Improve the design of session management

include/emqx.hrl

@@ -63,6 +63,7 @@
                      clean_start     := boolean(),
                      expiry_interval := non_neg_integer()}).
 
+-record(session, {client_id, sess_pid}).
 
 %%--------------------------------------------------------------------
 %% Message and Delivery

src/emqx.erl

@@ -1,5 +1,5 @@
 %%--------------------------------------------------------------------
-%% Copyright © 2013-2018 EMQ Inc. All rights reserved.
+%% Copyright (C) 2013-2018 EMQ Inc. All rights reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.

src/emqx_protocol.erl

@@ -219,8 +219,11 @@ process(?CONNECT_PACKET(Var), State0) ->
                     State2 = maybe_set_clientid(State1),
 
                     %% Start session
-                    case emqx_sm:start_session(CleanSess, {clientid(State2), Username}) of
-                        {ok, Session, SP} ->
+                    case emqx_sm:open_session(#{clean_start => CleanSess,
+                                                client_id => clientid(State2),
+                                                username => Username}) of
+                        {ok, Session} -> %% TODO:...
+                            SP = true, %% TODO:...
                             %% Register the client
                             emqx_cm:reg(client(State2)),
                             %% Start keepalive

src/emqx_session.erl

@@ -14,35 +14,6 @@
 %% limitations under the License.
 %%--------------------------------------------------------------------
 
-%%
-%% @doc MQTT Session
-%%
-%% A stateful interaction between a Client and a Server. Some Sessions
-%% last only as long as the Network Connection, others can span multiple
-%% consecutive Network Connections between a Client and a Server.
-%%
-%% The Session state in the Server consists of:
-%%
-%% The existence of a Session, even if the rest of the Session state is empty.
-%%
-%% The Client’s subscriptions.
-%%
-%% QoS 1 and QoS 2 messages which have been sent to the Client, but have not
-%% been completely acknowledged.
-%%
-%% QoS 1 and QoS 2 messages pending transmission to the Client.
-%%
-%% QoS 2 messages which have been received from the Client, but have not 
-%% been completely acknowledged.
-%%
-%% Optionally, QoS 0 messages pending transmission to the Client.
-%%
-%% If the session is currently disconnected, the time at which the Session state
-%% will be deleted.
-%%
-%% @end
-%%
-
 -module(emqx_session).
 
 -behaviour(gen_server).
@@ -76,6 +47,28 @@
 
 -define(MQueue, emqx_mqueue).
 
+%% A stateful interaction between a Client and a Server. Some Sessions
+%% last only as long as the Network Connection, others can span multiple
+%% consecutive Network Connections between a Client and a Server.
+%%
+%% The Session state in the Server consists of:
+%%
+%% The existence of a Session, even if the rest of the Session state is empty.
+%%
+%% The Client’s subscriptions.
+%%
+%% QoS 1 and QoS 2 messages which have been sent to the Client, but have not
+%% been completely acknowledged.
+%%
+%% QoS 1 and QoS 2 messages pending transmission to the Client.
+%%
+%% QoS 2 messages which have been received from the Client, but have not 
+%% been completely acknowledged.
+%%
+%% Optionally, QoS 0 messages pending transmission to the Client.
+%%
+%% If the session is currently disconnected, the time at which the Session state
+%% will be deleted.
 -record(state,
         {
          %% Clean Session Flag

src/emqx_session_sup.erl

@@ -20,18 +20,16 @@
 
 -include("emqx.hrl").
 
--export([start_link/0, start_session_process/1]).
+-export([start_link/0, start_session/1]).
 
 -export([init/1]).
 
-%% @doc Start session supervisor
 -spec(start_link() -> {ok, pid()}).
 start_link() ->
     supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
-%% @doc Start a session process
--spec(start_session_process(session()) -> {ok, pid()}).
-start_session_process(Session) ->
+-spec(start_session(session()) -> {ok, pid()}).
+start_session(Session) ->
     supervisor:start_child(?MODULE, [Session]).
 
 %%--------------------------------------------------------------------

src/emqx_sm.erl

@@ -20,220 +20,152 @@
 
 -include("emqx.hrl").
 
