.error_type,
+            input_value: match self.input_value {
+                InputValue::PyAny(input) => InputValue::PyAny(input.to_object(py).into_ref(py)),
+                InputValue::JsonInput(input) => InputValue::JsonInput(input),
+                InputValue::String(input) => InputValue::PyAny(input.to_object(py).into_ref(py)),
+            },
+            location: self.location,
         }
     }
 }
 
 #[cfg_attr(debug_assertions, derive(Debug))]
+#[derive(Clone)]
 pub enum InputValue<'a> {
     PyAny(&'a PyAny),
-    JsonInput(&'a JsonInput),
+    JsonInput(JsonInput),
     String(&'a str),
-    PyObject(PyObject),
-}
-
-impl<'a> From<PyObject> for InputValue<'a> {
-    fn from(py_object: PyObject) -> Self {
-        Self::PyObject(py_object)
-    }
 }
 
 impl<'a> ToPyObject for InputValue<'a> {
@@ -159,7 +157,6 @@ impl<'a> ToPyObject for InputValue<'a> {
             Self::PyAny(input) => input.into_py(py),
             Self::JsonInput(input) => input.to_object(py),
             Self::String(input) => input.into_py(py),
-            Self::PyObject(py_obj) => py_obj.into_py(py),
         }
     }
 }

src/errors/validation_exception.rs

@@ -22,7 +22,7 @@ use super::line_error::ValLineError;
 use super::location::Location;
 use super::types::{ErrorMode, ErrorType};
 use super::value_exception::PydanticCustomError;
-use super::ValError;
+use super::{InputValue, ValError};
 
 #[pyclass(extends=PyValueError, module="pydantic_core._pydantic_core")]
 #[derive(Clone)]
@@ -128,11 +128,11 @@ fn get_url_prefix(py: Python, include_url: bool) -> Option<&str> {
 }
 
 // used to convert a validation error back to ValError for wrap functions
-impl<'a> IntoPy<ValError<'a>> for ValidationError {
-    fn into_py(self, py: Python) -> ValError<'a> {
+impl ValidationError {
+    pub(crate) fn into_val_error(self, py: Python<'_>) -> ValError<'_> {
         self.line_errors
             .into_iter()
-            .map(|e| e.into_py(py))
+            .map(|e| e.into_val_line_error(py))
             .collect::<Vec<_>>()
             .into()
     }
@@ -322,13 +322,13 @@ impl<'a> IntoPy<PyLineError> for ValLineError<'a> {
     }
 }
 
-/// opposite of above, used to extract line errors from a validation error for wrap functions
-impl<'a> IntoPy<ValLineError<'a>> for PyLineError {
-    fn into_py(self, _py: Python) -> ValLineError<'a> {
+impl PyLineError {
+    /// Used to extract line errors from a validation error for wrap functions
+    fn into_val_line_error(self, py: Python<'_>) -> ValLineError<'_> {
         ValLineError {
             error_type: self.error_type,
             location: self.location,
-            input_value: self.input_value.into(),
+            input_value: InputValue::PyAny(self.input_value.into_ref(py)),
         }
     }
 }

src/input/input_json.rs

@@ -31,7 +31,8 @@ impl<'a> Input<'a> for JsonInput {
     }
 
     fn as_error_value(&'a self) -> InputValue<'a> {
-        InputValue::JsonInput(self)
+        // cloning JsonInput is cheap due to use of Arc
+        InputValue::JsonInput(self.clone())
     }
 
     fn is_none(&self) -> bool {
@@ -262,7 +263,7 @@ impl<'a> Input<'a> for JsonInput {
             JsonInput::String(s) => Ok(string_to_vec(s).into()),
             JsonInput::Object(object) => {
                 // return keys iterator to match python's behavior
-                let keys: Vec<JsonInput> = object.keys().map(|k| JsonInput::String(k.clone())).collect();
+                let keys: JsonArray = JsonArray::new(object.keys().map(|k| JsonInput::String(k.clone())).collect());
                 Ok(keys.into())
             }
             _ => Err(ValError::new(ErrorTypeDefaults::IterableType, self)),
@@ -550,5 +551,5 @@ impl<'a> Input<'a> for String {
 }
 
