Struct async_std::sync::RwLockUpgradableReadGuard

pub struct RwLockUpgradableReadGuard<'a, T>where
    T: ?Sized,{ /* private fields */ }

A guard that releases the upgradable read lock when dropped.

Implementations

impl<'a, T> RwLockUpgradableReadGuard<'a, T>where
    T: ?Sized,

pub fn downgrade(
    guard: RwLockUpgradableReadGuard<'a, T>
) -> RwLockReadGuard<'a, T>

Downgrades into a regular reader guard.

Examples

use async_lock::{RwLock, RwLockUpgradableReadGuard};

let lock = RwLock::new(1);

let reader = lock.upgradable_read().await;
assert_eq!(*reader, 1);

assert!(lock.try_upgradable_read().is_none());

let reader = RwLockUpgradableReadGuard::downgrade(reader);

assert!(lock.try_upgradable_read().is_some());

pub fn try_upgrade(
    guard: RwLockUpgradableReadGuard<'a, T>
) -> Result<RwLockWriteGuard<'a, T>, RwLockUpgradableReadGuard<'a, T>>

Attempts to upgrade into a write lock.

If a write lock could not be acquired at this time, then None is returned. Otherwise, an upgraded guard is returned that releases the write lock when dropped.

This function can only fail if there are other active read locks.

Examples

use async_lock::{RwLock, RwLockUpgradableReadGuard};

let lock = RwLock::new(1);

let reader = lock.upgradable_read().await;
assert_eq!(*reader, 1);

let reader2 = lock.read().await;
let reader = RwLockUpgradableReadGuard::try_upgrade(reader).unwrap_err();

drop(reader2);
let writer = RwLockUpgradableReadGuard::try_upgrade(reader).unwrap();

pub async fn upgrade(
    guard: RwLockUpgradableReadGuard<'a, T>
) -> impl Future<Output = RwLockWriteGuard<'a, T>>

Upgrades into a write lock.

Examples

use async_lock::{RwLock, RwLockUpgradableReadGuard};

let lock = RwLock::new(1);

let reader = lock.upgradable_read().await;
assert_eq!(*reader, 1);

let mut writer = RwLockUpgradableReadGuard::upgrade(reader).await;
*writer = 2;

Trait Implementations

impl<T> Debug for RwLockUpgradableReadGuard<'_, T>where
    T: Debug + ?Sized,

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

Formats the value using the given formatter.

impl<T> Deref for RwLockUpgradableReadGuard<'_, T>where
    T: ?Sized,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> Display for RwLockUpgradableReadGuard<'_, T>where
    T: Display + ?Sized,

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

Formats the value using the given formatter.

impl<T> Send for RwLockUpgradableReadGuard<'_, T>where
    T: Send + Sync + ?Sized,

impl<T> Sync for RwLockUpgradableReadGuard<'_, T>where
    T: Sync + ?Sized,