From 32ac28f7624e9aade8c7fafbf4325d3eb102cb7b Mon Sep 17 00:00:00 2001
From: Leandro Ostera <leandro@abstractmachines.dev>
Date: Wed, 17 Jul 2024 11:42:07 +0200
Subject: [PATCH] feat: introduce logger lifecycle (#97)

This change makes the Logger application startup process _block_ until
the logger is ready to take in requests. This means applications relying
on the logger will take a tiny bit longer to boot, but we can guarantee
that the log requests will not be dropped because of process spawn
order.

Close #82
---
 riot/lib/logger/logger.ml |  1 +
 riot/lib/logger_app.ml    | 16 ++++++++++++---
 riot/lib/ssl.ml           | 42 +++++++++++++++++++--------------------
 3 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/riot/lib/logger/logger.ml b/riot/lib/logger/logger.ml
index eb26c057..245b7ebf 100644
--- a/riot/lib/logger/logger.ml
+++ b/riot/lib/logger/logger.ml
@@ -3,6 +3,7 @@ module Log = Riot_runtime.Log
 open Global
 
 type opts = { print_source : bool; print_time : bool; color_output : bool }
+type config = { opts : opts; started_by : Riot_runtime.Core.Pid.t }
 
 type ('a, 'b) logger_format =
   (('a, Format.formatter, unit, 'b) format4 -> 'a) -> 'b
diff --git a/riot/lib/logger_app.ml b/riot/lib/logger_app.ml
index 10b324f7..85486dbb 100644
--- a/riot/lib/logger_app.ml
+++ b/riot/lib/logger_app.ml
@@ -5,6 +5,8 @@ open Logger.Make (struct
   let namespace = [ "riot"; "logger" ]
 end)
 
+type Message.t += Logger_ready
+
 module Formatter = struct
   type Message.t += Log of log
 
@@ -47,7 +49,8 @@ module Formatter = struct
     let pid =
       spawn_link (fun () ->
           Process.flag (Priority High);
-          formatter_loop config)
+          send config.started_by Logger_ready;
+          formatter_loop config.opts)
     in
     set_on_log (fun log -> send pid (Log log));
     Ok pid
@@ -59,5 +62,12 @@ let default_opts =
   { print_time = true; print_source = false; color_output = true }
 
 let start () =
-  let child_specs = [ Formatter.child_spec default_opts ] in
-  Supervisor.start_link ~child_specs ()
+  let this = self () in
+  let config = { opts = default_opts; started_by = this } in
+  let child_specs = [ Formatter.child_spec config ] in
+  let result = Supervisor.start_link ~child_specs () in
+  let `ready =
+    let selector msg = if msg = Logger_ready then `select `ready else `skip in
+    receive ~selector ()
+  in
+  result
diff --git a/riot/lib/ssl.ml b/riot/lib/ssl.ml
index 65fcbb91..ab275274 100644
--- a/riot/lib/ssl.ml
+++ b/riot/lib/ssl.ml
@@ -100,28 +100,28 @@ module Tls_unix = struct
     let handle tls cs =
       match Tls.Engine.handle_tls tls cs with
       | Ok (state', eof, `Response resp, `Data data) ->
-         trace (fun f -> f "tls.read_react->ok");
-         let state' =
-           match eof with
-           | Some `Eof -> `Eof
-           | _ -> inject_state state' t.state
-         in
-         t.state <- state';
-         Option.iter (try_write_t t) resp;
-         data
+          trace (fun f -> f "tls.read_react->ok");
+          let state' =
+            match eof with
+            | Some `Eof -> `Eof
+            | _ -> inject_state state' t.state
+          in
+          t.state <- state';
+          Option.iter (try_write_t t) resp;
+          data
       | Error (fail, `Response resp) ->
-         let state' =
-           match fail with
-           | `Alert a ->
-              trace (fun f -> f "tls.read_react->alert");
-              `Error (Tls_alert a)
-           | f ->
-              trace (fun f -> f "tls.read_react->error");
-              `Error (Tls_failure f)
-         in
-         t.state <- state';
-         write_t t resp;
-         read_react t
+          let state' =
+            match fail with
+            | `Alert a ->
+                trace (fun f -> f "tls.read_react->alert");
+                `Error (Tls_alert a)
+            | f ->
+                trace (fun f -> f "tls.read_react->error");
+                `Error (Tls_failure f)
+          in
+          t.state <- state';
+          write_t t resp;
+          read_react t
     in
 
     match t.state with