src/libstd/sys/common/mutex.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use sys::mutex as imp;
  12
  13 /// An OS-based mutual exclusion lock.
  14 ///
  15 /// This is the thinnest cross-platform wrapper around OS mutexes. All usage of
  16 /// this mutex is unsafe and it is recommended to instead use the safe wrapper
  17 /// at the top level of the crate instead of this type.
  18 pub struct Mutex(imp::Mutex);
  19
  20 unsafe impl Sync for Mutex {}
  21
  22 impl Mutex {
  23     /// Creates a new mutex for use.
  24     ///
  25     /// Behavior is undefined if the mutex is moved after it is
  26     /// first used with any of the functions below.
  27     pub const fn new() -> Mutex { Mutex(imp::Mutex::new()) }
  28
  29     /// Prepare the mutex for use.
  30     ///
  31     /// This should be called once the mutex is at a stable memory address.
  32     #[inline]
  33     pub unsafe fn init(&mut self) { self.0.init() }
  34
  35     /// Locks the mutex blocking the current thread until it is available.
  36     ///
  37     /// Behavior is undefined if the mutex has been moved between this and any
  38     /// previous function call.
  39     #[inline]
  40     pub unsafe fn lock(&self) { self.0.lock() }
  41
  42     /// Attempts to lock the mutex without blocking, returning whether it was
  43     /// successfully acquired or not.
  44     ///
  45     /// Behavior is undefined if the mutex has been moved between this and any
  46     /// previous function call.
  47     #[inline]
  48     pub unsafe fn try_lock(&self) -> bool { self.0.try_lock() }
  49
  50     /// Unlocks the mutex.
  51     ///
  52     /// Behavior is undefined if the current thread does not actually hold the
  53     /// mutex.
  54     #[inline]
  55     pub unsafe fn unlock(&self) { self.0.unlock() }
  56
  57     /// Deallocates all resources associated with this mutex.
  58     ///
  59     /// Behavior is undefined if there are current or will be future users of
  60     /// this mutex.
  61     #[inline]
  62     pub unsafe fn destroy(&self) { self.0.destroy() }
  63 }
  64
  65 // not meant to be exported to the outside world, just the containing module
  66 pub fn raw(mutex: &Mutex) -> &imp::Mutex { &mutex.0 }