pub(crate) fn unique_thread_exit()Expand description
Mitigation for https://github.com/rust-lang/rust/issues/126600
On glibc, libc::exit has been observed to not always be thread-safe.
It is currently unclear whether that is a glibc bug or allowed by the standard.
To mitigate this problem, we ensure that only one
Rust thread calls libc::exit (or returns from main) by calling this function before
calling libc::exit (or returning from main).
Technically, this is not enough to ensure soundness, since other code directly calling
libc::exit will still race with this.
This function does not itself call libc::exit. This is so it can also be used
to guard returning from main.
This function will return only the first time it is called in a process.
- If it is called again on the same thread as the first call, it will abort.
- If it is called again on a different thread, it will wait in a loop (waiting for the process to exit).