use std::cell::UnsafeCell;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::panic::AssertUnwindSafe;
use lock_api::RawMutex;
use crate::collection::utils;
use crate::handle_unwind::handle_unwind;
use crate::lockable::{Lockable, LockableGetMut, LockableIntoInner, OwnedLockable, RawLock};
use crate::poisonable::PoisonFlag;
use crate::{Keyable, ThreadKey};
use super::{Mutex, MutexGuard, MutexRef};
unsafe impl<T: ?Sized, R: RawMutex> RawLock for Mutex<T, R> {
fn poison(&self) {
self.poison.poison();
}
unsafe fn raw_write(&self) {
assert!(!self.poison.is_poisoned(), "The mutex has been killed");
// if the closure unwraps, then the mutex will be killed
let this = AssertUnwindSafe(self);
handle_unwind(|| this.raw.lock(), || self.poison())
}
unsafe fn raw_try_write(&self) -> bool {
if self.poison.is_poisoned() {
return false;
}
// if the closure unwraps, then the mutex will be killed
let this = AssertUnwindSafe(self);
handle_unwind(|| this.raw.try_lock(), || self.poison())
}
unsafe fn raw_unlock_write(&self) {
// if the closure unwraps, then the mutex will be killed
let this = AssertUnwindSafe(self);
handle_unwind(|| this.raw.unlock(), || self.poison())
}
// this is the closest thing to a read we can get, but Sharable isn't
// implemented for this
#[mutants::skip]
#[cfg(not(tarpaulin_include))]
unsafe fn raw_read(&self) {
self.raw_write()
}
#[mutants::skip]
#[cfg(not(tarpaulin_include))]
unsafe fn raw_try_read(&self) -> bool {
self.raw_try_write()
}
#[mutants::skip]
#[cfg(not(tarpaulin_include))]
unsafe fn raw_unlock_read(&self) {
self.raw_unlock_write()
}
}
unsafe impl<T, R: RawMutex> Lockable for Mutex<T, R> {
type Guard<'g>
= MutexRef<'g, T, R>
where
Self: 'g;
type DataMut<'a>
= &'a mut T
where
Self: 'a;
fn get_ptrs<'a>(&'a self, ptrs: &mut Vec<&'a dyn RawLock>) {
ptrs.push(self);
}
unsafe fn guard(&self) -> Self::Guard<'_> {
MutexRef::new(self)
}
unsafe fn data_mut(&self) -> Self::DataMut<'_> {
self.data.get().as_mut().unwrap_unchecked()
}
}
impl<T: Send, R: RawMutex> LockableIntoInner for Mutex<T, R> {
type Inner = T;
fn into_inner(self) -> Self::Inner {
self.into_inner()
}
}
impl<T: Send, R: RawMutex> LockableGetMut for Mutex<T, R> {
type Inner<'a>
= &'a mut T
where
Self: 'a;
fn get_mut(&mut self) -> Self::Inner<'_> {
self.get_mut()
}
}
unsafe impl<T: Send, R: RawMutex> OwnedLockable for Mutex<T, R> {}
impl<T, R: RawMutex> Mutex<T, R> {
/// Create a new unlocked `Mutex`.
///
/// # Examples
///
/// ```
/// use happylock::Mutex;
///
/// let mutex = Mutex::new(0);
/// ```
#[must_use]
pub const fn new(data: T) -> Self {
Self {
raw: R::INIT,
poison: PoisonFlag::new(),
data: UnsafeCell::new(data),
}
}
/// Returns the raw underlying mutex.
///
/// Note that you will most likely need to import the [`RawMutex`] trait
/// from `lock_api` to be able to call functions on the raw mutex.
///
/// # Safety
///
/// This method is unsafe because it allows unlocking a mutex while still
/// holding a reference to a [`MutexGuard`], and locking a mutex without
/// holding the [`ThreadKey`].
///
/// [`ThreadKey`]: `crate::ThreadKey`
#[must_use]
pub const unsafe fn raw(&self) -> &R {
&self.raw
}
}
#[mutants::skip]
#[cfg(not(tarpaulin_include))]
impl<T: Debug, R: RawMutex> Debug for Mutex<T, R> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// safety: this is just a try lock, and the value is dropped
// immediately after, so there's no risk of blocking ourselves
// or any other threads
// when i implement try_clone this code will become less unsafe
if let Some(value) = unsafe { self.try_lock_no_key() } {
f.debug_struct("Mutex").field("data", &&*value).finish()
} else {
struct LockedPlaceholder;
impl Debug for LockedPlaceholder {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.write_str("<locked>")
}
}
f.debug_struct("Mutex")
.field("data", &LockedPlaceholder)
.finish()
}
}
}
impl<T: Default, R: RawMutex> Default for Mutex<T, R> {
fn default() -> Self {
Self::new(T::default())
}
}
impl<T, R: RawMutex> From<T> for Mutex<T, R> {
fn from(value: T) -> Self {
Self::new(value)
}
}
// We don't need a `get_mut` because we don't have mutex poisoning. Hurray!
