Use DefaultHasher

Author: fraillt

opentelemetry-sdk/Cargo.toml

@@ -29,7 +29,6 @@ tokio = { workspace = true, features = ["rt", "time"], optional = true }
 tokio-stream = { workspace = true, optional = true }
 http = { workspace = true, optional = true }
 tracing = {workspace = true, optional = true}
-rustc-hash = "2.0.0"
 
 [package.metadata.docs.rs]
 all-features = true

opentelemetry-sdk/src/metrics/internal/hashed.rs

@@ -1,11 +1,9 @@
 use std::{
     borrow::{Borrow, Cow},
-    hash::{BuildHasher, Hash, Hasher},
+    hash::{BuildHasher, DefaultHasher, Hash, Hasher},
     ops::Deref,
 };
 
-use rustc_hash::*;
-
 /// Hash value only once, works with references and owned types.
 pub(crate) struct Hashed<'a, T>
 where
@@ -20,11 +18,10 @@ where
     T: ToOwned + Hash + ?Sized,
 {
     pub(crate) fn from_borrowed(value: &'a T) -> Self {
-        let mut hasher = FxHasher::default();
-        value.hash(&mut hasher);
+        let hash = calc_hash(&value);
         Self {
             value: Cow::Borrowed(value),
-            hash: hasher.finish(),
+            hash,
         }
     }
 
@@ -36,16 +33,6 @@ where
         }
     }
 
-    pub(crate) fn mutate(self, f: impl FnOnce(&mut <T as ToOwned>::Owned)) -> Hashed<'static, T> {
-        let mut value = self.value.into_owned();
-        f(&mut value);
-        let hash = calc_hash(value.borrow());
-        Hashed {
-            value: Cow::Owned(value),
-            hash,
-        }
-    }
-
     pub(crate) fn into_owned(self) -> Hashed<'static, T> {
         let value = self.value.into_owned();
         Hashed {
@@ -63,7 +50,7 @@ fn calc_hash<T>(value: T) -> u64
 where
     T: Hash,
 {
-    let mut hasher = FxHasher::default();
+    let mut hasher = DefaultHasher::default();
     value.hash(&mut hasher);
     hasher.finish()
 }

opentelemetry-sdk/src/metrics/internal/mod.rs

@@ -20,6 +20,8 @@ use hashed::{Hashed, HashedNoOpBuilder};
 use once_cell::sync::Lazy;
 use opentelemetry::{otel_warn, KeyValue};
 
+use super::sort_and_dedup;
+
 pub(crate) static STREAM_OVERFLOW_ATTRIBUTES: Lazy<Hashed<'static, [KeyValue]>> =
     Lazy::new(|| Hashed::from_owned(vec![KeyValue::new("otel.metric.overflow", "true")]));
 
@@ -97,11 +99,7 @@ where
         }
 
         // Try to retrieve and update the tracker with the attributes sorted.
-        let sorted_attrs = attributes.clone().mutate(|list| {
-            // use stable sort
-            list.sort_by(|a, b| a.key.cmp(&b.key));
-            dedup_remove_first(list, |a, b| a.key == b.key);
-        });
+        let sorted_attrs = Hashed::from_owned(sort_and_dedup(&attributes));
         if let Some(tracker) = trackers.get(&sorted_attrs) {
             tracker.update(value);
             return;
@@ -198,20 +196,6 @@ where
     }
 }
 
-fn dedup_remove_first<T>(values: &mut Vec<T>, is_eq: impl Fn(&T, &T) -> bool) {
-    // we cannot use vec.dedup_by because it will remove last duplicate not first
-    if values.len() > 1 {
-        let mut i = values.len() - 1;
-        while i != 0 {
-            let is_same = unsafe { is_eq(values.get_unchecked(i - 1), values.get_unchecked(i)) };
-            if is_same {
-                values.remove(i - 1);
-            }
-            i -= 1;
-        }
-    }
-}
-
 /// Clear and allocate exactly required amount of space for all attribute-sets
 fn prepare_data<T>(data: &mut Vec<T>, list_len: usize) {
     data.clear();
@@ -415,45 +399,9 @@ impl AtomicallyUpdate<f64> for f64 {
 
 #[cfg(test)]
 mod tests {
-    use std::usize;
 
     use super::*;
 
-    fn assert_deduped<const N: usize, const M: usize>(
-        input: [(i32, bool); N],
-        expect: [(i32, bool); M],
-    ) {
-        let mut list: Vec<(i32, bool)> = Vec::from(input);
-        dedup_remove_first(&mut list, |a, b| a.0 == b.0);
-        assert_eq!(list, expect);
-    }
-
-    #[test]
-    fn deduplicate_by_removing_first_element_from_sorted_array() {
-        assert_deduped([], []);
-        assert_deduped([(1, true)], [(1, true)]);
-        assert_deduped([(1, false), (1, false), (1, true)], [(1, true)]);
-        assert_deduped(
-            [(1, true), (2, false), (2, false), (2, true)],
-            [(1, true), (2, true)],
-        );
-        assert_deduped(
-            [(1, true), (1, false), (1, true), (2, true)],
-            [(1, true), (2, true)],
-        );
-        assert_deduped(
-            [
-                (1, false),
-                (1, true),
-                (2, false),
-                (2, true),
-                (3, false),
-                (3, true),
-            ],
-            [(1, true), (2, true), (3, true)],
-        );
-    }
-
     #[test]
     fn can_store_u64_atomic_value() {
         let atomic = u64::new_atomic_tracker(0);

opentelemetry-sdk/src/metrics/mod.rs

@@ -115,23 +115,27 @@ pub(crate) struct AttributeSet(Vec<KeyValue>, u64);
 
 impl From<&[KeyValue]> for AttributeSet {
     fn from(values: &[KeyValue]) -> Self {
-        let mut seen_keys = HashSet::with_capacity(values.len());
-        let vec = values
-            .iter()
-            .rev()
-            .filter_map(|kv| {
-                if seen_keys.insert(kv.key.clone()) {
-                    Some(kv.clone())
-                } else {
-                    None
-                }
-            })
-            .collect::<Vec<_>>();
-
-        AttributeSet::new(vec)
+        AttributeSet::new(sort_and_dedup(values))
     }
 }
 
+pub(crate) fn sort_and_dedup(values: &[KeyValue]) -> Vec<KeyValue> {
+    let mut seen_keys = HashSet::with_capacity(values.len());
+    let mut vec = values
+        .iter()
+        .rev()
+        .filter_map(|kv| {
+            if seen_keys.insert(kv.key.clone()) {
+                Some(kv.clone())
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>();
+    vec.sort_unstable_by(|a, b| a.key.cmp(&b.key));
+    vec
+}
+
 fn calculate_hash(values: &[KeyValue]) -> u64 {
     let mut hasher = DefaultHasher::new();
     values.iter().fold(&mut hasher, |mut hasher, item| {
@@ -142,8 +146,7 @@ fn calculate_hash(values: &[KeyValue]) -> u64 {
 }
 
 impl AttributeSet {
-    fn new(mut values: Vec<KeyValue>) -> Self {
-        values.sort_unstable_by(|a, b| a.key.cmp(&b.key));
+    fn new(values: Vec<KeyValue>) -> Self {
         let hash = calculate_hash(&values);
         AttributeSet(values, hash)
     }