     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82

    // 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 libc;
    use cell::UnsafeCell;

    pub struct RWLock { inner: UnsafeCell<libc::pthread_rwlock_t> }

    unsafe impl Send for RWLock {}
    unsafe impl Sync for RWLock {}

    impl RWLock {
        pub const fn new() -> RWLock {
            RWLock { inner: UnsafeCell::new(libc::PTHREAD_RWLOCK_INITIALIZER) }
        }
        #[inline]
        pub unsafe fn read(&self) {
            let r = libc::pthread_rwlock_rdlock(self.inner.get());

            // According to the pthread_rwlock_rdlock spec, this function **may**
            // fail with EDEADLK if a deadlock is detected. On the other hand
            // pthread mutexes will *never* return EDEADLK if they are initialized
            // as the "fast" kind (which ours always are). As a result, a deadlock
            // situation may actually return from the call to pthread_rwlock_rdlock
            // instead of blocking forever (as mutexes and Windows rwlocks do). Note
            // that not all unix implementations, however, will return EDEADLK for
            // their rwlocks.
            //
            // We roughly maintain the deadlocking behavior by panicking to ensure
            // that this lock acquisition does not succeed.
            if r == libc::EDEADLK {
                panic!("rwlock read lock would result in deadlock");
            } else {
                debug_assert_eq!(r, 0);
            }
        }
        #[inline]
        pub unsafe fn try_read(&self) -> bool {
            libc::pthread_rwlock_tryrdlock(self.inner.get()) == 0
        }
        #[inline]
        pub unsafe fn write(&self) {
            let r = libc::pthread_rwlock_wrlock(self.inner.get());
            // see comments above for why we check for EDEADLK
            if r == libc::EDEADLK {
                panic!("rwlock write lock would result in deadlock");
            } else {
                debug_assert_eq!(r, 0);
            }
        }
        #[inline]
        pub unsafe fn try_write(&self) -> bool {
            libc::pthread_rwlock_trywrlock(self.inner.get()) == 0
        }
        #[inline]
        pub unsafe fn read_unlock(&self) {
            let r = libc::pthread_rwlock_unlock(self.inner.get());
            debug_assert_eq!(r, 0);
        }
        #[inline]
        pub unsafe fn write_unlock(&self) { self.read_unlock() }
        #[inline]
        pub unsafe fn destroy(&self) {
            let r = libc::pthread_rwlock_destroy(self.inner.get());
            // On DragonFly pthread_rwlock_destroy() returns EINVAL if called on a
            // rwlock that was just initialized with
            // libc::PTHREAD_RWLOCK_INITIALIZER. Once it is used (locked/unlocked)
            // or pthread_rwlock_init() is called, this behaviour no longer occurs.
            if cfg!(target_os = "dragonfly") {
                debug_assert!(r == 0 || r == libc::EINVAL);
            } else {
                debug_assert_eq!(r, 0);
            }
        }
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)