use std::fmt::Debug;
use std::marker::PhantomData;
use crate::lockable::{Lockable, OwnedLockable, RawLock, Sharable};
use crate::Keyable;
use super::{utils, LockGuard, RefLockCollection};
#[must_use]
pub fn get_locks<L: Lockable>(data: &L) -> Vec<&dyn RawLock> {
let mut locks = Vec::new();
data.get_ptrs(&mut locks);
locks.sort_by_key(|lock| *lock as *const dyn RawLock);
locks
}
/// returns `true` if the sorted list contains a duplicate
#[must_use]
fn contains_duplicates(l: &[&dyn RawLock]) -> bool {
if l.is_empty() {
// Return early to prevent panic in the below call to `windows`
return false;
}
l.windows(2)
.any(|window| std::ptr::eq(window[0], window[1]))
}
impl<L> AsRef<L> for RefLockCollection<'_, L> {
fn as_ref(&self) -> &L {
self.data
}
}
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<L: Lockable + Send + Sync> RawLock for RefLockCollection<'_, L> {
unsafe fn lock(&self) {
for lock in &self.locks {
lock.lock();
}
}
unsafe fn try_lock(&self) -> bool {
utils::ordered_try_lock(&self.locks)
}
unsafe fn unlock(&self) {
for lock in &self.locks {
lock.unlock();
}
}
unsafe fn read(&self) {
for lock in &self.locks {
lock.read();
}
}
unsafe fn try_read(&self) -> bool {
utils::ordered_try_read(&self.locks)
}
unsafe fn unlock_read(&self) {
for lock in &self.locks {
lock.unlock_read();
}
}
}
unsafe impl<L: Lockable> Lockable for RefLockCollection<'_, 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 RawLock>) {
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<L: Sharable> Sharable for RefLockCollection<'_, L> {}
impl<L: Debug> Debug for RefLockCollection<'_, L> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct(stringify!(RefLockCollection))
.field("data", self.data)
.finish_non_exhaustive()
}
}
impl<'a, L: OwnedLockable + Default> From<&'a L> for RefLockCollection<'a, L> {
fn from(value: &'a L) -> Self {
Self::new(value)
}
}
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::Mutex;
/// use happylock::collection::RefLockCollection;
///
/// let data = (Mutex::new(0), Mutex::new(""));
/// let lock = RefLockCollection::new(&data);
/// ```
#[must_use]
pub fn new(data: &'a L) -> Self {
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::Mutex;
/// use happylock::collection::RefLockCollection;
///
/// let data1 = Mutex::new(0);
/// let data2 = Mutex::new("");
///
/// // safety: data1 and data2 refer to distinct mutexes
/// let data = (&data1, &data2);
/// let lock = unsafe { RefLockCollection::new_unchecked(&data) };
/// ```
#[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::Mutex;
/// use happylock::collection::RefLockCollection;
///
/// let data1 = Mutex::new(0);
/// let data2 = Mutex::new("");
///
/// // data1 and data2 refer to distinct mutexes, so this won't panic
/// let data = (&data1, &data2);
/// let lock = RefLockCollection::try_new(&data).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 { data, locks })
}
/// 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::{Mutex, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (Mutex::new(0), Mutex::new(""));
/// let lock = RefLockCollection::new(&data);
///
/// 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::{Mutex, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (Mutex::new(0), Mutex::new(""));
/// let lock = RefLockCollection::new(&data);
///
/// 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 {
if !utils::ordered_try_lock(&self.locks) {
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::{Mutex, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (Mutex::new(0), Mutex::new(""));
/// let lock = RefLockCollection::new(&data);
///
/// let mut guard = lock.lock(key);
/// *guard.0 += 1;
/// *guard.1 = "1";
/// let key = RefLockCollection::<(Mutex<i32>, Mutex<&str>)>::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: Sharable> RefLockCollection<'a, L> {
/// Locks the collection, so that other threads can still read from it
///
/// This function returns a guard that can be used to access the underlying
/// data immutably. When the guard is dropped, the locks in the collection
/// are also dropped.
