Vendor dependencies for 0.3.0 release

vendor/thread_local/src/cached.rs

@@ -0,0 +1,161 @@
+#![allow(deprecated)]
+
+use super::{IntoIter, IterMut, ThreadLocal};
+use std::fmt;
+use std::panic::UnwindSafe;
+use std::usize;
+
+/// Wrapper around [`ThreadLocal`].
+///
+/// This used to add a fast path for a single thread, however that has been
+/// obsoleted by performance improvements to [`ThreadLocal`] itself.
+#[deprecated(since = "1.1.0", note = "Use `ThreadLocal` instead")]
+pub struct CachedThreadLocal<T: Send> {
+    inner: ThreadLocal<T>,
+}
+
+impl<T: Send> Default for CachedThreadLocal<T> {
+    fn default() -> CachedThreadLocal<T> {
+        CachedThreadLocal::new()
+    }
+}
+
+impl<T: Send> CachedThreadLocal<T> {
+    /// Creates a new empty `CachedThreadLocal`.
+    #[inline]
+    pub fn new() -> CachedThreadLocal<T> {
+        CachedThreadLocal {
+            inner: ThreadLocal::new(),
+        }
+    }
+
+    /// Returns the element for the current thread, if it exists.
+    #[inline]
+    pub fn get(&self) -> Option<&T> {
+        self.inner.get()
+    }
+
+    /// Returns the element for the current thread, or creates it if it doesn't
+    /// exist.
+    #[inline]
+    pub fn get_or<F>(&self, create: F) -> &T
+    where
+        F: FnOnce() -> T,
+    {
+        self.inner.get_or(create)
+    }
+
+    /// Returns the element for the current thread, or creates it if it doesn't
+    /// exist. If `create` fails, that error is returned and no element is
+    /// added.
+    #[inline]
+    pub fn get_or_try<F, E>(&self, create: F) -> Result<&T, E>
+    where
+        F: FnOnce() -> Result<T, E>,
+    {
+        self.inner.get_or_try(create)
+    }
+
+    /// Returns a mutable iterator over the local values of all threads.
+    ///
+    /// Since this call borrows the `ThreadLocal` mutably, this operation can
+    /// be done safely---the mutable borrow statically guarantees no other
+    /// threads are currently accessing their associated values.
+    #[inline]
+    pub fn iter_mut(&mut self) -> CachedIterMut<T> {
+        CachedIterMut {
+            inner: self.inner.iter_mut(),
+        }
+    }
+
+    /// Removes all thread-specific values from the `ThreadLocal`, effectively
+    /// reseting it to its original state.
+    ///
+    /// Since this call borrows the `ThreadLocal` mutably, this operation can
+    /// be done safely---the mutable borrow statically guarantees no other
+    /// threads are currently accessing their associated values.
+    #[inline]
+    pub fn clear(&mut self) {
+        self.inner.clear();
+    }
+}
+
+impl<T: Send> IntoIterator for CachedThreadLocal<T> {
+    type Item = T;
+    type IntoIter = CachedIntoIter<T>;
+
+    fn into_iter(self) -> CachedIntoIter<T> {
+        CachedIntoIter {
+            inner: self.inner.into_iter(),
+        }
+    }
+}
+
+impl<'a, T: Send + 'a> IntoIterator for &'a mut CachedThreadLocal<T> {
+    type Item = &'a mut T;
+    type IntoIter = CachedIterMut<'a, T>;
+
+    fn into_iter(self) -> CachedIterMut<'a, T> {
+        self.iter_mut()
+    }
+}
+
+impl<T: Send + Default> CachedThreadLocal<T> {
+    /// Returns the element for the current thread, or creates a default one if
+    /// it doesn't exist.
+    pub fn get_or_default(&self) -> &T {
+        self.get_or(T::default)
+    }
+}
+
+impl<T: Send + fmt::Debug> fmt::Debug for CachedThreadLocal<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "ThreadLocal {{ local_data: {:?} }}", self.get())
+    }
+}
+
+impl<T: Send + UnwindSafe> UnwindSafe for CachedThreadLocal<T> {}
+
+/// Mutable iterator over the contents of a `CachedThreadLocal`.
+#[deprecated(since = "1.1.0", note = "Use `IterMut` instead")]
+pub struct CachedIterMut<'a, T: Send + 'a> {
+    inner: IterMut<'a, T>,
+}
+
+impl<'a, T: Send + 'a> Iterator for CachedIterMut<'a, T> {
+    type Item = &'a mut T;
+
+    #[inline]
+    fn next(&mut self) -> Option<&'a mut T> {
+        self.inner.next()
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<'a, T: Send + 'a> ExactSizeIterator for CachedIterMut<'a, T> {}
+
+/// An iterator that moves out of a `CachedThreadLocal`.
