Joseph Ferano
4001c3246c
A let-bound local is its own name under lldb now, and a redefinition module carries DWARF when the daemon was asked for it. Resolved against the println track in session.ml: the thunk keeps the render walk's appended slots and gains the names beside them, the walk's own scratch having none to keep.
296 lines
14 KiB
OCaml
296 lines
14 KiB
OCaml
(* The agent, end to end (NEXT.md, dev loop step 3).
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test_reload.ml proves the primitive with a C harness driving it. This one
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proves the thing the dev loop actually is: a program that is running its own
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loop, a redefinition arriving over a socket while it runs, and the swap
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becoming visible at a point the program chose.
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The split the agent exists for is between two threads. [dlopen] relocates a
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module and takes the loader lock — milliseconds, unbounded — so it happens
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on the listener thread. [flan_reload_install] is one store per function, and
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it must not land while a redefined function is on the stack, so it happens
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on the game thread when it asks. Everything here is arranged to make that
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observable rather than to make it fast. *)
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open Flan
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let failures = ref 0
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let fail fmt = Printf.ksprintf (fun s -> incr failures; print_endline ("FAIL " ^ s)) fmt
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let scratch = Filename.get_temp_dir_name ()
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let tmp name = Filename.concat scratch ("flan-agent-" ^ name)
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(* Poll for a condition rather than sleeping a fixed time: the program has to
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bind its socket before there is anything to connect to, and how long that
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takes is not ours to predict. *)
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let rec await ?(ms = 3000) f =
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if f () then true
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else if ms <= 0 then false
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else begin
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ignore (Unix.select [] [] [] 0.005);
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await ~ms:(ms - 5) f
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end
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(* The socket file appears at [bind], which is a moment before [listen], so a
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connect can lose that race and get ECONNREFUSED. Retry rather than sleep. *)
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let rec connect ?(ms = 2000) path =
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let s = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
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match Unix.connect s (Unix.ADDR_UNIX path) with
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| () -> s
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| exception Unix.Unix_error (Unix.ECONNREFUSED, _, _) when ms > 0 ->
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Unix.close s;
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ignore (Unix.select [] [] [] 0.005);
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connect ~ms:(ms - 5) path
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let send path line =
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let s = connect path in
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let msg = line ^ "\n" in
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ignore (Unix.write_substring s msg 0 (String.length msg));
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(* Read to EOF, not once: a reply arrives in several pieces, and closing
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after the first one is what made the agent take SIGPIPE. *)
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let buf = Bytes.create 512 in
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let b = Buffer.create 512 in
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let rec drain () =
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match Unix.read s buf 0 512 with
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| 0 -> ()
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| n -> Buffer.add_subbytes b buf 0 n; drain ()
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| exception Unix.Unix_error _ -> ()
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in
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drain ();
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Unix.close s;
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Buffer.contents b
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let () =
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match Sys.command "command -v clang > /dev/null 2>&1 && command -v llc > /dev/null 2>&1" with
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| 0 ->
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(* The session is the program the process is about to be built from. Going
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through it rather than calling Emit directly is the point: it is what
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knows [tick] is a name the host has, so the module binds to its cell as
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a symbol instead of inventing a registry entry nobody publishes. *)
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let t, l = Session.create ~file:"programs/agent.flan" () in
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(* A dev build, because that is what has cells to install into and exports
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them. The agent's own C and its -lpthread come from the package. *)
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let dev = { Build.default with Build.dev = true } in
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let exe = tmp "prog" in
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ignore
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(Build.executable ~opts:dev ~csrcs:l.Load.csrcs ~lflags:l.Load.lflags
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t.Session.host ~out:exe);
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(* And the same program without [--dev], which has to *link*. Its [main]
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calls [agent/start], so the package is reached and its C comes with it
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even through [Reach.link] — and that C refers to the dev runtime, so
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leaving it out made this an undefined symbol at the link rather than a
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missing flag. Nothing is run: with no cells the agent refuses every
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module, and linking is the whole claim. *)
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(match
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let p, csrcs, lflags = Reach.link l t.Session.host in
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Build.executable ~opts:Build.default ~csrcs ~lflags p
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~out:(tmp "prog-release")
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with
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| _ -> ()
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| exception Failure m -> fail "a release build of the agent: %s" m);
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(* Two evaluations from the one session, which is the daemon's loop and
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the thing no earlier test does. The first introduces a global the
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process was never built with; the second only reads it, and can only
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come back with 1007 if it found the storage the first one allocated
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rather than a fresh zeroed copy of it. *)
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let build_module src name =
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let c = Session.eval t src in
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let out = tmp name in
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ignore (Build.shared ~opts:dev ~ir:c.Session.ir ~out ());
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out
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in
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let so1 =
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build_module
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"(defvar acc i64) (defn tick [] i64 (set acc (+ acc 1000)) acc)"
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"tick1.so"
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in
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let so2 =
