refactor: use set_session in preparation for persistent sessions

apps/emqx/src/emqx_channel.erl

@@ -33,8 +33,6 @@
         , get_mqtt_conf/2
         , get_mqtt_conf/3
         , set_conn_state/2
-        , get_session/1
-        , set_session/2
         , stats/1
         , caps/1
         ]).
@@ -180,9 +178,6 @@ info(timers, #channel{timers = Timers}) -> Timers.
 set_conn_state(ConnState, Channel) ->
     Channel#channel{conn_state = ConnState}.
 
-get_session(#channel{session = Session}) ->
-    Session.
-
 set_session(Session, Channel) ->
     Channel#channel{session = Session}.
 
@@ -369,10 +364,10 @@ handle_in(?PUBACK_PACKET(PacketId, _ReasonCode, Properties), Channel
     case emqx_session:puback(PacketId, Session) of
         {ok, Msg, NSession} ->
             ok = after_message_acked(ClientInfo, Msg, Properties),
-            {ok, Channel#channel{session = NSession}};
+            {ok, set_session(NSession, Channel)};
         {ok, Msg, Publishes, NSession} ->
             ok = after_message_acked(ClientInfo, Msg, Properties),
-            handle_out(publish, Publishes, Channel#channel{session = NSession});
+            handle_out(publish, Publishes, set_session(NSession, Channel));
         {error, ?RC_PACKET_IDENTIFIER_IN_USE} ->
             ?SLOG(warning, #{msg => "puback_packetId_inuse", packetId => PacketId}),
             ok = emqx_metrics:inc('packets.puback.inuse'),
@@ -388,7 +383,7 @@ handle_in(?PUBREC_PACKET(PacketId, _ReasonCode, Properties), Channel
     case emqx_session:pubrec(PacketId, Session) of
         {ok, Msg, NSession} ->
             ok = after_message_acked(ClientInfo, Msg, Properties),
-            NChannel = Channel#channel{session = NSession},
+            NChannel = set_session(NSession, Channel),
             handle_out(pubrel, {PacketId, ?RC_SUCCESS}, NChannel);
         {error, RC = ?RC_PACKET_IDENTIFIER_IN_USE} ->
             ?SLOG(warning, #{msg => "pubrec_packetId_inuse", packetId => PacketId}),
@@ -403,7 +398,7 @@ handle_in(?PUBREC_PACKET(PacketId, _ReasonCode, Properties), Channel
 handle_in(?PUBREL_PACKET(PacketId, _ReasonCode), Channel = #channel{session = Session}) ->
     case emqx_session:pubrel(PacketId, Session) of
         {ok, NSession} ->
-            NChannel = Channel#channel{session = NSession},
+            NChannel = set_session(NSession, Channel),
             handle_out(pubcomp, {PacketId, ?RC_SUCCESS}, NChannel);
         {error, RC = ?RC_PACKET_IDENTIFIER_NOT_FOUND} ->
             ?SLOG(warning, #{msg => "pubrec_packetId_not_found", packetId => PacketId}),
@@ -414,9 +409,9 @@ handle_in(?PUBREL_PACKET(PacketId, _ReasonCode), Channel = #channel{session = Se
 handle_in(?PUBCOMP_PACKET(PacketId, _ReasonCode), Channel = #channel{session = Session}) ->
     case emqx_session:pubcomp(PacketId, Session) of
         {ok, NSession} ->
-            {ok, Channel#channel{session = NSession}};
+            {ok, set_session(NSession, Channel)};
         {ok, Publishes, NSession} ->
-            handle_out(publish, Publishes, Channel#channel{session = NSession});
+            handle_out(publish, Publishes, set_session(NSession, Channel));
         {error, ?RC_PACKET_IDENTIFIER_IN_USE} ->
             ok = emqx_metrics:inc('packets.pubcomp.inuse'),
             {ok, Channel};
@@ -624,7 +619,8 @@ do_publish(PacketId, Msg = #message{qos = ?QOS_2},
     case emqx_session:publish(PacketId, Msg, Session) of
         {ok, PubRes, NSession} ->
             RC = puback_reason_code(PubRes),
-            NChannel1 = ensure_timer(await_timer, Channel#channel{session = NSession}),
+            NChannel0 = set_session(NSession, Channel),
+            NChannel1 = ensure_timer(await_timer, NChannel0),
             NChannel2 = ensure_quota(PubRes, NChannel1),
             handle_out(pubrec, {PacketId, RC}, NChannel2);
         {error, RC = ?RC_PACKET_IDENTIFIER_IN_USE} ->
@@ -698,7 +694,7 @@ do_subscribe(TopicFilter, SubOpts = #{qos := QoS}, Channel =
     NSubOpts = enrich_subopts(maps:merge(?DEFAULT_SUBOPTS, SubOpts), Channel),
     case emqx_session:subscribe(ClientInfo, NTopicFilter, NSubOpts, Session) of
         {ok, NSession} ->
-            {QoS, Channel#channel{session = NSession}};
+            {QoS, set_session(NSession, Channel)};
         {error, RC} ->
             ?SLOG(warning, #{
                 msg => "cannot_subscribe_topic_filter",
@@ -728,7 +724,7 @@ do_unsubscribe(TopicFilter, SubOpts, Channel =
     TopicFilter1 = emqx_mountpoint:mount(MountPoint, TopicFilter),
     case emqx_session:unsubscribe(ClientInfo, TopicFilter1, SubOpts, Session) of
         {ok, NSession} ->
-            {?RC_SUCCESS, Channel#channel{session = NSession}};
+            {?RC_SUCCESS, set_session(NSession, Channel)};
         {error, RC} -> {RC, Channel}
     end.
 %%--------------------------------------------------------------------
@@ -765,8 +761,11 @@ maybe_update_expiry_interval(_Properties, Channel) -> Channel.
 handle_deliver(Delivers, Channel = #channel{conn_state = disconnected,
                                             session    = Session,
                                             clientinfo = #{clientid := ClientId}}) ->
-    NSession = emqx_session:enqueue(ignore_local(maybe_nack(Delivers), ClientId, Session), Session),
-    {ok, Channel#channel{session = NSession}};
+    Delivers1 = maybe_nack(Delivers),
+    Delivers2 = ignore_local(Delivers1, ClientId, Session),
+    NSession = emqx_session:enqueue(Delivers2, Session),
+    NChannel = set_session(NSession, Channel),
+    {ok, NChannel};
 
