keos::sync::rwlock

Struct RwLock

pub struct RwLock<T>where
    T: ?Sized + Send,{
    state: AtomicUsize,
    owner: SpinLock<Option<(u64, &'static Location<'static>)>>,
    data: UnsafeCell<T>,
}

Expand description

A reader-writer lock

This type of lock allows a number of readers or at most one writer at any point in time. The write portion of this lock typically allows modification of the underlying data (exclusive access) and the read portion of this lock typically allows for read-only access (shared access).

In comparison, a Mutex does not distinguish between readers or writers that acquire the lock, therefore blocking any threads waiting for the lock to become available. An RwLock will allow any number of readers to acquire the lock as long as a writer is not holding the lock.

The priority policy of the lock is dependent on the underlying operating system’s implementation, and this type does not guarantee that any particular policy will be used.

The type parameter T represents the data that this lock protects. It is required that T satisfies [Send] to be shared across threads and [Sync] to allow concurrent access through readers. The RAII guards returned from the locking methods implement [Deref] (and [DerefMut] for the write methods) to allow access to the content of the lock.

Fields§

§state: AtomicUsize§owner: SpinLock<Option<(u64, &'static Location<'static>)>>§data: UnsafeCell<T>

Implementations§

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impl<T> RwLock<T>
where T: Send,

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pub const fn new(data: T) -> RwLock<T>

Creates a new instance of an RwLock<T> which is unlocked.

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fn validate_state( &self, owner: SpinLockGuard<'_, Option<(u64, &'static Location<'static>)>>, )

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fn read_lock(&self)

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pub fn read(&self) -> RwLockReadGuard<'_, T>

Locks this rwlock with shared read access, blocking the current thread until it can be acquired.

The call ing thread will be blocked until there are no more writers which hold the lock. There may be other readers currently inside the lock when this method returns. This method does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

Returns an RAII guard which will release this thread’s shared access once it is dropped.

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pub fn try_read(&self) -> Result<RwLockReadGuard<'_, T>, WouldBlock>

Attempts to acquire this rwlock with shared read access.

If the access could not be granted at this time, then Err is returned. Otherwise, an RAII guard is returned which will release the shared access when it is dropped.

This function does not block.

This function does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

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fn write_lock(&self)

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pub fn write(&self) -> RwLockWriteGuard<'_, T>

Locks this rwlock with exclusive write access, blocking the current thread until it can be acquired.

This function will not return while other writers or other readers currently have access to the lock.

Returns an RAII guard which will drop the write access of this rwlock when dropped.

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pub fn try_write(&self) -> Result<RwLockWriteGuard<'_, T>, WouldBlock>

Attempts to lock this rwlock with exclusive write access.

If the lock could not be acquired at this time, then Err is returned. Otherwise, an RAII guard is returned which will release the lock when it is dropped.

This function does not block.

This function does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

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