+#[deprecated(since = "1.1.0", note = "Use `IntoIter` instead")]
+pub struct CachedIntoIter<T: Send> {
+    inner: IntoIter<T>,
+}
+
+impl<T: Send> Iterator for CachedIntoIter<T> {
+    type Item = T;
+
+    #[inline]
+    fn next(&mut self) -> Option<T> {
+        self.inner.next()
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<T: Send> ExactSizeIterator for CachedIntoIter<T> {}

vendor/thread_local/src/lib.rs

@@ -0,0 +1,683 @@
+// Copyright 2017 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.
+
+//! Per-object thread-local storage
+//!
+//! This library provides the `ThreadLocal` type which allows a separate copy of
+//! an object to be used for each thread. This allows for per-object
+//! thread-local storage, unlike the standard library's `thread_local!` macro
+//! which only allows static thread-local storage.
+//!
+//! Per-thread objects are not destroyed when a thread exits. Instead, objects
+//! are only destroyed when the `ThreadLocal` containing them is destroyed.
+//!
+//! You can also iterate over the thread-local values of all thread in a
+//! `ThreadLocal` object using the `iter_mut` and `into_iter` methods. This can
+//! only be done if you have mutable access to the `ThreadLocal` object, which
+//! guarantees that you are the only thread currently accessing it.
+//!
+//! Note that since thread IDs are recycled when a thread exits, it is possible
+//! for one thread to retrieve the object of another thread. Since this can only
+//! occur after a thread has exited this does not lead to any race conditions.
+//!
+//! # Examples
+//!
+//! Basic usage of `ThreadLocal`:
+//!
+//! ```rust
+//! use thread_local::ThreadLocal;
+//! let tls: ThreadLocal<u32> = ThreadLocal::new();
+//! assert_eq!(tls.get(), None);
+//! assert_eq!(tls.get_or(|| 5), &5);
+//! assert_eq!(tls.get(), Some(&5));
+//! ```
+//!
+//! Combining thread-local values into a single result:
+//!
+//! ```rust
+//! use thread_local::ThreadLocal;
+//! use std::sync::Arc;
+//! use std::cell::Cell;
+//! use std::thread;
+//!
+//! let tls = Arc::new(ThreadLocal::new());
+//!
+//! // Create a bunch of threads to do stuff
+//! for _ in 0..5 {
+//!     let tls2 = tls.clone();
+//!     thread::spawn(move || {
+//!         // Increment a counter to count some event...
+//!         let cell = tls2.get_or(|| Cell::new(0));
+//!         cell.set(cell.get() + 1);
+//!     }).join().unwrap();
+//! }
+//!
+//! // Once all threads are done, collect the counter values and return the
+//! // sum of all thread-local counter values.
+//! let tls = Arc::try_unwrap(tls).unwrap();
+//! let total = tls.into_iter().fold(0, |x, y| x + y.get());
+//! assert_eq!(total, 5);
+//! ```
+
+#![warn(missing_docs)]
+#![allow(clippy::mutex_atomic)]
+#![cfg_attr(feature = "nightly", feature(thread_local))]
+
+mod cached;
+mod thread_id;
+mod unreachable;
+
+#[allow(deprecated)]
+pub use cached::{CachedIntoIter, CachedIterMut, CachedThreadLocal};
+
+use std::cell::UnsafeCell;
+use std::fmt;
+use std::iter::FusedIterator;
+use std::mem;
+use std::mem::MaybeUninit;
+use std::panic::UnwindSafe;
+use std::ptr;
+use std::sync::atomic::{AtomicBool, AtomicPtr, AtomicUsize, Ordering};
+use thread_id::Thread;
+use unreachable::UncheckedResultExt;
+
+// Use usize::BITS once it has stabilized and the MSRV has been bumped.
+#[cfg(target_pointer_width = "16")]
+const POINTER_WIDTH: u8 = 16;
+#[cfg(target_pointer_width = "32")]
+const POINTER_WIDTH: u8 = 32;
+#[cfg(target_pointer_width = "64")]
+const POINTER_WIDTH: u8 = 64;
+
+/// The total number of buckets stored in each thread local.
+/// All buckets combined can hold up to `usize::MAX - 1` entries.
+const BUCKETS: usize = (POINTER_WIDTH - 1) as usize;
+
+/// Thread-local variable wrapper
+///
+/// See the [module-level documentation](index.html) for more.
+pub struct ThreadLocal<T: Send> {
+    /// The buckets in the thread local. The nth bucket contains `2^n`
+    /// elements. Each bucket is lazily allocated.
+    buckets: [AtomicPtr<Entry<T>>; BUCKETS],
+
+    /// The number of values in the thread local. This can be less than the real number of values,
+    /// but is never more.
