--- /dev/null
+pub use ::alloc::sync::Arc;
+use core::ops::{Deref, DerefMut};
+use core::time::Duration;
+
+use std::collections::HashSet;
+use std::cell::RefCell;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use std::sync::Mutex as StdMutex;
+use std::sync::MutexGuard as StdMutexGuard;
+use std::sync::RwLock as StdRwLock;
+use std::sync::RwLockReadGuard as StdRwLockReadGuard;
+use std::sync::RwLockWriteGuard as StdRwLockWriteGuard;
+use std::sync::Condvar as StdCondvar;
+
+#[cfg(feature = "backtrace")]
+use backtrace::Backtrace;
+
+pub type LockResult<Guard> = Result<Guard, ()>;
+
+pub struct Condvar {
+ inner: StdCondvar,
+}
+
+impl Condvar {
+ pub fn new() -> Condvar {
+ Condvar { inner: StdCondvar::new() }
+ }
+
+ pub fn wait<'a, T>(&'a self, guard: MutexGuard<'a, T>) -> LockResult<MutexGuard<'a, T>> {
+ let mutex: &'a Mutex<T> = guard.mutex;
+ self.inner.wait(guard.into_inner()).map(|lock| MutexGuard { mutex, lock }).map_err(|_| ())
+ }
+
+ #[allow(unused)]
+ pub fn wait_timeout<'a, T>(&'a self, guard: MutexGuard<'a, T>, dur: Duration) -> LockResult<(MutexGuard<'a, T>, ())> {
+ let mutex = guard.mutex;
+ self.inner.wait_timeout(guard.into_inner(), dur).map(|(lock, _)| (MutexGuard { mutex, lock }, ())).map_err(|_| ())
+ }
+
+ pub fn notify_all(&self) { self.inner.notify_all(); }
+}
+
+thread_local! {
+ /// We track the set of locks currently held by a reference to their `MutexMetadata`
+ static MUTEXES_HELD: RefCell<HashSet<Arc<MutexMetadata>>> = RefCell::new(HashSet::new());
+}
+static MUTEX_IDX: AtomicUsize = AtomicUsize::new(0);
+
+/// Metadata about a single mutex, by id, the set of things locked-before it, and the backtrace of
+/// when the Mutex itself was constructed.
+struct MutexMetadata {
+ mutex_idx: u64,
+ locked_before: StdMutex<HashSet<Arc<MutexMetadata>>>,
+ #[cfg(feature = "backtrace")]
+ mutex_construction_bt: Backtrace,
+}
+impl PartialEq for MutexMetadata {
+ fn eq(&self, o: &MutexMetadata) -> bool { self.mutex_idx == o.mutex_idx }
+}
+impl Eq for MutexMetadata {}
+impl std::hash::Hash for MutexMetadata {
+ fn hash<H: std::hash::Hasher>(&self, hasher: &mut H) { hasher.write_u64(self.mutex_idx); }
+}
+
+pub struct Mutex<T: Sized> {
+ inner: StdMutex<T>,
+ deps: Arc<MutexMetadata>,
+}
+
+#[must_use = "if unused the Mutex will immediately unlock"]
+pub struct MutexGuard<'a, T: Sized + 'a> {
+ mutex: &'a Mutex<T>,
+ lock: StdMutexGuard<'a, T>,
+}
+
+impl<'a, T: Sized> MutexGuard<'a, T> {
+ fn into_inner(self) -> StdMutexGuard<'a, T> {
+ // Somewhat unclear why we cannot move out of self.lock, but doing so gets E0509.
+ unsafe {
+ let v: StdMutexGuard<'a, T> = std::ptr::read(&self.lock);
+ std::mem::forget(self);
+ v
+ }
+ }
+}
+
+impl<T: Sized> Drop for MutexGuard<'_, T> {
+ fn drop(&mut self) {
+ MUTEXES_HELD.with(|held| {
+ held.borrow_mut().remove(&self.mutex.deps);
+ });
+ }
+}
+
+impl<T: Sized> Deref for MutexGuard<'_, T> {
+ type Target = T;
+
+ fn deref(&self) -> &T {
+ &self.lock.deref()
+ }
+}
+
+impl<T: Sized> DerefMut for MutexGuard<'_, T> {
+ fn deref_mut(&mut self) -> &mut T {
+ self.lock.deref_mut()
+ }
+}
+
+impl<T> Mutex<T> {
+ pub fn new(inner: T) -> Mutex<T> {
+ Mutex {
+ inner: StdMutex::new(inner),
+ deps: Arc::new(MutexMetadata {
+ locked_before: StdMutex::new(HashSet::new()),
+ mutex_idx: MUTEX_IDX.fetch_add(1, Ordering::Relaxed) as u64,
+ #[cfg(feature = "backtrace")]
+ mutex_construction_bt: Backtrace::new(),
+ }),
+ }
+ }
+
+ pub fn lock<'a>(&'a self) -> LockResult<MutexGuard<'a, T>> {
+ MUTEXES_HELD.with(|held| {
+ // For each mutex which is currently locked, check that no mutex's locked-before
+ // set includes the mutex we're about to lock, which would imply a lockorder
+ // inversion.
