salsa 0.28.0

A generic framework for on-demand, incrementalized computation (experimental)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223

use std::hint::black_box;

use salsa::Setter;

const MANY: usize = 256;
const TRACKED_FEW: usize = 32;

fn main() {
    divan::main();
}

/// Creates many input values directly.
#[divan::bench(args = [32, 64, 128, 256, 512, 1024, 10240])]
fn input_create_many(bencher: divan::Bencher, inputs: usize) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            db
        })
        .bench_local_refs(|db| {
            for value in 0..inputs {
                let input = InputValue::new(black_box(&*db), black_box(value));
                black_box(input);
            }
        });
}

/// Interns many distinct values inside a query.
#[divan::bench]
fn intern_distinct_many(bencher: divan::Bencher) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            let input = InternInput::new(black_box(&db), black_box(MANY), black_box(1));
            (db, input)
        })
        .bench_local_refs(|(db, input)| {
            let sum = intern_distinct_values(black_box(db), black_box(*input));
            assert_eq!(black_box(sum), MANY);
        });
}

/// Interns the same value many times inside a query.
#[divan::bench]
fn intern_same_many(bencher: divan::Bencher) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            let warm_input = InternInput::new(black_box(&db), black_box(MANY), black_box(1));
            let sum = intern_same_value(black_box(&db), black_box(warm_input));

            assert_eq!(black_box(sum), MANY);
            // Create a new input, so that we get a fresh `intern_same_value` query key.
            let input = InternInput::new(black_box(&db), black_box(MANY), black_box(1));
            (db, input)
        })
        .bench_local_refs(|(db, input)| {
            let sum = intern_same_value(black_box(db), black_box(*input));
            assert_eq!(black_box(sum), MANY);
        });
}

/// Creates many tracked structs inside a query.
#[divan::bench]
fn tracked_create_many(bencher: divan::Bencher) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            let input = TrackedInput::new(black_box(&db), black_box(MANY), black_box(1));
            (db, input)
        })
        .bench_local_refs(|(db, input)| {
            let sum = create_tracked(black_box(db), black_box(*input));
            assert_eq!(black_box(sum), MANY);
        });
}

/// Recreates many tracked structs and reuses their identities.
#[divan::bench]
fn tracked_reuse_many(bencher: divan::Bencher) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            let input = TrackedInput::new(black_box(&db), black_box(MANY), black_box(1));
            let sum = create_tracked(black_box(&db), black_box(input));
            assert_eq!(black_box(sum), MANY);
            (db, input)
        })
        .bench_local_refs(|(db, input)| {
            input.set_value(black_box(db)).to(black_box(2));
            let sum = create_tracked(black_box(db), black_box(*input));
            assert_eq!(black_box(sum), 2 * MANY);
        });
}

/// Recreates a small prefix of previously-created tracked structs.
#[divan::bench]
fn tracked_reuse_few(bencher: divan::Bencher) {
    bencher
        .with_inputs(|| {
            let db = salsa::DatabaseImpl::default();
            warm_db(&db);
            let input = TrackedInput::new(black_box(&db), black_box(MANY), black_box(1));
            let sum = create_tracked(black_box(&db), black_box(input));
            assert_eq!(black_box(sum), MANY);
            (db, input)
        })
        .bench_local_refs(|(db, input)| {
            // Recreate only a small prefix of the original outputs. This measures the case where
            // some identities are reused and the rest become stale outputs.
            input.set_count(black_box(db)).to(black_box(TRACKED_FEW));
            let sum = create_tracked(black_box(db), black_box(*input));
            assert_eq!(black_box(sum), TRACKED_FEW);
        });
}

fn warm_db(db: &salsa::DatabaseImpl) {
    let input = WarmupInput::new(black_box(db), black_box(13));
    let value = warmup_query(black_box(db), black_box(input));
    assert_eq!(black_box(value), 13);
}

#[salsa::input]
struct WarmupInput {
    #[returns(copy)]
    value: usize,
}

#[salsa::tracked(returns(copy))]
#[inline(never)]
fn warmup_query(db: &dyn salsa::Database, input: WarmupInput) -> usize {
    input.value(db)
}

#[salsa::input]
struct InputValue {
    #[returns(copy)]
    value: usize,
}

#[salsa::input]
struct InternInput {
    #[returns(copy)]
    count: usize,
    #[returns(copy)]
    value: usize,
}

#[salsa::interned]
struct InternedValue<'db> {
    #[returns(copy)]
    value: usize,
}

#[salsa::input]
struct TrackedInput {
    #[returns(copy)]
    count: usize,
    #[returns(copy)]
    value: usize,
}

#[salsa::tracked]
struct TrackedValue<'db> {
    #[returns(copy)]
    index: usize,
    #[tracked]
    #[returns(copy)]
    value: usize,
}

#[salsa::tracked(returns(copy))]
#[inline(never)]
fn create_tracked(db: &dyn salsa::Database, input: TrackedInput) -> usize {
    let count = input.count(db);
    let value = input.value(db);
    let mut sum = 0;

    for index in 0..count {
        let tracked = TrackedValue::new(db, index, value);
        black_box(tracked);
        sum += value;
    }

    sum
}

#[salsa::tracked(returns(copy))]
#[inline(never)]
fn intern_distinct_values(db: &dyn salsa::Database, input: InternInput) -> usize {
    let count = input.count(db);
    let value = input.value(db);
    let mut sum = 0;

    for offset in 0..count {
        let interned = InternedValue::new(db, value + offset);
        black_box(interned);
        sum += value;
    }

    sum
}

#[salsa::tracked(returns(copy))]
#[inline(never)]
fn intern_same_value(db: &dyn salsa::Database, input: InternInput) -> usize {
    let count = input.count(db);
    let value = input.value(db);
    let mut sum = 0;

    for _ in 0..count {
        let interned = InternedValue::new(db, value);
        black_box(interned);
        sum += value;
    }

    sum
}