Implement dummy Mutex, Condvar and RwLock

Author: devrandom

lightning/Cargo.toml

@@ -25,7 +25,11 @@ max_level_debug = []
 # This is unsafe to use in production because it may result in the counterparty publishing taking our funds.
 unsafe_revoked_tx_signing = []
 unstable = []
+
 no_std = ["hashbrown"]
+std = []
+
+default = ["std"]
 
 [dependencies]
 bitcoin = "0.26"

lightning/src/lib.rs

@@ -54,6 +54,10 @@ mod prelude {
 	pub use self::hashbrown::{HashMap, HashSet, hash_map};
 }
 
+#[cfg(feature = "std")]
 mod sync {
 	pub use ::std::sync::{Arc, Mutex, Condvar, MutexGuard, RwLock, RwLockReadGuard};
 }
+
+#[cfg(not(feature = "std"))]
+mod sync;

lightning/src/ln/channel.rs

@@ -46,6 +46,7 @@ use core::{cmp,mem,fmt};
 use core::ops::Deref;
 #[cfg(any(test, feature = "fuzztarget"))]
 use sync::Mutex;
+#[cfg(debug_assertions)]
 use sync;
 use bitcoin::hashes::hex::ToHex;
 use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0;

lightning/src/ln/channelmanager.rs

@@ -4959,6 +4959,7 @@ mod tests {
 	use ln::features::InitFeatures;
 	use ln::msgs::ChannelMessageHandler;
 
+	#[cfg(feature = "std")]
 	#[test]
 	fn test_wait_timeout() {
 		let persistence_notifier = Arc::new(PersistenceNotifier::new());

lightning/src/sync.rs

@@ -0,0 +1,115 @@
+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(())
+	}
+}