Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1051 insertions, 0 deletions

diff --git a/vendor/lock_api/src/remutex.rs b/vendor/lock_api/src/remutex.rs
new file mode 100644
index 0000000..74f2da3
--- /dev/null
+++ b/vendor/lock_api/src/remutex.rs
@@ -0,0 +1,1051 @@
+// Copyright 2018 Amanieu d'Antras
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+use crate::{
+    mutex::{RawMutex, RawMutexFair, RawMutexTimed},
+    GuardNoSend,
+};
+use core::{
+    cell::{Cell, UnsafeCell},
+    fmt,
+    marker::PhantomData,
+    mem,
+    num::NonZeroUsize,
+    ops::Deref,
+    sync::atomic::{AtomicUsize, Ordering},
+};
+
+#[cfg(feature = "arc_lock")]
+use alloc::sync::Arc;
+#[cfg(feature = "arc_lock")]
+use core::mem::ManuallyDrop;
+#[cfg(feature = "arc_lock")]
+use core::ptr;
+
+#[cfg(feature = "owning_ref")]
+use owning_ref::StableAddress;
+
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+/// Helper trait which returns a non-zero thread ID.
+///
+/// The simplest way to implement this trait is to return the address of a
+/// thread-local variable.
+///
+/// # Safety
+///
+/// Implementations of this trait must ensure that no two active threads share
+/// the same thread ID. However the ID of a thread that has exited can be
+/// re-used since that thread is no longer active.
+pub unsafe trait GetThreadId {
+    /// Initial value.
+    // A “non-constant” const item is a legacy way to supply an initialized value to downstream
+    // static items. Can hopefully be replaced with `const fn new() -> Self` at some point.
+    #[allow(clippy::declare_interior_mutable_const)]
+    const INIT: Self;
+
+    /// Returns a non-zero thread ID which identifies the current thread of
+    /// execution.
+    fn nonzero_thread_id(&self) -> NonZeroUsize;
+}
+
+/// A raw mutex type that wraps another raw mutex to provide reentrancy.
+///
+/// Although this has the same methods as the [`RawMutex`] trait, it does
+/// not implement it, and should not be used in the same way, since this
+/// mutex can successfully acquire a lock multiple times in the same thread.
+/// Only use this when you know you want a raw mutex that can be locked
+/// reentrantly; you probably want [`ReentrantMutex`] instead.
+///
+/// [`RawMutex`]: trait.RawMutex.html
+/// [`ReentrantMutex`]: struct.ReentrantMutex.html
+pub struct RawReentrantMutex<R, G> {
+    owner: AtomicUsize,
+    lock_count: Cell<usize>,
+    mutex: R,
+    get_thread_id: G,
+}
+
+unsafe impl<R: RawMutex + Send, G: GetThreadId + Send> Send for RawReentrantMutex<R, G> {}
+unsafe impl<R: RawMutex + Sync, G: GetThreadId + Sync> Sync for RawReentrantMutex<R, G> {}
+
+impl<R: RawMutex, G: GetThreadId> RawReentrantMutex<R, G> {
+    /// Initial value for an unlocked mutex.
+    #[allow(clippy::declare_interior_mutable_const)]
+    pub const INIT: Self = RawReentrantMutex {
+        owner: AtomicUsize::new(0),
+        lock_count: Cell::new(0),
+        mutex: R::INIT,
+        get_thread_id: G::INIT,
+    };
+
+    #[inline]
+    fn lock_internal<F: FnOnce() -> bool>(&self, try_lock: F) -> bool {
+        let id = self.get_thread_id.nonzero_thread_id().get();
+        if self.owner.load(Ordering::Relaxed) == id {
+            self.lock_count.set(
+                self.lock_count
+                    .get()
+                    .checked_add(1)
+                    .expect("ReentrantMutex lock count overflow"),
+            );
+        } else {
+            if !try_lock() {
+                return false;
+            }
+            self.owner.store(id, Ordering::Relaxed);
+            debug_assert_eq!(self.lock_count.get(), 0);
+            self.lock_count.set(1);
+        }
+        true
+    }
+
+    /// Acquires this mutex, blocking if it's held by another thread.
+    #[inline]
+    pub fn lock(&self) {
+        self.lock_internal(|| {
+            self.mutex.lock();
+            true
+        });
+    }
+
+    /// Attempts to acquire this mutex without blocking. Returns `true`
+    /// if the lock was successfully acquired and `false` otherwise.