// We have it anyway for documentation
impl<T: ?Sized, R> AsMut<T> for Mutex<T, R> {
fn as_mut(&mut self) -> &mut T {
self.get_mut()
}
}
impl<T, R> Mutex<T, R> {
/// Consumes this mutex, returning the underlying data.
///
/// # Examples
///
/// ```
/// use happylock::Mutex;
///
/// let mutex = Mutex::new(0);
/// assert_eq!(mutex.into_inner(), 0);
/// ```
#[must_use]
pub fn into_inner(self) -> T {
self.data.into_inner()
}
}
impl<T: ?Sized, R> Mutex<T, R> {
/// Returns a mutable reference to the underlying data.
///
/// Since this call borrows `Mutex` mutably, no actual locking is taking
/// place. The mutable borrow statically guarantees that no locks exist.
///
/// # Examples
///
/// ```
/// use happylock::{ThreadKey, Mutex};
///
/// let key = ThreadKey::get().unwrap();
/// let mut mutex = Mutex::new(0);
/// *mutex.get_mut() = 10;
/// assert_eq!(*mutex.lock(key), 10);
/// ```
#[must_use]
pub fn get_mut(&mut self) -> &mut T {
self.data.get_mut()
}
}
impl<T, R: RawMutex> Mutex<T, R> {
pub fn scoped_lock<'a, Ret>(
&'a self,
key: impl Keyable,
f: impl FnOnce(&'a mut T) -> Ret,
) -> Ret {
utils::scoped_write(self, key, f)
}
pub fn scoped_try_lock<'a, Key: Keyable, Ret>(
&'a self,
key: Key,
f: impl FnOnce(&'a mut T) -> Ret,
) -> Result<Ret, Key> {
utils::scoped_try_write(self, key, f)
}
/// Block the thread until this mutex can be locked, and lock it.
///
/// Upon returning, the thread is the only thread with a lock on the
/// `Mutex`. A [`MutexGuard`] is returned to allow a scoped unlock of this
/// `Mutex`. When the guard is dropped, this `Mutex` will unlock.
///
/// # Examples
///
/// ```
/// use std::{thread, sync::Arc};
/// use happylock::{Mutex, ThreadKey};
///
/// let mutex = Arc::new(Mutex::new(0));
/// let c_mutex = Arc::clone(&mutex);
///
/// thread::spawn(move || {
/// let key = ThreadKey::get().unwrap();
/// *c_mutex.lock(key) = 10;
/// }).join().expect("thread::spawn failed");
///
/// let key = ThreadKey::get().unwrap();
/// assert_eq!(*mutex.lock(key), 10);
/// ```
pub fn lock(&self, key: ThreadKey) -> MutexGuard<'_, T, R> {
unsafe {
// safety: we have the thread key
self.raw_write();
// safety: we just locked the mutex
MutexGuard::new(self, key)
}
}
/// Attempts to lock the `Mutex` without blocking.
///
/// If the access could not be granted at this time, then `Err` is
/// returned. Otherwise, an RAII guard is returned which will release the
/// lock when it is dropped.
///
/// # Errors
///
/// If the mutex could not be acquired because it is already locked, then
/// this call will return an error containing the given key.
///
/// # Examples
///
/// ```
/// use std::{thread, sync::Arc};
/// use happylock::{Mutex, ThreadKey};
///
/// let mutex = Arc::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(mut lock) = lock {
/// *lock = 10;
/// } else {
/// println!("try_lock failed");
/// }
/// }).join().expect("thread::spawn failed");
///
/// let key = ThreadKey::get().unwrap();
/// assert_eq!(*mutex.lock(key), 10);
/// ```
pub fn try_lock(&self, key: ThreadKey) -> Result<MutexGuard<'_, T, R>, ThreadKey> {
unsafe {
// safety: we have the key to the mutex
if self.raw_try_write() {
// safety: we just locked the mutex
Ok(MutexGuard::new(self, key))
} else {
Err(key)
}
}
}
/// Returns `true` if the mutex is currently locked
#[cfg(test)]
pub(crate) fn is_locked(&self) -> bool {
self.raw.is_locked()
}
/// Lock without a [`ThreadKey`]. It is undefined behavior to do this without
/// owning the [`ThreadKey`].
pub(crate) unsafe fn try_lock_no_key(&self) -> Option<MutexRef<'_, T, R>> {
self.raw_try_write().then_some(MutexRef(self, PhantomData))
}
/// Consumes the [`MutexGuard`], and consequently unlocks its `Mutex`.
///
/// # Examples
///
/// ```
/// use happylock::{ThreadKey, Mutex};
///
/// let key = ThreadKey::get().unwrap();
/// let mutex = Mutex::new(0);
///
/// let mut guard = mutex.lock(key);
/// *guard += 20;
///
/// let key = Mutex::unlock(guard);
/// ```
#[must_use]
pub fn unlock(guard: MutexGuard<'_, T, R>) -> ThreadKey {
drop(guard.mutex);
guard.thread_key
}
}
unsafe impl<R: RawMutex + Send, T: ?Sized + Send> Send for Mutex<T, R> {}
unsafe impl<R: RawMutex + Sync, T: ?Sized + Send> Sync for Mutex<T, R> {}
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