Refactor Hashtbl.find out of resources/table.ml

Signed-off-by: Andrii Sultanov <[email protected]>

ocaml/libs/resources/table.ml

@@ -41,7 +41,7 @@ struct
         Hashtbl.remove t k
     )
 
-  let find (t, m) k = with_lock m (fun () -> Hashtbl.find t k)
+  let find (t, m) k = with_lock m (fun () -> Hashtbl.find_opt t k)
 
   let with_find_moved_exn (t, m) k =
     let v =

ocaml/libs/stunnel/stunnel_cache.ml

@@ -74,10 +74,13 @@ let unlocked_gc () =
   ( if debug_enabled then
       let now = Unix.gettimeofday () in
       let string_of_id id =
-        let stunnel = Tbl.find !stunnels id in
-        Printf.sprintf "(id %s / idle %.2f age %.2f)" (id_of_stunnel stunnel)
-          (now -. Hashtbl.find !times id)
-          (now -. stunnel.Stunnel.connected_time)
+        match (Tbl.find !stunnels id, Hashtbl.find_opt !times id) with
+        | Some stunnel, Some stunnel_id ->
+            Printf.sprintf "(id %s / idle %.2f age %.2f)"
+              (id_of_stunnel stunnel) (now -. stunnel_id)
+              (now -. stunnel.Stunnel.connected_time)
+        | _ ->
+            Printf.sprintf "%s: found no entry for id=%d" __FUNCTION__ id
       in
       let string_of_endpoint ep = Printf.sprintf "%s:%d" ep.host ep.port in
       let string_of_index ep xs =
@@ -134,20 +137,24 @@ let unlocked_gc () =
     let oldest_ids = List.map fst oldest in
     List.iter
       (fun x ->
-        let stunnel = Tbl.find !stunnels x in
-        debug
-          "Expiring stunnel id %s since we have too many cached tunnels (limit \
-           is %d)"
-          (id_of_stunnel stunnel) max_stunnel
+        match Tbl.find !stunnels x with
+        | Some stunnel ->
+            debug
+              "Expiring stunnel id %s since we have too many cached tunnels \
+               (limit is %d)"
+              (id_of_stunnel stunnel) max_stunnel
+        | None ->
+            debug "%s: Couldn't find an expiring stunnel (id=%d) in the table"
+              __FUNCTION__ x
       )
       oldest_ids ;
     to_gc := !to_gc @ oldest_ids
   ) ;
   (* Disconnect all stunnels we wish to GC *)
   List.iter
     (fun id ->
-      let s = Tbl.find !stunnels id in
-      Stunnel.disconnect s
+      (* Only remove stunnel if we find it in the table *)
+      Option.iter (fun s -> Stunnel.disconnect s) (Tbl.find !stunnels id)
     )
     !to_gc ;
   (* Remove all reference to them from our cache hashtables *)
@@ -201,23 +208,33 @@ let with_remove ~host ~port verified f =
   let get_id () =
     with_lock m (fun () ->
         unlocked_gc () ;
-        let ids = Hashtbl.find !index ep in
-        let table = List.map (fun id -> (id, Hashtbl.find !times id)) ids in
+        let ( let* ) = Option.bind in
+        let* ids = Hashtbl.find_opt !index ep in
+        let table =
+          List.filter_map
+            (fun id ->
+              Option.map (fun time -> (id, time)) (Hashtbl.find_opt !times id)
+            )
+            ids
+        in
         let sorted = List.sort (fun a b -> compare (snd a) (snd b)) table in
         match sorted with
         | (id, time) :: _ ->
-            let stunnel = Tbl.find !stunnels id in
-            debug "Removing stunnel id %s (idle %.2f) from the cache"
-              (id_of_stunnel stunnel)
-              (Unix.gettimeofday () -. time) ;
+            Option.iter
+              (fun stunnel ->
+                debug "Removing stunnel id %s (idle %.2f) from the cache"
+                  (id_of_stunnel stunnel)
+                  (Unix.gettimeofday () -. time)
+              )
+              (Tbl.find !stunnels id) ;
             Hashtbl.remove !times id ;
             Hashtbl.replace !index ep (List.filter (fun x -> x <> id) ids) ;
-            id
+            Some id
         | _ ->
-            raise Not_found
+            None
     )
   in
-  let id_opt = try Some (get_id ()) with Not_found -> None in
+  let id_opt = get_id () in
   id_opt
   |> Option.map @@ fun id ->
      (* cannot call while holding above mutex or we deadlock *)