+    #[inline]
+    pub fn try_lock(&self) -> bool {
+        self.lock_internal(|| self.mutex.try_lock())
+    }
+
+    /// Unlocks this mutex. The inner mutex may not be unlocked if
+    /// this mutex was acquired previously in the current thread.
+    ///
+    /// # Safety
+    ///
+    /// This method may only be called if the mutex is held by the current thread.
+    #[inline]
+    pub unsafe fn unlock(&self) {
+        let lock_count = self.lock_count.get() - 1;
+        self.lock_count.set(lock_count);
+        if lock_count == 0 {
+            self.owner.store(0, Ordering::Relaxed);
+            self.mutex.unlock();
+        }
+    }
+
+    /// Checks whether the mutex is currently locked.
+    #[inline]
+    pub fn is_locked(&self) -> bool {
+        self.mutex.is_locked()
+    }
+
+    /// Checks whether the mutex is currently held by the current thread.
+    #[inline]
+    pub fn is_owned_by_current_thread(&self) -> bool {
+        let id = self.get_thread_id.nonzero_thread_id().get();
+        self.owner.load(Ordering::Relaxed) == id
+    }
+}
+
+impl<R: RawMutexFair, G: GetThreadId> RawReentrantMutex<R, G> {
+    /// Unlocks this mutex using a fair unlock protocol. The inner mutex
+    /// may not be unlocked if this mutex was acquired previously in the
+    /// current thread.
+    ///
+    /// # Safety
+    ///
+    /// This method may only be called if the mutex is held by the current thread.
+    #[inline]
+    pub unsafe fn unlock_fair(&self) {
+        let lock_count = self.lock_count.get() - 1;
+        self.lock_count.set(lock_count);
+        if lock_count == 0 {
+            self.owner.store(0, Ordering::Relaxed);
+            self.mutex.unlock_fair();
+        }
+    }
+
+    /// Temporarily yields the mutex to a waiting thread if there is one.
+    ///
+    /// This method is functionally equivalent to calling `unlock_fair` followed
+    /// by `lock`, however it can be much more efficient in the case where there
+    /// are no waiting threads.
+    ///
+    /// # Safety
+    ///
+    /// This method may only be called if the mutex is held by the current thread.
+    #[inline]
+    pub unsafe fn bump(&self) {
+        if self.lock_count.get() == 1 {
+            let id = self.owner.load(Ordering::Relaxed);
+            self.owner.store(0, Ordering::Relaxed);
+            self.lock_count.set(0);
+            self.mutex.bump();
+            self.owner.store(id, Ordering::Relaxed);
+            self.lock_count.set(1);
+        }
+    }
+}
+
+impl<R: RawMutexTimed, G: GetThreadId> RawReentrantMutex<R, G> {
+    /// Attempts to acquire this lock until a timeout is reached.
+    #[inline]
+    pub fn try_lock_until(&self, timeout: R::Instant) -> bool {
+        self.lock_internal(|| self.mutex.try_lock_until(timeout))
+    }
+
+    /// Attempts to acquire this lock until a timeout is reached.
+    #[inline]
+    pub fn try_lock_for(&self, timeout: R::Duration) -> bool {
+        self.lock_internal(|| self.mutex.try_lock_for(timeout))
+    }
+}
+
+/// A mutex which can be recursively locked by a single thread.
+///
+/// This type is identical to `Mutex` except for the following points:
+///
+/// - Locking multiple times from the same thread will work correctly instead of
+///   deadlocking.
+/// - `ReentrantMutexGuard` does not give mutable references to the locked data.
+///   Use a `RefCell` if you need this.
+///
+/// See [`Mutex`](struct.Mutex.html) for more details about the underlying mutex
+/// primitive.
+pub struct ReentrantMutex<R, G, T: ?Sized> {
+    raw: RawReentrantMutex<R, G>,
+    data: UnsafeCell<T>,
+}
+
+unsafe impl<R: RawMutex + Send, G: GetThreadId + Send, T: ?Sized + Send> Send
+    for ReentrantMutex<R, G, T>
+{
+}
+unsafe impl<R: RawMutex + Sync, G: GetThreadId + Sync, T: ?Sized + Send> Sync
+    for ReentrantMutex<R, G, T>
+{
+}
+
+impl<R: RawMutex, G: GetThreadId, T> ReentrantMutex<R, G, T> {
+    /// Creates a new reentrant mutex in an unlocked state ready for use.
