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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 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 (state : conn_state) : Sublanguage_context.t =
let br = state.session#branch in
let claims = state.claims in
let session = state.session in
{
Sublanguage_context.write_handle = br#branch_handle;
branch = (br :> Sublanguage_context.branch_view);
resolve = br#path;
switch_branch = fun name ->
match br#close () with
| Error e -> Error e
| Ok () ->
begin match B.open_branch claims name with
| Error e ->
begin match B.open_branch claims "master" with
| Ok mbr -> session#set_branch mbr
| Error _ -> ()
end;
Error e
| Ok new_br ->
session#set_branch new_br;
Ok new_br#multigroups
end
}
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
|
