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Diffstat (limited to 'src/collection/ref_collection.rs')
| -rw-r--r-- | src/collection/ref_collection.rs | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/src/collection/ref_collection.rs b/src/collection/ref_collection.rs new file mode 100644 index 0000000..3e4d5f8 --- /dev/null +++ b/src/collection/ref_collection.rs @@ -0,0 +1,245 @@ +use std::marker::PhantomData; + +use crate::{key::Keyable, lockable::Lock, Lockable, OwnedLockable}; + +use super::{LockGuard, RefLockCollection}; + +#[must_use] +fn get_locks<'a, L: Lockable<'a> + 'a>(data: &'a L) -> Vec<&'a 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<'a>> AsRef<L> for RefLockCollection<'a, L> { + fn as_ref(&self) -> &L { + self.data + } +} + +impl<'a, L: Lockable<'a>> AsRef<Self> for RefLockCollection<'a, L> { + fn as_ref(&self) -> &Self { + self + } +} + +impl<'a, L: Lockable<'a>> 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<'a> + 'a> 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<'a>> 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() + } +} |