Comments

1 files changed, 44 insertions, 0 deletions

diff --git a/src/collection/utils.rs b/src/collection/utils.rs
new file mode 100644
index 0000000..dc58399
--- /dev/null
+++ b/src/collection/utils.rs
@@ -0,0 +1,44 @@
+use crate::lockable::RawLock;
+
+/// Locks the locks in the order they are given. This causes deadlock if the
+/// locks contain duplicates, or if this is called by multiple threads with the
+/// locks in different orders.
+pub unsafe fn ordered_try_lock(locks: &[&dyn RawLock]) -> bool {
+	unsafe {
+		for (i, lock) in locks.iter().enumerate() {
+			// safety: we have the thread key
+			let success = lock.try_lock();
+
+			if !success {
+				for lock in &locks[0..i] {
+					// safety: this lock was already acquired
+					lock.unlock();
+				}
+				return false;
+			}
+		}
+
+		true
+	}
+}
+
+/// Locks the locks in the order they are given. This causes deadlock f this is
+/// called by multiple threads with the locks in different orders.
+pub unsafe fn ordered_try_read(locks: &[&dyn RawLock]) -> bool {
+	unsafe {
+		for (i, lock) in locks.iter().enumerate() {
+			// safety: we have the thread key
+			let success = lock.try_read();
+
+			if !success {
+				for lock in &locks[0..i] {
+					// safety: this lock was already acquired
+					lock.unlock_read();
+				}
+				return false;
+			}
+		}
+
+		true
+	}
+}