+    #[cfg(has_const_fn_trait_bound)]
+    #[inline]
+    pub const fn new(val: T) -> ReentrantMutex<R, G, T> {
+        ReentrantMutex {
+            data: UnsafeCell::new(val),
+            raw: RawReentrantMutex {
+                owner: AtomicUsize::new(0),
+                lock_count: Cell::new(0),
+                mutex: R::INIT,
+                get_thread_id: G::INIT,
+            },
+        }
+    }
+
+    /// Creates a new reentrant mutex in an unlocked state ready for use.
+    #[cfg(not(has_const_fn_trait_bound))]
+    #[inline]
+    pub fn new(val: T) -> ReentrantMutex<R, G, T> {
+        ReentrantMutex {
+            data: UnsafeCell::new(val),
+            raw: RawReentrantMutex {
+                owner: AtomicUsize::new(0),
+                lock_count: Cell::new(0),
+                mutex: R::INIT,
+                get_thread_id: G::INIT,
+            },
+        }
+    }
+
+    /// Consumes this mutex, returning the underlying data.
+    #[inline]
+    pub fn into_inner(self) -> T {
+        self.data.into_inner()
+    }
+}
+
+impl<R, G, T> ReentrantMutex<R, G, T> {
+    /// Creates a new reentrant mutex based on a pre-existing raw mutex and a
+    /// helper to get the thread ID.
+    ///
+    /// This allows creating a reentrant mutex in a constant context on stable
+    /// Rust.
+    #[inline]
+    pub const fn const_new(raw_mutex: R, get_thread_id: G, val: T) -> ReentrantMutex<R, G, T> {
+        ReentrantMutex {
+            data: UnsafeCell::new(val),
+            raw: RawReentrantMutex {
+                owner: AtomicUsize::new(0),
+                lock_count: Cell::new(0),
+                mutex: raw_mutex,
+                get_thread_id,
+            },
+        }
+    }
+}
+
+impl<R: RawMutex, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> {
+    /// Creates a new `ReentrantMutexGuard` without checking if the lock is held.
+    ///
+    /// # Safety
+    ///
+    /// This method must only be called if the thread logically holds the lock.
+    ///
+    /// Calling this function when a guard has already been produced is undefined behaviour unless
+    /// the guard was forgotten with `mem::forget`.
+    #[inline]
+    pub unsafe fn make_guard_unchecked(&self) -> ReentrantMutexGuard<'_, R, G, T> {
+        ReentrantMutexGuard {
+            remutex: &self,
+            marker: PhantomData,
+        }
+    }
+
+    /// Acquires a reentrant mutex, blocking the current thread until it is able
+    /// to do so.
+    ///
+    /// If the mutex is held by another thread then this function will block the
+    /// local thread until it is available to acquire the mutex. If the mutex is
+    /// already held by the current thread then this function will increment the
+    /// lock reference count and return immediately. Upon returning,
+    /// the thread is the only thread with the mutex held. An RAII guard is
+    /// returned to allow scoped unlock of the lock. When the guard goes out of
+    /// scope, the mutex will be unlocked.
+    #[inline]
+    pub fn lock(&self) -> ReentrantMutexGuard<'_, R, G, T> {
+        self.raw.lock();
+        // SAFETY: The lock is held, as required.
+        unsafe { self.make_guard_unchecked() }
+    }
+
+    /// Attempts to acquire this lock.
+    ///
+    /// If the lock could not be acquired at this time, then `None` is returned.
+    /// Otherwise, an RAII guard is returned. The lock will be unlocked when the
+    /// guard is dropped.
+    ///
+    /// This function does not block.
+    #[inline]
+    pub fn try_lock(&self) -> Option<ReentrantMutexGuard<'_, R, G, T>> {
+        if self.raw.try_lock() {
+            // SAFETY: The lock is held, as required.
+            Some(unsafe { self.make_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// Returns a mutable reference to the underlying data.
+    ///
+    /// Since this call borrows the `ReentrantMutex` mutably, no actual locking needs to
+    /// take place---the mutable borrow statically guarantees no locks exist.
+    #[inline]
+    pub fn get_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.data.get() }
+    }
+
+    /// Checks whether the mutex is currently locked.