 fn string_to_vec(s: &str) -> JsonArray {
-    s.chars().map(|c| JsonInput::String(c.to_string())).collect()
+    JsonArray::new(s.chars().map(|c| JsonInput::String(c.to_string())).collect())
 }

src/input/parse_json.rs

@@ -1,9 +1,11 @@
 use std::fmt;
+use std::sync::Arc;
 
 use num_bigint::BigInt;
 use pyo3::prelude::*;
 use pyo3::types::{PyDict, PyList};
 use serde::de::{Deserialize, DeserializeSeed, Error as SerdeError, MapAccess, SeqAccess, Visitor};
+use smallvec::SmallVec;
 
 use crate::lazy_index_map::LazyIndexMap;
 
@@ -20,8 +22,8 @@ pub enum JsonInput {
     Array(JsonArray),
     Object(JsonObject),
 }
-pub type JsonArray = Vec<JsonInput>;
-pub type JsonObject = LazyIndexMap<String, JsonInput>;
+pub type JsonArray = Arc<SmallVec<[JsonInput; 8]>>;
+pub type JsonObject = Arc<LazyIndexMap<String, JsonInput>>;
 
 impl ToPyObject for JsonInput {
     fn to_object(&self, py: Python<'_>) -> PyObject {
@@ -111,13 +113,13 @@ impl<'de> Deserialize<'de> for JsonInput {
             where
                 V: SeqAccess<'de>,
             {
-                let mut vec = Vec::new();
+                let mut vec = SmallVec::new();
 
                 while let Some(elem) = visitor.next_element()? {
                     vec.push(elem);
                 }
 
-                Ok(JsonInput::Array(vec))
+                Ok(JsonInput::Array(JsonArray::new(vec)))
             }
 
             fn visit_map<V>(self, mut visitor: V) -> Result<JsonInput, V::Error>
@@ -171,9 +173,9 @@ impl<'de> Deserialize<'de> for JsonInput {
                         while let Some((key, value)) = visitor.next_entry()? {
                             values.insert(key, value);
                         }
-                        Ok(JsonInput::Object(values))
+                        Ok(JsonInput::Object(Arc::new(values)))
                     }
-                    None => Ok(JsonInput::Object(LazyIndexMap::new())),
+                    None => Ok(JsonInput::Object(Arc::new(LazyIndexMap::new()))),
                 }
             }
         }

src/input/return_enums.rs

@@ -625,8 +625,8 @@ impl GenericPyIterator {
         }
     }
 
-    pub fn input<'a>(&'a self, py: Python<'a>) -> &'a PyAny {
-        self.obj.as_ref(py)
+    pub fn input_as_error_value<'py>(&self, py: Python<'py>) -> InputValue<'py> {
+        InputValue::PyAny(self.obj.clone_ref(py).into_ref(py))
     }
 
     pub fn index(&self) -> usize {
@@ -654,9 +654,8 @@ impl GenericJsonIterator {
         }
     }
 
-    pub fn input<'a>(&'a self, py: Python<'a>) -> &'a PyAny {
-        let input = JsonInput::Array(self.array.clone());
-        input.to_object(py).into_ref(py)
+    pub fn input_as_error_value<'py>(&self, _py: Python<'py>) -> InputValue<'py> {
+        InputValue::JsonInput(JsonInput::Array(self.array.clone()))
     }
 
     pub fn index(&self) -> usize {

src/lazy_index_map.rs

@@ -1,32 +1,36 @@
 use std::borrow::Borrow;
-use std::cell::RefCell;
 use std::cmp::{Eq, PartialEq};
 use std::fmt::Debug;
 use std::hash::Hash;
 use std::slice::Iter as SliceIter;
+use std::sync::OnceLock;
 
 use ahash::AHashMap;
+use smallvec::SmallVec;
 
 #[derive(Debug, Clone, Default)]
 pub struct LazyIndexMap<K, V> {
-    vec: Vec<(K, V)>,
-    map: RefCell<Option<AHashMap<K, usize>>>,
+    vec: SmallVec<[(K, V); 8]>,
+    map: OnceLock<AHashMap<K, usize>>,
 }
 
