RwLock in std::sync::nonpoison - Rust
Description: A reader-writer lock that does not keep track of lock poisoning.

## RwLock

# 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 const 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.

Source

#### pub fn with<F, R>(&self, f: F) -> R
where F: FnOnce(&T) -> R,

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

Locks this `RwLock` with shared read access to the underlying data by passing a reference to the given closure.

This method acquires the lock, calls the provided closure with a reference to the data, and returns the result of the closure. The lock is released after the closure completes, even if it panics.

##### §Examples

    #![feature(lock_value_accessors, nonpoison_rwlock)]

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

    let rwlock = RwLock::new(2);
    let result = rwlock.with(|data| *data + 3);

    assert_eq!(result, 5);

Source

#### pub fn with_mut<F, R>(&self, f: F) -> R
where F: FnOnce(&mut T) -> R,

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

Locks this `RwLock` with exclusive write access to the underlying data by passing a mutable reference to the given closure.

This method acquires the lock, calls the provided closure with a mutable reference to the data, and returns the result of the closure. The lock is released after the closure completes, even if it panics.

##### §Examples

    #![feature(lock_value_accessors, nonpoison_rwlock)]

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

    let rwlock = RwLock::new(2);

    let result = rwlock.with_mut(|data| {
        *data += 3;

        *data + 5
    });

    assert_eq!(*rwlock.read(), 5);
    assert_eq!(result, 10);

## Trait Implementations§

Source§

### impl<T: ?Sized + Debug> Debug for RwLock<T>

Source§

#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
Source§

### impl<T: Default> Default for RwLock<T>

Source§

#### fn default() -> RwLock<T>

Creates a new `RwLock<T>`, with the `Default` value for T.

Source§

### impl<T> From<T> for RwLock<T>

Source§

#### fn from(t: T) -> Self

Creates a new instance of an `RwLock<T>` which is unlocked. This is equivalent to `RwLock::new`.

Source§

### impl<T: ?Sized + Send> Send for RwLock<T>

Source§

### impl<T: ?Sized + Send + Sync> Sync for RwLock<T>

## Auto Trait Implementations§

§

### impl<T> !Freeze for RwLock<T>

§

### impl<T> !RefUnwindSafe for RwLock<T>

§

### impl<T> Unpin for RwLock<T>
where T: Unpin + ?Sized,

§

### impl<T> UnwindSafe for RwLock<T>
where T: UnwindSafe + ?Sized,

## Blanket Implementations§

Source§

### impl<T> Any for T
where T: 'static + ?Sized,

Source§

#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
Source§

### impl<T> Borrow<T> for T
where T: ?Sized,

Source§

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
Source§

### impl<T> BorrowMut<T> for T
where T: ?Sized,

Source§

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
Source§

### impl<T> From<!> for T

Source§

#### fn from(t: !) -> T

Converts to this type from the input type.
Source§

### impl<T> From<T> for T

Source§

#### fn from(t: T) -> T

Returns the argument unchanged.

Source§

### impl<T, U> Into<U> for T
where U: From<T>,

Source§

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

Source§

### impl<T, U> TryFrom<U> for T
where U: Into<T>,

Source§

#### type Error = Infallible

The type returned in the event of a conversion error.
Source§

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
Source§

### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

Source§

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
Source§

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.