-%% Mnesia Callbacks
--export([mnesia/1]).
+-export([start_link/1]).
 
--boot_mnesia({mnesia, [boot]}).
--copy_mnesia({mnesia, [copy]}).
+-export([open_session/1, lookup_session/1, close_session/1]).
+-export([resume_session/1, discard_session/1]).
+-export([register_session/1, unregister_session/2]).
 
-%% API Function Exports
--export([start_link/2]).
-
--export([open_session/1, start_session/2, lookup_session/1, register_session/3,
-         unregister_session/1, unregister_session/2]).
+%% lock_session/1, create_session/1, unlock_session/1,
 
 -export([dispatch/3]).
 
--export([local_sessions/0]).
-
-%% gen_server Function Exports
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
 
--record(state, {pool, id, monitors}).
-
--define(POOL, ?MODULE).
-
--define(TIMEOUT, 120000).
-
--define(LOG(Level, Format, Args, Session),
-            lager:Level("SM(~s): " ++ Format, [Session#session.client_id | Args])).
-
-%%--------------------------------------------------------------------
-%% Mnesia callbacks
-%%--------------------------------------------------------------------
-
-mnesia(boot) ->
-    %% Global Session Table
-    ok = ekka_mnesia:create_table(session, [
-                {type, set},
-                {ram_copies, [node()]},
-                {record_name, mqtt_session},
-                {attributes, record_info(fields, mqtt_session)}]);
+-record(state, {stats_fun, stats_timer, monitors = #{}}).
 
-mnesia(copy) ->
-    ok = ekka_mnesia:copy_table(mqtt_session).
+-spec(start_link(StatsFun :: fun()) -> {ok, pid()} | ignore | {error, term()}).
+start_link(StatsFun) ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [StatsFun], []).
 
-%%--------------------------------------------------------------------
-%% API
-%%--------------------------------------------------------------------
-
-%% Open a clean start session.
-open_session(Session = #{client_id := ClientId, clean_start := true, expiry_interval := Interval}) ->
+open_session(Session = #{client_id := ClientId, clean_start := true}) ->
     with_lock(ClientId,
               fun() ->
-                  {ResL, BadNodes} = emqx_rpc:multicall(ekka:nodelist(), ?MODULE, discard_session, [ClientId]),
-                  io:format("ResL: ~p, BadNodes: ~p~n", [ResL, BadNodes]),
-                  case Interval > 0 of
-                      true ->
-                          {ok, emqx_session_sup:start_session_process(Session)};
-                      false ->
-                          {ok, emqx_session:init_state(Session)}
-                  end
-              end).
-
-open_session(Session = #{client_id := ClientId, clean_start := false, expiry_interval := Interval}) ->
+                  case rpc:multicall(ekka:nodelist(), ?MODULE, discard_session, [ClientId]) of
+                      {_Res, []} -> ok;
+                      {_Res, BadNodes} -> emqx_log:error("[SM] Bad nodes found when lock a session: ~p", [BadNodes])
+                  end,
+                  {ok, emqx_session_sup:start_session(Session)}
+              end);
+
+open_session(Session = #{client_id := ClientId, clean_start := false}) ->
     with_lock(ClientId,
               fun() ->
-                  {ResL, BadNodes} = emqx_rpc:multicall(ekka:nodelist(), ?MODULE, lookup_session, [ClientId]),
-                  [SessionPid | _] = lists:flatten(ResL),
-
-                  
-                
+                  {ResL, _BadNodes} = emqx_rpc:multicall(ekka:nodelist(), ?MODULE, lookup_session, [ClientId]),
+                  case lists:flatten([Pid || Pid <- ResL, Pid =/= undefined]) of
+                      [] ->
+                          {ok, emqx_session_sup:start_session(Session)};
+                      [SessPid|_] ->
+                          case resume_session(SessPid) of
+                              ok -> {ok, SessPid};
+                              {error, Reason} ->
+                                  emqx_log:error("[SM] Failed to resume session: ~p, ~p", [Session, Reason]),
+                                  {ok, emqx_session_sup:start_session(Session)}
+                          end
+                  end
               end).
 
