From ea6c692ae5445085b89c5b2da7e5745a17f78dcf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=A1=D0=B5=D1=80=D0=B3=D0=B5=D0=B9=20=D0=9F=D1=80=D0=BE?=
 =?UTF-8?q?=D1=85=D0=BE=D1=80=D0=BE=D0=B2?= <seriy.pr@gmail.com>
Date: Sat, 6 Oct 2018 20:49:28 +0200
Subject: [PATCH] Add session_lifetime metric

---
 src/mtp_handler.erl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/mtp_handler.erl b/src/mtp_handler.erl
index 042d636..49927d7 100644
--- a/src/mtp_handler.erl
+++ b/src/mtp_handler.erl
@@ -168,8 +168,12 @@ handle_info(Other, S) ->
     lager:warning("Unexpected handle_info ~p", [Other]),
     {noreply, S}.
 
-terminate(_Reason, #state{}) ->
+terminate(_Reason, #state{started_at = Started}) ->
     mtp_metric:count_inc([?APP, in_connection_closed, total], 1, #{}),
+    Lifetime = erlang:system_time(millisecond) - Started,
+    metric:histogram_observe(
+      [?APP, session_lifetime, seconds],
+      erlang:convert_time_unit(Lifetime, millisecond, native), #{}),
     lager:debug("terminate ~p", [_Reason]),
     ok.