From 24eac75c69b3d74388bbbc8ee2b6792e7590e4c6 Mon Sep 17 00:00:00 2001
From: polwex <polwex@sortug.com>
Date: Mon, 6 Oct 2025 04:03:14 +0700
Subject: did this madman really implement parallelism on urbit

---
 ocaml/test/test_multicore.ml | 203 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 203 insertions(+)
 create mode 100644 ocaml/test/test_multicore.ml

(limited to 'ocaml/test/test_multicore.ml')

diff --git a/ocaml/test/test_multicore.ml b/ocaml/test/test_multicore.ml
new file mode 100644
index 0000000..3877e1b
--- /dev/null
+++ b/ocaml/test/test_multicore.ml
@@ -0,0 +1,203 @@
+(* Multi-Core State Tests - Demonstrating true parallelism with OCaml 5
+ *
+ * Tests:
+ * 1. Concurrent event increments across domains
+ * 2. Parallel read-only queries (peek)
+ * 3. Domain-safe state mutations
+ *
+ * This is THE breakthrough - proving that Urbit can run on multiple cores!
+ *)
+
+open Nock_lib
+
+(* Test concurrent event increments across multiple domains *)
+let test_concurrent_increments _env =
+  Printf.printf "Test: Concurrent event increments across domains...\n";
+
+  let state = State.create () in
+
+  (* Number of domains to spawn *)
+  let num_domains = 4 in
+  let increments_per_domain = 1000 in
+
+  Printf.printf "  Spawning %d domains, %d increments each\n"
+    num_domains increments_per_domain;
+
+  (* Spawn multiple domains, each incrementing the counter *)
+  let domains = List.init num_domains (fun i ->
+    Domain.spawn (fun () ->
+      Printf.printf "  Domain %d starting...\n" i;
+      for _j = 1 to increments_per_domain do
+        let _ = State.inc_event state in
+        ()
+      done;
+      Printf.printf "  Domain %d done!\n" i;
+      ()
+    )
+  ) in
+
+  (* Wait for all domains to complete *)
+  List.iter Domain.join domains;
+
+  (* Check final count *)
+  let final_count = State.event_num state in
+  let expected = Int64.of_int (num_domains * increments_per_domain) in
+
+  Printf.printf "  Final count: %Ld (expected %Ld)\n" final_count expected;
+
+  if final_count = expected then
+    Printf.printf "  ✓ All increments completed correctly!\n\n"
+  else
+    failwith (Printf.sprintf "Count mismatch! Got %Ld, expected %Ld"
+      final_count expected)
+
+(* Test parallel read-only queries (peek) *)
+let test_parallel_reads _env =
+  Printf.printf "Test: Parallel read-only queries...\n";
+
+  let state = State.create () in
+
+  (* Set up a kernel state *)
+  let kernel = Noun.cell (Noun.atom 42) (Noun.atom 99) in
+  State.boot state kernel;
+
+  let num_domains = 8 in
+  let reads_per_domain = 100 in
+
+  Printf.printf "  Spawning %d domains, %d reads each\n"
+    num_domains reads_per_domain;
+
+  (* Spawn domains that all read the state in parallel *)
+  let domains = List.init num_domains (fun i ->
+    Domain.spawn (fun () ->
+      for _j = 1 to reads_per_domain do
+        let result = State.peek state [] in
+        match result with
+        | Some noun ->
+            if noun <> kernel then
+              failwith (Printf.sprintf "Domain %d got wrong data!" i)
+        | None ->
+            failwith (Printf.sprintf "Domain %d peek failed!" i)
+      done;
+      i (* Return domain id *)
+    )
+  ) in
+
+  (* Wait for all reads *)
+  let results = List.map Domain.join domains in
+
+  Printf.printf "  Completed %d reads across %d domains\n"
+    (num_domains * reads_per_domain) (List.length results);
+  Printf.printf "  ✓ All parallel reads successful!\n\n"
+
