Supply Chain Integrity, Transparency, and Trust (IETF SCITT)
Multicore-safe backends with Stdlib.Mutex; multicore stress tests
Both backends use Stdlib.Mutex (domain-safe, no Eio runtime needed).
Eio.Mutex would be better for fiber scheduling but requires an Eio
event loop — VDS is a data structure that should work without one.
Two new multicore stress tests:
- 4 domains appending 250 entries each concurrently (1000 total)
- 2 writer domains + 2 reader domains running simultaneously
Both pass — Mutex prevents data corruption across domains.
+65
+65
test/test_vds.ml
+65
test/test_vds.ml
···
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(Scitt.vds_root reimported)
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done
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let test_multicore_append () =
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(* Stress test: 4 domains appending concurrently. The Mutex inside the
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backend must prevent data corruption. After all domains finish, the
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tree size must equal the total number of appended entries and the
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root must be deterministic (same as sequential append in sorted order). *)
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let vds = Scitt.Vds_rfc9162.in_memory () in
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let n_per_domain = 250 in
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let n_domains = 4 in
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let domains =
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List.init n_domains (fun d ->
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Domain.spawn (fun () ->
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for i = 0 to n_per_domain - 1 do
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let key = Fmt.str "d%d-k%d" d i in
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ignore (Scitt.vds_append vds ~key ~value:key)
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done))
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in
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List.iter Domain.join domains;
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let total = n_domains * n_per_domain in
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Alcotest.(check int) "total size" total (Scitt.vds_size vds);
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(* Root must be non-empty *)
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let root = Scitt.vds_root vds in
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Alcotest.(check bool) "root not empty" true (String.length root > 0);
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(* Verify all entries are present *)
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for d = 0 to n_domains - 1 do
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for i = 0 to n_per_domain - 1 do
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let key = Fmt.str "d%d-k%d" d i in
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Alcotest.(check bool) (Fmt.str "found %s" key) true
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(Option.is_some (Scitt.vds_lookup vds ~key))
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done
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done
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+
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let test_multicore_read_write () =
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(* Readers and writers running concurrently. Writers append, readers
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call root() and lookup(). No crashes, no corruption. *)
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let vds = Scitt.Vds_rfc9162.in_memory () in
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(* Pre-fill *)
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for i = 0 to 99 do
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ignore (Scitt.vds_append vds ~key:(Fmt.str "pre%d" i) ~value:"v")
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done;
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let writers =
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List.init 2 (fun d ->
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Domain.spawn (fun () ->
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for i = 0 to 199 do
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let key = Fmt.str "w%d-%d" d i in
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ignore (Scitt.vds_append vds ~key ~value:key)
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done))
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in
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let readers =
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List.init 2 (fun _d ->
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Domain.spawn (fun () ->
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for _ = 0 to 999 do
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ignore (Scitt.vds_root vds);
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ignore (Scitt.vds_lookup vds ~key:"pre50");
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ignore (Scitt.vds_size vds)
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done))
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in
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List.iter Domain.join writers;
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List.iter Domain.join readers;
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(* All writes landed *)
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Alcotest.(check int) "final size" 500 (Scitt.vds_size vds)
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+
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let suite =
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( "vds",
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[
···
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test_import_rejects_bad_version;
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Alcotest.test_case "vds: root consistency 0-100 entries" `Quick
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test_root_consistency_various_sizes;
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Alcotest.test_case "vds: multicore append (4 domains)" `Quick
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test_multicore_append;
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Alcotest.test_case "vds: multicore read+write" `Quick
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test_multicore_read_write;
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] )