Add an option to control stop time randomness

The --stop-time-interval option sets the upper bound on the number of
random hours added to the --stop-time of the daemon. It is optional,
with default 9 to match the current daemon behaviour.

Setting the option to 0 will disable the randomness entirely. This is
useful for ensuring that daemons will stop at deterministic intervals.

Author: cjjdespres

src/app/cli/src/cli_entrypoint/mina_cli_entrypoint.ml

@@ -547,6 +547,14 @@ let setup_daemon logger ~itn_features ~default_snark_worker_fee =
             were no slots won within an hour after the stop time) (Default: \
             %d)"
            Cli_lib.Default.stop_time )
+  and stop_time_interval =
+    flag "--stop-time-interval" ~aliases:[ "stop-time-interval" ] (optional int)
+      ~doc:
+        (sprintf
+           "UPTIME An upper bound (inclusive) on the random number of hours \
+            added to the stop-time. Setting it to zero disables this \
+            randomness. (Default: %d)"
+           Cli_lib.Default.stop_time_interval )
   and upload_blocks_to_gcloud =
     flag "--upload-blocks-to-gcloud"
       ~aliases:[ "upload-blocks-to-gcloud" ]
@@ -1289,6 +1297,10 @@ let setup_daemon logger ~itn_features ~default_snark_worker_fee =
             or_from_config YJ.Util.to_int_option "stop-time"
               ~default:Cli_lib.Default.stop_time stop_time
           in
+          let stop_time_interval =
+            or_from_config YJ.Util.to_int_option "stop-time-interval"
+              ~default:Cli_lib.Default.stop_time_interval stop_time_interval
+          in
           if enable_tracing then Mina_tracing.start conf_dir |> don't_wait_for ;
           let%bind () =
             if enable_internal_tracing then
@@ -1469,8 +1481,8 @@ Pass one of -peer, -peer-list-file, -seed, -peer-list-url.|} ;
                  ~log_precomputed_blocks ~start_filtered_logs
                  ~upload_blocks_to_gcloud ~block_reward_threshold ~uptime_url
                  ~uptime_submitter_keypair ~uptime_send_node_commit ~stop_time
-                 ~node_status_url ~graphql_control_port:itn_graphql_port
-                 ~simplified_node_stats
+                 ~stop_time_interval ~node_status_url
+                 ~graphql_control_port:itn_graphql_port ~simplified_node_stats
                  ~zkapp_cmd_limit:(ref compile_config.zkapp_cmd_limit)
                  ~itn_features ~compile_config ~hardfork_mode () )
           in

src/lib/cli_lib/default.ml

@@ -11,6 +11,8 @@ let conf_dir_name = ".mina-config"
 
 let stop_time = 168
 
+let stop_time_interval = 9
+
 let receiver_key_warning =
   "Warning: If the key is from a zkApp account, the account's receive \
    permission must be None."

src/lib/mina_lib/config.ml

@@ -62,6 +62,7 @@ type t =
   ; uptime_submitter_keypair : Keypair.t option [@default None]
   ; uptime_send_node_commit : bool [@default false]
   ; stop_time : int
+  ; stop_time_interval : int
   ; file_log_level : Logger.Level.t [@default Logger.Level.Info]
   ; log_level : Logger.Level.t [@default Logger.Level.Info]
   ; log_json : bool [@default false]

src/lib/mina_lib/mina_lib.ml

@@ -1229,7 +1229,12 @@ let check_and_stop_daemon t ~wait =
             `Check_in (Core.Time.Span.scale vrf_poll_interval 2.0) )
 
 let stop_long_running_daemon t =
-  let wait_mins = (t.config.stop_time * 60) + (Random.int 10 * 60) in
+  (* The Random.int upper bound is exclusive *)
+  let additional_wait_hours =
+    if t.config.stop_time_interval < 1 then 0
+    else Random.int (t.config.stop_time_interval + 1)
+  in
+  let wait_mins = (t.config.stop_time + additional_wait_hours) * 60 in
   [%log' info t.config.logger]
     "Stopping daemon after $wait mins and when there are no blocks to be \
      produced"