rename fast_thread_local -> thread_local_dtor; thread_local -> thread_local_key

Author: RalfJung

src/libstd/sys/unix/mod.rs

@@ -47,7 +47,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fd;
 pub mod fs;
 pub mod io;
@@ -68,7 +67,8 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_key;
+pub mod thread_local_dtor;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;

src/libstd/sys/unix/fast_thread_local.rs src/libstd/sys/unix/thread_local_dtor.rs

@@ -1,6 +1,9 @@
 #![cfg(target_thread_local)]
 #![unstable(feature = "thread_local_internals", issue = "none")]
 
+//! Provides thread-local destructors without an associated "key", which
+//! can be more efficient.
+
 // 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!
@@ -16,7 +19,7 @@
 ))]
 pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     use crate::mem;
-    use crate::sys_common::thread_local::register_dtor_fallback;
+    use crate::sys_common::thread_local_dtor::register_dtor_fallback;
 
     extern "C" {
         #[linkage = "extern_weak"]

src/libstd/sys/unix/thread_local.rs src/libstd/sys/unix/thread_local_key.rs

@@ -20,7 +20,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fs;
 pub mod handle;
 pub mod io;
@@ -35,7 +34,8 @@ pub mod process;
 pub mod rand;
 pub mod rwlock;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_key;
+pub mod thread_local_dtor;
 pub mod time;
 cfg_if::cfg_if! {
     if #[cfg(not(target_vendor = "uwp"))] {

src/libstd/sys/windows/mod.rs

@@ -1,4 +1,4 @@
 #![unstable(feature = "thread_local_internals", issue = "none")]
 #![cfg(target_thread_local)]
 
-pub use crate::sys_common::thread_local::register_dtor_fallback as register_dtor;
+pub use crate::sys_common::thread_local_dtor::register_dtor_fallback as register_dtor;

src/libstd/sys/windows/fast_thread_local.rs src/libstd/sys/windows/thread_local_dtor.rs

@@ -65,7 +65,8 @@ pub mod remutex;
 pub mod rwlock;
 pub mod thread;
 pub mod thread_info;
-pub mod thread_local;
+pub mod thread_local_key;
+pub mod thread_local_dtor;
 pub mod util;
 pub mod wtf8;
 

src/libstd/sys/windows/thread_local.rs src/libstd/sys/windows/thread_local_key.rs

@@ -0,0 +1,49 @@
+//! Thread-local destructor
+//!
+//! Besides thread-local "keys" (pointer-sized non-adressable thread-local store
+//! with an associated destructor), many platforms also provide thread-local
+//! destructors that are not associated with any particular data. These are
+//! often more efficient.
+//!
+//! This module provides a fallback implementation for that interface, based
+//! on the less efficient thread-local "keys". Each platform provides
+//! a `thread_local_dtor` module which will either re-export the fallback,
+//! or implement something more efficient.
+
+#![unstable(feature = "thread_local_internals", issue = "none")]
+#![allow(dead_code)] // sys isn't exported yet
+
+use crate::ptr;
+use crate::sys_common::thread_local_key::StaticKey;
+
+pub unsafe fn register_dtor_fallback(t: *mut u8, dtor: unsafe extern "C" 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 "C" 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 "C" 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.into_iter() {
+                dtor(ptr);
+            }
+            ptr = DTORS.get();
+            DTORS.set(ptr::null_mut());
+        }
+    }
+}

src/libstd/sys_common/mod.rs

@@ -4,7 +4,7 @@
 //! using the native OS-provided facilities (think `TlsAlloc` or
 //! `pthread_setspecific`). The interface of this differs from the other types
 //! of thread-local-storage provided in this crate in that OS-based TLS can only
-//! get/set pointers,
+//! get/set pointer-sized data, possibly with an associated destructor.
 //!
 //! This module also provides two flavors of TLS. One is intended for static
 //! initialization, and does not contain a `Drop` implementation to deallocate
@@ -14,7 +14,7 @@
 //! # Usage
 //!
 //! This module should likely not be used directly unless other primitives are
-//! being built on. types such as `thread_local::spawn::Key` are likely much
+//! being built on. Types such as `thread_local::spawn::Key` are likely much
 //! more useful in practice than this OS-based version which likely requires
 //! unsafe code to interoperate with.
 //!
@@ -48,9 +48,8 @@
 #![unstable(feature = "thread_local_internals", issue = "none")]
 #![allow(dead_code)] // sys isn't exported yet
 
-use crate::ptr;
 use crate::sync::atomic::{self, AtomicUsize, Ordering};
-use crate::sys::thread_local as imp;
+use crate::sys::thread_local_key as imp;
 use crate::sys_common::mutex::Mutex;
 
 /// A type for TLS keys that are statically allocated.
@@ -233,38 +232,6 @@ impl Drop for Key {
     }
 }
 
-pub unsafe fn register_dtor_fallback(t: *mut u8, dtor: unsafe extern "C" 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 "C" 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 "C" 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.into_iter() {
-                dtor(ptr);
-            }
-            ptr = DTORS.get();
-            DTORS.set(ptr::null_mut());
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::{Key, StaticKey};

src/libstd/sys_common/thread_local_dtor.rs

@@ -363,7 +363,7 @@ pub mod fast {
     use crate::cell::Cell;
     use crate::fmt;
     use crate::mem;
-    use crate::sys::fast_thread_local::register_dtor;
+    use crate::sys::thread_local_dtor::register_dtor;
 
     #[derive(Copy, Clone)]
     enum DtorState {
@@ -468,7 +468,7 @@ pub mod os {
     use crate::fmt;
     use crate::marker;
     use crate::ptr;
-    use crate::sys_common::thread_local::StaticKey as OsStaticKey;
+    use crate::sys_common::thread_local_key::StaticKey as OsStaticKey;
 
     pub struct Key<T> {
         // OS-TLS key that we'll use to key off.