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#![cfg(target_thread_local)]
#![unstable(feature = "thread_local_internals", issue = "0")]
use cell::{Cell, UnsafeCell};
use fmt;
use intrinsics;
use ptr;
pub struct Key<T> {
inner: UnsafeCell<Option<T>>,
dtor_registered: Cell<bool>,
dtor_running: Cell<bool>,
}
impl<T> fmt::Debug for Key<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("Key { .. }")
}
}
unsafe impl<T> ::marker::Sync for Key<T> { }
impl<T> Key<T> {
pub const fn new() -> Key<T> {
Key {
inner: UnsafeCell::new(None),
dtor_registered: Cell::new(false),
dtor_running: Cell::new(false)
}
}
pub fn get(&'static self) -> Option<&'static UnsafeCell<Option<T>>> {
unsafe {
if intrinsics::needs_drop::<T>() && self.dtor_running.get() {
return None
}
self.register_dtor();
}
Some(&self.inner)
}
unsafe fn register_dtor(&self) {
if !intrinsics::needs_drop::<T>() || self.dtor_registered.get() {
return
}
register_dtor(self as *const _ as *mut u8,
destroy_value::<T>);
self.dtor_registered.set(true);
}
}
#[cfg(any(target_os = "linux", target_os = "fuchsia"))]
unsafe fn register_dtor_fallback(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
use sys_common::thread_local as os;
static DTORS: os::StaticKey = os::StaticKey::new(Some(run_dtors));
type List = Vec<(*mut u8, unsafe extern fn(*mut u8))>;
if DTORS.get().is_null() {
let v: Box<List> = box Vec::new();
DTORS.set(Box::into_raw(v) as *mut u8);
}
let list: &mut List = &mut *(DTORS.get() as *mut List);
list.push((t, dtor));
unsafe extern fn run_dtors(mut ptr: *mut u8) {
while !ptr.is_null() {
let list: Box<List> = Box::from_raw(ptr as *mut List);
for &(ptr, dtor) in list.iter() {
dtor(ptr);
}
ptr = DTORS.get();
DTORS.set(ptr::null_mut());
}
}
}
#[cfg(target_os = "linux")]
unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
use mem;
use libc;
extern {
#[linkage = "extern_weak"]
static __dso_handle: *mut u8;
#[linkage = "extern_weak"]
static __cxa_thread_atexit_impl: *const libc::c_void;
}
if !__cxa_thread_atexit_impl.is_null() {
type F = unsafe extern fn(dtor: unsafe extern fn(*mut u8),
arg: *mut u8,
dso_handle: *mut u8) -> libc::c_int;
mem::transmute::<*const libc::c_void, F>(__cxa_thread_atexit_impl)
(dtor, t, &__dso_handle as *const _ as *mut _);
return
}
register_dtor_fallback(t, dtor);
}
#[cfg(target_os = "macos")]
unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
extern {
fn _tlv_atexit(dtor: unsafe extern fn(*mut u8),
arg: *mut u8);
}
_tlv_atexit(dtor, t);
}
#[cfg(target_os = "fuchsia")]
unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
register_dtor_fallback(t, dtor);
}
pub unsafe extern fn destroy_value<T>(ptr: *mut u8) {
let ptr = ptr as *mut Key<T>;
(*ptr).dtor_running.set(true);
if cfg!(target_os = "macos") {
ptr::read((*ptr).inner.get());
} else {
ptr::drop_in_place((*ptr).inner.get());
}
}