Initial vendor packages

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

1 files changed, 221 insertions, 0 deletions

diff --git a/vendor/spin/src/lib.rs b/vendor/spin/src/lib.rs
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+#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![deny(missing_docs)]
+
+//! This crate provides [spin-based](https://en.wikipedia.org/wiki/Spinlock) versions of the
+//! primitives in `std::sync` and `std::lazy`. Because synchronization is done through spinning,
+//! the primitives are suitable for use in `no_std` environments.
+//!
+//! # Features
+//!
+//! - `Mutex`, `RwLock`, `Once`/`SyncOnceCell`, and `SyncLazy` equivalents
+//!
+//! - Support for `no_std` environments
+//!
+//! - [`lock_api`](https://crates.io/crates/lock_api) compatibility
+//!
+//! - Upgradeable `RwLock` guards
+//!
+//! - Guards can be sent and shared between threads
+//!
+//! - Guard leaking
+//!
+//! - Ticket locks
+//!
+//! - Different strategies for dealing with contention
+//!
+//! # Relationship with `std::sync`
+//!
+//! While `spin` is not a drop-in replacement for `std::sync` (and
+//! [should not be considered as such](https://matklad.github.io/2020/01/02/spinlocks-considered-harmful.html))
+//! an effort is made to keep this crate reasonably consistent with `std::sync`.
+//!
+//! Many of the types defined in this crate have 'additional capabilities' when compared to `std::sync`:
+//!
+//! - Because spinning does not depend on the thread-driven model of `std::sync`, guards ([`MutexGuard`],
+//!   [`RwLockReadGuard`], [`RwLockWriteGuard`], etc.) may be sent and shared between threads.
+//!
+//! - [`RwLockUpgradableGuard`] supports being upgraded into a [`RwLockWriteGuard`].
+//!
+//! - Guards support [leaking](https://doc.rust-lang.org/nomicon/leaking.html).
+//!
+//! - [`Once`] owns the value returned by its `call_once` initializer.
+//!
+//! - [`RwLock`] supports counting readers and writers.
+//!
+//! Conversely, the types in this crate do not have some of the features `std::sync` has:
+//!
+//! - Locks do not track [panic poisoning](https://doc.rust-lang.org/nomicon/poisoning.html).
+//!
+//! ## Feature flags
+//!
+//! The crate comes with a few feature flags that you may wish to use.
+//!
+//! - `lock_api` enables support for [`lock_api`](https://crates.io/crates/lock_api)
+//!
+//! - `ticket_mutex` uses a ticket lock for the implementation of `Mutex`
+//!
+//! - `fair_mutex` enables a fairer implementation of `Mutex` that uses eventual fairness to avoid
+//!   starvation
+//!
+//! - `std` enables support for thread yielding instead of spinning
+
+#[cfg(any(test, feature = "std"))]
+extern crate core;
+
+#[cfg(feature = "portable_atomic")]
+extern crate portable_atomic;
+
+#[cfg(not(feature = "portable_atomic"))]
+use core::sync::atomic;
+#[cfg(feature = "portable_atomic")]
+use portable_atomic as atomic;
+
+#[cfg(feature = "barrier")]
+#[cfg_attr(docsrs, doc(cfg(feature = "barrier")))]
+pub mod barrier;
+#[cfg(feature = "lazy")]
+#[cfg_attr(docsrs, doc(cfg(feature = "lazy")))]
+pub mod lazy;
+#[cfg(feature = "mutex")]
+#[cfg_attr(docsrs, doc(cfg(feature = "mutex")))]
+pub mod mutex;
+#[cfg(feature = "once")]
+#[cfg_attr(docsrs, doc(cfg(feature = "once")))]
+pub mod once;
+pub mod relax;
+#[cfg(feature = "rwlock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+pub mod rwlock;
+
+#[cfg(feature = "mutex")]
+#[cfg_attr(docsrs, doc(cfg(feature = "mutex")))]
+pub use mutex::MutexGuard;
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+pub use relax::Yield;
+pub use relax::{RelaxStrategy, Spin};
+#[cfg(feature = "rwlock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+pub use rwlock::RwLockReadGuard;
+
+// Avoid confusing inference errors by aliasing away the relax strategy parameter. Users that need to use a different
+// relax strategy can do so by accessing the types through their fully-qualified path. This is a little bit horrible
+// but sadly adding a default type parameter is *still* a breaking change in Rust (for understandable reasons).
+
+/// A primitive that synchronizes the execution of multiple threads. See [`barrier::Barrier`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "barrier")]
+#[cfg_attr(docsrs, doc(cfg(feature = "barrier")))]
+pub type Barrier = crate::barrier::Barrier;
+