+    #[inline]
+    pub fn is_locked(&self) -> bool {
+        self.raw.is_locked()
+    }
+
+    /// Checks whether the mutex is currently held by the current thread.
+    #[inline]
+    pub fn is_owned_by_current_thread(&self) -> bool {
+        self.raw.is_owned_by_current_thread()
+    }
+
+    /// Forcibly unlocks the mutex.
+    ///
+    /// This is useful when combined with `mem::forget` to hold a lock without
+    /// the need to maintain a `ReentrantMutexGuard` object alive, for example when
+    /// dealing with FFI.
+    ///
+    /// # Safety
+    ///
+    /// This method must only be called if the current thread logically owns a
+    /// `ReentrantMutexGuard` but that guard has be discarded using `mem::forget`.
+    /// Behavior is undefined if a mutex is unlocked when not locked.
+    #[inline]
+    pub unsafe fn force_unlock(&self) {
+        self.raw.unlock();
+    }
+
+    /// Returns the underlying raw mutex object.
+    ///
+    /// Note that you will most likely need to import the `RawMutex` trait from
+    /// `lock_api` to be able to call functions on the raw mutex.
+    ///
+    /// # Safety
+    ///
+    /// This method is unsafe because it allows unlocking a mutex while
+    /// still holding a reference to a `ReentrantMutexGuard`.
+    #[inline]
+    pub unsafe fn raw(&self) -> &R {
+        &self.raw.mutex
+    }
+
+    /// Returns a raw pointer to the underlying data.
+    ///
+    /// This is useful when combined with `mem::forget` to hold a lock without
+    /// the need to maintain a `ReentrantMutexGuard` object alive, for example
+    /// when dealing with FFI.
+    ///
+    /// # Safety
+    ///
+    /// You must ensure that there are no data races when dereferencing the
+    /// returned pointer, for example if the current thread logically owns a
+    /// `ReentrantMutexGuard` but that guard has been discarded using
+    /// `mem::forget`.
+    #[inline]
+    pub fn data_ptr(&self) -> *mut T {
+        self.data.get()
+    }
+
+    /// Creates a new `ArcReentrantMutexGuard` without checking if the lock is held.
+    ///
+    /// # Safety
+    ///
+    /// This method must only be called if the thread logically holds the lock.
+    ///
+    /// Calling this function when a guard has already been produced is undefined behaviour unless
+    /// the guard was forgotten with `mem::forget`.
+    #[cfg(feature = "arc_lock")]
+    #[inline]
+    pub unsafe fn make_arc_guard_unchecked(self: &Arc<Self>) -> ArcReentrantMutexGuard<R, G, T> {
+        ArcReentrantMutexGuard {
+            remutex: self.clone(),
+            marker: PhantomData,
+        }
+    }
+
+    /// Acquires a reentrant mutex through an `Arc`.
+    ///
+    /// This method is similar to the `lock` method; however, it requires the `ReentrantMutex` to be inside of an
+    /// `Arc` and the resulting mutex guard has no lifetime requirements.
+    #[cfg(feature = "arc_lock")]
+    #[inline]
+    pub fn lock_arc(self: &Arc<Self>) -> ArcReentrantMutexGuard<R, G, T> {
+        self.raw.lock();
+        // SAFETY: locking guarantee is upheld
+        unsafe { self.make_arc_guard_unchecked() }
+    }
+
+    /// Attempts to acquire a reentrant mutex through an `Arc`.
+    ///
+    /// This method is similar to the `try_lock` method; however, it requires the `ReentrantMutex` to be inside
+    /// of an `Arc` and the resulting mutex guard has no lifetime requirements.
+    #[cfg(feature = "arc_lock")]
+    #[inline]
+    pub fn try_lock_arc(self: &Arc<Self>) -> Option<ArcReentrantMutexGuard<R, G, T>> {
+        if self.raw.try_lock() {
+            // SAFETY: locking guarantee is upheld
+            Some(unsafe { self.make_arc_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+}
+
+impl<R: RawMutexFair, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> {
+    /// Forcibly unlocks the mutex using a fair unlock protocol.
+    ///
+    /// This is useful when combined with `mem::forget` to hold a lock without
+    /// the need to maintain a `ReentrantMutexGuard` object alive, for example when
+    /// dealing with FFI.
+    ///
+    /// # Safety
+    ///
+    /// This method must only be called if the current thread logically owns a
+    /// `ReentrantMutexGuard` but that guard has be discarded using `mem::forget`.