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build_module "(defn tick [] i64 (set acc (+ acc 7)) acc)" "tick2.so"
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in
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let sock = tmp "sock" in
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let out = tmp "out" in
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(try Sys.remove sock with Sys_error _ -> ());
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let fd = Unix.openfile out [ Unix.O_WRONLY; Unix.O_CREAT; Unix.O_TRUNC ] 0o600 in
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let pid =
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Unix.create_process exe [| exe; sock |] Unix.stdin fd Unix.stderr
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in
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Unix.close fd;
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if not (await (fun () -> Sys.file_exists sock)) then begin
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fail "the program never bound its socket";
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(try Unix.kill pid Sys.sigkill with Unix.Unix_error _ -> ())
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end else begin
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(* Refusing junk comes first, while the program is still running: the
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daemon is a separate process and can send anything, and a bad path
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must not take down the program it was sent to. Nothing is queued by
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it, so the program is still waiting afterwards. *)
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let reply = send sock "/nonexistent/nope.so" in
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if String.length reply < 4 || String.sub reply 0 4 <> "err " then
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fail "a bad path was not refused: %S" reply;
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(* "ok" means queued, not installed — the store happens on the other
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thread, at a time this one does not choose. *)
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let lines () =
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let text = In_channel.with_open_bin out In_channel.input_all in
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List.length (String.split_on_char '\n' text) - 1
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in
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let reply = send sock so1 in
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if reply <> "ok\n" then fail "agent replied %S, wanted \"ok\\n\"" reply;
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(* Wait for the program to have consumed the first module before sending
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the second. Both at once is a legitimate thing for the agent to do —
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one poll installs everything queued — but then only the last one is
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ever observed and the sequencing is not what was tested. *)
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if not (await (fun () -> lines () >= 2)) then
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fail "the first reload was never installed";
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let reply = send sock so2 in
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if reply <> "ok\n" then fail "agent replied %S, wanted \"ok\\n\"" reply;
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let _, status = Unix.waitpid [] pid in
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let text = In_channel.with_open_bin out In_channel.input_all in
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(* 1 from the original [tick]; 1000 from a body that did not exist when
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the program started, over a global that did not either; 1007 from a
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second body that only reads it. That last number is the whole point of
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doing this twice — a registry that handed out fresh storage per module
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would say 7. *)
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if status <> Unix.WEXITED 0 || text <> "1\n1000\n1007\n" then
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fail "agent reload\n got: %S (%s)\n wanted: %S" text
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(match status with
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| Unix.WEXITED c -> Printf.sprintf "exit %d" c
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| Unix.WSIGNALED c -> Printf.sprintf "signal %d" c
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| Unix.WSTOPPED c -> Printf.sprintf "stopped %d" c)
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"1\n1000\n1007\n"
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end;
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(* ── The break loop, spec-conditions.md §2 ──────────────────────── *)
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(* The claim is that an unhandled [error] stops rather than dying, and can
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be resumed into a restart chosen from outside. A program that died would
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exit 134 with no output; one that stopped and was never resumed would
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hang and be killed by the timeout. Only a resume produces both numbers,
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and they differ, so a loop that always took the same restart fails. *)
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let bsock = tmp "break.sock" and bout = tmp "break.out" in
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(try Sys.remove bsock with Sys_error _ -> ());
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let bt, bl = Session.create ~file:"programs/break.flan" () in
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let bexe = tmp "break" in
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ignore
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(Build.executable ~opts:dev ~csrcs:bl.Load.csrcs ~lflags:bl.Load.lflags
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bt.Session.host ~out:bexe);
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let bfd = Unix.openfile bout [ Unix.O_WRONLY; Unix.O_CREAT; Unix.O_TRUNC ] 0o600 in
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let env =
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Array.append (Unix.environment ()) [| "FLAN_AGENT_SOCKET=" ^ bsock |]
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in
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let bpid =
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Unix.create_process_env bexe [| bexe |] env Unix.stdin bfd bfd
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in
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Unix.close bfd;
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if not (await (fun () -> Sys.file_exists bsock)) then
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fail "the broken program never listened"
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else begin
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(* It has to be *stopped* before the restarts are knowable: the listener
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refuses to walk a stack the game thread is still running on. *)
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let listed = ref "" in
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if not
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(await (fun () ->
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listed := send bsock "restarts";
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!listed <> "" && not (String.length !listed >= 3
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&& String.sub !listed 0 3 = "err")))
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then fail "the program never reached the break loop: %S" !listed
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else begin
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(* Innermost first, and both on offer. *)
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if !listed <> "0 + retry\n1 + use-placeholder\n.\n" then
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fail "restarts on offer\n got: %S\n wanted: %S" !listed
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"0 + retry\n1 + use-placeholder\n.\n";
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(* A name nothing offers is refused *here*, before the reply. Answering
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ok and discovering it on the game thread would report success for
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something that cannot happen. *)
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let bad = send bsock "restart nonesuch" in
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if not (String.length bad >= 3 && String.sub bad 0 3 = "err") then
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fail "a restart nobody offers was accepted: %S" bad;
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ignore (send bsock "restart retry");
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(* Wait for the *result* of that choice before making the next one.
