9e224c2bf1
The new semantics of this function are that the callbacks are run when the *main thread* exits, not when all threads have exited. This implies that other threads may still be running when the `at_exit` callbacks are invoked and users need to be prepared for this situation. Users in the standard library have been audited in accordance to these new rules as well. Closes #20012
88 lines
3.1 KiB
Rust
88 lines
3.1 KiB
Rust
// Copyright 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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use sys::rwlock as imp;
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/// An OS-based reader-writer lock.
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///
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/// This structure is entirely unsafe and serves as the lowest layer of a
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/// cross-platform binding of system rwlocks. It is recommended to use the
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/// safer types at the top level of this crate instead of this type.
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pub struct RWLock(imp::RWLock);
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/// Constant initializer for static RWLocks.
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pub const RWLOCK_INIT: RWLock = RWLock(imp::RWLOCK_INIT);
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impl RWLock {
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/// Creates a new instance of an RWLock.
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///
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/// Usage of an RWLock is undefined if it is moved after its first use (any
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/// function calls below).
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#[inline]
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#[allow(dead_code)] // sys is not exported yet
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pub unsafe fn new() -> RWLock { RWLock(imp::RWLock::new()) }
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/// Acquire shared access to the underlying lock, blocking the current
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/// thread to do so.
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///
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/// Behavior is undefined if the rwlock has been moved between this and any
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/// previous methodo call.
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#[inline]
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pub unsafe fn read(&self) { self.0.read() }
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/// Attempt to acquire shared access to this lock, returning whether it
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/// succeeded or not.
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///
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/// This function does not block the current thread.
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///
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/// Behavior is undefined if the rwlock has been moved between this and any
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/// previous methodo call.
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#[inline]
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pub unsafe fn try_read(&self) -> bool { self.0.try_read() }
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/// Acquire write access to the underlying lock, blocking the current thread
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/// to do so.
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///
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/// Behavior is undefined if the rwlock has been moved between this and any
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/// previous methodo call.
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#[inline]
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pub unsafe fn write(&self) { self.0.write() }
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/// Attempt to acquire exclusive access to this lock, returning whether it
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/// succeeded or not.
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///
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/// This function does not block the current thread.
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///
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/// Behavior is undefined if the rwlock has been moved between this and any
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/// previous methodo call.
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#[inline]
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pub unsafe fn try_write(&self) -> bool { self.0.try_write() }
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/// Unlock previously acquired shared access to this lock.
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///
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/// Behavior is undefined if the current thread does not have shared access.
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#[inline]
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pub unsafe fn read_unlock(&self) { self.0.read_unlock() }
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/// Unlock previously acquired exclusive access to this lock.
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///
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/// Behavior is undefined if the current thread does not currently have
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/// exclusive access.
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#[inline]
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pub unsafe fn write_unlock(&self) { self.0.write_unlock() }
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/// Destroy OS-related resources with this RWLock.
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///
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/// Behavior is undefined if there are any currently active users of this
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/// lock.
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#[inline]
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pub unsafe fn destroy(&self) { self.0.destroy() }
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}
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