use std::marker::PhantomData;
use crate::{key::Keyable, lockable::Lock, Lockable, OwnedLockable};
use super::{LockGuard, RefLockCollection};
#[must_use]
fn get_locks<L: Lockable>(data: &L) -> Vec<&dyn Lock> {
let mut locks = Vec::new();
data.get_ptrs(&mut locks);
locks.sort_by_key(|lock| std::ptr::from_ref(*lock));
locks
}
/// returns `true` if the sorted list contains a duplicate
#[must_use]
fn contains_duplicates(l: &[&dyn Lock]) -> bool {
l.windows(2).any(|window| {
std::ptr::addr_eq(std::ptr::from_ref(window[0]), std::ptr::from_ref(window[1]))
})
}
impl<'a, L: Lockable> AsRef<L> for RefLockCollection<'a, L> {
fn as_ref(&self) -> &L {
self.data
}
}
impl<'a, L: Lockable> AsRef<Self> for RefLockCollection<'a, L> {
fn as_ref(&self) -> &Self {
self
}
}
impl<'a, L: Lockable> AsMut<Self> for RefLockCollection<'a, L> {
fn as_mut(&mut self) -> &mut Self {
self
}
}
impl<'a, L> IntoIterator for &'a RefLockCollection<'a, L>
where
&'a L: IntoIterator,
{
type Item = <&'a L as IntoIterator>::Item;
type IntoIter = <&'a L as IntoIterator>::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self.data.into_iter()
}
}
impl<'a, L: OwnedLockable> RefLockCollection<'a, L> {
/// Creates a new collection of owned locks.
///
/// Because the locks are owned, there's no need to do any checks for
/// duplicate values.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex};
///
/// let data = (Mutex::new(0), Mutex::new(""));
/// let lock = LockCollection::new(&data);
/// ```
#[must_use]
pub fn new(data: &'a L) -> RefLockCollection<L> {
RefLockCollection {
locks: get_locks(data),
data,
}
}
}
impl<'a, L: Lockable> RefLockCollection<'a, L> {
/// Creates a new collections of locks.
///
/// # Safety
///
/// This results in undefined behavior if any locks are presented twice
/// within this collection.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex};
///
/// let data1 = Mutex::new(0);
/// let data2 = Mutex::new("");
///
/// // safety: data1 and data2 refer to distinct mutexes
/// let lock = unsafe { LockCollection::new_unchecked((&data1, &data2)) };
/// ```
#[must_use]
pub unsafe fn new_unchecked(data: &'a L) -> Self {
Self {
data,
locks: get_locks(data),
}
}
/// Creates a new collection of locks.
///
/// This returns `None` if any locks are found twice in the given
/// collection.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex};
///
/// let data1 = Mutex::new(0);
/// let data2 = Mutex::new("");
///
/// // data1 and data2 refer to distinct mutexes, so this won't panic
/// let lock = LockCollection::try_new((&data1, &data2)).unwrap();
/// ```
#[must_use]
pub fn try_new(data: &'a L) -> Option<Self> {
let locks = get_locks(data);
if contains_duplicates(&locks) {
return None;
}
Some(Self { locks, data })
}
/// Locks the collection
///
/// This function returns a guard that can be used to access the underlying
/// data. When the guard is dropped, the locks in the collection are also
/// dropped.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex, ThreadKey};
///
/// let key = ThreadKey::get().unwrap();
/// let lock = LockCollection::new((Mutex::new(0), Mutex::new("")));
///
/// let mut guard = lock.lock(key);
/// *guard.0 += 1;
/// *guard.1 = "1";
/// ```
pub fn lock<'key: 'a, Key: Keyable + 'key>(&'a self, key: Key) -> LockGuard<'a, 'key, L, Key> {
for lock in &self.locks {
// safety: we have the thread key
unsafe { lock.lock() };
}
LockGuard {
// safety: we've already acquired the lock
guard: unsafe { self.data.guard() },
key,
_phantom: PhantomData,
}
}
/// Attempts to lock the without blocking.
///
/// If successful, this method returns a guard that can be used to access
/// the data, and unlocks the data when it is dropped. Otherwise, `None` is
/// returned.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex, ThreadKey};
///
/// let key = ThreadKey::get().unwrap();
/// let lock = LockCollection::new((Mutex::new(0), Mutex::new("")));
///
/// match lock.try_lock(key) {
/// Some(mut guard) => {
/// *guard.0 += 1;
/// *guard.1 = "1";
/// },
/// None => unreachable!(),
/// };
///
/// ```
pub fn try_lock<'key: 'a, Key: Keyable + 'key>(
&'a self,
key: Key,
) -> Option<LockGuard<'a, 'key, L, Key>> {
let guard = unsafe {
for (i, lock) in self.locks.iter().enumerate() {
// safety: we have the thread key
let success = lock.try_lock();
if !success {
for lock in &self.locks[0..i] {
// safety: this lock was already acquired
lock.unlock();
}
return None;
}
}
// safety: we've acquired the locks
self.data.guard()
};
Some(LockGuard {
guard,
key,
_phantom: PhantomData,
})
}
/// Unlocks the underlying lockable data type, returning the key that's
/// associated with it.
///
/// # Examples
///
/// ```
/// use happylock::{LockCollection, Mutex, ThreadKey};
///
/// let key = ThreadKey::get().unwrap();
/// let lock = LockCollection::new((Mutex::new(0), Mutex::new("")));
///
/// let mut guard = lock.lock(key);
/// *guard.0 += 1;
/// *guard.1 = "1";
/// let key = LockCollection::unlock(guard);
/// ```
#[allow(clippy::missing_const_for_fn)]
pub fn unlock<'key: 'a, Key: Keyable + 'key>(guard: LockGuard<'a, 'key, L, Key>) -> Key {
drop(guard.guard);
guard.key
}
}
impl<'a, L: 'a> RefLockCollection<'a, L>
where
&'a L: IntoIterator,
{
/// Returns an iterator over references to each value in the collection.
#[must_use]
pub fn iter(&'a self) -> <&'a L as IntoIterator>::IntoIter {
self.into_iter()
}
}
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