| use crate::sys::thread; |
| use crate::sync::atomic::{AtomicUsize, Ordering::SeqCst}; |
| |
| const MAX_KEYS: usize = 128; |
| static NEXT_KEY: AtomicUsize = AtomicUsize::new(0); |
| |
| struct ThreadControlBlock { |
| keys: [*mut u8; MAX_KEYS], |
| } |
| |
| impl ThreadControlBlock { |
| fn new() -> ThreadControlBlock { |
| ThreadControlBlock { |
| keys: [core::ptr::null_mut(); MAX_KEYS], |
| } |
| } |
| |
| fn get() -> *mut ThreadControlBlock { |
| let ptr = thread::tcb_get(); |
| if !ptr.is_null() { |
| return ptr as *mut ThreadControlBlock |
| } |
| let tcb = Box::into_raw(Box::new(ThreadControlBlock::new())); |
| thread::tcb_set(tcb as *mut u8); |
| tcb |
| } |
| } |
| |
| pub type Key = usize; |
| |
| pub unsafe fn create(dtor: Option<unsafe extern fn(*mut u8)>) -> Key { |
| drop(dtor); // FIXME: need to figure out how to hook thread exit to run this |
| let key = NEXT_KEY.fetch_add(1, SeqCst); |
| if key >= MAX_KEYS { |
| NEXT_KEY.store(MAX_KEYS, SeqCst); |
| panic!("cannot allocate space for more TLS keys"); |
| } |
| // offset by 1 so we never hand out 0. This is currently required by |
| // `sys_common/thread_local.rs` where it can't cope with keys of value 0 |
| // because it messes up the atomic management. |
| return key + 1 |
| } |
| |
| pub unsafe fn set(key: Key, value: *mut u8) { |
| (*ThreadControlBlock::get()).keys[key - 1] = value; |
| } |
| |
| pub unsafe fn get(key: Key) -> *mut u8 { |
| (*ThreadControlBlock::get()).keys[key - 1] |
| } |
| |
| pub unsafe fn destroy(_key: Key) { |
| // FIXME: should implement this somehow, this isn't typically called but it |
| // can be called if two threads race to initialize a TLS slot and one ends |
| // up not being needed. |
| } |
| |
| #[inline] |
| pub fn requires_synchronized_create() -> bool { |
| false |
| } |