1 // Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
4 //
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
10
11 //! Task bookkeeping
12 //!
13 //! This module keeps track of the number of running tasks so that entry points
14 //! with libnative know when it's possible to exit the program (once all tasks
15 //! have exited).
16 //!
17 //! The green counterpart for this is bookkeeping on sched pools, and it's up to
18 //! each respective runtime to make sure that they call increment() and
19 //! decrement() manually.
20
21 #![experimental] // this is a massive code smell
22 #![doc(hidden)]
23
24 use sync::atomics;
25 use unstable::mutex::{StaticNativeMutex, NATIVE_MUTEX_INIT};
26
27 static mut TASK_COUNT: atomics::AtomicUint = atomics::INIT_ATOMIC_UINT;
28 static mut TASK_LOCK: StaticNativeMutex = NATIVE_MUTEX_INIT;
29
30 pub fn increment() {
31 let _ = unsafe { TASK_COUNT.fetch_add(1, atomics::SeqCst) };
32 }
33
34 pub fn decrement() {
35 unsafe {
36 if TASK_COUNT.fetch_sub(1, atomics::SeqCst) == 1 {
37 let guard = TASK_LOCK.lock();
38 guard.signal();
39 }
40 }
41 }
42
43 /// Waits for all other native tasks in the system to exit. This is only used by
44 /// the entry points of native programs
45 pub fn wait_for_other_tasks() {
46 unsafe {
47 let guard = TASK_LOCK.lock();
48 while TASK_COUNT.load(atomics::SeqCst) > 0 {
49 guard.wait();
50 }
51 }
52 }