erlang: supervisor one-for-one (+7 tests)

lib/erlang/runtime.sx

@@ -869,3 +869,58 @@
 (define
   er-load-gen-server!
   (fn () (erlang-load-module er-gen-server-source)))
+
+;; ── supervisor (OTP-lite, one-for-one) ──────────────────────────
+;; Each child spec is `{Id, StartFn}` — `StartFn/0` returns the
+;; child's pid. The supervisor `process_flag(trap_exit, true)`,
+;; links to every child, and on `{'EXIT', DeadPid, _}` calls the
+;; matching `StartFn` to bring up a fresh replacement. Strategy is
+;; one-for-one: only the dead child restarts; siblings keep running.
+(define
+  er-supervisor-source
+  "-module(supervisor).
+   start_link(Mod, Args) ->
+     spawn(fun () ->
+       process_flag(trap_exit, true),
+       case Mod:init(Args) of
+         {ok, ChildSpecs} ->
+           Children = lists:map(
+             fun (Spec) -> supervisor:start_child(Spec) end,
+             ChildSpecs),
+           supervisor:loop(Children)
+       end
+     end).
+   start_child({Id, StartFn}) ->
+     P = StartFn(),
+     link(P),
+     {Id, StartFn, P}.
+   which_children(Sup) ->
+     Sup ! {'$sup_which', self()},
+     receive {'$sup_children', Cs} -> Cs end.
+   stop(Sup) ->
+     Sup ! '$sup_stop',
+     ok.
+   loop(Children) ->
+     receive
+       {'EXIT', Dead, _Reason} ->
+         supervisor:loop(supervisor:restart(Children, Dead));
+       {'$sup_which', From} ->
+         From ! {'$sup_children', Children},
+         supervisor:loop(Children);
+       '$sup_stop' ->
+         ok
+     end.
+   restart([], _) -> [];
+   restart([{Id, SF, P} | T], Dead) ->
+     case P =:= Dead of
+       true ->
+         NewP = SF(),
+         link(NewP),
+         [{Id, SF, NewP} | T];
+       false ->
+         [{Id, SF, P} | supervisor:restart(T, Dead)]
+     end.")
+
+(define
+  er-load-supervisor!
+  (fn () (erlang-load-module er-supervisor-source)))

lib/erlang/scoreboard.json

@@ -1,11 +1,11 @@
 {
   "language": "erlang",
-  "total_pass": 425,
-  "total": 425,
+  "total_pass": 432,
+  "total": 432,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
-    {"name":"eval","pass":241,"total":241,"status":"ok"},
+    {"name":"eval","pass":248,"total":248,"status":"ok"},
     {"name":"runtime","pass":39,"total":39,"status":"ok"},
     {"name":"ring","pass":4,"total":4,"status":"ok"},
     {"name":"ping-pong","pass":4,"total":4,"status":"ok"},

lib/erlang/scoreboard.md

@@ -1,12 +1,12 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 425 / 425 tests passing**
+**Total: 432 / 432 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
 | ✅ | tokenize | 62 | 62 |
 | ✅ | parse | 52 | 52 |
-| ✅ | eval | 241 | 241 |
+| ✅ | eval | 248 | 248 |
 | ✅ | runtime | 39 | 39 |
 | ✅ | ring | 4 | 4 |
 | ✅ | ping-pong | 4 | 4 |

lib/erlang/tests/eval.sx

@@ -768,6 +768,81 @@
   (nm (ev "P = gen_server:start_link(stk, ignored), gen_server:call(P, pop)"))
   "empty")
 
+;; ── supervisor (one-for-one) ────────────────────────────────────
+(do
+  (er-load-supervisor!)
+  (erlang-load-module
+    "-module(echoer).
+     start() -> spawn(fun () -> echoer:loop() end).
+     loop() ->
+       receive
+         {ping, From} -> From ! pong, echoer:loop();
+         die -> exit(killed)
+       end.")
+  nil)
+
+(er-eval-test "sup starts children"
+  (do
+    (erlang-load-module
+      "-module(sup1). init(_) -> {ok, [{w1, fun () -> echoer:start() end}]}.")
+    (ev "Sup = supervisor:start_link(sup1, []), receive after 5 -> ok end, length(supervisor:which_children(Sup))"))
+  1)
+
+(er-eval-test "sup multiple children"
+  (do
+    (erlang-load-module
+      "-module(sup2).
+       init(_) -> {ok, [
+         {w1, fun () -> echoer:start() end},
+         {w2, fun () -> echoer:start() end},
+         {w3, fun () -> echoer:start() end}
+       ]}.")
+    (ev "Sup = supervisor:start_link(sup2, []), receive after 5 -> ok end, length(supervisor:which_children(Sup))"))
+  3)
+
+(er-eval-test "sup child responds"
+  (do
+    (erlang-load-module
+      "-module(sup3). init(_) -> {ok, [{w1, fun () -> echoer:start() end}]}.")
+    (nm (ev "Sup = supervisor:start_link(sup3, []), receive after 5 -> ok end, [{_, _, P1} | _] = supervisor:which_children(Sup), P1 ! {ping, self()}, receive pong -> ok end")))
+  "ok")
+
+(er-eval-test "sup restarts on exit"
+  (do
+    (erlang-load-module
+      "-module(sup4). init(_) -> {ok, [{w1, fun () -> echoer:start() end}]}.")
+    (nm
+      (ev "Sup = supervisor:start_link(sup4, []), receive after 5 -> ok end, [{_, _, P1} | _] = supervisor:which_children(Sup), P1 ! die, receive after 5 -> ok end, [{_, _, P2} | _] = supervisor:which_children(Sup), P1 =/= P2")))
+  "true")
+
+(er-eval-test "sup restarted child works"
+  (do
+    (erlang-load-module
+      "-module(sup5). init(_) -> {ok, [{w1, fun () -> echoer:start() end}]}.")
+    (nm
+      (ev "Sup = supervisor:start_link(sup5, []), receive after 5 -> ok end, [{_, _, P1} | _] = supervisor:which_children(Sup), P1 ! die, receive after 5 -> ok end, [{_, _, P2} | _] = supervisor:which_children(Sup), P2 ! {ping, self()}, receive pong -> ok end")))
+  "ok")
+
+(er-eval-test "sup one-for-one isolates failures"
+  (do
+    (erlang-load-module
+      "-module(sup6).
+       init(_) -> {ok, [
+         {w1, fun () -> echoer:start() end},
+         {w2, fun () -> echoer:start() end}
+       ]}.")
+    (nm
+      (ev "Sup = supervisor:start_link(sup6, []), receive after 5 -> ok end, [{_, _, P1}, {_, _, P2}] = supervisor:which_children(Sup), P1 ! die, receive after 5 -> ok end, [{_, _, _NewP1}, {_, _, P2Again}] = supervisor:which_children(Sup), P2 =:= P2Again")))
+  "true")
+
+(er-eval-test "sup stop"
+  (nm
+    (do
+      (erlang-load-module
+        "-module(sup7). init(_) -> {ok, [{w1, fun () -> echoer:start() end}]}.")
+      (ev "Sup = supervisor:start_link(sup7, []), receive after 5 -> ok end, supervisor:stop(Sup)")))
+  "ok")
+
 (define
   er-eval-test-summary
   (str "eval " er-eval-test-pass "/" er-eval-test-count))