New upstream version 1.20.0+dfsg1

[rustc.git] / src / libstd / sys_common / thread_local.rs

diff --git a/src/libstd/sys_common/thread_local.rs b/src/libstd/sys_common/thread_local.rs
index 0ade90e64c307e66e98edce22e3923ae9a74f1ef..1f889c7070719760a54874eef338634bd898265b 100644 (file)
--- a/src/libstd/sys_common/thread_local.rs
+++ b/src/libstd/sys_common/thread_local.rs
@@ -33,7 +33,7 @@
 //! Using a dynamically allocated TLS key. Note that this key can be shared
 //! among many threads via an `Arc`.
 //!
-//! ```rust,ignore
+//! ```ignore (cannot-doctest-private-modules)
 //! let key = Key::new(None);
 //! assert!(key.get().is_null());
 //! key.set(1 as *mut u8);
@@ -45,7 +45,7 @@
 //! Sometimes a statically allocated key is either required or easier to work
 //! with, however.
 //!
-//! ```rust,ignore
+//! ```ignore (cannot-doctest-private-modules)
 //! static KEY: StaticKey = INIT;
 //!
 //! unsafe {
@@ -58,8 +58,8 @@
 #![unstable(feature = "thread_local_internals", issue = "0")]
 #![allow(dead_code)] // sys isn't exported yet
 
+use ptr;
 use sync::atomic::{self, AtomicUsize, Ordering};
-
 use sys::thread_local as imp;
 use sys_common::mutex::Mutex;
 
@@ -74,7 +74,7 @@ use sys_common::mutex::Mutex;
 ///
 /// # Examples
 ///
-/// ```ignore
+/// ```ignore (cannot-doctest-private-modules)
 /// use tls::os::{StaticKey, INIT};
 ///
 /// static KEY: StaticKey = INIT;
@@ -105,7 +105,7 @@ pub struct StaticKey {
 ///
 /// # Examples
 ///
-/// ```rust,ignore
+/// ```ignore (cannot-doctest-private-modules)
 /// use tls::os::Key;
 ///
 /// let key = Key::new(None);
@@ -238,6 +238,39 @@ impl Drop for Key {
     }
 }
 
+pub 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.
+
+    static DTORS: StaticKey = 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(test)]
 mod tests {
     use super::{Key, StaticKey};