+ for locked in held.borrow().iter() {
+ for locked_dep in locked.locked_before.lock().unwrap().iter() {
+ if *locked_dep == self.deps {
+ #[cfg(feature = "backtrace")]
+ panic!("Tried to violate existing lockorder.\nMutex that should be locked after the current lock was created at the following backtrace.\nNote that to get a backtrace for the lockorder violation, you should set RUST_BACKTRACE=1\n{:?}", locked.mutex_construction_bt);
+ #[cfg(not(feature = "backtrace"))]
+ panic!("Tried to violate existing lockorder. Build with the backtrace feature for more info.");
+ }
+ }
+ // Insert any already-held mutexes in our locked-before set.
+ self.deps.locked_before.lock().unwrap().insert(Arc::clone(locked));
+ }
+ held.borrow_mut().insert(Arc::clone(&self.deps));
+ });
+ self.inner.lock().map(|lock| MutexGuard { mutex: self, lock }).map_err(|_| ())
+ }
+
+ pub fn try_lock<'a>(&'a self) -> LockResult<MutexGuard<'a, T>> {
+ let res = self.inner.try_lock().map(|lock| MutexGuard { mutex: self, lock }).map_err(|_| ());
+ if res.is_ok() {
+ MUTEXES_HELD.with(|held| {
+ // Since a try-lock will simply fail if the lock is held already, we do not
+ // consider try-locks to ever generate lockorder inversions. However, if a try-lock
+ // succeeds, we do consider it to have created lockorder dependencies.
+ for locked in held.borrow().iter() {
+ self.deps.locked_before.lock().unwrap().insert(Arc::clone(locked));
+ }
+ held.borrow_mut().insert(Arc::clone(&self.deps));
+ });
+ }
+ res
+ }
+}
+
+pub struct RwLock<T: ?Sized> {
+ inner: StdRwLock<T>
+}
+
+pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
+ lock: StdRwLockReadGuard<'a, T>,
+}
+
+pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
+ lock: StdRwLockWriteGuard<'a, T>,
+}
+
+impl<T: ?Sized> Deref for RwLockReadGuard<'_, T> {
+ type Target = T;
+
+ fn deref(&self) -> &T {
+ &self.lock.deref()
+ }
+}
+
+impl<T: ?Sized> Deref for RwLockWriteGuard<'_, T> {
+ type Target = T;
+
+ fn deref(&self) -> &T {
+ &self.lock.deref()
+ }
+}
+
+impl<T: ?Sized> DerefMut for RwLockWriteGuard<'_, T> {
+ fn deref_mut(&mut self) -> &mut T {
+ self.lock.deref_mut()
+ }
+}
+
+impl<T> RwLock<T> {
+ pub fn new(inner: T) -> RwLock<T> {
+ RwLock { inner: StdRwLock::new(inner) }
+ }
+
+ pub fn read<'a>(&'a self) -> LockResult<RwLockReadGuard<'a, T>> {
+ self.inner.read().map(|lock| RwLockReadGuard { lock }).map_err(|_| ())
+ }
+
+ pub fn write<'a>(&'a self) -> LockResult<RwLockWriteGuard<'a, T>> {
+ self.inner.write().map(|lock| RwLockWriteGuard { lock }).map_err(|_| ())
+ }
+
+ pub fn try_write<'a>(&'a self) -> LockResult<RwLockWriteGuard<'a, T>> {
+ self.inner.try_write().map(|lock| RwLockWriteGuard { lock }).map_err(|_| ())
+ }
+}
projects / rust-lightning / commitdiff