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use log::warn;
use std::{
any::{type_name, Any},
collections::HashMap,
ops::Deref,
panic::Location,
sync::{
atomic::{AtomicUsize, Ordering},
Arc, Mutex, Weak,
},
};
static RESOURCE_ID: AtomicUsize = AtomicUsize::new(0);
pub struct ResourceHandle<R> {
id: Option<usize>,
inner: Arc<(R, Mutex<HashMap<usize, &'static Location<'static>>>)>,
}
impl<R> ResourceHandle<R> {
pub fn new(res: R) -> Self {
Self {
id: None,
inner: Arc::new((res, Mutex::new(HashMap::new()))),
}
}
pub fn into_weak(self) -> WeakHandle<R> {
let inner = Arc::downgrade(&self.inner);
drop(self);
WeakHandle { inner }
}
pub fn try_unwrap(self) -> Option<R>
where
R: Any,
{
let inner = self.inner.clone();
drop(self);
match Arc::try_unwrap(inner) {
Ok((res, _)) => Some(res),
Err(inner) => {
let usages = inner
.1
.lock()
.unwrap()
.values()
.fold(String::new(), |s, loc| format!("{}\n- {}", s, loc));
warn!(
"Attempted to gain ownership resource `{}` but it is still being used. This is not, by itself, a \
problem but may indicate that a node task or event listener is not being stopped at the \
appropriate time during the shutdown process. Using arcane magic, we determined that the resource \
is still being used in the following places: {}",
type_name::<R>(),
usages,
);
None
}
}
}
}
impl<R> Clone for ResourceHandle<R> {
#[track_caller]
fn clone(&self) -> Self {
let new_id = RESOURCE_ID.fetch_add(1, Ordering::Relaxed);
self.inner.1.lock().unwrap().insert(new_id, Location::caller());
Self {
id: Some(new_id),
inner: self.inner.clone(),
}
}
}
impl<R> Deref for ResourceHandle<R> {
type Target = R;
fn deref(&self) -> &Self::Target {
&self.inner.0
}
}
impl<R> Drop for ResourceHandle<R> {
fn drop(&mut self) {
if let Some(id) = self.id {
self.inner.1.lock().unwrap().remove(&id);
}
}
}
pub struct WeakHandle<R> {
inner: Weak<(R, Mutex<HashMap<usize, &'static Location<'static>>>)>,
}
impl<R> WeakHandle<R> {
#[track_caller]
pub fn upgrade(&self) -> Option<ResourceHandle<R>> {
let new_id = RESOURCE_ID.fetch_add(1, Ordering::Relaxed);
let inner = self.inner.upgrade()?;
inner.1.lock().unwrap().insert(new_id, Location::caller());
Some(ResourceHandle {
id: Some(new_id),
inner,
})
}
}
impl<R> Clone for WeakHandle<R> {
fn clone(&self) -> Self {
Self {
inner: self.inner.clone(),
}
}
}