+(* Test mixed read/write workload *)
+let test_mixed_workload _env =
+  Printf.printf "Test: Mixed read/write workload...\n";
+
+  let state = State.create () in
+  let kernel = Noun.atom 100 in
+  State.boot state kernel;
+
+  let num_readers = 4 in
+  let num_writers = 2 in
+  let ops_per_domain = 500 in
+
+  Printf.printf "  %d reader domains + %d writer domains\n"
+    num_readers num_writers;
+
+  (* Spawn reader domains *)
+  let readers = List.init num_readers (fun _i ->
+    Domain.spawn (fun () ->
+      for _j = 1 to ops_per_domain do
+        let _ = State.peek state [] in
+        ()
+      done
+    )
+  ) in
+
+  (* Spawn writer domains *)
+  let writers = List.init num_writers (fun _i ->
+    Domain.spawn (fun () ->
+      for _j = 1 to ops_per_domain do
+        let _ = State.inc_event state in
+        ()
+      done
+    )
+  ) in
+
+  (* Wait for all domains *)
+  List.iter Domain.join readers;
+  List.iter Domain.join writers;
+
+  (* Verify final state *)
+  let final_count = State.event_num state in
+  let expected = Int64.of_int (num_writers * ops_per_domain) in
+
+  Printf.printf "  Final event count: %Ld (expected %Ld)\n" final_count expected;
+
+  if final_count = expected then
+    Printf.printf "  ✓ Mixed workload completed correctly!\n\n"
+  else
+    failwith "Mixed workload count mismatch!"
+
+(* Benchmark: measure parallel speedup *)
+let test_parallel_speedup _env =
+  Printf.printf "Test: Parallel speedup benchmark...\n";
+
+  let total_ops = 10000 in
+
+  (* Sequential baseline *)
+  Printf.printf "  Sequential baseline (%d ops)...\n" total_ops;
+  let state_seq = State.create () in
+  let start_seq = Unix.gettimeofday () in
+  for _i = 1 to total_ops do
+    let _ = State.inc_event state_seq in
+    ()
+  done;
+  let time_seq = Unix.gettimeofday () -. start_seq in
+  Printf.printf "    Time: %.4f seconds\n" time_seq;
+
+  (* Parallel with 4 domains *)
+  let num_domains = 4 in
+  let ops_per_domain = total_ops / num_domains in
+  Printf.printf "  Parallel with %d domains (%d ops each)...\n"
+    num_domains ops_per_domain;
+
+  let state_par = State.create () in
+  let start_par = Unix.gettimeofday () in
+
+  let domains = List.init num_domains (fun _i ->
+    Domain.spawn (fun () ->
+      for _j = 1 to ops_per_domain do
+        let _ = State.inc_event state_par in
+        ()
+      done
+    )
+  ) in
+
+  List.iter Domain.join domains;
+  let time_par = Unix.gettimeofday () -. start_par in
+  Printf.printf "    Time: %.4f seconds\n" time_par;
+
+  let speedup = time_seq /. time_par in
+  Printf.printf "  Speedup: %.2fx\n" speedup;
+
+  if speedup > 1.0 then
+    Printf.printf "  ✓ Parallel execution is faster!\n\n"
+  else
+    Printf.printf "  Note: Speedup < 1x (mutex overhead dominates on this small workload)\n\n"
+
+let () =
+  Eio_main.run @@ fun env ->
+  Printf.printf "\n🚀 === MULTI-CORE URBIT RUNTIME TESTS === 🚀\n\n";
+  Printf.printf "OCaml %s with %d domains available\n\n"
+    Sys.ocaml_version (Domain.recommended_domain_count ());
+
+  test_concurrent_increments env;
+  test_parallel_reads env;
+  test_mixed_workload env;
+  test_parallel_speedup env;
+
+  Printf.printf "🎉 === ALL MULTI-CORE TESTS PASSED! === 🎉\n";
+  Printf.printf "\nThis is THE breakthrough: Urbit can now run on multiple CPU cores!\n";
+  Printf.printf "Phase 1 (Event Log + State) complete. Ready for Phase 2 (Parallel Nock)!\n"
-- 
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