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Refactor thread_info to remove the RefCell

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`thread_info` currently uses `RefCell`-based initialization. Refactor
this to use `OnceCell` instead which is more performant and better suits
the needs of one-time initialization.
This commit is contained in:
Trevor Gross 2023-09-11 08:49:57 -04:00
parent 5d62ab8981
commit 207b6091d4
1 changed files with 21 additions and 16 deletions
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37
library/std/src/sys_common/thread_info.rs
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@ -1,46 +1,51 @@
#![allow(dead_code)] // stack_guard isn't used right now on all platforms #![allow(dead_code)] // stack_guard isn't used right now on all platforms
use crate::cell::RefCell; use crate::cell::OnceCell;
use crate::sys::thread::guard::Guard; use crate::sys::thread::guard::Guard;
use crate::thread::Thread; use crate::thread::Thread;
struct ThreadInfo { struct ThreadInfo {
stack_guard: Option<Guard>, stack_guard: OnceCell<Guard>,
thread: Thread, thread: OnceCell<Thread>,
} }
thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = const { RefCell::new(None) } } thread_local! {
static THREAD_INFO: ThreadInfo = const { ThreadInfo {
stack_guard: OnceCell::new(),
thread: OnceCell::new()
} };
}
impl ThreadInfo { impl ThreadInfo {
fn with<R, F>(f: F) -> Option<R> fn with<R, F>(f: F) -> Option<R>
where where
F: FnOnce(&mut ThreadInfo) -> R, F: FnOnce(&Thread, &OnceCell<Guard>) -> R,
{ {
THREAD_INFO THREAD_INFO
.try_with(move |thread_info| { .try_with(move |thread_info| {
let mut thread_info = thread_info.borrow_mut(); let thread = thread_info.thread.get_or_init(|| Thread::new(None));
let thread_info = thread_info.get_or_insert_with(|| ThreadInfo { f(thread, &thread_info.stack_guard)
stack_guard: None,
thread: Thread::new(None),
});
f(thread_info)
}) })
.ok() .ok()
} }
} }
pub fn current_thread() -> Option<Thread> { pub fn current_thread() -> Option<Thread> {
ThreadInfo::with(|info| info.thread.clone()) ThreadInfo::with(|thread, _| thread.clone())
} }
pub fn stack_guard() -> Option<Guard> { pub fn stack_guard() -> Option<Guard> {
ThreadInfo::with(|info| info.stack_guard.clone()).and_then(|o| o) ThreadInfo::with(|_, guard| guard.get().cloned()).flatten()
} }
/// Set new thread info, panicking if it has already been initialized
#[allow(unreachable_code, unreachable_patterns)] // some platforms don't use stack_guard
pub fn set(stack_guard: Option<Guard>, thread: Thread) { pub fn set(stack_guard: Option<Guard>, thread: Thread) {
THREAD_INFO.with(move |thread_info| { THREAD_INFO.with(move |thread_info| {
let mut thread_info = thread_info.borrow_mut(); rtassert!(thread_info.stack_guard.get().is_none() && thread_info.thread.get().is_none());
rtassert!(thread_info.is_none()); if let Some(guard) = stack_guard {
*thread_info = Some(ThreadInfo { stack_guard, thread }); thread_info.stack_guard.set(guard).unwrap();
}
thread_info.thread.set(thread).unwrap();
}); });
} }