Sharable API

1 files changed, 267 insertions, 0 deletions

diff --git a/src/collection/ref.rs b/src/collection/ref.rs
new file mode 100644
index 0000000..9fe34c9
--- /dev/null
+++ b/src/collection/ref.rs
@@ -0,0 +1,267 @@
+use std::marker::PhantomData;
+
+use crate::{key::Keyable, lockable::Lock, Lockable, OwnedLockable, Sharable};
+
+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::eq(window[0], 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()
+	}
+}
+
+unsafe impl<'c, L: Lockable> Lockable for RefLockCollection<'c, L> {
+	type Guard<'g> = L::Guard<'g> where Self: 'g;
+
+	type ReadGuard<'g> = L::ReadGuard<'g> where Self: 'g;
+
+	fn get_ptrs<'a>(&'a self, ptrs: &mut Vec<&'a dyn Lock>) {
+		ptrs.extend_from_slice(&self.locks);
+	}
+
+	unsafe fn guard(&self) -> Self::Guard<'_> {
+		self.data.guard()
+	}
+
+	unsafe fn read_guard(&self) -> Self::ReadGuard<'_> {
+		self.data.read_guard()
+	}
+}
+
+unsafe impl<'c, L: Sharable> Sharable for RefLockCollection<'c, L> {}
+
+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<'key, L::Guard<'a>, 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<'key, L::Guard<'a>, 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<'key, L::Guard<'a>, 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()
+	}
+}