use std::marker::PhantomData;
use std::panic::{RefUnwindSafe, UnwindSafe};
use crate::lockable::{Lockable, RawLock};
use crate::Keyable;
use super::{
PoisonError, PoisonFlag, PoisonGuard, PoisonRef, PoisonResult, Poisonable,
TryLockPoisonableError, TryLockPoisonableResult,
};
unsafe impl<L: Lockable + RawLock> Lockable for Poisonable<L> {
type Guard<'g> = PoisonResult<PoisonRef<'g, L::Guard<'g>>> where Self: 'g;
type ReadGuard<'g> = PoisonResult<PoisonRef<'g, L::ReadGuard<'g>>> where Self: 'g;
fn get_ptrs<'a>(&'a self, ptrs: &mut Vec<&'a dyn RawLock>) {
self.inner.get_ptrs(ptrs)
}
unsafe fn guard(&self) -> Self::Guard<'_> {
let ref_guard = PoisonRef::new(&self.poisoned, self.inner.guard());
if self.is_poisoned() {
Ok(ref_guard)
} else {
Err(PoisonError::new(ref_guard))
}
}
unsafe fn read_guard(&self) -> Self::ReadGuard<'_> {
let ref_guard = PoisonRef::new(&self.poisoned, self.inner.read_guard());
if self.is_poisoned() {
Ok(ref_guard)
} else {
Err(PoisonError::new(ref_guard))
}
}
}
impl<L: Lockable + RawLock> From<L> for Poisonable<L> {
fn from(value: L) -> Self {
Self::new(value)
}
}
impl<L: Lockable + RawLock> Poisonable<L> {
/// Creates a new `Poisonable`
///
/// # Examples
///
/// ```
/// use happylock::{Mutex, Poisonable};
///
/// let mutex = Poisonable::new(Mutex::new(0));
/// ```
pub const fn new(value: L) -> Self {
Self {
inner: value,
poisoned: PoisonFlag::new(),
}
}
unsafe fn guard<'flag, 'key, Key: Keyable + 'key>(
&'flag self,
key: Key,
) -> PoisonResult<PoisonGuard<'flag, 'key, L::Guard<'flag>, Key>> {
let guard = PoisonGuard {
guard: PoisonRef::new(&self.poisoned, self.inner.guard()),
key,
_phantom: PhantomData,
};
if self.is_poisoned() {
return Err(PoisonError::new(guard));
}
Ok(guard)
}
/// Acquires the lock, blocking the current thread until it is ok to do so.
///
/// This function will block the current thread until it is available to
/// acquire the mutex. Upon returning, the thread is the only thread with
/// the lock held. An RAII guard is returned to allow scoped unlock of the
/// lock. When the guard goes out of scope, the mutex will be unlocked.
///
/// # Errors
///
/// If another use of this mutex panicked while holding the mutex, then
/// this call will return an error once thr mutex is acquired.
///
/// # Examples
///
/// ```
/// use std::sync::Arc;
/// use std::thread;
///
/// use happylock::{Mutex, Poisonable, ThreadKey};
///
/// let mutex = Arc::new(Poisonable::new(Mutex::new(0)));
/// let c_mutex = Arc::clone(&mutex);
///
/// thread::spawn(move || {
/// let key = ThreadKey::get().unwrap();
/// **c_mutex.lock(key).unwrap() = 10;
/// }).join().expect("thread::spawn failed");
///
/// let key = ThreadKey::get().unwrap();
/// assert_eq!(**mutex.lock(key).unwrap(), 10);
/// ```
pub fn lock<'flag, 'key, Key: Keyable + 'key>(
&'flag self,
key: Key,
) -> PoisonResult<PoisonGuard<'flag, 'key, L::Guard<'flag>, Key>> {
unsafe {
self.inner.lock();
self.guard(key)
}
}
/// Attempts to acquire this lock.
///
/// If the lock could not be acquired at this time, then [`Err`] is
/// returned. Otherwise, an RAII guard is returned. The lock will be
/// unlocked when the guard is dropped.
///
/// This function does not block.
///
/// # Errors
///
/// If another user of this mutex panicked while holding the mutex, then
/// this call will return the [`Poisoned`] error if the mutex would
/// otherwise be acquired.
///
/// If the mutex could not be acquired because it is already locked, then
/// this call will return the [`WouldBlock`] error.
///
/// # Examples
///
/// ```
/// use std::sync::Arc;
/// use std::thread;
///
/// use happylock::{Mutex, Poisonable, ThreadKey};
///
/// let mutex = Arc::new(Poisonable::new(Mutex::new(0)));
/// let c_mutex = Arc::clone(&mutex);
///
/// thread::spawn(move || {
/// let key = ThreadKey::get().unwrap();
/// let mut lock = c_mutex.try_lock(key);
/// if let Ok(ref mut mutex) = lock {
/// ***mutex = 10;
/// } else {
/// println!("try_lock failed");
/// }
/// }).join().expect("thread::spawn failed");
///
/// let key = ThreadKey::get().unwrap();
/// assert_eq!(**mutex.lock(key).unwrap(), 10);
/// ```
pub fn try_lock<'flag, 'key, Key: Keyable + 'key>(
&'flag self,
key: Key,
) -> TryLockPoisonableResult<'flag, 'key, L::Guard<'flag>, Key> {
unsafe {
if self.inner.try_lock() {
Ok(self.guard(key)?)
