Hacker News Reader

Misleading title?

This is a Windows API bug with the slim reader/writer (SRW) locks. It's just that the bug was discovered via std::shared_mutex as that is implemented using SRW locks.

SRW locks: https://learn.microsoft.com/en-us/windows/win32/sync/slim-re...

Confirmation from a Microsoft employee that the bug has been raised internally with the Windows API team: https://old.reddit.com/r/cpp/comments/1b55686/maybe_possible...

View on HN

Ok, I've changed the title to say that. Thanks!

Yes, for example if you make a Rust std::sync:RWLock on Windows, it will literally be SRWLock because Microsoft advertises this API as having exactly the behaviour Rust wants so why would you build something worse instead ?

Rust's Mutex on Windows is also an SRWLock but it can't hit this bug because it deliberately only uses the exclusive locking.

So it doesn't use a shared lock when .read() is used?

Rust has both Mutex and RWLock. The Mutex only uses exclusive locks, there's no distinction between "read" and "write".

Oh sorry my morning brain thought the comment was all about RWLock

Reply on news.ycombinator.com