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%%% Copyright (c) 2019, Sunet.
%%% See LICENSE for licensing information.
%% A manager is a genserver for coordination of clients and vtokens.
%% Provide a lookup service for servers in need of a client to send
%% requests to, by keeping track of which module is current for a
%% given vtoken and spawn a p11p_client genserver "on demand".
%%
%% Provide a client event and a server event API for servers and
%% clients, respectively, where events like " token timed out" and
%% "p11 app hung up" can be reported.
%%
%% Keep track of successful p11 requests which might cause state
%% changes in a token, like logins. When switching token under the
%% feet of the p11 app, replay whatever is needed to the new
%% token.
%% Certain state changing p11 requests cannot be replayed, like
%% generation of a new key. Any such (successful) request invalidates
%% all other clients for the given vtoken.
-module(p11p_manager).
-behaviour(gen_server).
%% API.
-export([start_link/0]).
-export([client_for_token/1, server_event/2]). % For servers.
-export([client_event/2]). % For clients.
%% Genserver callbacks.
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
%% Records and types.
-record(client, {
tokname :: string(),
servid :: atom(),
modpath :: string(),
modenv :: [],
balance :: integer(),
pid :: pid() | undefined
}).
-record(vtoken, {
clients :: [#client{}], % Current client in hd().
%% Invokations left for current client or -1 for no
%% balancing.
balance_count = -1 :: integer(),
timeout :: non_neg_integer(),
retries :: non_neg_integer(),
server :: pid() | undefined % Active server, if any.
}).
-record(state, {
vtokens :: #{string() => #vtoken{}}
}).
%% API implementation.
-spec start_link() -> {ok, pid()} | {error, term()}.
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
-spec client_for_token(string()) -> pid().
client_for_token(TokName) ->
gen_server:call(?MODULE, {client_for_token, self(), TokName}).
server_event(Event, Args) ->
gen_server:cast(?MODULE, {server_event, Event, Args}).
client_event(Event, Args) ->
gen_server:cast(?MODULE, {client_event, Event, Args}).
%% Genserver callbacks.
init([]) ->
{ok, #state{vtokens = init_vtokens(p11p_config:tokens())}}.
handle_call({client_for_token, Server, TokNameIn}, _From,
S = #state{vtokens = VTokensIn}) ->
#{TokNameIn := VTokenIn} = VTokensIn,
ClientsIn = VTokenIn#vtoken.clients,
lager:debug("all clients: ~p", [ClientsIn]),
{Clients, BalanceCount} =
case VTokenIn#vtoken.balance_count of
0 ->
lager:debug("~p: balancing: next client", [self()]),
Rotated = rotate_clients(ClientsIn),
First = hd(Rotated),
{Rotated, First#client.balance - 1};
N when N > 0 ->
lager:debug("~p: balancing: ~B more invocations", [self(), N]),
{ClientsIn, N - 1};
-1 ->
{ClientsIn, -1}
end,
Current = hd(Clients),
case Current#client.pid of
undefined ->
Client = start_client(hd(Clients), Server, VTokenIn#vtoken.timeout),
VToken = VTokenIn#vtoken{clients = [Client | tl(Clients)],
server = Server,
balance_count = BalanceCount},
{reply, Client#client.pid, S#state{vtokens = VTokensIn#{TokNameIn := VToken}}};
Pid ->
{reply, Pid, S}
end;
handle_call(Call, _From, State) ->
lager:debug("Unhandled call: ~p~n", [Call]),
{reply, unhandled, State}.
%% Server done with client.
handle_cast({server_event, server_gone, TokNameIn}, S = #state{vtokens = Tokens}) ->
#{TokNameIn := TokenIn} = Tokens,
CurClient = hd(TokenIn#vtoken.clients),
ClientPid = CurClient#client.pid,
ok = p11p_client:stop(ClientPid, normal),
Clients = lists:map(fun(E) -> % Find and update.
case E#client.pid of
ClientPid -> E#client{pid = undefined};
_ -> E
end end,
TokenIn#vtoken.clients),
Token = TokenIn#vtoken{clients = Clients, server = undefined},
{noreply, S#state{vtokens = Tokens#{TokNameIn := Token}}};
%% Client reporting that a token has timed out -- mark current client
%% not running, inform server, rotate client list and start new
%% client.
