Tracking Issue for Thread::{into_raw, from_raw}

[ibraheemdev]

Feature gate: #![feature(thread_raw)]

This is a tracking issue for Thread::into_raw and Thread::from_raw.

These functions allow conversions between a Thread and a raw pointer, which is useful in concurrent code as it allows storing a Thread in an AtomicPtr.

Public API

// std::thread

impl Thread {
    fn into_raw(self) -> *const ();
    unsafe fn from_raw(ptr: *const ()) -> Thread;    
}

Steps / History

• ACP: ACP: add Thread::into_raw and Thread::from_raw libs-team#200
• Implementation: Add Thread::{into_raw, from_raw} #97524
• Final comment period (FCP)
• Stabilization PR

Unresolved Questions

• Do we want to commit to guaranteeing that Thread can always be represented as a pointer/integer?

[yanchith]

Not sure If I am missing something, but into_raw requires the thread by value, and that is not always available. E.g. JoinHandle::thread only gives out a shared reference.

How can I unpark a thread for which I just have a JoinHandle?

[ibraheemdev]

@yanchith Thread is cloneable, but it might make sense to have a as_raw method as well.

[yanchith]

Yeah, thanks! I didn't notice Thread was Clone. I am perfectly happy with that now.

Thread::as_raw: sure, if it can be designed such that the data inside the Arc inside Thread doesn't get dropped meanwhile. Thread::into_inner leaks the Arc, so that's taken care of.