library/std/src/sys_common/thread_info.rs

   1 #![allow(dead_code)] // stack_guard isn't used right now on all platforms
   2 #![allow(unused_unsafe)] // thread_local with `const {}` triggers this liny
   3
   4 use crate::cell::RefCell;
   5 use crate::sys::thread::guard::Guard;
   6 use crate::thread::Thread;
   7
   8 struct ThreadInfo {
   9     stack_guard: Option<Guard>,
  10     thread: Thread,
  11 }
  12
  13 thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = const { RefCell::new(None) } }
  14
  15 impl ThreadInfo {
  16     fn with<R, F>(f: F) -> Option<R>
  17     where
  18         F: FnOnce(&mut ThreadInfo) -> R,
  19     {
  20         THREAD_INFO
  21             .try_with(move |thread_info| {
  22                 let mut thread_info = thread_info.borrow_mut();
  23                 let thread_info = thread_info.get_or_insert_with(|| ThreadInfo {
  24                     stack_guard: None,
  25                     thread: Thread::new(None),
  26                 });
  27                 f(thread_info)
  28             })
  29             .ok()
  30     }
  31 }
  32
  33 /// Get an address that is unique per running thread.
  34 ///
  35 /// This can be used as a non-null usize-sized ID.
  36 pub fn current_thread_unique_ptr() -> usize {
  37     // Use a non-drop type to make sure it's still available during thread destruction.
  38     thread_local! { static X: u8 = 0 }
  39     X.with(|x| <*const _>::addr(x))
  40 }
  41
  42 pub fn current_thread() -> Option<Thread> {
  43     ThreadInfo::with(|info| info.thread.clone())
  44 }
  45
  46 pub fn stack_guard() -> Option<Guard> {
  47     ThreadInfo::with(|info| info.stack_guard.clone()).and_then(|o| o)
  48 }
  49
  50 pub fn set(stack_guard: Option<Guard>, thread: Thread) {
  51     THREAD_INFO.with(move |thread_info| {
  52         let mut thread_info = thread_info.borrow_mut();
  53         rtassert!(thread_info.is_none());
  54         *thread_info = Some(ThreadInfo { stack_guard, thread });
  55     });
  56 }