77 lines
2.3 KiB
Rust
77 lines
2.3 KiB
Rust
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// 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 sync::atomic;
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use alloc::{mod, heap};
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use libc::DWORD;
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use sys::sync as ffi;
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const SPIN_COUNT: DWORD = 4000;
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pub struct Mutex { inner: atomic::AtomicUint }
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pub const MUTEX_INIT: Mutex = Mutex { inner: atomic::INIT_ATOMIC_UINT };
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#[inline]
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pub unsafe fn raw(m: &super::Mutex) -> ffi::LPCRITICAL_SECTION {
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m.0.get()
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}
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impl Mutex {
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#[inline]
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pub unsafe fn new() -> Mutex {
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Mutex { inner: atomic::AtomicUint::new(init_lock() as uint) }
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}
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#[inline]
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pub unsafe fn lock(&self) {
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ffi::EnterCriticalSection(self.get())
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}
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#[inline]
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pub unsafe fn try_lock(&self) -> bool {
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ffi::TryEnterCriticalSection(self.get()) != 0
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}
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#[inline]
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pub unsafe fn unlock(&self) {
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ffi::LeaveCriticalSection(self.get())
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}
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pub unsafe fn destroy(&self) {
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let lock = self.inner.swap(0, atomic::SeqCst);
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if lock != 0 { free_lock(lock as ffi::LPCRITICAL_SECTION) }
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}
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unsafe fn get(&self) -> ffi::LPCRITICAL_SECTION {
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match self.inner.load(atomic::SeqCst) {
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0 => {}
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n => return n as ffi::LPCRITICAL_SECTION
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}
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let lock = init_lock();
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match self.inner.compare_and_swap(0, lock as uint, atomic::SeqCst) {
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0 => return lock as ffi::LPCRITICAL_SECTION,
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_ => {}
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}
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free_lock(lock);
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return self.inner.load(atomic::SeqCst) as ffi::LPCRITICAL_SECTION;
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}
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}
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unsafe fn init_lock() -> ffi::LPCRITICAL_SECTION {
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let block = heap::allocate(ffi::CRITICAL_SECTION_SIZE, 8)
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as ffi::LPCRITICAL_SECTION;
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if block.is_null() { alloc::oom() }
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ffi::InitializeCriticalSectionAndSpinCount(block, SPIN_COUNT);
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return block;
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}
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unsafe fn free_lock(h: ffi::LPCRITICAL_SECTION) {
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ffi::DeleteCriticalSection(h);
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heap::deallocate(h as *mut _, ffi::CRITICAL_SECTION_SIZE, 8);
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}
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