add global.ml

src/global.ml

@@ -0,0 +1,27 @@
+(* IMPROVE: use caqti pool
+   [connect_pool] with parameter [?post_connect] for preflight *)
+let db_conn =
+  let f Env.{ sw; stack; tcp; dns; fs= _ } =
+    let db_uri = Config.Exchangedb_postgres.config in
+    match Caqti_mnet.connect ~sw stack tcp dns db_uri with
+    | Error err ->
+        Fmt.failwith "Database connection failure: %a." Caqti_error.pp err
+    | Ok conn ->
+        let () = Pg.preflight conn in
+        Logs.info (fun m -> m "database connection initialized");
+        conn
+  in
+  let finally (module Conn : Pg.CONN) = Conn.disconnect () in
+  Vifu.Device.v ~name:"db_conn" ~finally [] f
+
+let keys =
+  let f (module Conn : Pg.CONN) (env : Env.t) =
+    let (module Fs : Fat.FS) =
+      (module struct
+        let t = env.fs
+      end)
+    in
+    (module Keys.Make (Conn) (Fs) : Keys.S)
+  in
+  let finally _keys = () in
+  Vifu.Device.v ~name:"keys" ~finally [ Vifu.Device.value db_conn ] f