loom: loom::std::parking_lot::RwLock try_read/try_write methods block

[martin-g]

Motivation

bd4ccae introduced a wrapper for the RwLock to get rid of poisoning aspects.

By mistake (?!) its try_read/write methods actually delegate to read/write() and this would lead to blocking

Solution

Delegate the to try_** methods of the delegate to avoid blocking.

[martin-g]

@tglane Could you please review since you introduced it with #6807 ?

[Darksonn]

Huh ... are these methods used anywhere?

[martin-g]

are these methods used anywhere?

No idea.
I just noticed that they call their blocking versions and it looked suspicious.

[Darksonn]

Yes definitely it should be fixed.

Try removing them and see if it still compiles.

[tglane]

@tglane Could you please review since you introduced it with #6807 ?

Yep, that's definitely a copy/paste mistake. I cannot completely remember why I added those functions to the type (I guess because the Mutex implementation I took for inspiration had them, too). So they should either be removed or call the try_* methods of the inner type. Good catch!

[martin-g]

Removing the try_** methods does not break the build:

diff --git i/tokio/src/loom/std/parking_lot.rs w/tokio/src/loom/std/parking_lot.rs
index 9367ae01..154c9607 100644
--- i/tokio/src/loom/std/parking_lot.rs
+++ w/tokio/src/loom/std/parking_lot.rs
@@ -100,21 +100,9 @@ impl<T> RwLock<T> {
         RwLockReadGuard(PhantomData, self.1.read())
     }

-    pub(crate) fn try_read(&self) -> Option<RwLockReadGuard<'_, T>> {
-        self.1
-            .try_read()
-            .map(|guard| RwLockReadGuard(PhantomData, guard))
-    }
-
     pub(crate) fn write(&self) -> RwLockWriteGuard<'_, T> {
         RwLockWriteGuard(PhantomData, self.1.write())
     }
-
-    pub(crate) fn try_write(&self) -> Option<RwLockWriteGuard<'_, T>> {
-        self.1
-            .try_write()
-            .map(|guard| RwLockWriteGuard(PhantomData, guard))
-    }
 }

cargo clean && cargo build --release && cargo test passes successfully!
I'm not sure how much more code in unused here.