+    /// Behavior is undefined if a mutex is unlocked when not locked.
+    #[inline]
+    pub unsafe fn force_unlock_fair(&self) {
+        self.raw.unlock_fair();
+    }
+}
+
+impl<R: RawMutexTimed, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> {
+    /// Attempts to acquire this lock until a timeout is reached.
+    ///
+    /// If the lock could not be acquired before the timeout expired, then
+    /// `None` is returned. Otherwise, an RAII guard is returned. The lock will
+    /// be unlocked when the guard is dropped.
+    #[inline]
+    pub fn try_lock_for(&self, timeout: R::Duration) -> Option<ReentrantMutexGuard<'_, R, G, T>> {
+        if self.raw.try_lock_for(timeout) {
+            // SAFETY: The lock is held, as required.
+            Some(unsafe { self.make_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// Attempts to acquire this lock until a timeout is reached.
+    ///
+    /// If the lock could not be acquired before the timeout expired, then
+    /// `None` is returned. Otherwise, an RAII guard is returned. The lock will
+    /// be unlocked when the guard is dropped.
+    #[inline]
+    pub fn try_lock_until(&self, timeout: R::Instant) -> Option<ReentrantMutexGuard<'_, R, G, T>> {
+        if self.raw.try_lock_until(timeout) {
+            // SAFETY: The lock is held, as required.
+            Some(unsafe { self.make_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// Attempts to acquire this lock until a timeout is reached, through an `Arc`.
+    ///
+    /// This method is similar to the `try_lock_for` method; however, it requires the `ReentrantMutex` to be
+    /// inside of an `Arc` and the resulting mutex guard has no lifetime requirements.
+    #[cfg(feature = "arc_lock")]
+    #[inline]
+    pub fn try_lock_arc_for(
+        self: &Arc<Self>,
+        timeout: R::Duration,
+    ) -> Option<ArcReentrantMutexGuard<R, G, T>> {
+        if self.raw.try_lock_for(timeout) {
+            // SAFETY: locking guarantee is upheld
+            Some(unsafe { self.make_arc_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// Attempts to acquire this lock until a timeout is reached, through an `Arc`.
+    ///
+    /// This method is similar to the `try_lock_until` method; however, it requires the `ReentrantMutex` to be
+    /// inside of an `Arc` and the resulting mutex guard has no lifetime requirements.
+    #[cfg(feature = "arc_lock")]
+    #[inline]
+    pub fn try_lock_arc_until(
+        self: &Arc<Self>,
+        timeout: R::Instant,
+    ) -> Option<ArcReentrantMutexGuard<R, G, T>> {
+        if self.raw.try_lock_until(timeout) {
+            // SAFETY: locking guarantee is upheld
+            Some(unsafe { self.make_arc_guard_unchecked() })
+        } else {
+            None
+        }
+    }
+}
+
+impl<R: RawMutex, G: GetThreadId, T: ?Sized + Default> Default for ReentrantMutex<R, G, T> {
+    #[inline]
+    fn default() -> ReentrantMutex<R, G, T> {
+        ReentrantMutex::new(Default::default())
+    }
+}
+
+impl<R: RawMutex, G: GetThreadId, T> From<T> for ReentrantMutex<R, G, T> {
+    #[inline]
+    fn from(t: T) -> ReentrantMutex<R, G, T> {
+        ReentrantMutex::new(t)
+    }
+}
+
+impl<R: RawMutex, G: GetThreadId, T: ?Sized + fmt::Debug> fmt::Debug for ReentrantMutex<R, G, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.try_lock() {
+            Some(guard) => f
+                .debug_struct("ReentrantMutex")
+                .field("data", &&*guard)
+                .finish(),
+            None => {
+                struct LockedPlaceholder;
+                impl fmt::Debug for LockedPlaceholder {
+                    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                        f.write_str("<locked>")
+                    }
+                }
+
+                f.debug_struct("ReentrantMutex")
+                    .field("data", &LockedPlaceholder)
+                    .finish()
+            }
+        }
+    }
+}
+
+// Copied and modified from serde
+#[cfg(feature = "serde")]
+impl<R, G, T> Serialize for ReentrantMutex<R, G, T>
+where
+    R: RawMutex,
+    G: GetThreadId,
+    T: Serialize + ?Sized,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        self.lock().serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de, R, G, T> Deserialize<'de> for ReentrantMutex<R, G, T>
+where
+    R: RawMutex,
+    G: GetThreadId,
+    T: Deserialize<'de> + ?Sized,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Deserialize::deserialize(deserializer).map(ReentrantMutex::new)
+    }
+}
+
+/// An RAII implementation of a "scoped lock" of a reentrant mutex. When this structure
+/// is dropped (falls out of scope), the lock will be unlocked.