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Asking whether it is stopped is not enough: it is still stopped in
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the first break until the resume lands, and a second choice sent
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then would be taken by the first one — which passes the listing
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check and then hangs, because the second break never gets an
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answer. The printed 7 is the only proof the first resume happened. *)
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let printed () =
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let t = In_channel.with_open_bin bout In_channel.input_all in
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List.exists (String.equal "7") (String.split_on_char '\n' t)
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in
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if not (await printed) then
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fail "the first restart never produced its value"
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else if not (await (fun () -> send bsock "restarts"
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= "0 + retry\n1 + use-placeholder\n.\n"))
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then fail "the program never stopped a second time"
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else begin
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ignore (send bsock "restart use-placeholder");
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(* -- Taking a restart by index ------------------------------- *)
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(* The third break is inside a [restart-case] whose name the frame
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below it also offers. Both are listed; §4's by-name walk can only
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ever reach the first. So this takes the *second*, and 900 is a
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value nothing else in the program can produce — the assertion on
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the output at the end is what makes this test about shadowing
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rather than about a reply. *)
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let printed2 () =
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let t = In_channel.with_open_bin bout In_channel.input_all in
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List.exists (String.equal "-1") (String.split_on_char '\n' t)
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in
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if not (await printed2) then
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fail "the second restart never produced its value"
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else if not (await (fun () -> send bsock "restarts"
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= "0 + retry\n1 + retry\n.\n"))
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then fail "the program never stopped on the shadowed pair"
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else begin
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(* Out of range is refused before the reply, like a bad name. *)
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let oob = send bsock "restart-at 7" in
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if not (String.length oob >= 3 && String.sub oob 0 3 = "err") then
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fail "an index nothing offers was accepted: %S" oob;
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(* The name rides along as a receipt, not as the lookup: an index
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whose name has moved is refused rather than silently taken,
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which is the same failure by-name lookup had. *)
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let drift = send bsock "restart-at 1 use-placeholder" in
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if not (String.length drift >= 3 && String.sub drift 0 3 = "err")
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then fail "an index whose name had drifted was accepted: %S" drift;
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ignore (send bsock "restart-at 1 retry")
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end
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end
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end
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end;
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let bstatus = ref (Unix.WEXITED 0) in
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let reaped =
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await ~ms:5000 (fun () ->
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match Unix.waitpid [ Unix.WNOHANG ] bpid with
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| 0, _ -> false
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| _, s -> bstatus := s; true)
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in
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if not reaped then begin
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(try Unix.kill bpid Sys.sigkill with Unix.Unix_error _ -> ());
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fail "the program never resumed out of the break loop"
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end
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else begin
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let text = In_channel.with_open_bin bout In_channel.input_all in
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let want = "7\n-1\n900\n" in
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let got =
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String.concat "\n"
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(List.filter
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(fun l -> l <> "" && not (String.length l >= 5 && String.sub l 0 5 = "flan:")
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&& not (String.length l >= 2 && String.sub l 0 2 = " "))
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(String.split_on_char '\n' text))
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in
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if !bstatus <> Unix.WEXITED 0 || got ^ "\n" <> want then
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fail "break loop transcript\n got: %S\n wanted: %S" got want
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end;
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List.iter (fun f -> try Sys.remove f with Sys_error _ -> ())
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[ exe; so1; so2; sock; out; bsock; bout; bexe ];
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if !failures = 0 then print_endline "agent: all tests passed"
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else begin
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Printf.printf "\n%d failure(s)\n" !failures;
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exit 1
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end
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| _ -> print_endline "agent: skipped (no clang or llc on PATH)"
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