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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.
47 lines
1.2 KiB
Rust
47 lines
1.2 KiB
Rust
use expect_test::expect;
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mod common;
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use common::{LogDatabase, Logger};
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use salsa::Database;
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#[salsa::input]
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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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struct MyTracked<'db> {
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field: u32,
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}
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#[salsa::tracked]
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fn tracked_fn(db: &dyn LogDatabase, input: MyInput) -> u32 {
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db.push_log(format!("tracked_fn({input:?})"));
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let t = MyTracked::new(db, input.field(db) * 2);
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tracked_fn_extra::specify(db, t, 2222);
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tracked_fn_extra(db, t)
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}
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#[salsa::tracked(specify)]
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fn tracked_fn_extra<'db>(db: &dyn LogDatabase, input: MyTracked<'db>) -> u32 {
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db.push_log(format!("tracked_fn_extra({input:?})"));
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0
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}
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#[test]
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fn execute() {
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let mut db: salsa::DatabaseImpl<Logger> = salsa::DatabaseImpl::default();
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let input = MyInput::new(&db, 22);
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assert_eq!(tracked_fn(&db, input), 2222);
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db.assert_logs(expect![[r#"
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[
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"tracked_fn(MyInput { [salsa id]: Id(0), field: 22 })",
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]"#]]);
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// A "synthetic write" causes the system to act *as though* some
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// input of durability `durability` has changed.
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db.synthetic_write(salsa::Durability::LOW);
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// Re-run the query on the original input. Nothing re-executes!
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assert_eq!(tracked_fn(&db, input), 2222);
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db.assert_logs(expect!["[]"]);
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}
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