pub struct MutexGuard<'a, T: ?Sized> { /* private fields */ }
Expand description

A handle to a held Mutex. The guard can be held across any .await point as it is Send.

As long as you have this guard, you have exclusive access to the underlying T. The guard internally borrows the Mutex, so the mutex will not be dropped while a guard exists.

The lock is automatically released whenever the guard is dropped, at which point lock will succeed yet again.

Implementations

Makes a new MappedMutexGuard for a component of the locked data.

This operation cannot fail as the MutexGuard passed in already locked the mutex.

This is an associated function that needs to be used as MutexGuard::map(...). A method would interfere with methods of the same name on the contents of the locked data.

Examples
use tokio::sync::{Mutex, MutexGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let foo = Mutex::new(Foo(1));

{
    let mut mapped = MutexGuard::map(foo.lock().await, |f| &mut f.0);
    *mapped = 2;
}

assert_eq!(Foo(2), *foo.lock().await);

Attempts to make a new MappedMutexGuard for a component of the locked data. The original guard is returned if the closure returns None.

This operation cannot fail as the MutexGuard passed in already locked the mutex.

This is an associated function that needs to be used as MutexGuard::try_map(...). A method would interfere with methods of the same name on the contents of the locked data.

Examples
use tokio::sync::{Mutex, MutexGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let foo = Mutex::new(Foo(1));

{
    let mut mapped = MutexGuard::try_map(foo.lock().await, |f| Some(&mut f.0))
        .expect("should not fail");
    *mapped = 2;
}

assert_eq!(Foo(2), *foo.lock().await);

Returns a reference to the original Mutex.

use tokio::sync::{Mutex, MutexGuard};

async fn unlock_and_relock<'l>(guard: MutexGuard<'l, u32>) -> MutexGuard<'l, u32> {
    println!("1. contains: {:?}", *guard);
    let mutex = MutexGuard::mutex(&guard);
    drop(guard);
    let guard = mutex.lock().await;
    println!("2. contains: {:?}", *guard);
    guard
}

Trait Implementations

Formats the value using the given formatter. Read more
The resulting type after dereferencing.
Dereferences the value.
Mutably dereferences the value.
Formats the value using the given formatter. Read more
Executes the destructor for this type. Read more

Auto Trait Implementations

Blanket Implementations

A guard object containing the value and keeping it alive. Read more
The loading method. Read more
Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
The equivalent of Access::load.

Returns the argument unchanged.

Calls U::from(self).

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

Converts the given value to a String. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.