Crate spin

This crate provides spin-based 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 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) 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.

• 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.

Feature flags

The crate comes with a few feature flags that you may wish to use.

• lock_api enables support for 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

Re-exports

• pub use relax::RelaxStrategy;
• pub use relax::Spin;

Modules

• once
  Synchronization primitives for one-time evaluation.
• relax
  Strategies that determine the behaviour of locks when encountering contention.

Type Aliases

• Once
  A primitive that provides lazy one-time initialization. See once::Once for documentation.