alice.pds.demo.boltless.dev
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1#![cfg(feature = "instrument")]
2
3use knot_bench::{RosterCount, build_members_checkpointed};
4use knot_cob::instrument::measure;
5
6#[test]
7fn a_checkpointed_member_write_reads_a_bounded_object_set() {
8 let small = build_members_checkpointed(RosterCount::new(512));
9 let large = build_members_checkpointed(RosterCount::new(1024));
10
11 let (_, full_small) = measure(|| small.full_fold());
12 let (_, full_large) = measure(|| large.full_fold());
13 let (_, write_small) = measure(|| small.probe());
14 let (_, write_large) = measure(|| large.probe());
15
16 assert_eq!(
17 full_small.get(),
18 2 * 512,
19 "full fold reads every change's commit and payload, so twice the member count"
20 );
21 assert_eq!(
22 full_large.get(),
23 2 * 1024,
24 "full fold the checkpoint replaces is linear in member count"
25 );
26 assert_eq!(
27 write_small.get(),
28 write_large.get(),
29 "a checkpointed member write reads only the bounded suffix, the same object count at \
30 512 members as at 1024"
31 );
32 assert!(
33 write_large.get() <= 2 * 256,
34 "per-write read set is bounded by twice the snapshot stride, not the member count, \
35 was {}",
36 write_large.get()
37 );
38 assert!(
39 write_large.get() < full_large.get() / 3,
40 "checkpoint cuts per-write object reads far below the full fold, {} vs {}",
41 write_large.get(),
42 full_large.get()
43 );
44}