#![cfg(target_thread_local)]
#![unstable(feature = "thread_local_internals", issue = "0")]
-use cell::{Cell, UnsafeCell};
-use fmt;
-use mem;
-use ptr;
-
-pub struct Key<T> {
- inner: UnsafeCell<Option<T>>,
-
- // Metadata to keep track of the state of the destructor. Remember that
- // these variables are thread-local, not global.
- 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 mem::needs_drop::<T>() && self.dtor_running.get() {
- return None
- }
- self.register_dtor();
- }
- Some(&self.inner)
- }
-
- unsafe fn register_dtor(&self) {
- if !mem::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)) {
- // The fallback implementation uses a vanilla OS-based TLS key to track
- // the list of destructors that need to be run for this thread. The key
- // then has its own destructor which runs all the other destructors.
- //
- // The destructor for DTORS is a little special in that it has a `while`
- // loop to continuously drain the list of registered destructors. It
- // *should* be the case that this loop always terminates because we
- // provide the guarantee that a TLS key cannot be set after it is
- // flagged for destruction.
- 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());
- }
- }
-}
-
// Since what appears to be glibc 2.18 this symbol has been shipped which
// GCC and clang both use to invoke destructors in thread_local globals, so
// let's do the same!
//
// Due to rust-lang/rust#18804, make sure this is not generic!
#[cfg(target_os = "linux")]
-unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
- use mem;
+pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
use libc;
+ use mem;
+ use sys_common::thread_local::register_dtor_fallback;
extern {
#[linkage = "extern_weak"]
// The disassembly of thread_local globals in C++ (at least produced by
// clang) will have this show up in the output.
#[cfg(target_os = "macos")]
-unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
+pub 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);
// Just use the thread_local fallback implementation, at least until there's
// a more direct implementation.
#[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>;
- // Right before we run the user destructor be sure to flag the
- // destructor as running for this thread so calls to `get` will return
- // `None`.
- (*ptr).dtor_running.set(true);
+pub use sys_common::thread_local::register_dtor_fallback as register_dtor;
+pub fn requires_move_before_drop() -> bool {
// The macOS implementation of TLS apparently had an odd aspect to it
// where the pointer we have may be overwritten while this destructor
// is running. Specifically if a TLS destructor re-accesses TLS it may
//
// Hence, we use `ptr::read` on macOS (to move to a "safe" location)
// instead of drop_in_place.
- if cfg!(target_os = "macos") {
- ptr::read((*ptr).inner.get());
- } else {
- ptr::drop_in_place((*ptr).inner.get());
- }
+ cfg!(target_os = "macos")
}
projects / rust.git / blobdiff