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// 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 cell::UnsafeCell;
use sys::sync as ffi;
pub struct RWLock { inner: UnsafeCell<ffi::pthread_rwlock_t> }
pub const RWLOCK_INIT: RWLock = RWLock {
inner: UnsafeCell { value: ffi::PTHREAD_RWLOCK_INITIALIZER },
};
impl RWLock {
#[inline]
pub unsafe fn new() -> RWLock {
// Might be moved and address is changing it is better to avoid
// initialization of potentially opaque OS data before it landed
RWLOCK_INIT
}
#[inline]
pub unsafe fn read(&self) {
let r = ffi::pthread_rwlock_rdlock(self.inner.get());
debug_assert_eq!(r, 0);
}
#[inline]
pub unsafe fn try_read(&self) -> bool {
ffi::pthread_rwlock_tryrdlock(self.inner.get()) == 0
}
#[inline]
pub unsafe fn write(&self) {
let r = ffi::pthread_rwlock_wrlock(self.inner.get());
debug_assert_eq!(r, 0);
}
#[inline]
pub unsafe fn try_write(&self) -> bool {
ffi::pthread_rwlock_trywrlock(self.inner.get()) == 0
}
#[inline]
pub unsafe fn read_unlock(&self) {
let r = ffi::pthread_rwlock_unlock(self.inner.get());
debug_assert_eq!(r, 0);
}
#[inline]
pub unsafe fn write_unlock(&self) { self.read_unlock() }
#[inline]
#[cfg(not(target_os = "dragonfly"))]
pub unsafe fn destroy(&self) {
let r = ffi::pthread_rwlock_destroy(self.inner.get());
debug_assert_eq!(r, 0);
}
#[inline]
#[cfg(target_os = "dragonfly")]
pub unsafe fn destroy(&self) {
use libc;
let r = ffi::pthread_rwlock_destroy(self.inner.get());
// On DragonFly pthread_rwlock_destroy() returns EINVAL if called on a
// rwlock that was just initialized with
// ffi::PTHREAD_RWLOCK_INITIALIZER. Once it is used (locked/unlocked)
// or pthread_rwlock_init() is called, this behaviour no longer occurs.
debug_assert!(r == 0 || r == libc::EINVAL);
}
}
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