+    values: AtomicUsize,
+}
+
+struct Entry<T> {
+    present: AtomicBool,
+    value: UnsafeCell<MaybeUninit<T>>,
+}
+
+impl<T> Drop for Entry<T> {
+    fn drop(&mut self) {
+        unsafe {
+            if *self.present.get_mut() {
+                ptr::drop_in_place((*self.value.get()).as_mut_ptr());
+            }
+        }
+    }
+}
+
+// ThreadLocal is always Sync, even if T isn't
+unsafe impl<T: Send> Sync for ThreadLocal<T> {}
+
+impl<T: Send> Default for ThreadLocal<T> {
+    fn default() -> ThreadLocal<T> {
+        ThreadLocal::new()
+    }
+}
+
+impl<T: Send> Drop for ThreadLocal<T> {
+    fn drop(&mut self) {
+        // Free each non-null bucket
+        for (i, bucket) in self.buckets.iter_mut().enumerate() {
+            let bucket_ptr = *bucket.get_mut();
+
+            let this_bucket_size = 1 << i;
+
+            if bucket_ptr.is_null() {
+                continue;
+            }
+
+            unsafe { deallocate_bucket(bucket_ptr, this_bucket_size) };
+        }
+    }
+}
+
+impl<T: Send> ThreadLocal<T> {
+    /// Creates a new empty `ThreadLocal`.
+    pub const fn new() -> ThreadLocal<T> {
+        let buckets = [ptr::null_mut::<Entry<T>>(); BUCKETS];
+        Self {
+            buckets: unsafe { mem::transmute(buckets) },
+            values: AtomicUsize::new(0),
+        }
+    }
+
+    /// Creates a new `ThreadLocal` with an initial capacity. If less than the capacity threads
+    /// access the thread local it will never reallocate. The capacity may be rounded up to the
+    /// nearest power of two.
+    pub fn with_capacity(capacity: usize) -> ThreadLocal<T> {
+        let allocated_buckets = usize::from(POINTER_WIDTH) - (capacity.leading_zeros() as usize);
+
+        let mut buckets = [ptr::null_mut(); BUCKETS];
+        for (i, bucket) in buckets[..allocated_buckets].iter_mut().enumerate() {
+            *bucket = allocate_bucket::<T>(1 << i);
+        }
+
+        Self {
+            // Safety: AtomicPtr has the same representation as a pointer and arrays have the same
+            // representation as a sequence of their inner type.
+            buckets: unsafe { mem::transmute(buckets) },
+            values: AtomicUsize::new(0),
+        }
+    }
+
+    /// Returns the element for the current thread, if it exists.
+    pub fn get(&self) -> Option<&T> {
+        self.get_inner(thread_id::get())
+    }
+
+    /// Returns the element for the current thread, or creates it if it doesn't
+    /// exist.
+    pub fn get_or<F>(&self, create: F) -> &T
+    where
+        F: FnOnce() -> T,
+    {
+        unsafe {
+            self.get_or_try(|| Ok::<T, ()>(create()))
+                .unchecked_unwrap_ok()
+        }
+    }
+
+    /// Returns the element for the current thread, or creates it if it doesn't
+    /// exist. If `create` fails, that error is returned and no element is
+    /// added.
+    pub fn get_or_try<F, E>(&self, create: F) -> Result<&T, E>
+    where
+        F: FnOnce() -> Result<T, E>,
+    {
+        let thread = thread_id::get();
+        if let Some(val) = self.get_inner(thread) {
+            return Ok(val);
+        }
+
+        Ok(self.insert(thread, create()?))
+    }
+
+    fn get_inner(&self, thread: Thread) -> Option<&T> {
+        let bucket_ptr =
+            unsafe { self.buckets.get_unchecked(thread.bucket) }.load(Ordering::Acquire);
+        if bucket_ptr.is_null() {
+            return None;
+        }
+        unsafe {
+            let entry = &*bucket_ptr.add(thread.index);
+            if entry.present.load(Ordering::Relaxed) {
+                Some(&*(&*entry.value.get()).as_ptr())
+            } else {
+                None
+            }
+        }
+    }
+
+    #[cold]
+    fn insert(&self, thread: Thread, data: T) -> &T {
+        let bucket_atomic_ptr = unsafe { self.buckets.get_unchecked(thread.bucket) };
+        let bucket_ptr: *const _ = bucket_atomic_ptr.load(Ordering::Acquire);
+
+        // If the bucket doesn't already exist, we need to allocate it
+        let bucket_ptr = if bucket_ptr.is_null() {
+            let new_bucket = allocate_bucket(thread.bucket_size);
+
+            match bucket_atomic_ptr.compare_exchange(
+                ptr::null_mut(),
+                new_bucket,
+                Ordering::AcqRel,
+                Ordering::Acquire,
+            ) {
+                Ok(_) => new_bucket,
+                // If the bucket value changed (from null), that means
+                // another thread stored a new bucket before we could,
+                // and we can free our bucket and use that one instead
+                Err(bucket_ptr) => {
+                    unsafe { deallocate_bucket(new_bucket, thread.bucket_size) }
+                    bucket_ptr
+                }
+            }
+        } else {
+            bucket_ptr
+        };
+
+        // Insert the new element into the bucket
+        let entry = unsafe { &*bucket_ptr.add(thread.index) };
+        let value_ptr = entry.value.get();
+        unsafe { value_ptr.write(MaybeUninit::new(data)) };
+        entry.present.store(true, Ordering::Release);
+
+        self.values.fetch_add(1, Ordering::Release);
+
+        unsafe { &*(&*value_ptr).as_ptr() }
+    }
+
+    /// Returns an iterator over the local values of all threads in unspecified
+    /// order.
