| // Copyright 2014 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. |
| |
| use sys::rwlock as imp; |
| |
| /// An OS-based reader-writer lock. |
| /// |
| /// This structure is entirely unsafe and serves as the lowest layer of a |
| /// cross-platform binding of system rwlocks. It is recommended to use the |
| /// safer types at the top level of this crate instead of this type. |
| pub struct RWLock(imp::RWLock); |
| |
| impl RWLock { |
| /// Creates a new reader-writer lock for use. |
| /// |
| /// Behavior is undefined if the reader-writer lock is moved after it is |
| /// first used with any of the functions below. |
| #[unstable(feature = "sys_internals", issue = "0")] // FIXME: min_const_fn |
| pub const fn new() -> RWLock { RWLock(imp::RWLock::new()) } |
| |
| /// Acquires shared access to the underlying lock, blocking the current |
| /// thread to do so. |
| /// |
| /// Behavior is undefined if the rwlock has been moved between this and any |
| /// previous method call. |
| #[inline] |
| pub unsafe fn read(&self) { self.0.read() } |
| |
| /// Attempts to acquire shared access to this lock, returning whether it |
| /// succeeded or not. |
| /// |
| /// This function does not block the current thread. |
| /// |
| /// Behavior is undefined if the rwlock has been moved between this and any |
| /// previous method call. |
| #[inline] |
| pub unsafe fn try_read(&self) -> bool { self.0.try_read() } |
| |
| /// Acquires write access to the underlying lock, blocking the current thread |
| /// to do so. |
| /// |
| /// Behavior is undefined if the rwlock has been moved between this and any |
| /// previous method call. |
| #[inline] |
| pub unsafe fn write(&self) { self.0.write() } |
| |
| /// Attempts to acquire exclusive access to this lock, returning whether it |
| /// succeeded or not. |
| /// |
| /// This function does not block the current thread. |
| /// |
| /// Behavior is undefined if the rwlock has been moved between this and any |
| /// previous method call. |
| #[inline] |
| pub unsafe fn try_write(&self) -> bool { self.0.try_write() } |
| |
| /// Unlocks previously acquired shared access to this lock. |
| /// |
| /// Behavior is undefined if the current thread does not have shared access. |
| #[inline] |
| pub unsafe fn read_unlock(&self) { self.0.read_unlock() } |
| |
| /// Unlocks previously acquired exclusive access to this lock. |
| /// |
| /// Behavior is undefined if the current thread does not currently have |
| /// exclusive access. |
| #[inline] |
| pub unsafe fn write_unlock(&self) { self.0.write_unlock() } |
| |
| /// Destroys OS-related resources with this RWLock. |
| /// |
| /// Behavior is undefined if there are any currently active users of this |
| /// lock. |
| #[inline] |
| pub unsafe fn destroy(&self) { self.0.destroy() } |
| } |