-lookup_session(ClientId) ->
-    ets:lookup(session, ClientId). 
+resume_session(SessPid) when node(SessPid) == node() ->
+    case is_process_alive(SessPid) of
+        true ->
+            emqx_session:resume(SessPid, self());
+        false ->
+            emqx_log:error("Cannot resume ~p which seems already dead!", [SessPid]),
+            {error, session_died}
+    end;
+    
+resume_session(SessPid) ->
+    case rpc:call(node(SessPid), emqx_session, resume, [SessPid]) of
+        ok -> {ok, SessPid};
+        {badrpc, Reason} ->
+            {error, Reason};
+        {error, Reason} ->
+            {error, Reason}
+    end.
 
+discard_session(ClientId) ->
+    case lookup_session(ClientId) of
+        undefined -> ok;
+        Pid -> emqx_session:discard(Pid)
+    end.
 
 lookup_session(ClientId) ->
-    ets:lookup(session, ClientId).
-
-with_lock(undefined, Fun) ->
-    Fun();
+    try ets:lookup_element(session, ClientId, 2) catch error:badarg -> undefined end.
 
+close_session(SessPid) ->
+    emqx_session:close(SessPid).    
 
 with_lock(ClientId, Fun) ->
     case emqx_sm_locker:lock(ClientId) of
-        true  -> Result = Fun(),
-                 ok = emqx_sm_locker:unlock(ClientId),
-                 Result;
-        false -> {error, client_id_unavailable}
-    end.
-
-%% @doc Start a session manager
--spec(start_link(atom(), pos_integer()) -> {ok, pid()} | ignore | {error, term()}).
-start_link(Pool, Id) ->
-    gen_server:start_link(?MODULE, [Pool, Id], []).
-
-%% @doc Start a session
--spec(start_session(boolean(), {binary(), binary() | undefined}) -> {ok, pid(), boolean()} | {error, term()}).
-start_session(CleanSess, {ClientId, Username}) ->
-    SM = gproc_pool:pick_worker(?POOL, ClientId),
-    call(SM, {start_session, CleanSess, {ClientId, Username}, self()}).
-
-%% @doc Lookup a Session
--spec(lookup_session(binary()) -> mqtt_session() | undefined).
-lookup_session(ClientId) ->
-    case mnesia:dirty_read(mqtt_session, ClientId) of
-        [Session] -> Session;
-        []        -> undefined
+        true -> Result = Fun(),
+                emqx_sm_locker:unlock(ClientId),
+                Result;
+        false -> {error, client_id_unavailable};
+        {error, Reason} -> {error, Reason}
     end.
 
-%% @doc Register a session with info.
--spec(register_session(binary(), boolean(), [tuple()]) -> true).
-register_session(ClientId, CleanSess, Properties) ->
-    ets:insert(mqtt_local_session, {ClientId, self(), CleanSess, Properties}).
-
-%% @doc Unregister a Session.
--spec(unregister_session(binary()) -> boolean()).
-unregister_session(ClientId) ->
-    unregister_session(ClientId, self()).
+-spec(register_session(client_id()) -> true).
+register_session(ClientId) ->
+    ets:insert(session, {ClientId, self()}).
 
 unregister_session(ClientId, Pid) ->
-    case ets:lookup(mqtt_local_session, ClientId) of
-        [LocalSess = {_, Pid, _, _}] ->
-            emqx_stats:del_session_stats(ClientId),
-            ets:delete_object(mqtt_local_session, LocalSess);
+    case ets:lookup(session, ClientId) of
+        [{_, Pid}] ->
+            ets:delete_object(session, {ClientId, Pid});
         _ ->
             false
     end.
 
 dispatch(ClientId, Topic, Msg) ->
-    try ets:lookup_element(mqtt_local_session, ClientId, 2) of
-        Pid -> Pid ! {dispatch, Topic, Msg}
-    catch
-        error:badarg -> 
-            emqx_hooks:run('message.dropped', [ClientId, Msg]),
-            ok %%TODO: How??
+    case lookup_session(ClientId) of
+        Pid when is_pid(Pid) ->
+            Pid ! {dispatch, Topic, Msg};
+        undefined ->
+            emqx_hooks:run('message.dropped', [ClientId, Msg])
     end.
 