+    ///
+    /// This call can be done safely, as `T` is required to implement [`Sync`].
+    pub fn iter(&self) -> Iter<'_, T>
+    where
+        T: Sync,
+    {
+        Iter {
+            thread_local: self,
+            raw: RawIter::new(),
+        }
+    }
+
+    /// Returns a mutable iterator over the local values of all threads in
+    /// unspecified order.
+    ///
+    /// Since this call borrows the `ThreadLocal` mutably, this operation can
+    /// be done safely---the mutable borrow statically guarantees no other
+    /// threads are currently accessing their associated values.
+    pub fn iter_mut(&mut self) -> IterMut<T> {
+        IterMut {
+            thread_local: self,
+            raw: RawIter::new(),
+        }
+    }
+
+    /// Removes all thread-specific values from the `ThreadLocal`, effectively
+    /// reseting it to its original state.
+    ///
+    /// Since this call borrows the `ThreadLocal` mutably, this operation can
+    /// be done safely---the mutable borrow statically guarantees no other
+    /// threads are currently accessing their associated values.
+    pub fn clear(&mut self) {
+        *self = ThreadLocal::new();
+    }
+}
+
+impl<T: Send> IntoIterator for ThreadLocal<T> {
+    type Item = T;
+    type IntoIter = IntoIter<T>;
+
+    fn into_iter(self) -> IntoIter<T> {
+        IntoIter {
+            thread_local: self,
+            raw: RawIter::new(),
+        }
+    }
+}
+
+impl<'a, T: Send + Sync> IntoIterator for &'a ThreadLocal<T> {
+    type Item = &'a T;
+    type IntoIter = Iter<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<'a, T: Send> IntoIterator for &'a mut ThreadLocal<T> {
+    type Item = &'a mut T;
+    type IntoIter = IterMut<'a, T>;
+
+    fn into_iter(self) -> IterMut<'a, T> {
+        self.iter_mut()
+    }
+}
+
+impl<T: Send + Default> ThreadLocal<T> {
+    /// Returns the element for the current thread, or creates a default one if
+    /// it doesn't exist.
+    pub fn get_or_default(&self) -> &T {
+        self.get_or(Default::default)
+    }
+}
+
+impl<T: Send + fmt::Debug> fmt::Debug for ThreadLocal<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "ThreadLocal {{ local_data: {:?} }}", self.get())
+    }
+}
+
+impl<T: Send + UnwindSafe> UnwindSafe for ThreadLocal<T> {}
+
+#[derive(Debug)]
+struct RawIter {
+    yielded: usize,
+    bucket: usize,
+    bucket_size: usize,
+    index: usize,
+}
+impl RawIter {
+    #[inline]
+    fn new() -> Self {
+        Self {
+            yielded: 0,
+            bucket: 0,
+            bucket_size: 1,
+            index: 0,
+        }
+    }
+
+    fn next<'a, T: Send + Sync>(&mut self, thread_local: &'a ThreadLocal<T>) -> Option<&'a T> {
+        while self.bucket < BUCKETS {
+            let bucket = unsafe { thread_local.buckets.get_unchecked(self.bucket) };
+            let bucket = bucket.load(Ordering::Acquire);
+
+            if !bucket.is_null() {
+                while self.index < self.bucket_size {
+                    let entry = unsafe { &*bucket.add(self.index) };
+                    self.index += 1;
+                    if entry.present.load(Ordering::Acquire) {
+                        self.yielded += 1;
+                        return Some(unsafe { &*(&*entry.value.get()).as_ptr() });
+                    }
+                }
+            }
+
+            self.next_bucket();
+        }
+        None
+    }
+    fn next_mut<'a, T: Send>(
+        &mut self,
+        thread_local: &'a mut ThreadLocal<T>,
+    ) -> Option<&'a mut Entry<T>> {
+        if *thread_local.values.get_mut() == self.yielded {
+            return None;
+        }
+
+        loop {
+            let bucket = unsafe { thread_local.buckets.get_unchecked_mut(self.bucket) };
+            let bucket = *bucket.get_mut();
+
+            if !bucket.is_null() {
+                while self.index < self.bucket_size {
+                    let entry = unsafe { &mut *bucket.add(self.index) };
+                    self.index += 1;
+                    if *entry.present.get_mut() {
+                        self.yielded += 1;
+                        return Some(entry);
+                    }
+                }
+            }
+
+            self.next_bucket();
+        }
+    }
+
+    #[inline]
+    fn next_bucket(&mut self) {
+        self.bucket_size <<= 1;
+        self.bucket += 1;
+        self.index = 0;
+    }
+
+    fn size_hint<T: Send>(&self, thread_local: &ThreadLocal<T>) -> (usize, Option<usize>) {
+        let total = thread_local.values.load(Ordering::Acquire);
+        (total - self.yielded, None)
+    }
+    fn size_hint_frozen<T: Send>(&self, thread_local: &ThreadLocal<T>) -> (usize, Option<usize>) {
+        let total = unsafe { *(&thread_local.values as *const AtomicUsize as *const usize) };
+        let remaining = total - self.yielded;
+        (remaining, Some(remaining))
+    }
+}
+
+/// Iterator over the contents of a `ThreadLocal`.