+///
+/// The data protected by the mutex can be accessed through this guard via its
+/// `Deref` implementation.
+#[clippy::has_significant_drop]
+#[must_use = "if unused the ReentrantMutex will immediately unlock"]
+pub struct ReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> {
+    remutex: &'a ReentrantMutex<R, G, T>,
+    marker: PhantomData<(&'a T, GuardNoSend)>,
+}
+
+unsafe impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> ReentrantMutexGuard<'a, R, G, T> {
+    /// Returns a reference to the original `ReentrantMutex` object.
+    pub fn remutex(s: &Self) -> &'a ReentrantMutex<R, G, T> {
+        s.remutex
+    }
+
+    /// Makes a new `MappedReentrantMutexGuard` for a component of the locked data.
+    ///
+    /// This operation cannot fail as the `ReentrantMutexGuard` passed
+    /// in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `ReentrantMutexGuard::map(...)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    #[inline]
+    pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedReentrantMutexGuard<'a, R, G, U>
+    where
+        F: FnOnce(&T) -> &U,
+    {
+        let raw = &s.remutex.raw;
+        let data = f(unsafe { &*s.remutex.data.get() });
+        mem::forget(s);
+        MappedReentrantMutexGuard {
+            raw,
+            data,
+            marker: PhantomData,
+        }
+    }
+
+    /// Attempts to make  a new `MappedReentrantMutexGuard` for a component of the
+    /// locked data. The original guard is return if the closure returns `None`.
+    ///
+    /// This operation cannot fail as the `ReentrantMutexGuard` passed
+    /// in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `ReentrantMutexGuard::try_map(...)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    #[inline]
+    pub fn try_map<U: ?Sized, F>(
+        s: Self,
+        f: F,
+    ) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self>
+    where
+        F: FnOnce(&T) -> Option<&U>,
+    {
+        let raw = &s.remutex.raw;
+        let data = match f(unsafe { &*s.remutex.data.get() }) {
+            Some(data) => data,
+            None => return Err(s),
+        };
+        mem::forget(s);
+        Ok(MappedReentrantMutexGuard {
+            raw,
+            data,
+            marker: PhantomData,
+        })
+    }
+
+    /// Temporarily unlocks the mutex to execute the given function.
+    ///
+    /// This is safe because `&mut` guarantees that there exist no other
+    /// references to the data protected by the mutex.
+    #[inline]
+    pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
+    where
+        F: FnOnce() -> U,
+    {
+        // Safety: A ReentrantMutexGuard always holds the lock.
+        unsafe {
+            s.remutex.raw.unlock();
+        }
+        defer!(s.remutex.raw.lock());
+        f()
+    }
+}
+
+impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a>
+    ReentrantMutexGuard<'a, R, G, T>
+{
+    /// Unlocks the mutex using a fair unlock protocol.
+    ///
+    /// By default, mutexes are unfair and allow the current thread to re-lock
+    /// the mutex before another has the chance to acquire the lock, even if
+    /// that thread has been blocked on the mutex for a long time. This is the
+    /// default because it allows much higher throughput as it avoids forcing a
+    /// context switch on every mutex unlock. This can result in one thread
+    /// acquiring a mutex many more times than other threads.
+    ///
+    /// However in some cases it can be beneficial to ensure fairness by forcing
+    /// the lock to pass on to a waiting thread if there is one. This is done by
+    /// using this method instead of dropping the `ReentrantMutexGuard` normally.
+    #[inline]
+    pub fn unlock_fair(s: Self) {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.unlock_fair();
+        }
+        mem::forget(s);
+    }
+
+    /// Temporarily unlocks the mutex to execute the given function.
+    ///
+    /// The mutex is unlocked a fair unlock protocol.
+    ///
+    /// This is safe because `&mut` guarantees that there exist no other
+    /// references to the data protected by the mutex.
+    #[inline]
+    pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
+    where
+        F: FnOnce() -> U,
+    {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.unlock_fair();
+        }
+        defer!(s.remutex.raw.lock());
+        f()
+    }
+
+    /// Temporarily yields the mutex to a waiting thread if there is one.
