+pub use ::alloc::sync::Arc;
+use core::ops::{Deref, DerefMut};
+use core::time::Duration;
+use core::cell::{RefCell, Ref, RefMut};
+
+pub type LockResult<Guard> = Result<Guard, ()>;
+
+pub struct Condvar {}
+
+impl Condvar {
+ pub fn new() -> Condvar {
+ Condvar { }
+ }
+
+ pub fn wait<'a, T>(&'a self, guard: MutexGuard<'a, T>) -> LockResult<MutexGuard<'a, T>> {
+ Ok(guard)
+ }
+
+ #[allow(unused)]
+ pub fn wait_timeout<'a, T>(&'a self, guard: MutexGuard<'a, T>, _dur: Duration) -> LockResult<(MutexGuard<'a, T>, ())> {
+ Ok((guard, ()))
+ }
+
+ pub fn notify_all(&self) {}
+}
+
+pub struct Mutex<T: ?Sized> {
+ inner: RefCell<T>
+}
+
+#[must_use = "if unused the Mutex will immediately unlock"]
+pub struct MutexGuard<'a, T: ?Sized + 'a> {
+ lock: RefMut<'a, T>,
+}
+
+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: RefCell::new(inner) }
+ }
+
+ pub fn lock<'a>(&'a self) -> LockResult<MutexGuard<'a, T>> {
+ Ok(MutexGuard { lock: self.inner.borrow_mut() })
+ }
+
+ pub fn try_lock<'a>(&'a self) -> LockResult<MutexGuard<'a, T>> {
+ Ok(MutexGuard { lock: self.inner.borrow_mut() })
+ }
+}
+
+pub struct RwLock<T: ?Sized> {
+ inner: RefCell<T>
+}
+
+pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
+ lock: Ref<'a, T>,
+}
+
+pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
+ lock: RefMut<'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: RefCell::new(inner) }
+ }
+
+ pub fn read<'a>(&'a self) -> LockResult<RwLockReadGuard<'a, T>> {
+ Ok(RwLockReadGuard { lock: self.inner.borrow() })
+ }
+
+ pub fn write<'a>(&'a self) -> LockResult<RwLockWriteGuard<'a, T>> {
+ Ok(RwLockWriteGuard { lock: self.inner.borrow_mut() })
+ }
+
+ pub fn try_write<'a>(&'a self) -> LockResult<RwLockWriteGuard<'a, T>> {
+ // There is no try, grasshopper - only used for tests and expected to fail
+ Err(())
+ }
+}