+#[derive(Debug)]
+pub struct Iter<'a, T: Send + Sync> {
+    thread_local: &'a ThreadLocal<T>,
+    raw: RawIter,
+}
+
+impl<'a, T: Send + Sync> Iterator for Iter<'a, T> {
+    type Item = &'a T;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.raw.next(self.thread_local)
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.raw.size_hint(self.thread_local)
+    }
+}
+impl<T: Send + Sync> FusedIterator for Iter<'_, T> {}
+
+/// Mutable iterator over the contents of a `ThreadLocal`.
+pub struct IterMut<'a, T: Send> {
+    thread_local: &'a mut ThreadLocal<T>,
+    raw: RawIter,
+}
+
+impl<'a, T: Send> Iterator for IterMut<'a, T> {
+    type Item = &'a mut T;
+    fn next(&mut self) -> Option<&'a mut T> {
+        self.raw
+            .next_mut(self.thread_local)
+            .map(|entry| unsafe { &mut *(&mut *entry.value.get()).as_mut_ptr() })
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.raw.size_hint_frozen(self.thread_local)
+    }
+}
+
+impl<T: Send> ExactSizeIterator for IterMut<'_, T> {}
+impl<T: Send> FusedIterator for IterMut<'_, T> {}
+
+// Manual impl so we don't call Debug on the ThreadLocal, as doing so would create a reference to
+// this thread's value that potentially aliases with a mutable reference we have given out.
+impl<'a, T: Send + fmt::Debug> fmt::Debug for IterMut<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("IterMut").field("raw", &self.raw).finish()
+    }
+}
+
+/// An iterator that moves out of a `ThreadLocal`.
+#[derive(Debug)]
+pub struct IntoIter<T: Send> {
+    thread_local: ThreadLocal<T>,
+    raw: RawIter,
+}
+
+impl<T: Send> Iterator for IntoIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<T> {
+        self.raw.next_mut(&mut self.thread_local).map(|entry| {
+            *entry.present.get_mut() = false;
+            unsafe {
+                std::mem::replace(&mut *entry.value.get(), MaybeUninit::uninit()).assume_init()
+            }
+        })
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.raw.size_hint_frozen(&self.thread_local)
+    }
+}
+
+impl<T: Send> ExactSizeIterator for IntoIter<T> {}
+impl<T: Send> FusedIterator for IntoIter<T> {}
+
+fn allocate_bucket<T>(size: usize) -> *mut Entry<T> {
+    Box::into_raw(
+        (0..size)
+            .map(|_| Entry::<T> {
+                present: AtomicBool::new(false),
+                value: UnsafeCell::new(MaybeUninit::uninit()),
+            })
+            .collect(),
+    ) as *mut _
+}
+
+unsafe fn deallocate_bucket<T>(bucket: *mut Entry<T>, size: usize) {
+    let _ = Box::from_raw(std::slice::from_raw_parts_mut(bucket, size));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use std::cell::RefCell;
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::atomic::Ordering::Relaxed;
+    use std::sync::Arc;
+    use std::thread;
+
+    fn make_create() -> Arc<dyn Fn() -> usize + Send + Sync> {
+        let count = AtomicUsize::new(0);
+        Arc::new(move || count.fetch_add(1, Relaxed))
+    }
+
+    #[test]
+    fn same_thread() {
+        let create = make_create();
+        let mut tls = ThreadLocal::new();
+        assert_eq!(None, tls.get());
+        assert_eq!("ThreadLocal { local_data: None }", format!("{:?}", &tls));
+        assert_eq!(0, *tls.get_or(|| create()));
+        assert_eq!(Some(&0), tls.get());
+        assert_eq!(0, *tls.get_or(|| create()));
+        assert_eq!(Some(&0), tls.get());
+        assert_eq!(0, *tls.get_or(|| create()));