-call(SM, Req) ->
-    gen_server:call(SM, Req, ?TIMEOUT). %%infinity).
-
-%% @doc for debug.
-local_sessions() ->
-    ets:tab2list(mqtt_local_session).
-
 %%--------------------------------------------------------------------
-%% gen_server Callbacks
+%% gen_server callbacks
 %%--------------------------------------------------------------------
 
-init([Pool, Id]) ->
-    gproc_pool:connect_worker(Pool, {Pool, Id}),
-    {ok, #state{pool = Pool, id = Id, monitors = dict:new()}}.
-
-%% Persistent Session
-handle_call({start_session, false, {ClientId, Username}, ClientPid}, _From, State) ->
-    case lookup_session(ClientId) of
-        undefined ->
-            %% Create session locally
-            create_session({false, {ClientId, Username}, ClientPid}, State);
-        Session ->
-            case resume_session(Session, ClientPid) of
-                {ok, SessPid} ->
-                    {reply, {ok, SessPid, true}, State};
-                {error, Erorr} ->
-                    {reply, {error, Erorr}, State}
-            end
-    end;
-
-%% Transient Session
-handle_call({start_session, true, {ClientId, Username}, ClientPid}, _From, State) ->
-    Client = {true, {ClientId, Username}, ClientPid},
-    case lookup_session(ClientId) of
-        undefined ->
-            create_session(Client, State);
-        Session ->
-            case destroy_session(Session) of
-                ok ->
-                    create_session(Client, State);
-                {error, Error} ->
-                    {reply, {error, Error}, State}
-            end
-    end;
+init([StatsFun]) ->
+    {ok, TRef} = timer:send_interval(timer:seconds(1), stats),
+    {ok, #state{stats_fun = StatsFun, stats_timer = TRef}}.
 
 handle_call(Req, _From, State) ->
-    lager:error("[MQTT-SM] Unexpected Request: ~p", [Req]),
+    emqx_log:error("[SM] Unexpected request: ~p", [Req]),
     {reply, ignore, State}.
 
+handle_cast({monitor_session, SessionPid, ClientId},
+            State = #state{monitors = Monitors}) ->
+    MRef = erlang:monitor(process, SessionPid),
+    {noreply, State#state{monitors = maps:put(MRef, ClientId, Monitors)}};
+
 handle_cast(Msg, State) ->
-    lager:error("[MQTT-SM] Unexpected Message: ~p", [Msg]),
+    emqx_log:error("[SM] Unexpected msg: ~p", [Msg]),
     {noreply, State}.
 
-handle_info({'DOWN', MRef, process, DownPid, _Reason}, State) ->
-    case dict:find(MRef, State#state.monitors) of
-        {ok, ClientId} ->
-            case mnesia:dirty_read({mqtt_session, ClientId}) of
-                [] ->
-                    ok;
-                [Sess = #mqtt_session{sess_pid = DownPid}] ->
-                    mnesia:dirty_delete_object(Sess);
-                [_Sess] ->
-                    ok
-            end,
-            {noreply, erase_monitor(MRef, State), hibernate};
+handle_info(stats, State) ->
+    {noreply, setstats(State), hibernate};
+
+handle_info({'DOWN', MRef, process, DownPid, _Reason},
+            State = #state{monitors = Monitors}) ->
+    case maps:find(MRef, Monitors) of
+        {ok, {ClientId, Pid}} ->
+            ets:delete_object(session, {ClientId, Pid}),
+            {noreply, setstats(State#state{monitors = maps:remove(MRef, Monitors)})};
         error ->
-            lager:error("MRef of session ~p not found", [DownPid]),
+            emqx_log:error("session ~p not found", [DownPid]),
             {noreply, State}
     end;
 
 handle_info(Info, State) ->
-    lager:error("[MQTT-SM] Unexpected Info: ~p", [Info]),
+    emqx_log:error("[SM] Unexpected info: ~p", [Info]),
     {noreply, State}.
 