+    ///
+    /// This method is functionally equivalent to calling `unlock_fair` followed
+    /// by `lock`, however it can be much more efficient in the case where there
+    /// are no waiting threads.
+    #[inline]
+    pub fn bump(s: &mut Self) {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.bump();
+        }
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+    type Target = T;
+    #[inline]
+    fn deref(&self) -> &T {
+        unsafe { &*self.remutex.data.get() }
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+    #[inline]
+    fn drop(&mut self) {
+        // Safety: A ReentrantMutexGuard always holds the lock.
+        unsafe {
+            self.remutex.raw.unlock();
+        }
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (**self).fmt(f)
+    }
+}
+
+#[cfg(feature = "owning_ref")]
+unsafe impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> StableAddress
+    for ReentrantMutexGuard<'a, R, G, T>
+{
+}
+
+/// An RAII mutex guard returned by the `Arc` locking operations on `ReentrantMutex`.
+///
+/// This is similar to the `ReentrantMutexGuard` struct, except instead of using a reference to unlock the
+/// `Mutex` it uses an `Arc<ReentrantMutex>`. This has several advantages, most notably that it has an `'static`
+/// lifetime.
+#[cfg(feature = "arc_lock")]
+#[clippy::has_significant_drop]
+#[must_use = "if unused the ReentrantMutex will immediately unlock"]
+pub struct ArcReentrantMutexGuard<R: RawMutex, G: GetThreadId, T: ?Sized> {
+    remutex: Arc<ReentrantMutex<R, G, T>>,
+    marker: PhantomData<GuardNoSend>,
+}
+
+#[cfg(feature = "arc_lock")]
+impl<R: RawMutex, G: GetThreadId, T: ?Sized> ArcReentrantMutexGuard<R, G, T> {
+    /// Returns a reference to the `ReentrantMutex` this object is guarding, contained in its `Arc`.
+    pub fn remutex(s: &Self) -> &Arc<ReentrantMutex<R, G, T>> {
+        &s.remutex
+    }
+
+    /// Temporarily unlocks the mutex to execute the given function.
+    ///
+    /// This is safe because `&mut` guarantees that there exist no other
+    /// references to the data protected by the mutex.
+    #[inline]
+    pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
+    where
+        F: FnOnce() -> U,
+    {
+        // Safety: A ReentrantMutexGuard always holds the lock.
+        unsafe {
+            s.remutex.raw.unlock();
+        }
+        defer!(s.remutex.raw.lock());
+        f()
+    }
+}
+
+#[cfg(feature = "arc_lock")]
+impl<R: RawMutexFair, G: GetThreadId, T: ?Sized> ArcReentrantMutexGuard<R, G, T> {
+    /// Unlocks the mutex using a fair unlock protocol.
+    ///
+    /// This is functionally identical to the `unlock_fair` method on [`ReentrantMutexGuard`].
+    #[inline]
+    pub fn unlock_fair(s: Self) {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.unlock_fair();
+        }
+
+        // SAFETY: ensure that the Arc's refcount is decremented
+        let mut s = ManuallyDrop::new(s);
+        unsafe { ptr::drop_in_place(&mut s.remutex) };
+    }
+
+    /// Temporarily unlocks the mutex to execute the given function.
+    ///
+    /// This is functionally identical to the `unlocked_fair` method on [`ReentrantMutexGuard`].
+    #[inline]
+    pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
+    where
+        F: FnOnce() -> U,
+    {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.unlock_fair();
+        }
+        defer!(s.remutex.raw.lock());
+        f()
+    }
+
+    /// Temporarily yields the mutex to a waiting thread if there is one.
+    ///
+    /// This is functionally equivalent to the `bump` method on [`ReentrantMutexGuard`].
+    #[inline]
+    pub fn bump(s: &mut Self) {
+        // Safety: A ReentrantMutexGuard always holds the lock
+        unsafe {
+            s.remutex.raw.bump();
+        }
+    }
+}
+
+#[cfg(feature = "arc_lock")]
+impl<R: RawMutex, G: GetThreadId, T: ?Sized> Deref for ArcReentrantMutexGuard<R, G, T> {
+    type Target = T;
+    #[inline]
+    fn deref(&self) -> &T {
+        unsafe { &*self.remutex.data.get() }
+    }
+}
+
+#[cfg(feature = "arc_lock")]
+impl<R: RawMutex, G: GetThreadId, T: ?Sized> Drop for ArcReentrantMutexGuard<R, G, T> {
+    #[inline]
+    fn drop(&mut self) {
+        // Safety: A ReentrantMutexGuard always holds the lock.
