%%%-------------------------------------------------------------------
%%% Created : 12 Jan 2017 by Evgeny Khramtsov <ekhramtsov@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2022 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%-------------------------------------------------------------------
-module(mod_bosh_mnesia).
-behaviour(gen_server).
-behaviour(mod_bosh).
%% mod_bosh API
-export([init/0, open_session/2, close_session/1, find_session/1,
use_cache/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3, start_link/0]).
-include("logger.hrl").
-include_lib("stdlib/include/ms_transform.hrl").
-define(CALL_TIMEOUT, timer:minutes(10)).
-record(bosh, {sid = <<"">> :: binary(),
timestamp = erlang:timestamp() :: erlang:timestamp(),
pid = self() :: pid()}).
-record(state, {nodes = #{} :: #{node() => {pid(), reference()}}}).
-type state() :: #state{}.
%%%===================================================================
%%% API
%%%===================================================================
-spec init() -> ok | {error, any()}.
init() ->
Spec = {?MODULE, {?MODULE, start_link, []},
transient, 5000, worker, [?MODULE]},
case supervisor:start_child(ejabberd_backend_sup, Spec) of
{ok, _Pid} -> ok;
{error, {already_started, _}} -> ok;
Err -> Err
end.
-spec start_link() -> {ok, pid()} | {error, any()}.
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
use_cache() ->
false.
-spec open_session(binary(), pid()) -> ok.
open_session(SID, Pid) ->
Session = #bosh{sid = SID, timestamp = erlang:timestamp(), pid = Pid},
gen_server:call(?MODULE, {write, Session}, ?CALL_TIMEOUT).
-spec close_session(binary()) -> ok.
close_session(SID) ->
case mnesia:dirty_read(bosh, SID) of
[Session] ->
gen_server:call(?MODULE, {delete, Session}, ?CALL_TIMEOUT);
[] ->
ok
end.
-spec find_session(binary()) -> {ok, pid()} | {error, notfound}.
find_session(SID) ->
case mnesia:dirty_read(bosh, SID) of
[#bosh{pid = Pid}] ->
{ok, Pid};
[] ->
{error, notfound}
end.
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
-spec init([]) -> {ok, state()}.
init([]) ->
setup_database(),
multicast({join, node(), self()}),
mnesia:subscribe(system),
{ok, #state{}}.
-spec handle_call(_, _, state()) -> {reply, ok, state()} | {noreply, state()}.
handle_call({write, Session} = Msg, _From, State) ->
write_session(Session),
multicast(Msg),
{reply, ok, State};
handle_call({delete, Session} = Msg, _From, State) ->
delete_session(Session),
multicast(Msg),
{reply, ok, State};
handle_call(Request, From, State) ->
?WARNING_MSG("Unexpected call from ~p: ~p", [From, Request]),
{noreply, State}.
-spec handle_cast(_, state()) -> {noreply, state()}.
handle_cast(Msg, State) ->
?WARNING_MSG("Unexpected cast: ~p", [Msg]),
{noreply, State}.
-spec handle_info(_, state()) -> {noreply, state()}.
handle_info({write, Session}, State) ->
write_session(Session),
{noreply, State};
handle_info({delete, Session}, State) ->
delete_session(Session),
{noreply, State};
handle_info({join, Node, Pid}, State) ->
ejabberd_cluster:send(Pid, {joined, node(), self()}),
case maps:find(Node, State#state.nodes) of
{ok, {Pid, _}} ->
ok;
_ ->
ejabberd_cluster:send(Pid, {join, node(), self()})
end,
{noreply, State};
handle_info({joined, Node, Pid}, State) ->
case maps:find(Node, State#state.nodes) of
{ok, {Pid, _}} ->
{noreply, State};
Ret ->
MRef = erlang:monitor(process, {?MODULE, Node}),
Nodes = maps:put(Node, {Pid, MRef}, State#state.nodes),
case Ret of
error -> ejabberd_cluster:send(Pid, {first, self()});
_ -> ok
end,
{noreply, State#state{nodes = Nodes}}
end;
handle_info({first, From}, State) ->
ejabberd_cluster:send(From, {replica, node(), first_session()}),
{noreply, State};
handle_info({next, From, Key}, State) ->
ejabberd_cluster:send(From, {replica, node(), next_session(Key)}),
{noreply, State};
handle_info({replica, _From, '$end_of_table'}, State) ->
{noreply, State};
handle_info({replica, From, Session}, State) ->
write_session(Session),
ejabberd_cluster:send(From, {next, self(), Session#bosh.sid}),
{noreply, State};
handle_info({'DOWN', _, process, {?MODULE, _}, _Info}, State) ->
{noreply, State};
handle_info({mnesia_system_event, {mnesia_down, Node}}, State) ->
Sessions =
ets:select(
bosh,
ets:fun2ms(
fun(#bosh{pid = Pid} = S) when node(Pid) == Node ->
S
end)),
lists:foreach(
fun(S) ->
mnesia:dirty_delete_object(S)
end, Sessions),
Nodes = maps:remove(Node, State#state.nodes),
{noreply, State#state{nodes = Nodes}};
handle_info({mnesia_system_event, _}, State) ->
{noreply, State};
handle_info(Info, State) ->
?WARNING_MSG("Unexpected info: ~p", [Info]),
{noreply, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================
-spec write_session(#bosh{}) -> ok.
write_session(#bosh{pid = Pid1, sid = SID, timestamp = T1} = S1) ->
case mnesia:dirty_read(bosh, SID) of
[#bosh{pid = Pid2, timestamp = T2} = S2] ->
if Pid1 == Pid2 ->
mnesia:dirty_write(S1);
T1 < T2 ->
ejabberd_cluster:send(Pid2, replaced),
mnesia:dirty_write(S1);
true ->
ejabberd_cluster:send(Pid1, replaced),
mnesia:dirty_write(S2)
end;
[] ->
mnesia:dirty_write(S1)
end.
-spec delete_session(#bosh{}) -> ok.
delete_session(#bosh{sid = SID, pid = Pid1}) ->
case mnesia:dirty_read(bosh, SID) of
[#bosh{pid = Pid2}] ->
if Pid1 == Pid2 ->
mnesia:dirty_delete(bosh, SID);
true ->
ok
end;
[] ->
ok
end.
-spec multicast(_) -> ok.
multicast(Msg) ->
lists:foreach(
fun(Node) when Node /= node() ->
ejabberd_cluster:send({?MODULE, Node}, Msg);
(_) ->
ok
end, ejabberd_cluster:get_nodes()).
setup_database() ->
case catch mnesia:table_info(bosh, attributes) of
[sid, pid] ->
mnesia:delete_table(bosh);
_ ->
ok
end,
ejabberd_mnesia:create(?MODULE, bosh,
[{ram_copies, [node()]}, {local_content, true},
{attributes, record_info(fields, bosh)}]).
-spec first_session() -> #bosh{} | '$end_of_table'.
first_session() ->
case mnesia:dirty_first(bosh) of
'$end_of_table' ->
'$end_of_table';
First ->
read_session(First)
end.
-spec next_session(binary()) -> #bosh{} | '$end_of_table'.
next_session(Prev) ->
case mnesia:dirty_next(bosh, Prev) of
'$end_of_table' ->
'$end_of_table';
Next ->
read_session(Next)
end.
-spec read_session(binary()) -> #bosh{} | '$end_of_table'.
read_session(Key) ->
case mnesia:dirty_read(bosh, Key) of
[#bosh{pid = Pid} = Session] when node(Pid) == node() ->
Session;
_ ->
next_session(Key)
end.
