Fix accumulator only accumulating direct children

src/function/accumulated.rs

@@ -1,4 +1,4 @@
-use crate::{accumulator, storage::DatabaseGen, Id};
+use crate::{accumulator, hash::FxHashSet, storage::DatabaseGen, DatabaseKeyIndex, Id};
 
 use super::{Configuration, IngredientImpl};
 
@@ -21,14 +21,24 @@ where
         // First ensure the result is up to date
         self.fetch(db, key);
 
-        let database_key_index = self.database_key_index(key);
-        accumulator.produced_by(runtime, database_key_index, &mut output);
+        let db_key = self.database_key_index(key);
+        let mut visited: FxHashSet<DatabaseKeyIndex> = FxHashSet::default();
+        let mut stack: Vec<DatabaseKeyIndex> = vec![db_key];
 
-        if let Some(origin) = self.origin(key) {
-            for input in origin.inputs() {
-                if let Ok(input) = input.try_into() {
-                    accumulator.produced_by(runtime, input, &mut output);
-                }
+        while let Some(k) = stack.pop() {
+            if visited.insert(k) {
+                accumulator.produced_by(runtime, k, &mut output);
+
+                let origin = db.lookup_ingredient(k.ingredient_index).origin(k.key_index);
+                let inputs = origin.iter().flat_map(|origin| origin.inputs());
+                // Careful: we want to push in execution order, so reverse order to
+                // ensure the first child that was executed will be the first child popped
+                // from the stack.
+                stack.extend(
+                    inputs
+                        .flat_map(|input| TryInto::<DatabaseKeyIndex>::try_into(input).into_iter())
+                        .rev(),
+                );
             }
         }
 

src/runtime/local_state.rs

@@ -77,7 +77,7 @@ pub enum QueryOrigin {
 
 impl QueryOrigin {
     /// Indices for queries *read* by this query
-    pub(crate) fn inputs(&self) -> impl Iterator<Item = DependencyIndex> + '_ {
+    pub(crate) fn inputs(&self) -> impl DoubleEndedIterator<Item = DependencyIndex> + '_ {
         let opt_edges = match self {
             QueryOrigin::Derived(edges) | QueryOrigin::DerivedUntracked(edges) => Some(edges),
             QueryOrigin::Assigned(_) | QueryOrigin::BaseInput => None,
@@ -86,7 +86,7 @@ impl QueryOrigin {
     }
 
     /// Indices for queries *written* by this query (if any)
-    pub(crate) fn outputs(&self) -> impl Iterator<Item = DependencyIndex> + '_ {
+    pub(crate) fn outputs(&self) -> impl DoubleEndedIterator<Item = DependencyIndex> + '_ {
         let opt_edges = match self {
             QueryOrigin::Derived(edges) | QueryOrigin::DerivedUntracked(edges) => Some(edges),
             QueryOrigin::Assigned(_) | QueryOrigin::BaseInput => None,
@@ -127,7 +127,7 @@ impl QueryEdges {
     /// Returns the (tracked) inputs that were executed in computing this memoized value.
     ///
     /// These will always be in execution order.
-    pub(crate) fn inputs(&self) -> impl Iterator<Item = DependencyIndex> + '_ {
+    pub(crate) fn inputs(&self) -> impl DoubleEndedIterator<Item = DependencyIndex> + '_ {
         self.input_outputs
             .iter()
             .filter(|(edge_kind, _)| *edge_kind == EdgeKind::Input)
@@ -137,7 +137,7 @@ impl QueryEdges {
     /// Returns the (tracked) outputs that were executed in computing this memoized value.
     ///
     /// These will always be in execution order.
-    pub(crate) fn outputs(&self) -> impl Iterator<Item = DependencyIndex> + '_ {
+    pub(crate) fn outputs(&self) -> impl DoubleEndedIterator<Item = DependencyIndex> + '_ {
         self.input_outputs
             .iter()
             .filter(|(edge_kind, _)| *edge_kind == EdgeKind::Output)

tests/accumulate-chain.rs

@@ -0,0 +1,57 @@
+//! Test that when having nested tracked functions
+//! we don't drop any values when accumulating.
+
+mod common;
+
+use expect_test::expect;
+use salsa::{Accumulator, Database};
+use test_log::test;
+
+#[salsa::accumulator]
+struct Log(#[allow(dead_code)] String);
+
+#[salsa::tracked]
+fn push_logs(db: &dyn Database) {
+    push_a_logs(db);
+}
+
+#[salsa::tracked]
+fn push_a_logs(db: &dyn Database) {
+    Log("log a".to_string()).accumulate(db);
+    push_b_logs(db);
+}
+
+#[salsa::tracked]
+fn push_b_logs(db: &dyn Database) {
+    // No logs
+    push_c_logs(db);
+}
+
+#[salsa::tracked]
+fn push_c_logs(db: &dyn Database) {
+    // No logs
+    push_d_logs(db);
+}
+
+#[salsa::tracked]
+fn push_d_logs(db: &dyn Database) {
+    Log("log d".to_string()).accumulate(db);
+}
+
+#[test]
+fn accumulate_chain() {
+    salsa::default_database().attach(|db| {
+        let logs = push_logs::accumulated::<Log>(db);
+        // Check that we get all the logs.
+        expect![[r#"
+            [
+                Log(
+                    "log a",
+                ),
+                Log(
+                    "log d",
+                ),
+            ]"#]]
+        .assert_eq(&format!("{:#?}", logs));
+    })
+}