 handle_deliver(Delivers, Channel = #channel{takeover = true,
                                             pendings = Pendings,
@@ -779,10 +778,10 @@ handle_deliver(Delivers, Channel = #channel{session = Session,
                                             clientinfo = #{clientid := ClientId}}) ->
     case emqx_session:deliver(ignore_local(Delivers, ClientId, Session), Session) of
         {ok, Publishes, NSession} ->
-            NChannel = Channel#channel{session = NSession},
+            NChannel = set_session(NSession, Channel),
             handle_out(publish, Publishes, ensure_timer(retry_timer, NChannel));
         {ok, NSession} ->
-            {ok, Channel#channel{session = NSession}}
+            {ok, set_session(NSession, Channel)}
     end.
 
 ignore_local(Delivers, Subscriber, Session) ->
@@ -898,13 +897,13 @@ return_connack(AckPacket, Channel) ->
     case maybe_resume_session(Channel) of
         ignore -> {ok, Replies, Channel};
         {ok, Publishes, NSession} ->
-            NChannel = Channel#channel{session  = NSession,
-                                       resuming = false,
+            NChannel0 = Channel#channel{resuming = false,
                                        pendings = []
                                       },
-            {Packets, NChannel1} = do_deliver(Publishes, NChannel),
+            NChannel1 = set_session(NSession, NChannel0),
+            {Packets, NChannel2} = do_deliver(Publishes, NChannel1),
             Outgoing = [{outgoing, Packets} || length(Packets) > 0],
-            {ok, Replies ++ Outgoing, NChannel1}
+            {ok, Replies ++ Outgoing, NChannel2}
     end.
 
 %%--------------------------------------------------------------------
@@ -1063,9 +1062,9 @@ handle_timeout(_TRef, retry_delivery,
                Channel = #channel{session = Session}) ->
     case emqx_session:retry(Session) of
         {ok, NSession} ->
-            {ok, clean_timer(retry_timer, Channel#channel{session = NSession})};
+            {ok, clean_timer(retry_timer, set_session(NSession, Channel))};
         {ok, Publishes, Timeout, NSession} ->
-            NChannel = Channel#channel{session = NSession},
+            NChannel = set_session(NSession, Channel),
             handle_out(publish, Publishes, reset_timer(retry_timer, Timeout, NChannel))
     end;
 
@@ -1076,9 +1075,9 @@ handle_timeout(_TRef, expire_awaiting_rel,
                Channel = #channel{session = Session}) ->
     case emqx_session:expire(awaiting_rel, Session) of
         {ok, NSession} ->
-            {ok, clean_timer(await_timer, Channel#channel{session = NSession})};
+            {ok, clean_timer(await_timer, set_session(NSession, Channel))};
         {ok, Timeout, NSession} ->
-            {ok, reset_timer(await_timer, Timeout, Channel#channel{session = NSession})}
+            {ok, reset_timer(await_timer, Timeout, set_session(NSession, Channel))}
     end;
 
 handle_timeout(_TRef, expire_session, Channel) ->