use std::marker::PhantomData;
use crate::{lockable::Lock, Keyable, Lockable, OwnedLockable};
use super::{LockGuard, RetryingLockCollection};
fn contains_duplicates<L: Lockable>(data: L) -> bool {
let mut locks = Vec::new();
data.get_ptrs(&mut locks);
let mut locks: Vec<_> = locks.into_iter().map(|l| l as *const dyn Lock).collect();
locks.sort_unstable();
locks.windows(2).any(|w| std::ptr::addr_eq(w[0], w[1]))
}
impl<L: OwnedLockable> RetryingLockCollection<L> {
#[must_use]
pub const fn new(data: L) -> Self {
Self { data }
}
}
impl<'a, L: OwnedLockable> RetryingLockCollection<&'a L> {
#[must_use]
pub const fn new_ref(data: &'a L) -> Self {
Self { data }
}
}
impl<L: Lockable> RetryingLockCollection<L> {
#[must_use]
pub const unsafe fn new_unchecked(data: L) -> Self {
Self { data }
}
pub fn try_new(data: L) -> Option<Self> {
contains_duplicates(&data).then_some(Self { data })
}
pub fn lock<'a, 'key: 'a, Key: Keyable + 'key>(
&'a self,
key: Key,
) -> LockGuard<'a, 'key, L, Key> {
let mut first_index = 0;
let mut locks = Vec::new();
self.data.get_ptrs(&mut locks);
if locks.is_empty() {
return LockGuard {
// safety: there's no data being returned
guard: unsafe { self.data.guard() },
key,
_phantom: PhantomData,
};
}
let guard = unsafe {
'outer: loop {
// safety: we have the thread key
locks[first_index].lock();
for (i, lock) in locks.iter().enumerate() {
if i == first_index {
continue;
}
// safety: we have the thread key
if !lock.try_lock() {
for lock in locks.iter().take(i) {
// safety: we already locked all of these
lock.unlock();
}
if first_index >= i {
// safety: this is already locked and can't be unlocked
// by the previous loop
locks[first_index].unlock();
}
first_index = i;
continue 'outer;
}
}
// safety: we locked all the data
break self.data.guard();
}
};
LockGuard {
guard,
key,
_phantom: PhantomData,
}
}
pub fn try_lock<'a, 'key: 'a, Key: Keyable + 'key>(
&'a self,
key: Key,
) -> Option<LockGuard<'a, 'key, L, Key>> {
let mut locks = Vec::new();
self.data.get_ptrs(&mut locks);
if locks.is_empty() {
return Some(LockGuard {
// safety: there's no data being returned
guard: unsafe { self.data.guard() },
key,
_phantom: PhantomData,
});
}
let guard = unsafe {
for (i, lock) in locks.iter().enumerate() {
// safety: we have the thread key
if !lock.try_lock() {
for lock in locks.iter().take(i) {
// safety: we already locked all of these
lock.unlock();
}
return None;
}
}
// safety: we locked all the data
self.data.guard()
};
Some(LockGuard {
guard,
key,
_phantom: PhantomData,
})
}
pub fn unlock<'key, Key: Keyable + 'key>(guard: LockGuard<'_, 'key, L, Key>) -> Key {
drop(guard.guard);
guard.key
}
}
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