From 82f07fe6d1ee294bae43f311bf8a400e24c2f95f Mon Sep 17 00:00:00 2001
From: Michael Davis <mcarsondavis@gmail.com>
Date: Mon, 17 Feb 2025 17:28:57 -0500
Subject: [PATCH] Migrate helix-event to foldhash

This is following `hashbrown`'s switch in v0.15 from ahash to foldhash
for its `default-haster` feature, applied only to helix-event for now.

I don't have a strong preference between the two. Benchmarks in
Spellbook, which is particularly sensitive to hashers and hash table
performance, show no perceptible difference. Foldhash is dependency-free
though.

Once we migrate to the new tree-sitter bindings and highlighter we
should be able to eliminate the remaining dependencies on ahash.
---
 Cargo.lock                  | 6 ++++--
 Cargo.toml                  | 1 +
 helix-event/Cargo.toml      | 4 ++--
 helix-event/src/registry.rs | 8 ++++----
 helix-event/src/runtime.rs  | 7 ++++---
 5 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index e1fb1685..c6b2efa1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1310,6 +1310,8 @@ version = "0.15.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bf151400ff0baff5465007dd2f3e717f3fe502074ca563069ce3a6629d07b289"
 dependencies = [
+ "allocator-api2",
+ "equivalent",
  "foldhash",
 ]
 
@@ -1371,10 +1373,10 @@ dependencies = [
 name = "helix-event"
 version = "25.1.1"
 dependencies = [
- "ahash",
  "anyhow",
+ "foldhash",
  "futures-executor",
- "hashbrown 0.14.5",
+ "hashbrown 0.15.2",
  "log",
  "once_cell",
  "parking_lot",
diff --git a/Cargo.toml b/Cargo.toml
index 56234a86..ab0f8b48 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -45,6 +45,7 @@ tempfile = "3.16.0"
 bitflags = "2.8"
 unicode-segmentation = "1.2"
 ropey = { version = "1.6.1", default-features = false, features = ["simd"] }
+foldhash = "0.1"
 
 [workspace.package]
 version = "25.1.1"
diff --git a/helix-event/Cargo.toml b/helix-event/Cargo.toml
index ee4038e6..c6ab11c6 100644
--- a/helix-event/Cargo.toml
+++ b/helix-event/Cargo.toml
@@ -12,8 +12,8 @@ homepage.workspace = true
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-ahash = "0.8.11"
-hashbrown = "0.14.5"
+foldhash.workspace = true
+hashbrown = "0.15"
 tokio = { version = "1", features = ["rt", "rt-multi-thread", "time", "sync", "parking_lot", "macros"] }
 # the event registry is essentially read only but must be an rwlock so we can
 # setup new events on initialization, hardware-lock-elision hugely benefits this case
diff --git a/helix-event/src/registry.rs b/helix-event/src/registry.rs
index d43c48ac..551d7014 100644
--- a/helix-event/src/registry.rs
+++ b/helix-event/src/registry.rs
@@ -14,8 +14,8 @@ use crate::hook::ErasedHook;
 use crate::runtime_local;
 
 pub struct Registry {
-    events: HashMap<&'static str, TypeId, ahash::RandomState>,
-    handlers: HashMap<&'static str, Vec<ErasedHook>, ahash::RandomState>,
+    events: HashMap<&'static str, TypeId, foldhash::fast::FixedState>,
+    handlers: HashMap<&'static str, Vec<ErasedHook>, foldhash::fast::FixedState>,
 }
 
 impl Registry {
@@ -105,8 +105,8 @@ runtime_local! {
     static REGISTRY: RwLock<Registry> = RwLock::new(Registry {
         // hardcoded random number is good enough here we don't care about DOS resistance
         // and avoids the additional complexity of `Option<Registry>`
-        events: HashMap::with_hasher(ahash::RandomState::with_seeds(423, 9978, 38322, 3280080)),
-        handlers: HashMap::with_hasher(ahash::RandomState::with_seeds(423, 99078, 382322, 3282938)),
+        events: HashMap::with_hasher(foldhash::fast::FixedState::with_seed(72536814787)),
+        handlers: HashMap::with_hasher(foldhash::fast::FixedState::with_seed(72536814787)),
     });
 }
 
diff --git a/helix-event/src/runtime.rs b/helix-event/src/runtime.rs
index 8da465ef..02d66fb6 100644
--- a/helix-event/src/runtime.rs
+++ b/helix-event/src/runtime.rs
@@ -41,8 +41,9 @@ macro_rules! runtime_local {
 
 #[cfg(feature = "integration_test")]
 pub struct RuntimeLocal<T: 'static> {
-    data:
-        parking_lot::RwLock<hashbrown::HashMap<tokio::runtime::Id, &'static T, ahash::RandomState>>,
+    data: parking_lot::RwLock<
+        hashbrown::HashMap<tokio::runtime::Id, &'static T, foldhash::fast::FixedState>,
+    >,
     init: fn() -> T,
 }
 
@@ -53,7 +54,7 @@ impl<T> RuntimeLocal<T> {
     pub const fn __new(init: fn() -> T) -> Self {
         Self {
             data: parking_lot::RwLock::new(hashbrown::HashMap::with_hasher(
-                ahash::RandomState::with_seeds(423, 9978, 38322, 3280080),
+                foldhash::fast::FixedState::with_seed(12345678910),
             )),
             init,
         }