Struct RwLock

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

Expand description

A reader-writer lock that does not keep track of lock poisoning.

For more information about reader-writer locks, check out the documentation for the poisoning variant of this lock (which can be found at poison::RwLock).

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(5);

// many reader locks can be held at once
{
    let r1 = lock.read();
    let r2 = lock.read();
    assert_eq!(*r1, 5);
    assert_eq!(*r2, 5);
} // read locks are dropped at this point

// only one write lock may be held, however
{
    let mut w = lock.write();
    *w += 1;
    assert_eq!(*w, 6);
} // write lock is dropped here

Implementations§

Source §

impl<T> RwLock<T>

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

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

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(5);

Source

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

🔬This is a nightly-only experimental API. (lock_value_accessors #133407)

Returns the contained value by cloning it.

§Examples

#![feature(nonpoison_rwlock)]
#![feature(lock_value_accessors)]

use std::sync::nonpoison::RwLock;

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

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

Source

pub fn set(&self, value: T)

🔬This is a nightly-only experimental API. (lock_value_accessors #133407)

Sets the contained value.

§Examples

#![feature(nonpoison_rwlock)]
#![feature(lock_value_accessors)]

use std::sync::nonpoison::RwLock;

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

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

Source

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

🔬This is a nightly-only experimental API. (lock_value_accessors #133407)

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

§Examples

#![feature(nonpoison_rwlock)]
#![feature(lock_value_accessors)]

use std::sync::nonpoison::RwLock;

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

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

Source §

impl<T: ?Sized> RwLock<T>

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

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.

§Panics

This function might panic when called if the lock is already held by the current thread.

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::Arc;
use std::sync::nonpoison::RwLock;
use std::thread;

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

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

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

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

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

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(1);

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

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

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.

§Panics

This function might panic when called if the lock is already held by the current thread.

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(1);

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

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

Source

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

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

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 WouldBlock error if the RwLock could not be acquired because it was already locked.

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(1);

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

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

Source

pub fn into_inner(self) -> T
where T: Sized,

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

Consumes this RwLock, returning the underlying data.

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let lock = RwLock::new(String::new());
{
    let mut s = lock.write();
    *s = "modified".to_owned();
}
assert_eq!(lock.into_inner(), "modified");

Source

pub fn get_mut(&mut self) -> &mut T

🔬This is a nightly-only experimental API. (nonpoison_rwlock #134645)

Returns a mutable reference to the underlying data.

Since this call borrows the RwLock mutably, no actual locking needs to take place – the mutable borrow statically guarantees no new locks can be acquired while this reference exists. Note that this method does not clear any previously abandoned locks (e.g., via forget() on a RwLockReadGuard or RwLockWriteGuard).

§Examples

#![feature(nonpoison_rwlock)]

use std::sync::nonpoison::RwLock;

let mut lock = RwLock::new(0);
*lock.get_mut() = 10;
assert_eq!(*lock.read(), 10);

Source

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

🔬This is a nightly-only experimental API. (rwlock_data_ptr #140368)

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.