Use `rustc-hash` for most of our `HashMap` and `HashSet` instances

5 files changed, 10 insertions, 12 deletions

diff --git a/futures/src/backend/native/async_std.rs b/futures/src/backend/native/async_std.rs
index 52b0e914..b7da5e90 100644
--- a/futures/src/backend/native/async_std.rs
+++ b/futures/src/backend/native/async_std.rs
@@ -18,8 +18,7 @@ impl crate::Executor for Executor {
 
 pub mod time {
     //! Listen and react to time.
-    use crate::core::Hasher;
-    use crate::subscription::{self, Subscription};
+    use crate::subscription::{self, Hasher, Subscription};
 
     /// Returns a [`Subscription`] that produces messages at a set interval.
     ///
diff --git a/futures/src/backend/native/smol.rs b/futures/src/backend/native/smol.rs
index 00d13d35..aaf1518c 100644
--- a/futures/src/backend/native/smol.rs
+++ b/futures/src/backend/native/smol.rs
@@ -17,8 +17,7 @@ impl crate::Executor for Executor {
 
 pub mod time {
     //! Listen and react to time.
-    use crate::core::Hasher;
-    use crate::subscription::{self, Subscription};
+    use crate::subscription::{self, Hasher, Subscription};
 
     /// Returns a [`Subscription`] that produces messages at a set interval.
     ///
diff --git a/futures/src/backend/native/tokio.rs b/futures/src/backend/native/tokio.rs
index 4698a105..3ab7f675 100644
--- a/futures/src/backend/native/tokio.rs
+++ b/futures/src/backend/native/tokio.rs
@@ -22,8 +22,7 @@ impl crate::Executor for Executor {
 
 pub mod time {
     //! Listen and react to time.
-    use crate::core::Hasher;
-    use crate::subscription::{self, Subscription};
+    use crate::subscription::{self, Hasher, Subscription};
 
     /// Returns a [`Subscription`] that produces messages at a set interval.
     ///
diff --git a/futures/src/subscription.rs b/futures/src/subscription.rs
index 7537c022..93e35608 100644
--- a/futures/src/subscription.rs
+++ b/futures/src/subscription.rs
@@ -4,7 +4,6 @@ mod tracker;
 pub use tracker::Tracker;
 
 use crate::core::event::{self, Event};
-use crate::core::Hasher;
 use crate::futures::{Future, Stream};
 use crate::{BoxStream, MaybeSend};
 
@@ -18,6 +17,9 @@ use std::hash::Hash;
 /// It is the input of a [`Subscription`].
 pub type EventStream = BoxStream<(Event, event::Status)>;
 
+/// The hasher used for identifying subscriptions.
+pub type Hasher = rustc_hash::FxHasher;
+
 /// A request to listen to external events.
 ///
 /// Besides performing async actions on demand with `Command`, most
diff --git a/futures/src/subscription/tracker.rs b/futures/src/subscription/tracker.rs
index 15ed5b87..277a446b 100644
--- a/futures/src/subscription/tracker.rs
+++ b/futures/src/subscription/tracker.rs
@@ -1,12 +1,11 @@
 use crate::core::event::{self, Event};
-use crate::core::Hasher;
-use crate::subscription::Recipe;
+use crate::subscription::{Hasher, Recipe};
 use crate::{BoxFuture, MaybeSend};
 
 use futures::channel::mpsc;
 use futures::sink::{Sink, SinkExt};
+use rustc_hash::FxHashMap;
 
-use std::collections::HashMap;
 use std::hash::Hasher as _;
 
 /// A registry of subscription streams.
@@ -18,7 +17,7 @@ use std::hash::Hasher as _;
 /// [`Subscription`]: crate::Subscription
 #[derive(Debug, Default)]
 pub struct Tracker {
-    subscriptions: HashMap<u64, Execution>,
+    subscriptions: FxHashMap<u64, Execution>,
 }
 
 #[derive(Debug)]
@@ -31,7 +30,7 @@ impl Tracker {
     /// Creates a new empty [`Tracker`].
     pub fn new() -> Self {
         Self {
-            subscriptions: HashMap::new(),
+            subscriptions: FxHashMap::default(),
         }
     }