Suggestion: use rapidhash for KeyHasher

Cargo.toml

@@ -19,7 +19,6 @@ repository = "https://github.com/metrics-rs/metrics"
 homepage = "https://github.com/metrics-rs/metrics"
 
 [workspace.dependencies]
-ahash = { version = "0.8", default-features = false }
 aho-corasick = { version = "1", default-features = false }
 approx = { version = "0.5", default-features = false }
 base64 = { version = "0.22", default-features = false, features = ["std"] }
@@ -66,6 +65,7 @@ quickcheck_macros = { version = "1", default-features = false }
 radix_trie = { version = "0.2", default-features = false }
 rand = { version = "0.9", default-features = false, features = [ "thread_rng" ] }
 rand_xoshiro = { version = "0.7", default-features = false }
+rapidhash = { version = "4.1.1", default-features = false }
 ratatui = { version = "0.29", default-features = false }
 rustls = { version = "0.23", default-features = false }
 sketches-ddsketch = { version = "0.3", default-features = false }

metrics-util/Cargo.toml

@@ -46,7 +46,6 @@ name = "bucket-crusher"
 required-features = ["storage"]
 
 [dependencies]
-ahash = { workspace = true, optional = true }
 aho-corasick = { workspace = true, features = ["std"], optional = true }
 crossbeam-epoch = { workspace = true, features = ["alloc", "std"], optional = true }
 crossbeam-utils = { workspace = true, optional = true }

metrics/Cargo.toml

@@ -23,7 +23,7 @@ name = "macros"
 harness = false
 
 [dependencies]
-ahash = { workspace = true }
+rapidhash = { workspace = true }
 
 [target.'cfg(target_pointer_width = "32")'.dependencies]
 portable-atomic = { version = "1", default-features = false, features = [

metrics/src/common.rs

@@ -1,6 +1,6 @@
 use std::hash::Hasher;
 
-use ahash::AHasher;
+use rapidhash::fast::RapidHasher;
 
 use crate::cow::Cow;
 
@@ -19,12 +19,25 @@ pub type SharedString = Cow<'static, str>;
 
 /// Key-specific hashing algorithm.
 ///
-/// Currently uses AHash - <https://github.com/tkaitchuck/aHash>
+/// Currently uses rapidhash - <https://github.com/hoxxep/rapidhash>
 ///
 /// For any use-case within a `metrics`-owned or adjacent crate, where hashing of a key is required,
 /// this is the hasher that will be used.
-#[derive(Debug, Default)]
-pub struct KeyHasher(AHasher);
+pub struct KeyHasher(RapidHasher<'static>);
+
+impl std::fmt::Debug for KeyHasher {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("KeyHasher").finish_non_exhaustive()
+    }
+}
+
+impl Default for KeyHasher {
+    fn default() -> Self {
+        // The seed should be randomized on application start if DoS resistance is required, but
+        // ahash was also previously using fixed seeds by default.
+        KeyHasher(RapidHasher::default_const())
+    }
+}
 
 impl Hasher for KeyHasher {
     fn finish(&self) -> u64 {