 /// Like [IndexMap](https://docs.rs/indexmap/latest/indexmap/) but only builds the lookup map when it's needed.
 impl<K, V> LazyIndexMap<K, V>
 where
     K: Clone + Debug + Eq + Hash,
-    V: Clone + Debug,
+    V: Debug,
 {
     pub fn new() -> Self {
         Self {
-            vec: Vec::new(),
-            map: RefCell::new(None),
+            vec: SmallVec::new(),
+            map: OnceLock::new(),
         }
     }
 
     pub fn insert(&mut self, key: K, value: V) {
+        if let Some(map) = self.map.get_mut() {
+            map.insert(key.clone(), self.vec.len());
+        }
         self.vec.push((key, value));
     }
 
@@ -39,22 +43,14 @@ where
         K: Borrow<Q> + PartialEq<Q>,
         Q: Hash + Eq,
     {
-        let mut map = self.map.borrow_mut();
-        if let Some(map) = map.as_ref() {
-            map.get(key).map(|&i| &self.vec[i].1)
-        } else {
-            let mut new_map = AHashMap::with_capacity(self.vec.len());
-            let mut value = None;
-            // reverse here so the last value is the one that's returned
-            for (index, (k, v)) in self.vec.iter().enumerate().rev() {
-                if value.is_none() && k == key {
-                    value = Some(v);
-                }
-                new_map.insert(k.clone(), index);
-            }
-            *map = Some(new_map);
-            value
-        }
+        let map = self.map.get_or_init(|| {
+            self.vec
+                .iter()
+                .enumerate()
+                .map(|(index, (key, _))| (key.clone(), index))
+                .collect()
+        });
+        map.get(key).map(|&i| &self.vec[i].1)
     }
 
     pub fn keys(&self) -> impl Iterator<Item = &K> {

src/validators/function.rs

@@ -504,7 +504,7 @@ pub fn convert_err<'a>(py: Python<'a>, err: PyErr, input: &'a impl Input<'a>) ->
         } else if let Ok(pydantic_error_type) = err.value(py).extract::<PydanticKnownError>() {
             pydantic_error_type.into_val_error(input)
         } else if let Ok(validation_error) = err.value(py).extract::<ValidationError>() {
-            validation_error.into_py(py)
+            validation_error.into_val_error(py)
         } else {
             py_err_string!(err.value(py), ValueError, input)
         }

src/validators/generator.rs

@@ -127,14 +127,14 @@ impl ValidatorIterator {
                         Some(validator) => {
                             if let Some(max_length) = max_length {
                                 if index >= max_length {
-                                    let val_error = ValError::new(
+                                    let val_error = ValError::new_custom_input(
                                         ErrorType::TooLong {
                                             field_type: "Generator".to_string(),
                                             max_length,
                                             actual_length: index + 1,
                                             context: None,
                                         },
-                                        $iter.input(py),
+                                        $iter.input_as_error_value(py),
                                     );
                                     return Err(ValidationError::from_val_error(
                                         py,
@@ -153,14 +153,14 @@ impl ValidatorIterator {
                     None => {
                         if let Some(min_length) = min_length {
                             if $iter.index() < min_length {
-                                let val_error = ValError::new(
+                                let val_error = ValError::new_custom_input(
                                     ErrorType::TooShort {
                                         field_type: "Generator".to_string(),
                                         min_length,
                                         actual_length: $iter.index(),
                                         context: None,
                                     },
-                                    $iter.input(py),
+                                    $iter.input_as_error_value(py),
                                 );
                                 return Err(ValidationError::from_val_error(
                                     py,

src/validators/json.rs

@@ -55,7 +55,7 @@ impl Validator for JsonValidator {
         match self.validator {
             Some(ref validator) => match validator.validate(py, &json_value, state) {
                 Ok(v) => Ok(v),
-                Err(err) => Err(err.duplicate(py)),
+                Err(err) => Err(err.into_owned(py)),
             },
             None => Ok(json_value.to_object(py)),
         }