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//! Extension traits for `std::sync::RwLock`.
use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
/// Extension trait with useful methods for [`std::sync::RwLock`].
///
/// [`std::sync::RwLock`]: https://doc.rust-lang.org/std/sync/struct.RwLock.html
pub trait RwLockExt<T> {
/// Shorthand for `lock.read().unwrap()` with a better panic message.
///
/// This method is intended to be used in situations where poisoned locks are
/// considered an exceptional situation and should always result in panic.
///
/// # Examples
///
/// ```
/// use std::sync::{Arc, RwLock};
/// use stdext::prelude::*;
///
/// let lock = Arc::new(RwLock::new(1));
///
/// let n = lock.force_read();
/// assert_eq!(*n, 1);
/// ```
fn force_read(&self) -> RwLockReadGuard<T>;
/// Shorthand for `lock.write().unwrap()` with a better panic message.
///
/// This method is intended to be used in situations where poisoned locks are
/// considered an exceptional situation and should always result in panic.
///
/// # Examples
///
/// ```
/// use std::sync::{Arc, RwLock};
/// use stdext::prelude::*;
///
/// let lock = Arc::new(RwLock::new(1));
///
/// {
/// let mut n = lock.force_write();
/// *n = 2;
/// }
///
/// let n = lock.force_read();
/// assert_eq!(*n, 2);
/// ```
fn force_write(&self) -> RwLockWriteGuard<T>;
}
impl<T> RwLockExt<T> for RwLock<T> {
fn force_read(&self) -> RwLockReadGuard<T> {
self.read()
.expect("Unable to obtain read lock: RwLock is poisoned")
}
fn force_write(&self) -> RwLockWriteGuard<T> {
self.write()
.expect("Unable to obtain write lock: RwLock is poisoned")
}
}