+        assert_eq!(Some(&0), tls.get());
+        assert_eq!("ThreadLocal { local_data: Some(0) }", format!("{:?}", &tls));
+        tls.clear();
+        assert_eq!(None, tls.get());
+    }
+
+    #[test]
+    fn different_thread() {
+        let create = make_create();
+        let tls = Arc::new(ThreadLocal::new());
+        assert_eq!(None, tls.get());
+        assert_eq!(0, *tls.get_or(|| create()));
+        assert_eq!(Some(&0), tls.get());
+
+        let tls2 = tls.clone();
+        let create2 = create.clone();
+        thread::spawn(move || {
+            assert_eq!(None, tls2.get());
+            assert_eq!(1, *tls2.get_or(|| create2()));
+            assert_eq!(Some(&1), tls2.get());
+        })
+        .join()
+        .unwrap();
+
+        assert_eq!(Some(&0), tls.get());
+        assert_eq!(0, *tls.get_or(|| create()));
+    }
+
+    #[test]
+    fn iter() {
+        let tls = Arc::new(ThreadLocal::new());
+        tls.get_or(|| Box::new(1));
+
+        let tls2 = tls.clone();
+        thread::spawn(move || {
+            tls2.get_or(|| Box::new(2));
+            let tls3 = tls2.clone();
+            thread::spawn(move || {
+                tls3.get_or(|| Box::new(3));
+            })
+            .join()
+            .unwrap();
+            drop(tls2);
+        })
+        .join()
+        .unwrap();
+
+        let mut tls = Arc::try_unwrap(tls).unwrap();
+
+        let mut v = tls.iter().map(|x| **x).collect::<Vec<i32>>();
+        v.sort_unstable();
+        assert_eq!(vec![1, 2, 3], v);
+
+        let mut v = tls.iter_mut().map(|x| **x).collect::<Vec<i32>>();
+        v.sort_unstable();
+        assert_eq!(vec![1, 2, 3], v);
+
+        let mut v = tls.into_iter().map(|x| *x).collect::<Vec<i32>>();
+        v.sort_unstable();
+        assert_eq!(vec![1, 2, 3], v);
+    }
+
+    #[test]
+    fn miri_iter_soundness_check() {
+        let tls = Arc::new(ThreadLocal::new());
+        let _local = tls.get_or(|| Box::new(1));
+
+        let tls2 = tls.clone();
+        let join_1 = thread::spawn(move || {
+            let _tls = tls2.get_or(|| Box::new(2));
+            let iter = tls2.iter();
+            for item in iter {
+                println!("{:?}", item);
+            }
+        });
+
+        let iter = tls.iter();
+        for item in iter {
+            println!("{:?}", item);
+        }
+
+        join_1.join().ok();
+    }
+
+    #[test]
+    fn test_drop() {
+        let local = ThreadLocal::new();
+        struct Dropped(Arc<AtomicUsize>);
+        impl Drop for Dropped {
+            fn drop(&mut self) {
+                self.0.fetch_add(1, Relaxed);
+            }
+        }
+
+        let dropped = Arc::new(AtomicUsize::new(0));
+        local.get_or(|| Dropped(dropped.clone()));
+        assert_eq!(dropped.load(Relaxed), 0);
+        drop(local);
+        assert_eq!(dropped.load(Relaxed), 1);
+    }
+
+    #[test]
+    fn test_earlyreturn_buckets() {
+        struct Dropped(Arc<AtomicUsize>);
+        impl Drop for Dropped {
+            fn drop(&mut self) {
+                self.0.fetch_add(1, Relaxed);
+            }
+        }
+        let dropped = Arc::new(AtomicUsize::new(0));
+
+        // We use a high `id` here to guarantee that a lazily allocated bucket somewhere in the middle is used.
+        // Neither iteration nor `Drop` must early-return on `null` buckets that are used for lower `buckets`.