+        unsafe {
+            self.remutex.raw.unlock();
+        }
+    }
+}
+
+/// An RAII mutex guard returned by `ReentrantMutexGuard::map`, which can point to a
+/// subfield of the protected data.
+///
+/// The main difference between `MappedReentrantMutexGuard` and `ReentrantMutexGuard` is that the
+/// former doesn't support temporarily unlocking and re-locking, since that
+/// could introduce soundness issues if the locked object is modified by another
+/// thread.
+#[clippy::has_significant_drop]
+#[must_use = "if unused the ReentrantMutex will immediately unlock"]
+pub struct MappedReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> {
+    raw: &'a RawReentrantMutex<R, G>,
+    data: *const T,
+    marker: PhantomData<&'a T>,
+}
+
+unsafe impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a>
+    MappedReentrantMutexGuard<'a, R, G, T>
+{
+    /// Makes a new `MappedReentrantMutexGuard` for a component of the locked data.
+    ///
+    /// This operation cannot fail as the `MappedReentrantMutexGuard` passed
+    /// in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `MappedReentrantMutexGuard::map(...)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    #[inline]
+    pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedReentrantMutexGuard<'a, R, G, U>
+    where
+        F: FnOnce(&T) -> &U,
+    {
+        let raw = s.raw;
+        let data = f(unsafe { &*s.data });
+        mem::forget(s);
+        MappedReentrantMutexGuard {
+            raw,
+            data,
+            marker: PhantomData,
+        }
+    }
+
+    /// Attempts to make  a new `MappedReentrantMutexGuard` for a component of the
+    /// locked data. The original guard is return if the closure returns `None`.
+    ///
+    /// This operation cannot fail as the `MappedReentrantMutexGuard` passed
+    /// in already locked the mutex.
+    ///
+    /// This is an associated function that needs to be
+    /// used as `MappedReentrantMutexGuard::try_map(...)`. A method would interfere with methods of
+    /// the same name on the contents of the locked data.
+    #[inline]
+    pub fn try_map<U: ?Sized, F>(
+        s: Self,
+        f: F,
+    ) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self>
+    where
+        F: FnOnce(&T) -> Option<&U>,
+    {
+        let raw = s.raw;
+        let data = match f(unsafe { &*s.data }) {
+            Some(data) => data,
+            None => return Err(s),
+        };
+        mem::forget(s);
+        Ok(MappedReentrantMutexGuard {
+            raw,
+            data,
+            marker: PhantomData,
+        })
+    }
+}
+
+impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a>
+    MappedReentrantMutexGuard<'a, R, G, T>
+{
+    /// Unlocks the mutex using a fair unlock protocol.
+    ///
+    /// By default, mutexes are unfair and allow the current thread to re-lock
+    /// the mutex before another has the chance to acquire the lock, even if
+    /// that thread has been blocked on the mutex for a long time. This is the
+    /// default because it allows much higher throughput as it avoids forcing a
+    /// context switch on every mutex unlock. This can result in one thread
+    /// acquiring a mutex many more times than other threads.
+    ///
+    /// However in some cases it can be beneficial to ensure fairness by forcing
+    /// the lock to pass on to a waiting thread if there is one. This is done by
+    /// using this method instead of dropping the `ReentrantMutexGuard` normally.
+    #[inline]
+    pub fn unlock_fair(s: Self) {
+        // Safety: A MappedReentrantMutexGuard always holds the lock
+        unsafe {
+            s.raw.unlock_fair();
+        }
+        mem::forget(s);
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+    type Target = T;
+    #[inline]
+    fn deref(&self) -> &T {
+        unsafe { &*self.data }
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+    #[inline]
+    fn drop(&mut self) {
+        // Safety: A MappedReentrantMutexGuard always holds the lock.
+        unsafe {
+            self.raw.unlock();
+        }
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (**self).fmt(f)
+    }
+}
+
+#[cfg(feature = "owning_ref")]
+unsafe impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> StableAddress
+    for MappedReentrantMutexGuard<'a, R, G, T>
+{
+}