Implement a fairer locking strategy for a new mutex type

Cargo.toml

@@ -27,6 +27,9 @@ spin_mutex = ["mutex"]
 # Enables `TicketMutex`.
 ticket_mutex = ["mutex"]
 
+# Enables `FairMutex`.
+fair_mutex = ["mutex"]
+
 # Enables the non-default ticket mutex implementation for `Mutex`.
 use_ticket_mutex = ["mutex", "ticket_mutex"]
 

src/lib.rs

@@ -54,6 +54,9 @@
 //! - `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
 
@@ -192,3 +195,26 @@ pub mod lock_api {
  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.
+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();
+ }
+}

src/mutex.rs

@@ -27,6 +27,13 @@ pub mod ticket;
 #[cfg_attr(docsrs, doc(cfg(feature = "ticket_mutex")))]
 pub use self::ticket::{TicketMutex, TicketMutexGuard};
 
+#[cfg(feature = "fair_mutex")]
+#[cfg_attr(docsrs, doc(cfg(feature = "fair_mutex")))]
+pub mod fair;
+#[cfg(feature = "fair_mutex")]
+#[cfg_attr(docsrs, doc(cfg(feature = "fair_mutex")))]
+pub use self::fair::{FairMutex, FairMutexGuard, Starvation};
+
 use core::{
  fmt,
  ops::{Deref, DerefMut},