auto merge of #5909 : brson/rust/rt4, r=graydon

This is just a bunch of minor changes and simplifications to the structure of core::rt. It makes ownership of the ~Scheduler more strict (though it is still mutably aliased sometimes), turns the scheduler cleanup_jobs vector into just a single job, shunts the thread-local scheduler code off to its own file.

Author: bors

src/libcore/rt/mod.rs

@@ -32,6 +32,7 @@ macro_rules! rtdebug (
     ($( $arg:expr),+) => ( $(let _ = $arg)*; )
 )
 
+#[path = "sched/mod.rs"]
 mod sched;
 mod rtio;
 pub mod uvll;

src/libcore/rt/sched/local.rs

@@ -0,0 +1,100 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Access to the thread-local Scheduler
+
+use ptr::mut_null;
+use libc::c_void;
+use cast::transmute;
+
+use super::Scheduler;
+use tls = super::super::thread_local_storage;
+#[cfg(test)] use super::super::uvio::UvEventLoop;
+
+/// Give the Scheduler to thread-local storage
+pub fn put(sched: ~Scheduler) {
+    unsafe {
+        let key = tls_key();
+        let void_sched: *mut c_void = transmute::<~Scheduler, *mut c_void>(sched);
+        tls::set(key, void_sched);
+    }
+}
+
+/// Take ownership of the Scheduler from thread-local storage
+pub fn take() -> ~Scheduler {
+    unsafe {
+        let key = tls_key();
+        let void_sched: *mut c_void = tls::get(key);
+        assert!(void_sched.is_not_null());
+        let sched = transmute::<*mut c_void, ~Scheduler>(void_sched);
+        tls::set(key, mut_null());
+        return sched;
+    }
+}
+
+/// Borrow a mutable reference to the thread-local Scheduler
+/// # Safety Note
+/// Because this leaves the Scheduler in thread-local storage it is possible
+/// For the Scheduler pointer to be aliased
+pub unsafe fn borrow() -> &mut Scheduler {
+    unsafe {
+        let key = tls_key();
+        let mut void_sched: *mut c_void = tls::get(key);
+        assert!(void_sched.is_not_null());
+        {
+            let void_sched_ptr = &mut void_sched;
+            let sched: &mut ~Scheduler = {
+                transmute::<&mut *mut c_void, &mut ~Scheduler>(void_sched_ptr)
+            };
+            let sched: &mut Scheduler = &mut **sched;
+            return sched;
+        }
+    }
+}
+
+fn tls_key() -> tls::Key {
+    unsafe {
+        let key: *mut c_void = rust_get_sched_tls_key();
+        let key: &mut tls::Key = transmute(key);
+        return *key;
+    }
+}
+
+extern {
+    fn rust_get_sched_tls_key() -> *mut c_void;
+}
+
+#[test]
+fn thread_local_scheduler_smoke_test() {
+    let scheduler = ~UvEventLoop::new_scheduler();
+    put(scheduler);
+    let _scheduler = take();
+}
+
+#[test]
+fn thread_local_scheduler_two_instances() {
+    let scheduler = ~UvEventLoop::new_scheduler();
+    put(scheduler);
+    let _scheduler = take();
+    let scheduler = ~UvEventLoop::new_scheduler();
+    put(scheduler);
+    let _scheduler = take();
+}
+
+#[test]
+fn borrow_smoke_test() {
+    let scheduler = ~UvEventLoop::new_scheduler();
+    put(scheduler);
+    unsafe {
+        let _scheduler = borrow();
+    }
+    let _scheduler = take();
+}
+