Unsupported,
}
-pub(crate) trait LockTestExt {
+pub(crate) trait LockTestExt<'a> {
fn held_by_thread(&self) -> LockHeldState;
+ type ExclLock;
+ /// If two instances of the same mutex are being taken at the same time, it's very easy to have
+ /// a lockorder inversion and risk deadlock. Thus, we default to disabling such locks.
+ ///
+ /// However, sometimes they cannot be avoided. In such cases, this method exists to take a
+ /// mutex while avoiding a test failure. It is deliberately verbose and includes the term
+ /// "unsafe" to indicate that special care needs to be taken to ensure no deadlocks are
+ /// possible.
+ fn unsafe_well_ordered_double_lock_self(&'a self) -> Self::ExclLock;
}
#[cfg(all(feature = "std", not(feature = "_bench_unstable"), test))]
#[cfg(all(feature = "std", any(feature = "_bench_unstable", not(test))))]
mod ext_impl {
use super::*;
- impl<T> LockTestExt for Mutex<T> {
+ impl<'a, T: 'a> LockTestExt<'a> for Mutex<T> {
#[inline]
fn held_by_thread(&self) -> LockHeldState { LockHeldState::Unsupported }
+ type ExclLock = MutexGuard<'a, T>;
+ #[inline]
+ fn unsafe_well_ordered_double_lock_self(&'a self) -> MutexGuard<T> { self.lock().unwrap() }
}
- impl<T> LockTestExt for RwLock<T> {
+ impl<'a, T: 'a> LockTestExt<'a> for RwLock<T> {
#[inline]
fn held_by_thread(&self) -> LockHeldState { LockHeldState::Unsupported }
+ type ExclLock = RwLockWriteGuard<'a, T>;
+ #[inline]
+ fn unsafe_well_ordered_double_lock_self(&'a self) -> RwLockWriteGuard<T> { self.write().unwrap() }
}
}