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
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160

use std::sync::{LockResult, TryLockResult, TryLockError, PoisonError};

/// An instrumented version of `std::sync::RwLock`
pub struct RwLock<T>{
    inner: T,
    key: usize,
    poisoned: bool,
    manager: std::sync::Arc<crate::lock_manager::LockManager>,
}

impl<T> RwLock<T> {
    pub fn new(inner: T) -> Self {
        let manager = crate::lock_manager::LockManager::get_global_manager();
        let key = manager.create_lock();
        RwLock {
            inner,
            poisoned: false,
            manager,
            key,
        }
    }

    pub fn into_inner(self) -> T {
        self.inner
    }

    pub fn get_mut(&mut self) -> &mut T {
        &mut self.inner
    }

    pub fn is_poisoned(&self) -> bool {
        self.poisoned
    }

    pub fn try_read(&self) -> TryLockResult<RwLockReadGuard<T>> {
        let mut guard = self.manager.write_lock();
        let representation = guard.locks.get_mut(&self.key).unwrap();
        if representation.try_read_lock() {
            let returned_guard = RwLockReadGuard {
                inner: &self,
            };
            if self.is_poisoned() {
                Err(TryLockError::Poisoned(
                    PoisonError::new(returned_guard),
                ))
            } else {
                Ok(returned_guard)
            }
        } else {
            Err(TryLockError::WouldBlock)
        }
    }

    pub fn try_write(&self) -> TryLockResult<RwLockWriteGuard<T>> {
        let mut guard = self.manager.write_lock();
        let representation = guard.locks.get_mut(&self.key).unwrap();
        if representation.try_write_lock() {
            let returned_guard = RwLockWriteGuard {
                inner: unsafe { &mut *(self as *const _ as *mut _) },
            };
            if self.is_poisoned() {
                Err(TryLockError::Poisoned(
                    PoisonError::new(returned_guard),
                ))
            } else {
                Ok(returned_guard)
            }
        } else {
            Err(TryLockError::WouldBlock)
        }
    }

    pub fn read(&self) -> LockResult<RwLockReadGuard<T>> {
        loop {
            let mut guard = self.manager.write_lock();
            let representation = guard.locks.get_mut(&self.key).unwrap();
            if representation.try_read_lock() {
                let returned_guard = RwLockReadGuard {
                    inner: &self,
                };
                if self.is_poisoned() {
                    return Err(PoisonError::new(returned_guard))
                } else {
                    return Ok(returned_guard)
                }
            } else {
                representation.subscribe_read();
                guard.analyse();
                std::thread::yield_now();
            }
        }
    }

    pub fn write(&self) -> LockResult<RwLockWriteGuard<T>> {
        loop {
            let mut guard = self.manager.write_lock();
            let representation = guard.locks.get_mut(&self.key).unwrap();
            if representation.try_write_lock() {
                let returned_guard = RwLockWriteGuard {
                    inner: unsafe { &mut *(self as *const _ as *mut _) },
                };
                if self.is_poisoned() {
                    return Err(PoisonError::new(returned_guard))
                } else {
                    return Ok(returned_guard)
                }
            } else {
                representation.subscribe_write();
                guard.analyse();
                std::thread::yield_now();
            }
        }
    }
}

pub struct RwLockReadGuard<'l, T> {
    inner: &'l RwLock<T>
}
impl<'l, T> std::ops::Deref for RwLockReadGuard<'l, T> {
    type Target = T;
    fn deref(&self) -> &<Self as std::ops::Deref>::Target {
        &self.inner.inner
    }
}
impl<'l, T> Drop for RwLockReadGuard<'l, T> {
    fn drop(&mut self) {
        let mut guard = self.inner.manager.write_lock();
        guard.locks.get_mut(&self.inner.key).unwrap().unlock();
        if std::thread::panicking() {
            unsafe {(*(&self.inner as *const _ as *mut RwLock<T>)).poisoned = true};
        }
    }
}
pub struct RwLockWriteGuard<'l, T> {
    inner: &'l mut RwLock<T>
}

impl<'l, T> std::ops::Deref for RwLockWriteGuard<'l, T> {
    type Target = T;
    fn deref(&self) -> &<Self as std::ops::Deref>::Target {
        &self.inner.inner
    }
}
impl<'l, T> std::ops::DerefMut for RwLockWriteGuard<'l, T> {
    fn deref_mut(&mut self) -> &mut <Self as std::ops::Deref>::Target {
        &mut self.inner.inner
    }
}
impl<'l, T> Drop for RwLockWriteGuard<'l, T> {
    fn drop(&mut self) {
        let mut guard = self.inner.manager.write_lock();
        guard.locks.get_mut(&self.inner.key).unwrap().unlock();
        if std::thread::panicking() {
            self.inner.poisoned = true;
        }
    }
}

unsafe impl<T: Send> Send for RwLock<T> {}
unsafe impl<T: Send> Sync for RwLock<T> {}