handle_cast({client_event, timeout, TokName}, State) ->
#{TokName := VToken} = State#state.vtokens,
client_timeout(TokName, VToken, State);
handle_cast({start_client, VTokName}, State = #state{vtokens = VTokens}) ->
#{VTokName := VToken} = VTokens,
Client = start_client(hd(VToken#vtoken.clients),
VToken#vtoken.server,
VToken#vtoken.timeout),
NewVToken = VToken#vtoken{clients = [Client | tl(VToken#vtoken.clients)]},
lager:debug("~p: vtoken updated: ~p", [self(), NewVToken]),
{noreply, State#state{vtokens = VTokens#{VTokName := NewVToken}}};
handle_cast(Cast, State) ->
lager:debug("Unhandled cast: ~p~n", [Cast]),
{noreply, State}.
handle_info({Port, {exit_status, Status}}, State) ->
%% FIXME: do we need to be trapping exits explicitly?
lager:info("~p: process ~p exited with ~p", [self(), Port, Status]),
{noreply, State};
handle_info(Info, State) ->
lager:debug("~p: Unhandled info: ~p~n", [self(), Info]),
{noreply, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVersion, State, _Extra) ->
{ok, State}.
%% Private functions
-spec init_vtokens([p11p_config:token()]) -> #{string() => #vtoken{}}.
init_vtokens(ConfTokens) ->
init_vtokens(ConfTokens, #{}).
init_vtokens([], Acc)->
lager:debug("~p: created tokens from config: ~p", [self(), Acc]),
Acc;
init_vtokens([H|T], Acc)->
init_vtokens(T, Acc#{p11p_config:nameof(H) => new_vtoken(H)}).
new_vtoken(Conf) ->
Name = p11p_config:nameof(Conf),
Balances = p11p_config:token_balance(Name),
Clients = clients(Name,
p11p_config:modules_for_token(Name),
Balances),
CurrentClient = hd(Clients),
#vtoken{
clients = Clients,
balance_count = CurrentClient#client.balance,
timeout = p11p_config:token_timeout(Name),
retries = p11p_config:token_retries(Name)
}.
clients(TokName, Modules, []) ->
clients(TokName, Modules, [-1 || _ <- lists:seq(1, length(Modules))]);
clients(TokName, ConfModules, ConfBalance) ->
clients(TokName, ConfModules, ConfBalance, []).
clients(_, [], _, Acc) ->
Acc;
clients(TokName, [Module|Modules], [Balance|Balances], Acc) ->
ModName = p11p_config:nameof(Module),
ServName = "p11p_client:" ++ TokName ++ ":" ++ ModName,
clients(TokName, Modules, Balances,
[#client{tokname = TokName,
servid = list_to_atom(ServName),
modpath = p11p_config:module_path(Module),
modenv = p11p_config:module_env(Module),
balance = Balance} | Acc]).
%% -spec balance(p11p_config:token_mode_t(), non_neg_integer()) -> integer().
%% balance({balance, Ratios}, N) ->
%% lists:nth(N, Ratios);
%% balance(_, _) ->
%% -1.
%% -spec balance_count(p11p_config:token_mode_t()) -> integer().
%% balance_count(#vtoken{mode = {balance, _}, balance_count = C}) ->
%% C - 1;
%% balance_count(_) ->
%% -1.
rotate_clients(L) ->
lists:reverse([hd(L) | lists:reverse(tl(L))]).
rotate_clients(L, UpdatedCurr) ->
lists:reverse([UpdatedCurr | lists:reverse(tl(L))]).
next_client(VToken = #vtoken{clients = Clients}) ->
OldC = hd(Clients),
NewClients = rotate_clients(Clients, OldC#client{pid = undefined}),
gen_server:cast(self(), {start_client, OldC#client.tokname}),
VToken#vtoken{clients = NewClients}.
client_timeout(TokName,
VToken = #vtoken{retries = Retries},
State = #state{vtokens = VTokens})
when Retries > 0 ->
lager:debug("~p: ~s: token timed out, switching token", [self(), TokName]),
p11p_server:token_gone(VToken#vtoken.server, false),
NewToken = next_client(VToken),
NewVTokens = VTokens#{TokName := NewToken#vtoken{retries = Retries - 1}},
{noreply, State#state{vtokens = NewVTokens}};
client_timeout(TokName,
VToken,
State) ->
lager:debug("~p: ~s: token timed out, disconnecting app", [self(), TokName]),
p11p_server:token_gone(VToken#vtoken.server, true),
{stop, State}.
start_client(Client, Server, Timeout) ->
{ok, Pid} = p11p_client:start_link(Client#client.servid,
Client#client.tokname,
Server,
Client#client.modpath,
Client#client.modenv,
Timeout),
Client#client{pid = Pid}.
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