WIP make loom work in tokio-util

tokio-util/Cargo.toml

@@ -58,6 +58,9 @@ futures-test = "0.3.5"
 parking_lot = "0.12.0"
 tempfile = "3.1.0"
 
+[target.'cfg(loom)'.dev-dependencies]
+loom = { version = "0.5.2", features = ["futures", "checkpoint"] }
+
 [package.metadata.docs.rs]
 all-features = true
 # enable unstable features in the documentation

tokio-util/src/either.rs

@@ -164,7 +164,7 @@ where
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(loom)))]
 mod tests {
     use super::*;
     use tokio::io::{repeat, AsyncReadExt, Repeat};

tokio-util/src/loom.rs

@@ -1 +1,5 @@
+#[cfg(not(loom))]
 pub(crate) use std::sync;
+
+#[cfg(loom)]
+pub(crate) use loom::sync;

tokio-util/src/sync/cancellation_token/tree_node.rs

@@ -298,12 +298,15 @@ pub(crate) fn cancel(node: &Arc<TreeNode>) {
     if locked_node.is_cancelled {
         return;
     }
+    println!("a");
 
     // One by one, adopt grandchildren and then cancel and detach the child
     while let Some(child) = locked_node.children.pop() {
+        println!("b1");
         // This can't deadlock because the mutex we are already
         // holding is the parent of child.
         let mut locked_child = child.inner.lock().unwrap();
+        println!("b2");
 
         // Detach the child from node
         // No need to modify node.children, as the child already got removed with `.pop`
@@ -356,10 +359,12 @@ pub(crate) fn cancel(node: &Arc<TreeNode>) {
         // Now the child is cancelled and detached and all its children are adopted.
         // Just continue until all (including adopted) children are cancelled and detached.
     }
+    println!("c");
 
     // Cancel the node itself.
     locked_node.is_cancelled = true;
     locked_node.children = Vec::new();
     drop(locked_node);
     node.waker.notify_waiters();
+    println!("d");
 }

tokio-util/src/sync/mod.rs

@@ -13,3 +13,6 @@ pub use poll_semaphore::PollSemaphore;
 
 mod reusable_box;
 pub use reusable_box::ReusableBoxFuture;
+
+#[cfg(loom)]
+mod tests;

tokio-util/src/sync/tests/loom_cancellation_token.rs

@@ -48,6 +48,7 @@ fn cancel_token_owned() {
 #[test]
 fn cancel_with_child() {
     loom::model(|| {
+        println!("FOO");
         let token = CancellationToken::new();
         let token1 = token.clone();
         let token2 = token.clone();
@@ -153,20 +154,27 @@ fn drop_and_cancel_token() {
 #[test]
 fn cancel_parent_and_child() {
     loom::model(|| {
+        println!("FOO");
         let token1 = CancellationToken::new();
         let token2 = token1.clone();
         let child_token = token1.child_token();
 
         let th1 = thread::spawn(move || {
+            println!("drop parent");
             drop(token1);
+            println!("drop parent done");
         });
 
         let th2 = thread::spawn(move || {
+            println!("cancel parent");
             token2.cancel();
+            println!("cancel parent done");
         });
 
         let th3 = thread::spawn(move || {
+            println!("cancel child");
             child_token.cancel();
+            println!("cancel child done");
         });
 
         assert_ok!(th1.join());

tokio-util/src/sync/tests/mod.rs

@@ -1 +1 @@
-
+mod loom_cancellation_token;