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|
-module(mem3).
-author('brad@cloudant.com').
-behaviour(gen_server).
%% API
-export([start_link/2, start_link/3, stop/0, stop/1]).
-export([clock/0, state/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
%% includes
-include("../include/config.hrl").
-include("../include/common.hrl").
%%====================================================================
%% API
%%====================================================================
start_link(Node, ErlNodes) ->
start_link(Node, ErlNodes, []).
start_link(Node, ErlNodes, Args) ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [Node, ErlNodes, Args], []).
stop() ->
stop(?MODULE).
stop(Server) ->
gen_server:cast(Server, stop).
clock() ->
gen_server:call(?MODULE, clock).
state() ->
gen_server:call(?MODULE, state).
%%====================================================================
%% gen_server callbacks
%%====================================================================
%% start up membership server
init([Node, Nodes, Args]) ->
process_flag(trap_exit,true),
showroom_log:message(info, "membership: membership server starting...", []),
net_kernel:monitor_nodes(true),
Options = lists:flatten(Args),
Config = configuration:get_config(),
OldState = read_latest_state_file(Config),
State = handle_init(Node, Nodes, Options, OldState, Config),
{ok, State}.
%% new node joining to this node
handle_call({join, _JoiningNode, _Options}, _From, State) ->
{reply, ok, State};
%% clock
handle_call(clock, _From, State = #mem{clock=Clock}) ->
{reply, Clock, State};
%% state
handle_call(state, _From, State) ->
{reply, State, State};
%% ignored call
handle_call(Msg, _From, State) ->
showroom_log:message(info, "membership: ignored call: ~p", [Msg]),
{reply, ignored, State}.
%% stop
handle_cast(stop, State) ->
{stop, normal, State};
%% ignored cast
handle_cast(Msg, State) ->
showroom_log:message(info, "membership: ignored cast: ~p", [Msg]),
{noreply, State}.
%% @doc handle nodedown messages because we have
%% net_kernel:monitor_nodes(true)
handle_info({nodedown, Node}, State) ->
showroom_log:message(alert, "membership: nodedown from ~p", [Node]),
{noreply, State};
%% @doc handle nodeup messages because we have
%% net_kernel:monitor_nodes(true)
handle_info({nodeup, Node}, State) ->
showroom_log:message(alert, "membership: nodeup Node: ~p", [Node]),
{noreply, State};
%% ignored info
handle_info(Info, State) ->
showroom_log:message(info, "membership: ignored info: ~p", [Info]),
{noreply, State}.
% terminate
terminate(_Reason, _State) ->
ok.
% ignored code change
code_change(OldVsn, State, _Extra) ->
io:format("Unknown Old Version!~nOldVsn: ~p~nState : ~p~n", [OldVsn, State]),
{ok, State}.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
% we could be:
% 1. starting fresh node into a fresh cluster (we're one of first nodes)
% 2. starting fresh node into an existing cluster (need to join)
% 3. rejoining a cluster after some downtime
% 4. replacing a node in an existing cluster
handle_init(Node, [], nil, Options, Config) ->
% no other erlang nodes, no old state
Hints = proplists:get_value(hints, Options),
Map = create_map(Config, [{Node, Hints}]),
?debugFmt("~nmap: ~p~n", [Map]);
handle_init(_Node, [], _OldState, _Options, _Config) ->
% no other erlang nodes, old state
% network partition?
ok;
handle_init(_Node, _ErlNodes, nil, _Options, _Config) ->
% other erlang nodes, no old state
ok;
handle_init(_Node, _ErlNodes, _OldState, _Options, _Config) ->
% other erlang nodes, old state
% network partition?
ok.
find_latest_state_filename(Config) ->
?debugFmt("~nConfig: ~p~n", [Config]),
Dir = Config#config.directory,
case file:list_dir(Dir) of
{ok, Filenames} ->
Timestamps = [list_to_integer(TS) || {"state", TS} <-
[list_to_tuple(string:tokens(FN, ".")) || FN <- Filenames]],
SortedTimestamps = lists:reverse(lists:sort(Timestamps)),
case SortedTimestamps of
[Latest | _] ->
{ok, Dir ++ "/state." ++ integer_to_list(Latest)};
_ ->
throw({error, not_found})
end;
{error, Reason} ->
throw({error, Reason})
end.
read_latest_state_file(Config) ->
try
{ok, File} = find_latest_state_filename(Config),
case file:consult(File) of
{ok, #mem{}=State} -> State;
_Else -> throw({error, bad_mem_state_file})
end
catch
_:Error ->
showroom_log:message(info, "membership: ~p", [Error]),
nil
end.
%% @doc given Config and a list of Nodes, construct a Fullmap
create_map(#config{q=Q}, Nodes) ->
[{FirstNode,_}|_] = Nodes,
Pmap = lists:foldl(fun({Node, Hints}, Map) ->
partitions:join(Node, Map, Hints)
end, partitions:create(Q, FirstNode), Nodes),
make_fullmap(Pmap).
%% @doc construct a table with all partitions, with the primary node and all
%% replication partner nodes as well.
make_fullmap(PMap) ->
{Nodes, _Parts} = lists:unzip(PMap),
NodeParts = lists:flatmap(
fun({Node,Part}) ->
Partners = replication:partners(Node, lists:usort(Nodes)),
PartnerList = [{Partner, Part, partner} || Partner <- Partners],
[{Node, Part, primary} | PartnerList]
end, PMap),
NodeParts.
|
