From 910987e8e56cbed33c84de7544fb6ad805f16224 Mon Sep 17 00:00:00 2001
From: anlicheng <244108715@qq.com>
Date: Mon, 20 Apr 2026 20:56:29 +0800
Subject: [PATCH] fix subscription

---
 src/efka_subscription.erl | 43 +++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/efka_subscription.erl b/src/efka_subscription.erl
index b7e8ede..0bf7770 100644
--- a/src/efka_subscription.erl
+++ b/src/efka_subscription.erl
@@ -88,12 +88,22 @@ handle_call({subscribe, Topic, SubscriberPid}, _From, State = #state{subscribers
     Components = of_components(Topic),
     case is_valid_components(Components) of
         true ->
-            Sub = #subscriber{topic = Topic, subscriber_pid = SubscriberPid, components = Components, order = order_num(Components)},
-            %% 建立到SubscriberPid的monitor，进程退出需要清理订阅
-            erlang:monitor(process, SubscriberPid),
-            %% 处理遗留的消息
-            RestRemainingMessages = dispatch_remaining_messages(Sub, RemainingMessages),
-            {reply, ok, State#state{subscribers = Subscribers ++ [Sub], remaining_messages = RestRemainingMessages}};
+            case has_subscription(Topic, SubscriberPid, Subscribers) of
+                true ->
+                    {reply, ok, State};
+                false ->
+                    Sub = #subscriber{topic = Topic, subscriber_pid = SubscriberPid, components = Components, order = order_num(Components)},
+                    %% 只有首次看到该pid时才建立monitor，避免重复monitor
+                    case has_subscriber_pid(SubscriberPid, Subscribers) of
+                        true ->
+                            ok;
+                        false ->
+                            erlang:monitor(process, SubscriberPid)
+                    end,
+                    %% 处理遗留的消息
+                    RestRemainingMessages = dispatch_remaining_messages(Sub, RemainingMessages),
+                    {reply, ok, State#state{subscribers = Subscribers ++ [Sub], remaining_messages = RestRemainingMessages}}
+            end;
         false ->
             {reply, {error, <<"invalid topic name">>}, State}
     end;
@@ -114,13 +124,13 @@ handle_call(debug_info, _From, State = #state{subscribers = Subscribers, remaini
 handle_cast({publish, Topic, Qos, Content}, State = #state{subscribers = Subscribers, remaining_messages = RemainingMessages}) ->
     MatchedSubscribers = match_subscribers(Subscribers, Topic),
     logger:debug("[efka_subscription] topic: ~p, content: ~p, match subscribers: ~p", [Topic, Content, MatchedSubscribers]),
-    case length(MatchedSubscribers) > 0 of
-        true ->
+    case MatchedSubscribers of
+        [_|_] ->
             broadcast(Topic, Content, MatchedSubscribers),
             {noreply, State};
-        false when Qos =:= 0 ->
+        [] when Qos =:= 0 ->
             {noreply, State};
-        false ->
+        [] ->
             {noreply, State#state{remaining_messages = [{Topic, Content}|RemainingMessages]}}
     end.
 
@@ -178,6 +188,17 @@ match_subscribers(Subscribers, Topic) when is_list(Subscribers), is_binary(Topic
 contain_channel(Pid, Subscribers) when is_pid(Pid), is_list(Subscribers) ->
     lists:search(fun(#subscriber{subscriber_pid = Pid0}) -> Pid == Pid0 end, Subscribers) /= false.
 
+-spec has_subscriber_pid(pid(), [#subscriber{}]) -> boolean().
+has_subscriber_pid(SubscriberPid, Subscribers) when is_pid(SubscriberPid), is_list(Subscribers) ->
+    lists:any(fun(#subscriber{subscriber_pid = SubscriberPid0}) -> SubscriberPid =:= SubscriberPid0 end, Subscribers).
+
+-spec has_subscription(binary(), pid(), [#subscriber{}]) -> boolean().
+has_subscription(Topic, SubscriberPid, Subscribers)
+  when is_binary(Topic), is_pid(SubscriberPid), is_list(Subscribers) ->
+    lists:any(fun(#subscriber{topic = Topic0, subscriber_pid = SubscriberPid0}) ->
+        Topic =:= Topic0 andalso SubscriberPid =:= SubscriberPid0
+    end, Subscribers).
+
 %% 开始对比订阅的topic和发布的topic的Components信息
 %% *表示单级匹配，+表示多级匹配；+只能出现一次，并且只能在末尾
 -spec match_components(list(), list()) -> boolean().
@@ -227,7 +248,7 @@ dispatch_remaining_messages(#subscriber{subscriber_pid = SubscriberPid, componen
     %% 处理遗留的消息
     lists:foldl(fun({Topic0, Content0}, Acc) ->
         Components0 = of_components(Topic0),
-        case match_components(Components0, Components) of
+        case match_components(Components, Components0) of
             true ->
                 SubscriberPid ! {topic_broadcast, Topic0, Content0},
                 Acc;