Struct kernel::sync::RwSemaphore

pub struct RwSemaphore<T: ?Sized> { /* private fields */ }

Exposes the kernel’s struct rw_semaphore.

It’s a read/write mutex. That is, it allows multiple readers to acquire it concurrently, but only one writer at a time. On contention, waiters sleep.

A RwSemaphore must first be initialised with a call to RwSemaphore::init_lock before it can be used. The rwsemaphore_init macro is provided to automatically assign a new lock class to an RwSemaphore instance.

Since it may block, RwSemaphore needs to be used with care in atomic contexts.

Implementations

impl<T> RwSemaphore<T>

pub unsafe fn new(t: T) -> Self

Constructs a new rw semaphore.

Safety

The caller must call RwSemaphore::init_lock before using the rw semaphore.

impl<T: ?Sized> RwSemaphore<T>

pub fn write(&self) -> Guard<'_, Self>

Locks the rw semaphore in write (exclusive) mode and gives the caller access to the data protected by it. Only one thread at a time is allowed to access the protected data.

pub fn read(&self) -> Guard<'_, Self, ReadLock>

Locks the rw semaphore in read (shared) mode and gives the caller access to the data protected by it. Only one thread at a time is allowed to access the protected data.

Trait Implementations

impl<T: ?Sized> Lock<ReadLock> for RwSemaphore<T>

type Inner = T

The type of the data protected by the lock.

type GuardContext = EmptyGuardContext

The type of context, if any, that needs to be stored in the guard.

fn lock_noguard(&self) -> EmptyGuardContext

Acquires the lock, making the caller its owner.

unsafe fn unlock(&self, _: &mut EmptyGuardContext)

Releases the lock, giving up ownership of the lock.

fn locked_data(&self) -> &UnsafeCell<T>

Returns the data protected by the lock.

fn relock(&self, ctx: &mut Self::GuardContext)

Reacquires the lock, making the caller its owner.

impl<T: ?Sized> Lock<WriteLock> for RwSemaphore<T>

type Inner = T

The type of the data protected by the lock.

type GuardContext = EmptyGuardContext

The type of context, if any, that needs to be stored in the guard.

fn lock_noguard(&self) -> EmptyGuardContext

Acquires the lock, making the caller its owner.

unsafe fn unlock(&self, _: &mut EmptyGuardContext)

Releases the lock, giving up ownership of the lock.

fn locked_data(&self) -> &UnsafeCell<T>

Returns the data protected by the lock.

fn relock(&self, ctx: &mut Self::GuardContext)

Reacquires the lock, making the caller its owner.

impl<T> LockFactory for RwSemaphore<T>

type LockedType<U> = RwSemaphore<U>

The parametrised type of the mutual exclusion primitive that can be created by this factory.

unsafe fn new_lock<U>(data: U) -> RwSemaphore<U>

Constructs a new instance of the mutual exclusion primitive.

impl<T> LockIniter for RwSemaphore<T>

fn init_lock(
    self: Pin<&mut Self>,
    name: &'static CStr,
    key: &'static LockClassKey
)

Initialises the lock instance so that it can be safely used.

impl<T: ?Sized + Send> Send for RwSemaphore<T>

impl<T: ?Sized + Send + Sync> Sync for RwSemaphore<T>