dae48a07f3
Also convert a number of `static mut` to just a plain old `static` and remove some unsafe blocks.
61 lines
1.8 KiB
Rust
61 lines
1.8 KiB
Rust
// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Task bookkeeping
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//!
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//! This module keeps track of the number of running tasks so that entry points
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//! with libnative know when it's possible to exit the program (once all tasks
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//! have exited).
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//!
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//! The green counterpart for this is bookkeeping on sched pools, and it's up to
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//! each respective runtime to make sure that they call increment() and
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//! decrement() manually.
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use core::atomic;
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use core::ops::Drop;
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use mutex::{StaticNativeMutex, NATIVE_MUTEX_INIT};
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static TASK_COUNT: atomic::AtomicUint = atomic::INIT_ATOMIC_UINT;
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static TASK_LOCK: StaticNativeMutex = NATIVE_MUTEX_INIT;
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pub struct Token { _private: () }
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impl Drop for Token {
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fn drop(&mut self) { decrement() }
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}
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/// Increment the number of live tasks, returning a token which will decrement
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/// the count when dropped.
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pub fn increment() -> Token {
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let _ = TASK_COUNT.fetch_add(1, atomic::SeqCst);
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Token { _private: () }
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}
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pub fn decrement() {
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unsafe {
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if TASK_COUNT.fetch_sub(1, atomic::SeqCst) == 1 {
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let guard = TASK_LOCK.lock();
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guard.signal();
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}
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}
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}
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/// Waits for all other native tasks in the system to exit. This is only used by
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/// the entry points of native programs
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pub fn wait_for_other_tasks() {
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unsafe {
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let guard = TASK_LOCK.lock();
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while TASK_COUNT.load(atomic::SeqCst) > 0 {
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guard.wait();
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}
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}
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}
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