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use std::fmt;
use std::marker;
use std::ops::Deref;
use sys;
use poison::{self, TryLockError, TryLockResult, LockResult};
pub struct ReentrantMutex<T> {
inner: Box<sys::ReentrantMutex>,
poison: poison::Flag,
data: T,
}
unsafe impl<T: Send> Send for ReentrantMutex<T> {}
unsafe impl<T: Send> Sync for ReentrantMutex<T> {}
#[must_use]
pub struct ReentrantMutexGuard<'a, T: 'a> {
__lock: &'a ReentrantMutex<T>,
__poison: poison::Guard,
__marker: marker::PhantomData<*mut ()>,
}
impl<T> ReentrantMutex<T> {
pub fn new(t: T) -> ReentrantMutex<T> {
unsafe {
let mut mutex = ReentrantMutex {
inner: Box::new(sys::ReentrantMutex::uninitialized()),
poison: poison::Flag::new(),
data: t,
};
mutex.inner.init();
mutex
}
}
pub fn lock(&self) -> LockResult<ReentrantMutexGuard<T>> {
unsafe { self.inner.lock() }
ReentrantMutexGuard::new(&self)
}
pub fn try_lock(&self) -> TryLockResult<ReentrantMutexGuard<T>> {
if unsafe { self.inner.try_lock() } {
Ok(try!(ReentrantMutexGuard::new(&self)))
} else {
Err(TryLockError::WouldBlock)
}
}
}
impl<T> Drop for ReentrantMutex<T> {
fn drop(&mut self) {
unsafe { self.inner.destroy() }
}
}
impl<T: fmt::Debug + 'static> fmt::Debug for ReentrantMutex<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.try_lock() {
Ok(guard) => write!(f, "ReentrantMutex {{ data: {:?} }}", &*guard),
Err(TryLockError::Poisoned(err)) => {
write!(f, "ReentrantMutex {{ data: Poisoned({:?}) }}", &**err.get_ref())
},
Err(TryLockError::WouldBlock) => write!(f, "ReentrantMutex {{ <locked> }}")
}
}
}
impl<'mutex, T> ReentrantMutexGuard<'mutex, T> {
fn new(lock: &'mutex ReentrantMutex<T>)
-> LockResult<ReentrantMutexGuard<'mutex, T>> {
poison::map_result(lock.poison.borrow(), |guard| {
ReentrantMutexGuard {
__lock: lock,
__poison: guard,
__marker: marker::PhantomData,
}
})
}
}
impl<'mutex, T> Deref for ReentrantMutexGuard<'mutex, T> {
type Target = T;
fn deref<'a>(&'a self) -> &'a T {
&self.__lock.data
}
}
impl<'a, T> Drop for ReentrantMutexGuard<'a, T> {
#[inline]
fn drop(&mut self) {
unsafe {
self.__lock.poison.done(&self.__poison);
self.__lock.inner.unlock();
}
}
}
#[cfg(test)]
mod test {
use super::{ReentrantMutex, ReentrantMutexGuard};
use std::cell::RefCell;
use std::sync::Arc;
use std::thread;
#[test]
fn smoke() {
let m = ReentrantMutex::new(());
{
let a = m.lock().unwrap();
{
let b = m.lock().unwrap();
{
let c = m.lock().unwrap();
assert_eq!(*c, ());
}
assert_eq!(*b, ());
}
assert_eq!(*a, ());
}
}
#[test]
fn is_mutex() {
let m = Arc::new(ReentrantMutex::new(RefCell::new(0)));
let lock = m.lock().unwrap();
{
let mc = m.clone();
let handle = thread::spawn(move || {
let lock = mc.lock().unwrap();
assert_eq!(*lock.borrow(), 4950);
});
for i in 0..100 {
let mut lock = m.lock().unwrap();
*lock.borrow_mut() += i;
}
drop(lock);
drop(handle);
}
}
#[test]
#[allow(unused_must_use)]
fn trylock_works() {
let m = Arc::new(ReentrantMutex::new(()));
let _lock1 = m.try_lock().unwrap();
let _lock2 = m.try_lock().unwrap();
{
let m = m.clone();
thread::spawn(move || {
let lock = m.try_lock();
assert!(lock.is_err());
}).join();
}
let _lock3 = m.try_lock().unwrap();
}
pub struct Answer<'a>(pub ReentrantMutexGuard<'a, RefCell<u32>>);
impl<'a> Drop for Answer<'a> {
fn drop(&mut self) {
*self.0.borrow_mut() = 42;
}
}
#[test]
fn poison_works() {
let m = Arc::new(ReentrantMutex::new(RefCell::new(0)));
{
let mc = m.clone();
let _result = thread::spawn(move ||{
let lock = mc.lock().unwrap();
*lock.borrow_mut() = 1;
let lock2 = mc.lock().unwrap();
*lock.borrow_mut() = 2;
let _answer = Answer(lock2);
panic!("What the answer to my lifetimes dilemma is?");
drop(_answer);
}).join();
}
let r = m.lock().err().unwrap().into_inner();
assert_eq!(*r.borrow(), 42);
}
}