From d20aff012dff09b4edb2cc6955e9038ae057df3d Mon Sep 17 00:00:00 2001
From: dignifiedquire <me@dignifiedquire.com>
Date: Tue, 4 Nov 2025 14:12:26 +0100
Subject: [PATCH] perf: use IdentityMap

---
 Cargo.lock                          | 13 ++++++++++---
 quinn-proto/Cargo.toml              |  1 +
 quinn-proto/src/connection/paths.rs | 10 +++++++++-
 quinn-proto/src/connection/timer.rs |  6 +++---
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c12129d92..7e794a9fa 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -744,7 +744,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.1",
 ]
 
 [[package]]
@@ -1028,6 +1028,12 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 
+[[package]]
+name = "identity-hash"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dfdd7caa900436d8f13b2346fe10257e0c05c1f1f9e351f4f5d57c03bd5f45da"
+
 [[package]]
 name = "idna"
 version = "1.1.0"
@@ -1117,6 +1123,7 @@ dependencies = [
  "fastbloom",
  "getrandom 0.3.3",
  "hex-literal",
+ "identity-hash",
  "lazy_static",
  "lru-slab",
  "qlog",
@@ -1705,7 +1712,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.52.0",
+ "windows-sys 0.61.1",
 ]
 
 [[package]]
@@ -2447,7 +2454,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.61.1",
 ]
 
 [[package]]
diff --git a/quinn-proto/Cargo.toml b/quinn-proto/Cargo.toml
index 1c34fdbc9..0494ce898 100644
--- a/quinn-proto/Cargo.toml
+++ b/quinn-proto/Cargo.toml
@@ -52,6 +52,7 @@ slab = { workspace = true }
 thiserror = { workspace = true }
 tinyvec = { workspace = true, features = ["alloc"] }
 tracing = { workspace = true }
+identity-hash = "0.1.0"
 
 # Feature flags & dependencies for wasm
 # wasm-bindgen is assumed for a wasm*-*-unknown target
diff --git a/quinn-proto/src/connection/paths.rs b/quinn-proto/src/connection/paths.rs
index 0047e2ee9..cd9083582 100644
--- a/quinn-proto/src/connection/paths.rs
+++ b/quinn-proto/src/connection/paths.rs
@@ -18,9 +18,17 @@ use crate::{
 use qlog::events::quic::MetricsUpdated;
 
 /// Id representing different paths when using multipath extension
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Default, Hash)]
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Default)]
 pub struct PathId(pub(crate) u32);
 
+impl std::hash::Hash for PathId {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        state.write_u32(self.0);
+    }
+}
+
+impl identity_hash::IdentityHashable for PathId {}
+
 impl coding::Codec for PathId {
     fn decode<B: bytes::Buf>(r: &mut B) -> coding::Result<Self> {
         let v = VarInt::decode(r)?;
diff --git a/quinn-proto/src/connection/timer.rs b/quinn-proto/src/connection/timer.rs
index a835e4e70..82c842a58 100644
--- a/quinn-proto/src/connection/timer.rs
+++ b/quinn-proto/src/connection/timer.rs
@@ -1,4 +1,4 @@
-use rustc_hash::FxHashMap;
+use identity_hash::{IdentityHashable, IntMap};
 
 use crate::Instant;
 
@@ -86,7 +86,7 @@ const STACK_TIMERS: usize = 4;
 #[derive(Debug, Clone)]
 struct SmallMap<K, V, const SIZE: usize> {
     stack: [Option<(K, V)>; SIZE],
-    heap: Option<FxHashMap<K, V>>,
+    heap: Option<IntMap<K, V>>,
 }
 
 impl<K, V, const SIZE: usize> Default for SmallMap<K, V, SIZE> {
@@ -100,7 +100,7 @@ impl<K, V, const SIZE: usize> Default for SmallMap<K, V, SIZE> {
 
 impl<K, V, const SIZE: usize> SmallMap<K, V, SIZE>
 where
-    K: std::cmp::Eq + std::hash::Hash,
+    K: std::cmp::Eq + std::hash::Hash + IdentityHashable,
 {
     fn insert(&mut self, key: K, value: V) -> Option<V> {
         // check stack for space