+        let thread = Thread::new(1234);
+        assert!(thread.bucket > 1);
+
+        let mut local = ThreadLocal::new();
+        local.insert(thread, Dropped(dropped.clone()));
+
+        let item = local.iter().next().unwrap();
+        assert_eq!(item.0.load(Relaxed), 0);
+        let item = local.iter_mut().next().unwrap();
+        assert_eq!(item.0.load(Relaxed), 0);
+        drop(local);
+        assert_eq!(dropped.load(Relaxed), 1);
+    }
+
+    #[test]
+    fn is_sync() {
+        fn foo<T: Sync>() {}
+        foo::<ThreadLocal<String>>();
+        foo::<ThreadLocal<RefCell<String>>>();
+    }
+}

vendor/thread_local/src/thread_id.rs

@@ -0,0 +1,210 @@
+// Copyright 2017 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::POINTER_WIDTH;
+use std::cell::Cell;
+use std::cmp::Reverse;
+use std::collections::BinaryHeap;
+use std::sync::Mutex;
+
+/// Thread ID manager which allocates thread IDs. It attempts to aggressively
+/// reuse thread IDs where possible to avoid cases where a ThreadLocal grows
+/// indefinitely when it is used by many short-lived threads.
+struct ThreadIdManager {
+    free_from: usize,
+    free_list: Option<BinaryHeap<Reverse<usize>>>,
+}
+
+impl ThreadIdManager {
+    const fn new() -> Self {
+        Self {
+            free_from: 0,
+            free_list: None,
+        }
+    }
+
+    fn alloc(&mut self) -> usize {
+        if let Some(id) = self.free_list.as_mut().and_then(|heap| heap.pop()) {
+            id.0
+        } else {
+            // `free_from` can't overflow as each thread takes up at least 2 bytes of memory and
+            // thus we can't even have `usize::MAX / 2 + 1` threads.
+
+            let id = self.free_from;
+            self.free_from += 1;
+            id
+        }
+    }
+
+    fn free(&mut self, id: usize) {
+        self.free_list
+            .get_or_insert_with(BinaryHeap::new)
+            .push(Reverse(id));
+    }
+}
+
+static THREAD_ID_MANAGER: Mutex<ThreadIdManager> = Mutex::new(ThreadIdManager::new());
+
+/// Data which is unique to the current thread while it is running.
+/// A thread ID may be reused after a thread exits.
+#[derive(Clone, Copy)]
+pub(crate) struct Thread {
+    /// The thread ID obtained from the thread ID manager.
+    pub(crate) id: usize,
+    /// The bucket this thread's local storage will be in.
+    pub(crate) bucket: usize,
+    /// The size of the bucket this thread's local storage will be in.
+    pub(crate) bucket_size: usize,
+    /// The index into the bucket this thread's local storage is in.
+    pub(crate) index: usize,
+}
+impl Thread {
+    pub(crate) fn new(id: usize) -> Self {
+        let bucket = usize::from(POINTER_WIDTH) - ((id + 1).leading_zeros() as usize) - 1;
+        let bucket_size = 1 << bucket;
+        let index = id - (bucket_size - 1);
+
+        Self {
+            id,
+            bucket,
+            bucket_size,
+            index,
+        }
+    }
+}
+
+cfg_if::cfg_if! {
+    if #[cfg(feature = "nightly")] {
+        // This is split into 2 thread-local variables so that we can check whether the
+        // thread is initialized without having to register a thread-local destructor.
+        //
+        // This makes the fast path smaller.
+        #[thread_local]
+        static mut THREAD: Option<Thread> = None;
+        thread_local! { static THREAD_GUARD: ThreadGuard = const { ThreadGuard { id: Cell::new(0) } }; }
+
+        // Guard to ensure the thread ID is released on thread exit.
+        struct ThreadGuard {
+            // We keep a copy of the thread ID in the ThreadGuard: we can't
+            // reliably access THREAD in our Drop impl due to the unpredictable
+            // order of TLS destructors.
+            id: Cell<usize>,
+        }
+
+        impl Drop for ThreadGuard {
+            fn drop(&mut self) {
+                // Release the thread ID. Any further accesses to the thread ID
+                // will go through get_slow which will either panic or
+                // initialize a new ThreadGuard.
+                unsafe {
+                    THREAD = None;
+                }
+                THREAD_ID_MANAGER.lock().unwrap().free(self.id.get());
+            }
+        }
+
+        /// Returns a thread ID for the current thread, allocating one if needed.
+        #[inline]
+        pub(crate) fn get() -> Thread {
+            if let Some(thread) = unsafe { THREAD } {
+                thread
+            } else {
+                get_slow()
+            }
+        }
+
+        /// Out-of-line slow path for allocating a thread ID.
+        #[cold]
+         fn get_slow() -> Thread {
+            let new = Thread::new(THREAD_ID_MANAGER.lock().unwrap().alloc());
+            unsafe {
+                THREAD = Some(new);
+            }
+            THREAD_GUARD.with(|guard| guard.id.set(new.id));
+            new
+        }
+    } else {
+        // This is split into 2 thread-local variables so that we can check whether the
+        // thread is initialized without having to register a thread-local destructor.
