salsa/tests/accumulate-reuse.rs

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//! Accumulator re-use test.
//!
//! Tests behavior when a query's only inputs
//! are the accumulated values from another query.
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mod common;
use common::{HasLogger, Logger};
use expect_test::expect;
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use salsa::prelude::*;
use test_log::test;
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#[salsa::db]
trait Db: salsa::Database + HasLogger {}
#[salsa::input]
struct List {
value: u32,
next: Option<List>,
}
#[salsa::accumulator]
struct Integers(u32);
#[salsa::tracked]
fn compute(db: &dyn Db, input: List) -> u32 {
db.push_log(format!("compute({:?})", input,));
// always pushes 0
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Integers(0).accumulate(db);
let result = if let Some(next) = input.next(db) {
let next_integers = compute::accumulated::<Integers>(db, next);
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let v = input.value(db) + next_integers.iter().map(|i| i.0).sum::<u32>();
v
} else {
input.value(db)
};
// return value changes
result
}
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#[salsa::db]
#[derive(Default)]
struct Database {
storage: salsa::Storage<Self>,
logger: Logger,
}
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#[salsa::db]
impl salsa::Database for Database {
fn salsa_event(&self, _event: salsa::Event) {}
}
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#[salsa::db]
impl Db for Database {}
impl HasLogger for Database {
fn logger(&self) -> &Logger {
&self.logger
}
}
#[test]
fn test1() {
let mut db = Database::default();
let l1 = List::new(&db, 1, None);
let l2 = List::new(&db, 2, Some(l1));
assert_eq!(compute(&db, l2), 2);
db.assert_logs(expect![[r#"
[
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"compute(List { [salsa id]: 1, value: 2, next: Some(List { [salsa id]: 0, value: 1, next: None }) })",
"compute(List { [salsa id]: 0, value: 1, next: None })",
]"#]]);
// When we mutate `l1`, we should re-execute `compute` for `l1`,
// but we should not have to re-execute `compute` for `l2`.
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// The only input for `compute(l1)` is the accumulated values from `l1`,
// which have not changed.
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l1.set_value(&mut db).to(2);
assert_eq!(compute(&db, l2), 2);
db.assert_logs(expect![[r#"
[
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"compute(List { [salsa id]: 1, value: 2, next: Some(List { [salsa id]: 0, value: 2, next: None }) })",
"compute(List { [salsa id]: 0, value: 2, next: None })",
]"#]]);
}