-terminate(_Reason, #state{pool = Pool, id = Id}) ->
-    gproc_pool:disconnect_worker(Pool, {Pool, Id}).
+terminate(_Reason, _State = #state{stats_timer = TRef}) ->
+    timer:cancel(TRef).
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
@@ -242,100 +174,6 @@ code_change(_OldVsn, State, _Extra) ->
 %% Internal functions
 %%--------------------------------------------------------------------
 
-%% Create Session Locally
-create_session({CleanSess, {ClientId, Username}, ClientPid}, State) ->
-    case create_session(CleanSess, {ClientId, Username}, ClientPid) of
-        {ok, SessPid} ->
-            {reply, {ok, SessPid, false},
-                monitor_session(ClientId, SessPid, State)};
-        {error, Error} ->
-            {reply, {error, Error}, State}
-    end.
-
-create_session(CleanSess, {ClientId, Username}, ClientPid) ->
-    case emqx_session_sup:start_session(CleanSess, {ClientId, Username}, ClientPid) of
-        {ok, SessPid} ->
-            Session = #mqtt_session{client_id = ClientId, sess_pid = SessPid, clean_sess = CleanSess},
-            case insert_session(Session) of
-                {aborted, {conflict, ConflictPid}} ->
-                    %% Conflict with othe node?
-                    lager:error("SM(~s): Conflict with ~p", [ClientId, ConflictPid]),
-                    {error, mnesia_conflict};
-                {atomic, ok} ->
-                    {ok, SessPid}
-            end;
-        {error, Error} ->
-            {error, Error}
-    end.
-
-insert_session(Session = #mqtt_session{client_id = ClientId}) ->
-    mnesia:transaction(
-      fun() ->
-        case mnesia:wread({mqtt_session, ClientId}) of
-            [] ->
-                mnesia:write(mqtt_session, Session, write);
-            [#mqtt_session{sess_pid = SessPid}] ->
-                mnesia:abort({conflict, SessPid})
-        end
-      end).
-
-%% Local node
-resume_session(Session = #mqtt_session{client_id = ClientId, sess_pid = SessPid}, ClientPid)
-    when node(SessPid) =:= node() ->
-
-    case is_process_alive(SessPid) of
-        true ->
-            emqx_session:resume(SessPid, ClientId, ClientPid),
-            {ok, SessPid};
-        false ->
-            ?LOG(error, "Cannot resume ~p which seems already dead!", [SessPid], Session),
-            {error, session_died}
-    end;
-
-%% Remote node
-resume_session(Session = #mqtt_session{client_id = ClientId, sess_pid = SessPid}, ClientPid) ->
-    Node = node(SessPid),
-    case rpc:call(Node, emqx_session, resume, [SessPid, ClientId, ClientPid]) of
-        ok ->
-            {ok, SessPid};
-        {badrpc, nodedown} ->
-            ?LOG(error, "Session died for node '~s' down", [Node], Session),
-            remove_session(Session),
-            {error, session_nodedown};
-        {badrpc, Reason} ->
-            ?LOG(error, "Failed to resume from node ~s for ~p", [Node, Reason], Session),
-            {error, Reason}
-    end.
-
-%% Local node
-destroy_session(Session = #mqtt_session{client_id = ClientId, sess_pid = SessPid})
-    when node(SessPid) =:= node() ->
-    emqx_session:destroy(SessPid, ClientId),
-    remove_session(Session);
-
-%% Remote node
-destroy_session(Session = #mqtt_session{client_id = ClientId, sess_pid  = SessPid}) ->
-    Node = node(SessPid),
-    case rpc:call(Node, emqx_session, destroy, [SessPid, ClientId]) of
-        ok ->
-            remove_session(Session);
-        {badrpc, nodedown} ->
-            ?LOG(error, "Node '~s' down", [Node], Session),
-            remove_session(Session);
-        {badrpc, Reason} ->
-            ?LOG(error, "Failed to destory ~p on remote node ~p for ~s",
-                 [SessPid, Node, Reason], Session),
-            {error, Reason}
-     end.
-
-remove_session(Session) ->
-    mnesia:dirty_delete_object(Session).
-
-monitor_session(ClientId, SessPid, State = #state{monitors = Monitors}) ->
-    MRef = erlang:monitor(process, SessPid),
-    State#state{monitors = dict:store(MRef, ClientId, Monitors)}.
-
-erase_monitor(MRef, State = #state{monitors = Monitors}) ->
-    erlang:demonitor(MRef, [flush]),
-    State#state{monitors = dict:erase(MRef, Monitors)}.
+setstats(State = #state{stats_fun = StatsFun}) ->
+    StatsFun(ets:info(session, size)), State.
 

