bee_runtime/
resource.rs

1// Copyright 2020-2021 IOTA Stiftung
2// SPDX-License-Identifier: Apache-2.0
3
4//! Types that allow access to and management of node resources.
5
6use std::{
7    any::{type_name, Any},
8    collections::HashMap,
9    ops::Deref,
10    panic::Location,
11    sync::{
12        atomic::{AtomicUsize, Ordering},
13        Arc, Mutex, Weak,
14    },
15};
16
17use log::warn;
18
19static RESOURCE_ID: AtomicUsize = AtomicUsize::new(0);
20
21/// An owning handle to a node resource.
22pub struct ResourceHandle<R> {
23    id: Option<usize>,
24    inner: Arc<(R, Mutex<HashMap<usize, &'static Location<'static>>>)>,
25}
26
27impl<R> ResourceHandle<R> {
28    /// Wrap the given resource into a [`ResourceHandle`], providing shared immutable access to it.
29    pub fn new(res: R) -> Self {
30        Self {
31            id: None,
32            inner: Arc::new((res, Mutex::new(HashMap::new()))),
33        }
34    }
35
36    /// Turn this owned resource handle into a weak non-owning handle.
37    pub fn into_weak(self) -> WeakHandle<R> {
38        let inner = Arc::downgrade(&self.inner);
39        drop(self);
40        WeakHandle { inner }
41    }
42
43    /// Attempt to gain ownership over the resource, returning `None` if the resource is still in use.
44    pub fn try_unwrap(self) -> Option<R>
45    where
46        R: Any,
47    {
48        let inner = self.inner.clone();
49        drop(self);
50        match Arc::try_unwrap(inner) {
51            Ok((res, _)) => Some(res),
52            Err(inner) => {
53                let usages = inner
54                    .1
55                    .lock()
56                    .unwrap()
57                    .values()
58                    .fold(String::new(), |s, loc| format!("{}\n- {}", s, loc));
59                warn!(
60                    "Attempted to gain ownership resource `{}` but it is still being used. This is not, by itself, a \
61                    problem but may indicate that a node task or event listener is not being stopped at the \
62                    appropriate time during the shutdown process. Using arcane magic, we determined that the resource \
63                    is still being used in the following places: {}",
64                    type_name::<R>(),
65                    usages,
66                );
67                None
68            }
69        }
70    }
71}
72
73impl<R> Clone for ResourceHandle<R> {
74    #[track_caller]
75    fn clone(&self) -> Self {
76        let new_id = RESOURCE_ID.fetch_add(1, Ordering::Relaxed);
77        self.inner.1.lock().unwrap().insert(new_id, Location::caller());
78        Self {
79            id: Some(new_id),
80            inner: self.inner.clone(),
81        }
82    }
83}
84
85impl<R> Deref for ResourceHandle<R> {
86    type Target = R;
87
88    fn deref(&self) -> &Self::Target {
89        &self.inner.0
90    }
91}
92
93impl<R> Drop for ResourceHandle<R> {
94    fn drop(&mut self) {
95        if let Some(id) = self.id {
96            self.inner.1.lock().unwrap().remove(&id);
97        }
98    }
99}
100
101/// An non-owning handle to a node resource.
102pub struct WeakHandle<R> {
103    inner: Weak<(R, Mutex<HashMap<usize, &'static Location<'static>>>)>,
104}
105
106impl<R> WeakHandle<R> {
107    /// Attempt to turn this owned resource handle into a weak non-owning handle, if it still exists.
108    #[track_caller]
109    pub fn upgrade(&self) -> Option<ResourceHandle<R>> {
110        let new_id = RESOURCE_ID.fetch_add(1, Ordering::Relaxed);
111        let inner = self.inner.upgrade()?;
112        inner.1.lock().unwrap().insert(new_id, Location::caller());
113        Some(ResourceHandle {
114            id: Some(new_id),
115            inner,
116        })
117    }
118}
119
120impl<R> Clone for WeakHandle<R> {
121    fn clone(&self) -> Self {
122        Self {
123            inner: self.inner.clone(),
124        }
125    }
126}
bee_runtime/resource.rs

bee_runtime/
resource.rs
