RwLockUpgradableReadGuard in async_std::sync - Rust (original) (raw)

Struct RwLockUpgradableReadGuard

Source

pub struct RwLockUpgradableReadGuard<'a, T>

where
    T: ?Sized,

{ /* private fields */ }

Expand description

A guard that releases the upgradable read lock when dropped.

Source§

Source

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());

Source

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();

Source

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;

Source

Upgrades into a write lock.

§Blocking

This function will block the current thread until it is able to acquire the write lock.

§Examples

use async_lock::{RwLock, RwLockUpgradableReadGuard};

let lock = RwLock::new(1);

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

let mut writer = RwLockUpgradableReadGuard::upgrade_blocking(reader);
*writer = 2;