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|
module Make =
functor
(T : Transport.TRANSPORT)
(NT : Nt.S)
->
struct
module type SubS = Sublanguage.S
module Sess = Session.Make (NT)
module B = Branch.Make (NT)
module SC = Sublanguage_context.Make (NT)
module Error = struct
open Condition
let syntax_error msg = condition "syntax-error" msg empty
let unrecognized_sublanguage tag =
condition "unrecognized-sublanguage" "Unrecognized sublanguage" ("tag" |=| of_string tag)
let malformed_expression expr =
condition "malformed-expression" "Malformed expression" ("expression" |=| of_sexp expr)
end
(** Per-connection state: session owns the active branch. The branch's
[relation_path] becomes the context resolver, so all sublanguages
address the full RNT namespace rather than a single multigroup. **)
type conn_state = {claims: Nt.claims; session: Sess.session}
(** Build a fresh execution context from the current session state. Called
at the top of every handle_sublanguage so it always reflects the live
branch after any prior VCL switch. **)
let make_ctx ({session; claims} : conn_state) : Sublanguage_context.t =
SC.make_ctx session claims
let read_command input =
try Ok (Sexplib.Sexp.input_sexp input)
with Sexplib.Sexp.Parse_error {err_msg; _} -> Error (Error.syntax_error err_msg)
let sublanguages =
List.fold_right
(fun (module Language : SubS) ->
Utilities.StringMap.add Language.name (module Language : SubS) )
[ (module Drl.Sublanguage.Make (NT) : SubS);
(module Ddl.Sublanguage.Make (NT) : SubS);
(module Dml.Sublanguage.Make (NT) : SubS);
(module Icl.Sublanguage.Make (NT) : SubS);
(module Prl.Sublanguage.Make (NT) : SubS);
(module Scl.Sublanguage.Make (NT) : SubS);
(module Vcl.Sublanguage.Make (NT) : SubS) ]
Utilities.StringMap.empty
let find_language tag =
Utilities.StringMap.find_opt tag sublanguages
|> Option.to_result ~none:(Error.unrecognized_sublanguage tag)
let execute_sublanguage ctx expr (module Language : SubS) =
Language.parse_sexp expr |> Utilities.Result.fmap (Language.execute ctx)
let execute_command ctx = function
| Sexplib.Sexp.(List [Atom tag; expr]) ->
find_language tag |> Utilities.Result.fmap (execute_sublanguage ctx expr)
| s -> Error (Error.malformed_expression s)
let tuple_to_sexp (t : Tuple.materialized) =
let open Sexplib.Sexp in
List
( Tuple.AttributeMap.bindings t.Tuple.attributes
|> List.map (fun (k, attr) ->
List [Atom k; Conventions.AbstractValue.sexp_of_t attr.Attribute.value] ) )
let output_response out_ch sexp =
let response = Sexplib.Sexp.to_string sexp in
output_string out_ch response;
output_string out_ch "\n";
flush out_ch;
Utilities.print_with_time response
let send_error out_ch e =
output_response out_ch Sexplib.Sexp.(List [Atom "error"; Condition.to_sexp e])
(* Serializes a sublanguage result. [branch] is the write target whose
tip and name surface in Cursor / Transition responses. *)
let serialize (branch : B.branch) =
let open Sexplib.Sexp in
function
| Error e -> List [Atom "error"; Condition.to_sexp e]
| Ok (Sublanguage_types.Cursor {cursor_id; rows; has_more}) ->
let row_sexps = List.map tuple_to_sexp rows in
List
[ Atom "cursor";
List [Atom "id"; Atom cursor_id];
List [Atom "rows"; List row_sexps];
List [Atom "row_count"; Atom (string_of_int (List.length row_sexps))];
List [Atom "has_more"; Atom (string_of_bool has_more)];
List [Atom "snapshot"; Atom branch#tip];
List [Atom "branch"; Atom branch#name] ]
| Ok (Sublanguage_types.Query _rel) ->
List [Atom "error"; Atom "unexpected Query result: use Cursor path"]
| Ok (Sublanguage_types.Transition _new_cache) ->
List
[ Atom "ok";
List [Atom "snapshot"; Atom branch#tip];
List [Atom "branch"; Atom branch#name] ]
| Ok (Sublanguage_types.SessionSwitch name) ->
List [Atom "ok"; List [Atom "message"; Atom ("Switched to branch " ^ name)]]
| Ok (Sublanguage_types.CreateMultigroup name) ->
List [Atom "ok"; List [Atom "message"; Atom ("Multigroup " ^ name ^ " created")]]
let handle_sublanguage output state sexp =
let ctx = make_ctx !state in
match execute_command ctx sexp with
| Error e -> send_error output e
| Ok result ->
(* Sync updated schema_cache back into the branch mirror on any
state-advancing result (DDL, ICL, VCL). For VCL the session
already holds the new branch; refresh_mg is a no-op on it but
correct for DDL/ICL which stay on the same branch. *)
( match result with
| Sublanguage_types.Transition delta -> !state.session#branch#apply_delta delta
| _ -> () );
serialize !state.session#branch (Ok result) |> output_response output
let handle_client connection =
let input = T.input connection in
let output = T.output connection in
match NT.authenticate Nt.PlainText with
| Error e ->
(* FIXME: why is this a syntax error? *)
send_error output e
| Ok claims -> (
match Sess.open_session claims ~branch_name:"master" with
| Error e -> send_error output e
| Ok sess -> (
let state = ref {claims; session= sess} in
try
while true do
match read_command input with
| Error e -> send_error output e
| Ok sexp -> handle_sublanguage output state sexp
done
with
| End_of_file -> ignore (!state.session#close ())
| e ->
ignore (!state.session#close ());
Printf.eprintf "Error handling connection: %s" (Printexc.to_string e) ) )
let spawn_handler connection = Stdlib.Domain.spawn (fun () -> handle_client connection)
let run transport =
T.listen transport;
while true do
T.accept transport |> spawn_handler |> ignore
done
end
|
