libs/maybe_sync/lib.rs - main - githubmirror/deno

libs/maybe_sync/lib.rs
140 строк3 KB
Bartek Iwańczuk
perf: use FxHash for hot internal hash maps (#36100)
20 июл 2026, 12:09
20 июл 2026, 12:09f9ea4e8
// Copyright 2018-2026 the Deno authors. MIT license.

pub use inner::*;

#[cfg(feature = "sync")]
mod inner {
  #![allow(
    clippy::disallowed_types,
    reason = "implementation the rule says to use"
  )]

  pub use core::marker::Send as MaybeSend;
  pub use core::marker::Sync as MaybeSync;
  pub use std::sync::Arc as MaybeArc;
  pub use std::sync::OnceLock as MaybeOnceLock;

  pub type MaybeDashMap<K, V, S = rustc_hash::FxBuildHasher> =
    dashmap::DashMap<K, V, S>;
  pub type MaybeDashSet<T, S = rustc_hash::FxBuildHasher> =
    dashmap::DashSet<T, S>;
}

#[cfg(not(feature = "sync"))]
mod inner {
  pub use std::cell::OnceCell as MaybeOnceLock;
  use std::cell::Ref;
  use std::cell::RefCell;
  use std::collections::HashMap;
  use std::hash::BuildHasher;
  use std::hash::Hash;
  pub use std::rc::Rc as MaybeArc;

  use rustc_hash::FxBuildHasher;

  pub trait MaybeSync {}
  impl<T> MaybeSync for T where T: ?Sized {}
  pub trait MaybeSend {}
  impl<T> MaybeSend for T where T: ?Sized {}

  // Wrapper struct that exposes a subset of `DashMap` API.
  pub struct MaybeDashMap<K, V, S = FxBuildHasher>(RefCell<HashMap<K, V, S>>);

  // manual impl to avoid requiring `S: Debug` (ex. `FxBuildHasher`
  // does not implement `Debug`)
  impl<K: std::fmt::Debug, V: std::fmt::Debug, S> std::fmt::Debug
    for MaybeDashMap<K, V, S>
  {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      std::fmt::Debug::fmt(&self.0, f)
    }
  }

  impl<K, V, S> Default for MaybeDashMap<K, V, S>
  where
    K: Eq + Hash,
    S: Default + BuildHasher + Clone,
  {
    fn default() -> Self {
      Self(RefCell::new(Default::default()))
    }
  }

  impl<K: Eq + Hash, V, S: BuildHasher> MaybeDashMap<K, V, S> {
    pub fn get<'a, Q: Eq + Hash + ?Sized>(
      &'a self,
      key: &Q,
    ) -> Option<Ref<'a, V>>
    where
      K: std::borrow::Borrow<Q>,
    {
      Ref::filter_map(self.0.borrow(), |map| map.get(key)).ok()
    }

    pub fn insert(&self, key: K, value: V) -> Option<V> {
      let mut inner = self.0.borrow_mut();
      inner.insert(key, value)
    }

    pub fn clear(&self) {
      self.0.borrow_mut().clear();
    }

    pub fn remove(&self, key: &K) -> Option<(K, V)> {
      self.0.borrow_mut().remove_entry(key)
    }

    #[allow(clippy::len_without_is_empty)]
    pub fn len(&self) -> usize {
      self.0.borrow().len()
    }
  }

  // Wrapper struct that exposes a subset of `DashMap` API.
  pub struct MaybeDashSet<V, S = FxBuildHasher>(
    RefCell<std::collections::HashSet<V, S>>,
  );

  // manual impl to avoid requiring `S: Debug` (ex. `FxBuildHasher`
  // does not implement `Debug`)
  impl<V: std::fmt::Debug, S> std::fmt::Debug for MaybeDashSet<V, S> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      std::fmt::Debug::fmt(&self.0, f)
    }
  }

  impl<V, S> Default for MaybeDashSet<V, S>
  where
    V: Eq + Hash,
    S: Default + BuildHasher + Clone,
  {
    fn default() -> Self {
      Self(RefCell::new(Default::default()))
    }
  }

  impl<V: Eq + Hash, S: BuildHasher> MaybeDashSet<V, S> {
    pub fn insert(&self, value: V) -> bool {
      let mut inner = self.0.borrow_mut();
      inner.insert(value)
    }
  }
}

#[allow(
  clippy::disallowed_types,
  reason = "implementation the rule says to use"
)]
#[inline]
pub fn new_rc<T>(value: T) -> MaybeArc<T> {
  MaybeArc::new(value)
}

#[allow(
  clippy::disallowed_types,
  reason = "implementation the rule says to use"
)]
#[inline]
pub fn new_arc<T>(value: T) -> std::sync::Arc<T> {
  std::sync::Arc::new(value)
}