%%%----------------------------------------------------------------------
%%% File : ejabberd_cluster_mnesia.erl
%%% Author : Christophe Romain <christophe.romain@process-one.net>
%%% Purpose : ejabberd clustering management via Mnesia
%%% Created : 7 Oct 2015 by Christophe Romain <christophe.romain@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(ejabberd_cluster_mnesia).
-behaviour(ejabberd_cluster).
%% API
-export([init/0, get_nodes/0, join/1, leave/1,
get_known_nodes/0, node_id/0, get_node_by_id/1,
send/2, wait_for_sync/1, subscribe/1]).
-include("logger.hrl").
-spec init() -> ok.
init() ->
ok.
-spec get_nodes() -> [node()].
get_nodes() ->
mnesia:system_info(running_db_nodes).
-spec get_known_nodes() -> [node()].
get_known_nodes() ->
lists:usort(mnesia:system_info(db_nodes)
++ mnesia:system_info(extra_db_nodes)).
-spec join(node()) -> ok | {error, any()}.
join(Node) ->
case {node(), net_adm:ping(Node)} of
{Node, _} ->
{error, {not_master, Node}};
{_, pong} ->
application:stop(ejabberd),
application:stop(mnesia),
mnesia:delete_schema([node()]),
application:start(mnesia),
case mnesia:change_config(extra_db_nodes, [Node]) of
{ok, _} ->
replicate_database(Node),
wait_for_sync(infinity),
application:stop(mnesia),
application:start(ejabberd);
{error, Reason} ->
{error, Reason}
end;
_ ->
{error, {no_ping, Node}}
end.
-spec leave(node()) -> ok | {error, any()}.
leave(Node) ->
case {node(), net_adm:ping(Node)} of
{Node, _} ->
Cluster = get_nodes()--[Node],
leave(Cluster, Node);
{_, pong} ->
rpc:call(Node, ?MODULE, leave, [Node], 10000);
{_, pang} ->
case mnesia:del_table_copy(schema, Node) of
{atomic, ok} -> ok;
{aborted, Reason} -> {error, Reason}
end
end.
leave([], Node) ->
{error, {no_cluster, Node}};
leave([Master|_], Node) ->
application:stop(ejabberd),
application:stop(mnesia),
spawn(fun() ->
rpc:call(Master, mnesia, del_table_copy, [schema, Node]),
mnesia:delete_schema([node()]),
erlang:halt(0)
end),
ok.
-spec node_id() -> binary().
node_id() ->
integer_to_binary(erlang:phash2(node())).
-spec get_node_by_id(binary()) -> node().
get_node_by_id(Hash) ->
try binary_to_integer(Hash) of
I -> match_node_id(I)
catch _:_ ->
node()
end.
-spec send({atom(), node()}, term()) -> boolean().
send(Dst, Msg) ->
case erlang:send(Dst, Msg, [nosuspend, noconnect]) of
ok -> true;
_ -> false
end.
-spec wait_for_sync(timeout()) -> ok.
wait_for_sync(Timeout) ->
?INFO_MSG("Waiting for Mnesia synchronization to complete", []),
mnesia:wait_for_tables(mnesia:system_info(local_tables), Timeout),
ok.
-spec subscribe(_) -> ok.
subscribe(_) ->
ok.
%%%===================================================================
%%% Internal functions
%%%===================================================================
replicate_database(Node) ->
mnesia:change_table_copy_type(schema, node(), disc_copies),
lists:foreach(
fun(Table) ->
Type = rpc:call(Node, mnesia, table_info, [Table, storage_type]),
mnesia:add_table_copy(Table, node(), Type)
end, mnesia:system_info(tables)--[schema]).
-spec match_node_id(integer()) -> node().
match_node_id(I) ->
match_node_id(I, get_nodes()).
-spec match_node_id(integer(), [node()]) -> node().
match_node_id(I, [Node|Nodes]) ->
case erlang:phash2(Node) of
I -> Node;
_ -> match_node_id(I, Nodes)
end;
match_node_id(_I, []) ->
node().
