      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
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126

    // Copyright 2016 Amanieu d'Antras
    //
    // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
    // http://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 lock_api::{self, GetThreadId};
    use raw_mutex::RawMutex;

    /// Implementation of the `GetThreadId` trait for `lock_api::ReentrantMutex`.
    pub struct RawThreadId;

    unsafe impl GetThreadId for RawThreadId {
        const INIT: RawThreadId = RawThreadId;

        fn nonzero_thread_id(&self) -> usize {
            // The address of a thread-local variable is guaranteed to be unique to the
            // current thread, and is also guaranteed to be non-zero.
            thread_local!(static KEY: u8 = unsafe { ::std::mem::uninitialized() });
            KEY.with(|x| x as *const _ as usize)
        }
    }

    /// A mutex which can be recursively locked by a single thread.
    ///
    /// This type is identical to `Mutex` except for the following points:
    ///
    /// - Locking multiple times from the same thread will work correctly instead of
    ///   deadlocking.
    /// - `ReentrantMutexGuard` does not give mutable references to the locked data.
    ///   Use a `RefCell` if you need this.
    ///
    /// See [`Mutex`](struct.Mutex.html) for more details about the underlying mutex
    /// primitive.
    pub type ReentrantMutex<T> = lock_api::ReentrantMutex<RawMutex, RawThreadId, T>;

    /// An RAII implementation of a "scoped lock" of a reentrant mutex. When this structure
    /// is dropped (falls out of scope), the lock will be unlocked.
    ///
    /// The data protected by the mutex can be accessed through this guard via its
    /// `Deref` implementation.
    pub type ReentrantMutexGuard<'a, T> = lock_api::ReentrantMutexGuard<'a, RawMutex, RawThreadId, T>;

    /// An RAII mutex guard returned by `ReentrantMutexGuard::map`, which can point to a
    /// subfield of the protected data.
    ///
    /// The main difference between `MappedReentrantMutexGuard` and `ReentrantMutexGuard` is that the
    /// former doesn't support temporarily unlocking and re-locking, since that
    /// could introduce soundness issues if the locked object is modified by another
    /// thread.
    pub type MappedReentrantMutexGuard<'a, T> =
        lock_api::MappedReentrantMutexGuard<'a, RawMutex, RawThreadId, T>;

    #[cfg(test)]
    mod tests {
        use std::cell::RefCell;
        use std::sync::Arc;
        use std::thread;
        use ReentrantMutex;

        #[test]
        fn smoke() {
            let m = ReentrantMutex::new(());
            {
                let a = m.lock();
                {
                    let b = m.lock();
                    {
                        let c = m.lock();
                        assert_eq!(*c, ());
                    }
                    assert_eq!(*b, ());
                }
                assert_eq!(*a, ());
            }
        }

        #[test]
        fn is_mutex() {
            let m = Arc::new(ReentrantMutex::new(RefCell::new(0)));
            let m2 = m.clone();
            let lock = m.lock();
            let child = thread::spawn(move || {
                let lock = m2.lock();
                assert_eq!(*lock.borrow(), 4950);
            });
            for i in 0..100 {
                let lock = m.lock();
                *lock.borrow_mut() += i;
            }
            drop(lock);
            child.join().unwrap();
        }

        #[test]
        fn trylock_works() {
            let m = Arc::new(ReentrantMutex::new(()));
            let m2 = m.clone();
            let _lock = m.try_lock();
            let _lock2 = m.try_lock();
            thread::spawn(move || {
                let lock = m2.try_lock();
                assert!(lock.is_none());
            })
            .join()
            .unwrap();
            let _lock3 = m.try_lock();
        }

        #[test]
        fn test_reentrant_mutex_debug() {
            let mutex = ReentrantMutex::new(vec![0u8, 10]);

            assert_eq!(format!("{:?}", mutex), "ReentrantMutex { data: [0, 10] }");
            assert_eq!(
                format!("{:#?}", mutex),
                "ReentrantMutex {
        data: [
            0,
            10
        ]
    }"
            );
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## 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`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)