Merge commit 'ddf105b646' into sync-from-ra

crates/salsa/tests/parallel/parallel_cycle_none_recover.rs

@@ -0,0 +1,69 @@
+//! Test a cycle where no queries recover that occurs across threads.
+//! See the `../cycles.rs` for a complete listing of cycle tests,
+//! both intra and cross thread.
+
+use crate::setup::{Knobs, ParDatabaseImpl};
+use expect_test::expect;
+use salsa::ParallelDatabase;
+use test_log::test;
+
+#[test]
+fn parallel_cycle_none_recover() {
+    let db = ParDatabaseImpl::default();
+    db.knobs().signal_on_will_block.set(3);
+
+    let thread_a = std::thread::spawn({
+        let db = db.snapshot();
+        move || db.a(-1)
+    });
+
+    let thread_b = std::thread::spawn({
+        let db = db.snapshot();
+        move || db.b(-1)
+    });
+
+    // We expect B to panic because it detects a cycle (it is the one that calls A, ultimately).
+    // Right now, it panics with a string.
+    let err_b = thread_b.join().unwrap_err();
+    if let Some(c) = err_b.downcast_ref::<salsa::Cycle>() {
+        expect![[r#"
+            [
+                "a(-1)",
+                "b(-1)",
+            ]
+        "#]]
+        .assert_debug_eq(&c.unexpected_participants(&db));
+    } else {
+        panic!("b failed in an unexpected way: {:?}", err_b);
+    }
+
+    // We expect A to propagate a panic, which causes us to use the sentinel
+    // type `Canceled`.
+    assert!(thread_a.join().unwrap_err().downcast_ref::<salsa::Cycle>().is_some());
+}
+
+#[salsa::query_group(ParallelCycleNoneRecover)]
+pub(crate) trait TestDatabase: Knobs {
+    fn a(&self, key: i32) -> i32;
+    fn b(&self, key: i32) -> i32;
+}
+
+fn a(db: &dyn TestDatabase, key: i32) -> i32 {
+    // Wait to create the cycle until both threads have entered
+    db.signal(1);
+    db.wait_for(2);
+
+    db.b(key)
+}
+
+fn b(db: &dyn TestDatabase, key: i32) -> i32 {
+    // Wait to create the cycle until both threads have entered
+    db.wait_for(1);
+    db.signal(2);
+
+    // Wait for thread A to block on this thread
+    db.wait_for(3);
+
+    // Now try to execute A
+    db.a(key)
+}