Struct Spinlock 

pub struct Spinlock { /* private fields */ }

The underlying raw reader-writer primitive that implements lock_api::RawRwLock

This is fundamentally a spinlock, in that blocking operations on the lock will spin until they succeed in acquiring/releasing the lock.

To achieve the ability to share the underlying data with multiple readers, or hold exclusive access for one writer, the lock state is based on a “locked” count, where shared access increments the count by an even number, and acquiring exclusive access relies on the use of the lowest order bit to stop further shared acquisition, and indicate that the lock is exclusively held (the difference between the two is irrelevant from the perspective of a thread attempting to acquire the lock, but internally the state uses usize::MAX as the “exclusively locked” sentinel).

This mechanism gets us the following:

• Whether the lock has been acquired (shared or exclusive)
• Whether the lock is being exclusively acquired
• How many times the lock has been acquired
• Whether the acquisition(s) are exclusive or shared

Further implementation details, such as how we manage draining readers once an attempt to exclusively acquire the lock occurs, are described below.

NOTE: This is a simple implementation, meant for use in no-std environments; there are much more robust/performant implementations available when OS primitives can be used.

Implementations

impl Spinlock

pub const fn new() -> Self

Trait Implementations

impl Default for Spinlock

fn default() -> Self

Returns the “default value” for a type.

impl RawRwLock for Spinlock

fn lock_shared(&self)

The operation invoked when calling RwLock::read, blocks the caller until acquired

fn try_lock_shared(&self) -> bool

The operation invoked when calling RwLock::try_read, returns whether or not the lock was acquired

unsafe fn unlock_shared(&self)

The operation invoked when dropping a RwLockReadGuard

fn lock_exclusive(&self)

The operation invoked when calling RwLock::write, blocks the caller until acquired

fn try_lock_exclusive(&self) -> bool

The operation invoked when calling RwLock::try_write, returns whether or not the lock was acquired

unsafe fn unlock_exclusive(&self)

The operation invoked when dropping a RwLockWriteGuard

const INIT: Spinlock

Initial value for an unlocked RwLock.

type GuardMarker = GuardSend

Marker type which determines whether a lock guard should be Send. Use one of the GuardSend or GuardNoSend helper types here.

fn is_locked(&self) -> bool

Checks if this RwLock is currently locked in any way.

fn is_locked_exclusive(&self) -> bool

Check if this RwLock is currently exclusively locked.