Add an operations section to ChannelManager docs

[rust-lightning] / lightning / src / sync / mod.rs

diff --git a/lightning/src/sync/mod.rs b/lightning/src/sync/mod.rs
index 584338031fc060bd5178a2321802767c5792101c..348bd90274ae1632b1cec63cf98e9249d9ac7425 100644 (file)
--- a/lightning/src/sync/mod.rs
+++ b/lightning/src/sync/mod.rs
@@ -1,9 +1,56 @@
-#[cfg(all(feature = "std", not(feature = "_bench_unstable"), test))]
-pub use crate::debug_sync::*;
-#[cfg(all(feature = "std", any(feature = "_bench_unstable", not(test))))]
-pub use ::std::sync::{Arc, Mutex, Condvar, MutexGuard, RwLock, RwLockReadGuard, RwLockWriteGuard};
-#[cfg(all(feature = "std", any(feature = "_bench_unstable", not(test))))]
-pub use crate::util::fairrwlock::FairRwLock;
+#[allow(dead_code)] // Depending on the compilation flags some variants are never used
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum LockHeldState {
+       HeldByThread,
+       NotHeldByThread,
+       #[cfg(any(ldk_bench, not(test)))]
+       Unsupported,
+}
+
+pub(crate) trait LockTestExt<'a> {
+       fn held_by_thread(&self) -> LockHeldState;
+       type ExclLock;
+       /// If two instances of the same mutex are being taken at the same time, it's very easy to have
+       /// a lockorder inversion and risk deadlock. Thus, we default to disabling such locks.
+       ///
+       /// However, sometimes they cannot be avoided. In such cases, this method exists to take a
+       /// mutex while avoiding a test failure. It is deliberately verbose and includes the term
+       /// "unsafe" to indicate that special care needs to be taken to ensure no deadlocks are
+       /// possible.
+       fn unsafe_well_ordered_double_lock_self(&'a self) -> Self::ExclLock;
+}
+
+#[cfg(all(feature = "std", not(ldk_bench), test))]
+mod debug_sync;
+#[cfg(all(feature = "std", not(ldk_bench), test))]
+pub use debug_sync::*;
+#[cfg(all(feature = "std", not(ldk_bench), test))]
+// Note that to make debug_sync's regex work this must not contain `debug_string` in the module name
+mod test_lockorder_checks;
+
+#[cfg(all(feature = "std", any(ldk_bench, not(test))))]
+pub(crate) mod fairrwlock;
+#[cfg(all(feature = "std", any(ldk_bench, not(test))))]
+pub use {std::sync::{Arc, Mutex, Condvar, MutexGuard, RwLock, RwLockReadGuard, RwLockWriteGuard}, fairrwlock::FairRwLock};
+
+#[cfg(all(feature = "std", any(ldk_bench, not(test))))]
+mod ext_impl {
+       use super::*;
+       impl<'a, T: 'a> LockTestExt<'a> for Mutex<T> {
+               #[inline]
+               fn held_by_thread(&self) -> LockHeldState { LockHeldState::Unsupported }
+               type ExclLock = MutexGuard<'a, T>;
+               #[inline]
+               fn unsafe_well_ordered_double_lock_self(&'a self) -> MutexGuard<T> { self.lock().unwrap() }
+       }
+       impl<'a, T: 'a> LockTestExt<'a> for RwLock<T> {
+               #[inline]
+               fn held_by_thread(&self) -> LockHeldState { LockHeldState::Unsupported }
+               type ExclLock = RwLockWriteGuard<'a, T>;
+               #[inline]
+               fn unsafe_well_ordered_double_lock_self(&'a self) -> RwLockWriteGuard<T> { self.write().unwrap() }
+       }
+}
 
 #[cfg(not(feature = "std"))]
 mod nostd_sync;