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daaa78056a
Under this design, *all* databases are a `DatabaseImpl<U>`, where the `U` implements `UserData` (you can use `()` if there is none). Code would default to `&dyn salsa::Database` but if you want to give access to the userdata, you can define a custom database trait `MyDatabase: salsa::Databse` so long as you * annotate `MyDatabase` trait definition of impls of `MyDatabase` with `#[salsa::db]` * implement `MyDatabase` for `DatabaseImpl<U>` where `U` is your userdata (this could be a blanket impl, if you don't know the precise userdata type). The `tests/common/mod.rs` shows the pattern.
91 lines
2.7 KiB
Rust
91 lines
2.7 KiB
Rust
//! Delete cascade:
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//!
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//! * when we delete memoized data, also delete outputs from that data
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mod common;
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use common::{DiscardLogger, LogDatabase};
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use expect_test::expect;
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use salsa::{DatabaseImpl, Setter};
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use test_log::test;
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#[salsa::input(singleton)]
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struct MyInput {
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field: u32,
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}
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#[salsa::tracked]
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fn final_result(db: &dyn LogDatabase, input: MyInput) -> u32 {
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db.push_log(format!("final_result({:?})", input));
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let mut sum = 0;
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for tracked_struct in create_tracked_structs(db, input) {
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sum += contribution_from_struct(db, tracked_struct);
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}
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sum
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}
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#[salsa::tracked]
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struct MyTracked<'db> {
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field: u32,
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}
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#[salsa::tracked]
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fn create_tracked_structs(db: &dyn LogDatabase, input: MyInput) -> Vec<MyTracked<'_>> {
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db.push_log(format!("intermediate_result({:?})", input));
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(0..input.field(db))
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.map(|i| MyTracked::new(db, i))
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.collect()
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}
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#[salsa::tracked]
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fn contribution_from_struct<'db>(db: &'db dyn LogDatabase, tracked: MyTracked<'db>) -> u32 {
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let m = MyTracked::new(db, tracked.field(db));
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copy_field(db, m) * 2
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}
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#[salsa::tracked]
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fn copy_field<'db>(db: &'db dyn LogDatabase, tracked: MyTracked<'db>) -> u32 {
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tracked.field(db)
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}
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#[test]
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fn basic() {
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let mut db: DatabaseImpl<DiscardLogger> = Default::default();
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// Creates 3 tracked structs
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let input = MyInput::new(&db, 3);
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assert_eq!(final_result(&db, input), 2 * 2 + 2);
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db.assert_logs(expect![[r#"
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[
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"final_result(MyInput { [salsa id]: Id(0), field: 3 })",
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"intermediate_result(MyInput { [salsa id]: Id(0), field: 3 })",
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]"#]]);
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// Creates only 2 tracked structs in this revision, should delete 1
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//
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// Expect to see 6 DidDiscard events. Three from the primary struct:
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//
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// * the struct itself
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// * the struct's field
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// * the `contribution_from_struct` result
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//
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// and then 3 more from the struct created by `contribution_from_struct`:
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//
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// * the struct itself
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// * the struct's field
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// * the `copy_field` result
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input.set_field(&mut db).to(2);
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assert_eq!(final_result(&db, input), 2);
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db.assert_logs(expect![[r#"
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[
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"intermediate_result(MyInput { [salsa id]: Id(0), field: 2 })",
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"salsa_event(WillDiscardStaleOutput { execute_key: create_tracked_structs(0), output_key: MyTracked(2) })",
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"salsa_event(DidDiscard { key: MyTracked(2) })",
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"salsa_event(DidDiscard { key: contribution_from_struct(2) })",
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"salsa_event(DidDiscard { key: MyTracked(5) })",
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"salsa_event(DidDiscard { key: copy_field(5) })",
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"final_result(MyInput { [salsa id]: Id(0), field: 2 })",
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]"#]]);
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}
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