+/// A value which is initialized on the first access. See [`lazy::Lazy`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "lazy")]
+#[cfg_attr(docsrs, doc(cfg(feature = "lazy")))]
+pub type Lazy<T, F = fn() -> T> = crate::lazy::Lazy<T, F>;
+
+/// A primitive that synchronizes the execution of multiple threads. See [`mutex::Mutex`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "mutex")]
+#[cfg_attr(docsrs, doc(cfg(feature = "mutex")))]
+pub type Mutex<T> = crate::mutex::Mutex<T>;
+
+/// A primitive that provides lazy one-time initialization. See [`once::Once`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "once")]
+#[cfg_attr(docsrs, doc(cfg(feature = "once")))]
+pub type Once<T = ()> = crate::once::Once<T>;
+
+/// A lock that provides data access to either one writer or many readers. See [`rwlock::RwLock`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "rwlock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+pub type RwLock<T> = crate::rwlock::RwLock<T>;
+
+/// A guard that provides immutable data access but can be upgraded to [`RwLockWriteGuard`]. See
+/// [`rwlock::RwLockUpgradableGuard`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "rwlock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+pub type RwLockUpgradableGuard<'a, T> = crate::rwlock::RwLockUpgradableGuard<'a, T>;
+
+/// A guard that provides mutable data access. See [`rwlock::RwLockWriteGuard`] for documentation.
+///
+/// A note for advanced users: this alias exists to avoid subtle type inference errors due to the default relax
+/// strategy type parameter. If you need a non-default relax strategy, use the fully-qualified path.
+#[cfg(feature = "rwlock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+pub type RwLockWriteGuard<'a, T> = crate::rwlock::RwLockWriteGuard<'a, T>;
+
+/// Spin synchronisation primitives, but compatible with [`lock_api`](https://crates.io/crates/lock_api).
+#[cfg(feature = "lock_api")]
+#[cfg_attr(docsrs, doc(cfg(feature = "lock_api")))]
+pub mod lock_api {
+    /// A lock that provides mutually exclusive data access (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "mutex")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "mutex")))]
+    pub type Mutex<T> = lock_api_crate::Mutex<crate::Mutex<()>, T>;
+
+    /// A guard that provides mutable data access (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "mutex")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "mutex")))]
+    pub type MutexGuard<'a, T> = lock_api_crate::MutexGuard<'a, crate::Mutex<()>, T>;
+
+    /// A lock that provides data access to either one writer or many readers (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "rwlock")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+    pub type RwLock<T> = lock_api_crate::RwLock<crate::RwLock<()>, T>;
+
+    /// A guard that provides immutable data access (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "rwlock")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+    pub type RwLockReadGuard<'a, T> = lock_api_crate::RwLockReadGuard<'a, crate::RwLock<()>, T>;
+
+    /// A guard that provides mutable data access (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "rwlock")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+    pub type RwLockWriteGuard<'a, T> = lock_api_crate::RwLockWriteGuard<'a, crate::RwLock<()>, T>;
+
+    /// A guard that provides immutable data access but can be upgraded to [`RwLockWriteGuard`] (compatible with [`lock_api`](https://crates.io/crates/lock_api)).
+    #[cfg(feature = "rwlock")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rwlock")))]
+    pub type RwLockUpgradableReadGuard<'a, T> =
+        lock_api_crate::RwLockUpgradableReadGuard<'a, crate::RwLock<()>, T>;
+}
+
+/// In the event of an invalid operation, it's best to abort the current process.
+#[cfg(feature = "fair_mutex")]
+fn abort() -> ! {
+    #[cfg(not(feature = "std"))]
+    {
+        // Panicking while panicking is defined by Rust to result in an abort.
+        struct Panic;
+
+        impl Drop for Panic {
+            fn drop(&mut self) {
+                panic!("aborting due to invalid operation");
+            }
+        }
+
+        let _panic = Panic;
+        panic!("aborting due to invalid operation");
+    }
+
+    #[cfg(feature = "std")]
+    {
+        std::process::abort();
+    }
+}