Log diagnostics

Summary:
For tracking error lifetimes in the IDE we need to know when it was first observed - this will almost always be as a diagnostic.

This diff adds logging for diagnostics in open files.

Reviewed By: CatherineGasnier

Differential Revision: D71121584

fbshipit-source-id: 1be4c1142e463b6abc456110feff44fb1d0fb428

Author: Michael Thomas

hphp/hack/src/client/clientLsp.ml

@@ -3450,6 +3450,12 @@ let publish_and_report_after_recomputing_live_squiggles
           uris
     in
     let params = ide_diagnostics_to_lsp_diagnostics file_path diagnostics in
+    let _ =
+      (* Log diagnostics so we can track error lifetime *)
+      Option.iter
+        (Telemetry.of_json_opt (Lsp_fmt.print_diagnostics params))
+        ~f:HackEventLogger.Diagnostics.log
+    in
     let notification = PublishDiagnosticsNotification params in
     notify_jsonrpc ~powered_by:Serverless_ide notification;
     report_recheck_telemetry ~trigger ~ref_unblocked_time uri (Ok diagnostics);

hphp/hack/src/utils/core/telemetry.ml

@@ -13,6 +13,10 @@ type key_value_pair = string * Hh_json.json [@@deriving show]
 (** This list is in reverse order (i.e. most recent first) *)
 type t = key_value_pair list [@@deriving show]
 
+let of_json_opt = function
+  | Hh_json.JSON_Object kvs -> Some kvs
+  | _ -> None
+
 (* Ignore - we only use the generated `pp_key_value_pair` in deriving `show` for t *)
 let _ = show_key_value_pair
 

hphp/hack/src/utils/core/telemetry.mli

@@ -14,6 +14,8 @@ val to_string : ?pretty:bool -> t -> string
 
 val to_json : t -> Hh_json.json
 
+val of_json_opt : Hh_json.json -> t option
+
 (** `diff ~all current ~prev` is for when `current` and `prev` have the same structure.
 It produces a hybrid telemetry object where, element by element, if they're the same
 then we only see the current element, but if they're different then we see both.