src/emqx_sm_helper.erl

@@ -1,87 +0,0 @@
-%%--------------------------------------------------------------------
-%% Copyright © 2013-2018 EMQ Inc. All rights reserved.
-%%
-%% Licensed under the Apache License, Version 2.0 (the "License");
-%% you may not use this file except in compliance with the License.
-%% You may obtain a copy of the License at
-%%
-%%     http://www.apache.org/licenses/LICENSE-2.0
-%%
-%% Unless required by applicable law or agreed to in writing, software
-%% distributed under the License is distributed on an "AS IS" BASIS,
-%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-%% See the License for the specific language governing permissions and
-%% limitations under the License.
-%%--------------------------------------------------------------------
-
--module(emqx_sm_helper).
-
--behaviour(gen_server).
-
--include("emqx.hrl").
-
--include_lib("stdlib/include/ms_transform.hrl").
-
-%% API Function Exports
--export([start_link/1]).
-
-%% gen_server Function Exports
--export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
-
--record(state, {stats_fun, ticker}).
-
--define(LOCK, {?MODULE, clean_sessions}).
-
-%% @doc Start a session helper
--spec(start_link(fun()) -> {ok, pid()} | ignore | {error, term()}).
-start_link(StatsFun) ->
-    gen_server:start_link({local, ?MODULE}, ?MODULE, [StatsFun], []).
-
-init([StatsFun]) ->
-    ekka:monitor(membership),
-    {ok, TRef} = timer:send_interval(timer:seconds(1), tick),
-    {ok, #state{stats_fun = StatsFun, ticker = TRef}}.
-
-handle_call(Req, _From, State) ->
-    lager:error("[SM-HELPER] Unexpected Call: ~p", [Req]),
-    {reply, ignore, State}.
-
-handle_cast(Msg, State) ->
-    lager:error("[SM-HELPER] Unexpected Cast: ~p", [Msg]),
-    {noreply, State}.
-
-handle_info({membership, {mnesia, down, Node}}, State) ->
-    Fun = fun() ->
-            ClientIds =
-            mnesia:select(mqtt_session, [{#mqtt_session{client_id = '$1', sess_pid = '$2', _ = '_'},
-                                         [{'==', {node, '$2'}, Node}], ['$1']}]),
-            lists:foreach(fun(ClientId) -> mnesia:delete({mqtt_session, ClientId}) end, ClientIds)
-          end,
-    global:trans({?LOCK, self()}, fun() -> mnesia:async_dirty(Fun) end),
-    {noreply, State, hibernate};
-
-handle_info({membership, _Event}, State) ->
-    {noreply, State};
-
-handle_info(tick, State) ->
-    {noreply, setstats(State), hibernate};
-
-handle_info(Info, State) ->
-    lager:error("[SM-HELPER] Unexpected Info: ~p", [Info]),
-    {noreply, State}.
-
-terminate(_Reason, _State = #state{ticker = TRef}) ->
-    timer:cancel(TRef),
-    ekka:unmonitor(membership).
-
-code_change(_OldVsn, State, _Extra) ->
-    {ok, State}.
-
-%%--------------------------------------------------------------------
-%% Internal functions
-%%--------------------------------------------------------------------
-
-setstats(State = #state{stats_fun = StatsFun}) ->
-    StatsFun(ets:info(mqtt_local_session, size)), State.
-

src/emqx_sm_locker.erl

@@ -18,26 +18,16 @@
 
 -include("emqx.hrl").
 
--export([start_link/0]).
-
 %% Lock/Unlock API based on canal-lock.
 -export([lock/1, unlock/1]).
 