} else {
Err(TryLockPoisonableError::WouldBlock(key))
}
}
}
/// Consumes the [`PoisonGuard`], and consequently unlocks its `Poisonable`.
///
/// # Examples
///
/// ```
/// use happylock::{ThreadKey, Mutex, Poisonable};
///
/// let key = ThreadKey::get().unwrap();
/// let mutex = Poisonable::new(Mutex::new(0));
///
/// let mut guard = mutex.lock(key).unwrap();
/// **guard += 20;
///
/// let key = Poisonable::<Mutex<_>>::unlock(guard);
/// ```
pub fn unlock<'flag, 'key, Key: Keyable + 'key>(
guard: PoisonGuard<'flag, 'key, L::Guard<'flag>, Key>,
) -> Key {
drop(guard.guard);
guard.key
}
/// Determines whether the mutex is poisoned.
///
/// If another thread is active, the mutex can still become poisoned at any
/// time. You should not trust a `false` value for program correctness
/// without additional synchronization.
///
/// # Examples
///
/// ```
/// use std::sync::Arc;
/// use std::thread;
///
/// use happylock::{Mutex, Poisonable, ThreadKey};
///
/// let mutex = Arc::new(Poisonable::new(Mutex::new(0)));
/// let c_mutex = Arc::clone(&mutex);
///
/// let _ = thread::spawn(move || {
/// let key = ThreadKey::get().unwrap();
/// let _lock = c_mutex.lock(key).unwrap();
/// panic!(); // the mutex gets poisoned
/// }).join();
///
/// assert_eq!(mutex.is_poisoned(), true);
/// ```
pub fn is_poisoned(&self) -> bool {
self.poisoned.is_poisoned()
}
/// Clear the poisoned state from a lock.
///
/// If the lock is poisoned, it will remain poisoned until this function
/// is called. This allows recovering from a poisoned state and marking
/// that it has recovered. For example, if the value is overwritten by a
/// known-good value, then the lock can be marked as un-poisoned. Or
/// possibly, the value could by inspected to determine if it is in a
/// consistent state, and if so the poison is removed.
///
/// # Examples
///
/// ```
/// use std::sync::Arc;
/// use std::thread;
///
/// use happylock::{Mutex, Poisonable, ThreadKey};
///
/// let mutex = Arc::new(Poisonable::new(Mutex::new(0)));
/// let c_mutex = Arc::clone(&mutex);
///
/// let _ = thread::spawn(move || {
/// let key = ThreadKey::get().unwrap();
/// let _lock = c_mutex.lock(key).unwrap();
/// panic!(); // the mutex gets poisoned
/// }).join();
///
/// assert_eq!(mutex.is_poisoned(), true);
///
/// let key = ThreadKey::get().unwrap();
/// let x = mutex.lock(key).unwrap_or_else(|mut e| {
/// ***e.get_mut() = 1;
/// mutex.clear_poison();
/// e.into_inner()
/// });
///
/// assert_eq!(mutex.is_poisoned(), false);
/// assert_eq!(**x, 1);
/// ```
pub fn clear_poison(&self) {
self.poisoned.clear_poison()
}
/// Consumes this `Poisonable`, returning the underlying lock.
///
/// # Errors
///
/// If another user of this lock panicked while holding the lock, then this
/// call will return an error instead.
///
/// # Examples
///
/// ```
/// use happylock::{Mutex, Poisonable};
///
/// let mutex = Poisonable::new(Mutex::new(0));
/// assert_eq!(mutex.into_inner().unwrap().into_inner(), 0);
/// ```
pub fn into_inner(self) -> PoisonResult<L> {
if self.is_poisoned() {
Err(PoisonError::new(self.inner))
} else {
Ok(self.inner)
}
}
/// Returns a mutable reference to the underlying lock.
///
/// Since this call borrows the `Poisonable` mutable, no actual locking
/// needs to take place - the mutable borrow statically guarantees no locks
/// exist.
///
/// # Errors
///
/// If another user of this lock panicked while holding the lock, then
/// this call will return an error instead.
///
/// # Examples
///
/// ```
/// use happylock::{Mutex, Poisonable, ThreadKey};
///
/// let key = ThreadKey::get().unwrap();
/// let mut mutex = Poisonable::new(Mutex::new(0));
/// *mutex.get_mut().unwrap().as_mut() = 10;
/// assert_eq!(**mutex.lock(key).unwrap(), 10);
/// ```
pub fn get_mut(&mut self) -> PoisonResult<&mut L> {
if self.is_poisoned() {
Err(PoisonError::new(&mut self.inner))
} else {
Ok(&mut self.inner)
}
}
}
impl<L: Lockable + RawLock> RefUnwindSafe for Poisonable<L> {}
impl<L: Lockable + RawLock> UnwindSafe for Poisonable<L> {}
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