Struct ArcStdRwLock

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pub struct ArcStdRwLock<T> { /* private fields */ }

Expand description

Standard-library read-write lock wrapper.

Provides an Arc-wrapped std::sync::RwLock for synchronous shared state. Read operations can execute concurrently, while write operations have exclusive access. Unlike ArcRwLock, this type preserves standard-library poison behavior.

§Type Parameters

T - The type protected by this lock.

Implementations§

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impl<T> ArcStdRwLock<T>

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pub fn new(data: T) -> Self

Creates a new standard read-write lock.

§Arguments

data - The data to be protected.

§Returns

A new ArcStdRwLock protecting data.

§Example

use qubit_lock::ArcStdRwLock;

let lock = ArcStdRwLock::new(vec![1, 2, 3]);

Methods from Deref<Target = RwLock<T>>§

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pub fn get_cloned(&self) -> Result<T, PoisonError<()>>
where T: Clone,

🔬This is a nightly-only experimental API. (lock_value_accessors)

Returns the contained value by cloning it.

§Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

§Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.get_cloned().unwrap(), 7);

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pub fn set(&self, value: T) -> Result<(), PoisonError<T>>

🔬This is a nightly-only experimental API. (lock_value_accessors)

Sets the contained value.

§Errors

This function will return an error containing the provided value if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

§Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.get_cloned().unwrap(), 7);
lock.set(11).unwrap();
assert_eq!(lock.get_cloned().unwrap(), 11);

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pub fn replace(&self, value: T) -> Result<T, PoisonError<T>>

🔬This is a nightly-only experimental API. (lock_value_accessors)

Replaces the contained value with value, and returns the old contained value.

§Errors

This function will return an error containing the provided value if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

§Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.replace(11).unwrap(), 7);
assert_eq!(lock.get_cloned().unwrap(), 11);

1.0.0 · Source

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

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

The calling 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.

§Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. The failure will occur immediately after the lock has been acquired. The acquired lock guard will be contained in the returned error.

§Panics

This function might panic when called if the lock is already held by the current thread in read or write mode.

§Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(1));
let c_lock = Arc::clone(&lock);

let n = lock.read().unwrap();
assert_eq!(*n, 1);

thread::spawn(move || {
    let r = c_lock.read();
    assert!(r.is_ok());
}).join().unwrap();

1.0.0 · Source

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

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.

§Errors

This function will return the Poisoned error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. Poisoned will only be returned if the lock would have otherwise been acquired. An acquired lock guard will be contained in the returned error.

This function will return the WouldBlock error if the RwLock could not be acquired because it was already locked exclusively.

§Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

match lock.try_read() {
    Ok(n) => assert_eq!(*n, 1),
    Err(_) => unreachable!(),
};

1.0.0 · Source

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

§Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. An error will be returned when the lock is acquired. The acquired lock guard will be contained in the returned error.

§Panics

This function might panic when called if the lock is already held by the current thread in read or write mode.

§Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

let mut n = lock.write().unwrap();
*n = 2;

assert!(lock.try_read().is_err());

1.0.0 · Source

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

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.

§Errors

This function will return the Poisoned error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. Poisoned will only be returned if the lock would have otherwise been acquired. An acquired lock guard will be contained in the returned error.

This function will return the WouldBlock error if the RwLock could not be acquired because it was already locked.

§Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

let n = lock.read().unwrap();
assert_eq!(*n, 1);

assert!(lock.try_write().is_err());

1.2.0 · Source

pub fn is_poisoned(&self) -> bool

Determines whether the lock is poisoned.

If another thread is active, the lock can still become poisoned at any time. You should not trust a false value for program correctness without additional synchronization.

§Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(0));
let c_lock = Arc::clone(&lock);

let _ = thread::spawn(move || {
    let _lock = c_lock.write().unwrap();
    panic!(); // the lock gets poisoned
}).join();
assert_eq!(lock.is_poisoned(), true);

1.77.0 · Source

pub fn clear_poison(&self)

Clear the poisoned state from a lock.

If the lock is poisoned, it will remain poisoned until this function is called. This allows recovering from a poisoned state and marking that it has recovered. For example, if the value is overwritten by a known-good value, then the lock can be marked as un-poisoned. Or possibly, the value could be inspected to determine if it is in a consistent state, and if so the poison is removed.

§Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(0));
let c_lock = Arc::clone(&lock);

let _ = thread::spawn(move || {
    let _lock = c_lock.write().unwrap();
    panic!(); // the lock gets poisoned
}).join();

assert_eq!(lock.is_poisoned(), true);
let guard = lock.write().unwrap_or_else(|mut e| {
    **e.get_mut() = 1;
    lock.clear_poison();
    e.into_inner()
});
assert_eq!(lock.is_poisoned(), false);
assert_eq!(*guard, 1);

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pub fn data_ptr(&self) -> *mut T

🔬This is a nightly-only experimental API. (rwlock_data_ptr)

Returns a raw pointer to the underlying data.

The returned pointer is always non-null and properly aligned, but it is the user’s responsibility to ensure that any reads and writes through it are properly synchronized to avoid data races, and that it is not read or written through after the lock is dropped.

Trait Implementations§

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impl<T> AsRef<RwLock<T>> for ArcStdRwLock<T>

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fn as_ref(&self) -> &RwLock<T>

Returns a reference to the underlying standard read-write lock.

This is useful when callers need guard-based APIs such as RwLock::read or RwLock::write instead of the closure-based Lock methods.

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impl<T> Clone for ArcStdRwLock<T>

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fn clone(&self) -> Self

Clones this standard read-write lock handle.

§Returns

A new handle sharing the same underlying read-write lock and protected value.

1.0.0 (const: unstable) · Source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

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impl<T: Default> Default for ArcStdRwLock<T>

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fn default() -> Self

Creates an Arc-wrapped standard read-write lock containing T::default().

§Returns

A new ArcStdRwLock protecting the default value for T.

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impl<T> Deref for ArcStdRwLock<T>

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fn deref(&self) -> &Self::Target

Dereferences this wrapper to the underlying standard read-write lock.

When Lock is in scope, read and write with closure arguments still call the trait methods on this wrapper. Use explicit dereferencing or AsRef::as_ref when you want the native guard-based RwLock methods.

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