From 4313ed0cf37e98545f851a99112b4204d72a2fa2 Mon Sep 17 00:00:00 2001
From: Feng <ery.lee@gmail.com>
Date: Thu, 11 Jun 2015 13:57:00 +0800
Subject: [PATCH] comment

---
 apps/emqttd/src/emqttd_session.erl | 55 +++++++++++++++++-------------
 1 file changed, 31 insertions(+), 24 deletions(-)

diff --git a/apps/emqttd/src/emqttd_session.erl b/apps/emqttd/src/emqttd_session.erl
index 313b8eb3d..8350b89b8 100644
--- a/apps/emqttd/src/emqttd_session.erl
+++ b/apps/emqttd/src/emqttd_session.erl
@@ -69,15 +69,21 @@
         %% Inflight window size
         inflight_window = 40,
 
-        %% Inflight qos1, qos2 messages sent to the client but unacked, QoS 1 and QoS 2 messages which have been sent to the Client, but have not been completely acknowledged.
+        %% Inflight qos1, qos2 messages sent to the client but unacked,
+        %% QoS 1 and QoS 2 messages which have been sent to the Client,
+        %% but have not been completely acknowledged.
         %% Client <- Broker
         inflight_queue :: list(),
 
-        %% Inflight qos2 messages received from client and waiting for pubrel. QoS 2 messages which have been received from the Client, but have not been completely acknowledged.
+        %% Inflight qos2 messages received from client and waiting for pubrel.
+        %% QoS 2 messages which have been received from the Client,
+        %% but have not been completely acknowledged.
         %% Client -> Broker
         awaiting_queue :: list(),
 
-        %% All qos1, qos2 messages published to when client is disconnected. QoS 1 and QoS 2 messages pending transmission to the Client.
+        %% All qos1, qos2 messages published to when client is disconnected.
+        %% QoS 1 and QoS 2 messages pending transmission to the Client.
+        %%
         %% Optionally, QoS 0 messages pending transmission to the Client.
         pending_queue  :: emqttd_mqueue:mqueue(),
 
@@ -209,33 +215,34 @@ puback(SessPid, {?PUBCOMP, PacketId}) when is_pid(SessPid) ->
 %% @end
 %%------------------------------------------------------------------------------
 -spec subscribe(session(), [{binary(), mqtt_qos()}]) -> {ok, session(), [mqtt_qos()]}.
-subscribe(SessState = #session_state{clientid = ClientId, submap = SubMap}, Topics) ->
+subscribe(SessState = #session_state{clientid = ClientId, subscriptions = Subscriptions}, Topics) ->
 
     %% subscribe first and don't care if the subscriptions have been existed
     {ok, GrantedQos} = emqttd_pubsub:subscribe(Topics),
 
     lager:info([{client, ClientId}], "Client ~s subscribe ~p. Granted QoS: ~p",
-                   [ClientId, Topics, GrantedQos]),
+               [ClientId, Topics, GrantedQos]),
 
+    Subscriptions1 =
+    lists:foldl(fun({Topic, Qos}, Acc) ->
+                case lists:keyfind(Topic, 1, Acc) of
+                    {Topic, Qos} ->
+                        lager:warning([{client, ClientId}], "~s resubscribe ~p: qos = ~p", [ClientId, Topic, Qos]), Acc;
+                    {Topic, Old} ->
+                        lager:warning([{client, ClientId}], "~s resubscribe ~p: old qos=~p, new qos=~p",
+                                          [ClientId, Topic, Old, Qos]),
+                        lists:keyreplace(Topic, 1, Acc, {Topic, Qos});
+                    false ->
+                        %%TODO: the design is ugly, rewrite later...:(
+                        %% <MQTT V3.1.1>: 3.8.4
+                        %% Where the Topic Filter is not identical to any existing Subscription’s filter,
+                        %% a new Subscription is created and all matching retained messages are sent.
+                        emqttd_msg_store:redeliver(Topic, self()),
+                        [{Topic, Qos} | Acc]
+                end
+        end, Subscriptions, Topics),
 
-    %% <MQTT V3.1.1>: 3.8.4
-    %% Where the Topic Filter is not identical to any existing Subscription’s filter,
-    %% a new Subscription is created and all matching retained messages are sent.
-    lists:foreach(fun({Name, _Qos}) ->
-          case maps:is_key(Name, SubMap) of
-          true ->
-              lager:warning("~s resubscribe ~p", [ClientId, Name]);
-          false ->
-              %%TODO: this is not right, rewrite later...
-              emqttd_msg_store:redeliver(Name, self())
-          end
-    end, Topics),
-
-    SubMap1 = lists:foldl(fun({Name, Qos}, Acc) ->
-                                  maps:put(Name, Qos, Acc)
-                          end, SubMap, Topics),
-
-    {ok, SessState#session_state{submap = SubMap1}, GrantedQos};
+    {ok, SessState#session_state{subscriptions = Subscriptions1}, GrantedQos};
 
 subscribe(SessPid, Topics) when is_pid(SessPid) ->
     {ok, GrantedQos} = gen_server:call(SessPid, {subscribe, Topics}),
@@ -246,7 +253,7 @@ subscribe(SessPid, Topics) when is_pid(SessPid) ->
 %% @end
 %%------------------------------------------------------------------------------
 -spec unsubscribe(session(), [binary()]) -> {ok, session()}.
-unsubscribe(SessState = #session_state{clientid = ClientId, submap = SubMap}, Topics) ->
+unsubscribe(SessState = #session_state{clientid = ClientId, subscriptions = Subscriptions}, Topics) ->
     %%TODO: refactor later.
     case Topics -- maps:keys(SubMap) of
         [] -> ok;