///
/// # Examples
///
/// ```
/// use happylock::{RwLock, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (RwLock::new(0), RwLock::new(""));
/// let lock = RefLockCollection::new(&data);
///
/// let mut guard = lock.read(key);
/// assert_eq!(*guard.0, 0);
/// assert_eq!(*guard.1, "");
/// ```
pub fn read<'key: 'a, Key: Keyable + 'key>(
&'a self,
key: Key,
) -> LockGuard<'key, L::ReadGuard<'a>, Key> {
for lock in &self.locks {
// safety: we have the thread key
unsafe { lock.read() };
}
LockGuard {
// safety: we've already acquired the lock
guard: unsafe { self.data.read_guard() },
key,
_phantom: PhantomData,
}
}
/// Attempts to lock the without blocking, in such a way that other threads
/// can still read from the collection.
///
/// If successful, this method returns a guard that can be used to access
/// the data immutably, and unlocks the data when it is dropped. Otherwise,
/// `None` is returned.
///
/// # Examples
///
/// ```
/// use happylock::{RwLock, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (RwLock::new(5), RwLock::new("6"));
/// let lock = RefLockCollection::new(&data);
///
/// match lock.try_read(key) {
/// Some(mut guard) => {
/// assert_eq!(*guard.0, 5);
/// assert_eq!(*guard.1, "6");
/// },
/// None => unreachable!(),
/// };
///
/// ```
pub fn try_read<'key: 'a, Key: Keyable + 'key>(
&'a self,
key: Key,
) -> Option<LockGuard<'key, L::ReadGuard<'a>, Key>> {
let guard = unsafe {
if !utils::ordered_try_read(&self.locks) {
return None;
}
// safety: we've acquired the locks
self.data.read_guard()
};
Some(LockGuard {
guard,
key,
_phantom: PhantomData,
})
}
/// Unlocks the underlying lockable data type, returning the key that's
/// associated with it.
///
/// # Examples
///
/// ```
/// use happylock::{RwLock, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = (RwLock::new(0), RwLock::new(""));
/// let lock = RefLockCollection::new(&data);
///
/// let mut guard = lock.read(key);
/// let key = RefLockCollection::<(RwLock<i32>, RwLock<&str>)>::unlock_read(guard);
/// ```
#[allow(clippy::missing_const_for_fn)]
pub fn unlock_read<'key: 'a, Key: Keyable + 'key>(
guard: LockGuard<'key, L::ReadGuard<'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.
///
/// # Examples
///
/// ```
/// use happylock::{Mutex, ThreadKey};
/// use happylock::collection::RefLockCollection;
///
/// let key = ThreadKey::get().unwrap();
/// let data = [Mutex::new(26), Mutex::new(1)];
/// let lock = RefLockCollection::new(&data);
///
/// let mut iter = lock.iter();
/// let mutex = iter.next().unwrap();
/// let guard = mutex.lock(key);
///
/// assert_eq!(*guard, 26);
/// ```
#[must_use]
pub fn iter(&'a self) -> <&'a L as IntoIterator>::IntoIter {
self.into_iter()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{Mutex, ThreadKey};
#[test]
fn non_duplicates_allowed() {
let mutex1 = Mutex::new(0);
let mutex2 = Mutex::new(1);
assert!(RefLockCollection::try_new(&[&mutex1, &mutex2]).is_some())
}
#[test]
fn duplicates_not_allowed() {
let mutex1 = Mutex::new(0);
assert!(RefLockCollection::try_new(&[&mutex1, &mutex1]).is_none())
}
#[test]
fn works_in_collection() {
let key = ThreadKey::get().unwrap();
let mutex1 = Mutex::new(0);
let mutex2 = Mutex::new(1);
let collection0 = [&mutex1, &mutex2];
let collection1 = RefLockCollection::try_new(&collection0).unwrap();
let collection = RefLockCollection::try_new(&collection1).unwrap();
let guard = collection.lock(key);
assert!(mutex1.is_locked());
assert!(mutex2.is_locked());
drop(guard);
}
}
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