+        //
+        // This makes the fast path smaller.
+        thread_local! { static THREAD: Cell<Option<Thread>> = const { Cell::new(None) }; }
+        thread_local! { static THREAD_GUARD: ThreadGuard = const { ThreadGuard { id: Cell::new(0) } }; }
+
+        // Guard to ensure the thread ID is released on thread exit.
+        struct ThreadGuard {
+            // We keep a copy of the thread ID in the ThreadGuard: we can't
+            // reliably access THREAD in our Drop impl due to the unpredictable
+            // order of TLS destructors.
+            id: Cell<usize>,
+        }
+
+        impl Drop for ThreadGuard {
+            fn drop(&mut self) {
+                // Release the thread ID. Any further accesses to the thread ID
+                // will go through get_slow which will either panic or
+                // initialize a new ThreadGuard.
+                let _ = THREAD.try_with(|thread| thread.set(None));
+                THREAD_ID_MANAGER.lock().unwrap().free(self.id.get());
+            }
+        }
+
+        /// Returns a thread ID for the current thread, allocating one if needed.
+        #[inline]
+        pub(crate) fn get() -> Thread {
+            THREAD.with(|thread| {
+                if let Some(thread) = thread.get() {
+                    thread
+                } else {
+                    get_slow(thread)
+                }
+            })
+        }
+
+        /// Out-of-line slow path for allocating a thread ID.
+        #[cold]
+        fn get_slow(thread: &Cell<Option<Thread>>) -> Thread {
+            let new = Thread::new(THREAD_ID_MANAGER.lock().unwrap().alloc());
+            thread.set(Some(new));
+            THREAD_GUARD.with(|guard| guard.id.set(new.id));
+            new
+        }
+    }
+}
+
+#[test]
+fn test_thread() {
+    let thread = Thread::new(0);
+    assert_eq!(thread.id, 0);
+    assert_eq!(thread.bucket, 0);
+    assert_eq!(thread.bucket_size, 1);
+    assert_eq!(thread.index, 0);
+
+    let thread = Thread::new(1);
+    assert_eq!(thread.id, 1);
+    assert_eq!(thread.bucket, 1);
+    assert_eq!(thread.bucket_size, 2);
+    assert_eq!(thread.index, 0);
+
+    let thread = Thread::new(2);
+    assert_eq!(thread.id, 2);
+    assert_eq!(thread.bucket, 1);
+    assert_eq!(thread.bucket_size, 2);
+    assert_eq!(thread.index, 1);
+
+    let thread = Thread::new(3);
+    assert_eq!(thread.id, 3);
+    assert_eq!(thread.bucket, 2);
+    assert_eq!(thread.bucket_size, 4);
+    assert_eq!(thread.index, 0);
+
+    let thread = Thread::new(19);
+    assert_eq!(thread.id, 19);
+    assert_eq!(thread.bucket, 4);
+    assert_eq!(thread.bucket_size, 16);
+    assert_eq!(thread.index, 4);
+}

vendor/thread_local/src/unreachable.rs

@@ -0,0 +1,57 @@
+// Copyright 2017 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 std::hint::unreachable_unchecked;
+
+/// An extension trait for `Option<T>` providing unchecked unwrapping methods.
+pub trait UncheckedOptionExt<T> {
+    /// Get the value out of this Option without checking for None.
+    unsafe fn unchecked_unwrap(self) -> T;
+
+    /// Assert that this Option is a None to the optimizer.
+    unsafe fn unchecked_unwrap_none(self);
+}
+
+/// An extension trait for `Result<T, E>` providing unchecked unwrapping methods.
+pub trait UncheckedResultExt<T, E> {
+    /// Get the value out of this Result without checking for Err.
+    unsafe fn unchecked_unwrap_ok(self) -> T;
+
+    /// Get the error out of this Result without checking for Ok.
+    unsafe fn unchecked_unwrap_err(self) -> E;
+}
+
+impl<T> UncheckedOptionExt<T> for Option<T> {
+    unsafe fn unchecked_unwrap(self) -> T {
+        match self {
+            Some(x) => x,
+            None => unreachable_unchecked(),
+        }
+    }
+
+    unsafe fn unchecked_unwrap_none(self) {
+        if self.is_some() {
+            unreachable_unchecked()
+        }
+    }
+}
+
+impl<T, E> UncheckedResultExt<T, E> for Result<T, E> {
+    unsafe fn unchecked_unwrap_ok(self) -> T {
+        match self {
+            Ok(x) => x,
+            Err(_) => unreachable_unchecked(),
+        }
+    }
+
+    unsafe fn unchecked_unwrap_err(self) -> E {
+        match self {
+            Ok(_) => unreachable_unchecked(),
+            Err(e) => e,
+        }
+    }
+}