From a95bc37de0f975ad0239a54ef10a014096a02f41 Mon Sep 17 00:00:00 2001
From: zhongwencool <zhongwencool@gmail.com>
Date: Wed, 12 Jun 2024 20:29:03 +0800
Subject: [PATCH] feat: cache dispatch_rule

---
 src/minirest.erl | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/minirest.erl b/src/minirest.erl
index 8192aad..a89da53 100644
--- a/src/minirest.erl
+++ b/src/minirest.erl
@@ -26,9 +26,8 @@ start(Name, Options) ->
     start(Name, ranch_opts(Options), maps:without([ranch_options], Options)).
 
 start(Name, RanchOptions, Options) ->
+    init_dispatch(Name, Options),
     Protocol = maps:get(protocol, Options, http),
-    Dispatch = merge_dispatch([], Options),
-    persistent_term:put(Name, Dispatch),
     ProtoOpts = maps:get(protocol_options, Options, #{}),
     CowboyOptions = middlewares(Options,
         ProtoOpts#{
@@ -37,6 +36,17 @@ start(Name, RanchOptions, Options) ->
                   }),
     start_listener(Protocol, Name, RanchOptions, CowboyOptions).
 
+%% Because it is too slow to generate a fully new dispatch rules in update_dispatch/1.
+%% This cache allows the listener to find the complete dispatch rules ASAP.
+%% eg. emqx restarts the listener when the cluster join/leave.
+init_dispatch(Name, Options) ->
+    case persistent_term:get(Name, undefined) of
+        undefined ->
+            Dispatch = merge_dispatch([], Options),
+            persistent_term:put(Name, Dispatch);
+        _ -> ok
+    end.
+
 update_dispatch(Name) ->
     [Name, _Transport, _SocketOpts, _Protocol, StartArgs]
         = ranch_server:get_listener_start_args(Name),