-%% @doc Starts the lock server
--spec(start_link() -> {ok, pid()} | ignore | {error, any()}).
-start_link() ->
-    canal_lock:start_link(?MODULE, 1).
-
 %% @doc Lock a clientid
--spec(lock(client_id()) -> boolean()).
+-spec(lock(client_id()) -> boolean() | {error, term()}).
 lock(ClientId) ->
-    case canal_lock:acquire(?MODULE, ClientId, 1, 1) of
-        {acquired, 1} -> true;
-        full -> false
-    end.
+    emqx_rpc:call(ekka:leader(), emqx_sm_locker, lock, [ClientId]).
 
 %% @doc Unlock a clientid
 -spec(unlock(client_id()) -> ok).
 unlock(ClientId) ->
-    canal_lock:release(?MODULE, ClientId, 1, 1).
+    emqx_rpc:call(ekka:leader(), emqx_locker, unlock, [ClientId]).
 

src/emqx_sm_sup.erl

@@ -18,31 +18,28 @@
 
 -behaviour(supervisor).
 
-
--define(SM, emqx_sm).
-
--define(HELPER, emqx_sm_helper).
-
-%% API
 -export([start_link/0]).
 
-%% Supervisor callbacks
 -export([init/1]).
 
 start_link() ->
     supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
 init([]) ->
-    %% Create session tables
-    _ = ets:new(mqtt_local_session, [public, ordered_set, named_table, {write_concurrency, true}]),
+    %% Create tables
+    create_tabs(),
 
-    %% Helper
     StatsFun = emqx_stats:statsfun('sessions/count', 'sessions/max'),
-    Helper = {?HELPER, {?HELPER, start_link, [StatsFun]},
-              permanent, 5000, worker, [?HELPER]},
 
-    %% SM Pool Sup
-    MFA = {?SM, start_link, []},
-    PoolSup = emqx_pool_sup:spec([?SM, hash, erlang:system_info(schedulers), MFA]),
-    {ok, {{one_for_all, 10, 3600}, [Helper, PoolSup]}}.
+    SM = {emqx_sm, {emqx_sm, start_link, [StatsFun]},
+          permanent, 5000, worker, [emqx_sm]},
+
+    {ok, {{one_for_all, 0, 3600}, [SM]}}.
+
+create_tabs() ->
+    lists:foreach(fun create_tab/1, [session, session_stats, session_attrs]).
+
+create_tab(Tab) ->
+    emqx_tables:create(Tab, [public, ordered_set, named_table,
+                             {write_concurrency, true}]).
 

src/emqx_sup.erl

@@ -57,6 +57,7 @@ init([]) ->
     {ok, {{one_for_all, 0, 1},
           [?CHILD(emqx_ctl, worker),
            ?CHILD(emqx_hooks, worker),
+           ?CHILD(emqx_locker, worker),
            ?CHILD(emqx_stats, worker),
            ?CHILD(emqx_metrics, worker),
            ?CHILD(emqx_router_sup, supervisor),

src/emqx_tables.erl

@@ -0,0 +1,27 @@
+%%--------------------------------------------------------------------
+%% Copyright © 2013-2018 EMQ Inc. All rights reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqx_tables).
+
+-export([create/2]).
+
+create(Tab, Opts) ->
+    case ets:info(Tab, name) of
+        undefined ->
+            ets:new(Tab, lists:usort([named_table|Opts]));
+        Tab -> Tab
+    end.
+

src/emqx_trace_sup.erl

@@ -14,21 +14,19 @@
 %% limitations under the License.
 %%--------------------------------------------------------------------
 
--module(emqx_trace_sup).
+-module(emqx_tracer_sup).
 
 -behaviour(supervisor).
 
-%% API
 -export([start_link/0]).
 
-%% Supervisor callbacks
 -export([init/1]).
 
 start_link() ->
     supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
 init([]) ->
-    Trace = {trace, {emqx_trace, start_link, []},
-             permanent, 5000, worker, [emqx_trace]},
-    {ok, {{one_for_one, 10, 3600}, [Trace]}}.
+    Tracer = {tracer, {emqx_tracer, start_link, []},
+              permanent, 5000, worker, [emqx_tracer]},
+    {ok, {{one_for_one, 10, 3600}, [Tracer]}}.