tests/accumulate-execution-order.rs

@@ -0,0 +1,64 @@
+//! Demonstrates that accumulation is done in the order
+//! in which things were originally executed.
+
+mod common;
+
+use expect_test::expect;
+use salsa::{Accumulator, Database};
+use test_log::test;
+
+#[salsa::accumulator]
+struct Log(#[allow(dead_code)] String);
+
+#[salsa::tracked]
+fn push_logs(db: &dyn Database) {
+    push_a_logs(db);
+}
+
+#[salsa::tracked]
+fn push_a_logs(db: &dyn Database) {
+    Log("log a".to_string()).accumulate(db);
+    push_b_logs(db);
+    push_c_logs(db);
+    push_d_logs(db);
+}
+
+#[salsa::tracked]
+fn push_b_logs(db: &dyn Database) {
+    Log("log b".to_string()).accumulate(db);
+    push_d_logs(db);
+}
+
+#[salsa::tracked]
+fn push_c_logs(db: &dyn Database) {
+    Log("log c".to_string()).accumulate(db);
+}
+
+#[salsa::tracked]
+fn push_d_logs(db: &dyn Database) {
+    Log("log d".to_string()).accumulate(db);
+}
+
+#[test]
+fn accumulate_execution_order() {
+    salsa::default_database().attach(|db| {
+        let logs = push_logs::accumulated::<Log>(db);
+        // Check that we get logs in execution order
+        expect![[r#"
+            [
+                Log(
+                    "log a",
+                ),
+                Log(
+                    "log b",
+                ),
+                Log(
+                    "log d",
+                ),
+                Log(
+                    "log c",
+                ),
+            ]"#]]
+        .assert_eq(&format!("{:#?}", logs));
+    })
+}

tests/accumulate-no-duplicates.rs

@@ -0,0 +1,104 @@
+//! Test that we don't get duplicate accumulated values
+
+mod common;
+
+use expect_test::expect;
+use salsa::{Accumulator, Database};
+use test_log::test;
+
+// A(1) {
+//   B
+//   B
+//   C {
+//     D {
+//       A(2) {
+//         B
+//       }
+//       B
+//     }
+//     E
+//   }
+//   B
+// }
+
+#[salsa::accumulator]
+struct Log(#[allow(dead_code)] String);
+
+#[salsa::input]
+struct MyInput {
+    n: u32,
+}
+
+#[salsa::tracked]
+fn push_logs(db: &dyn Database) {
+    push_a_logs(db, MyInput::new(db, 1));
+}
+
+#[salsa::tracked]
+fn push_a_logs(db: &dyn Database, input: MyInput) {
+    Log("log a".to_string()).accumulate(db);
+    if input.n(db) == 1 {
+        push_b_logs(db);
+        push_b_logs(db);
+        push_c_logs(db);
+        push_b_logs(db);
+    } else {
+        push_b_logs(db);
+    }
+}
+
+#[salsa::tracked]
+fn push_b_logs(db: &dyn Database) {
+    Log("log b".to_string()).accumulate(db);
+}
+
+#[salsa::tracked]
+fn push_c_logs(db: &dyn Database) {
+    Log("log c".to_string()).accumulate(db);
+    push_d_logs(db);
+    push_e_logs(db);
+}
+
+// Note this isn't tracked
+fn push_d_logs(db: &dyn Database) {
+    Log("log d".to_string()).accumulate(db);
+    push_a_logs(db, MyInput::new(db, 2));
+    push_b_logs(db);
+}
+
+#[salsa::tracked]
+fn push_e_logs(db: &dyn Database) {
+    Log("log e".to_string()).accumulate(db);
+}
+
+#[test]
+fn accumulate_no_duplicates() {
+    salsa::default_database().attach(|db| {
+        let logs = push_logs::accumulated::<Log>(db);
+        // Test that there aren't duplicate B logs.
+        // Note that log A appears twice, because they both come
+        // from different inputs.
+        expect![[r#"
+            [
+                Log(
+                    "log a",
+                ),
+                Log(
+                    "log b",
+                ),
+                Log(
+                    "log c",
+                ),
+                Log(
+                    "log d",
+                ),
+                Log(
+                    "log a",
+                ),
+                Log(
+                    "log e",
+                ),
+            ]"#]]
+        .assert_eq(&format!("{:#?}", logs));
+    })
+}